xref: /rk3399_rockchip-uboot/README (revision b45c48a7c30734272371fede01e96f499a314664)
1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arc			Files generic to ARC architecture
136    /cpu		CPU specific files
137      /arc700		Files specific to ARC 700 CPUs
138    /lib		Architecture specific library files
139  /arm			Files generic to ARM architecture
140    /cpu		CPU specific files
141      /arm720t		Files specific to ARM 720 CPUs
142      /arm920t		Files specific to ARM 920 CPUs
143	/at91		Files specific to Atmel AT91RM9200 CPU
144	/imx		Files specific to Freescale MC9328 i.MX CPUs
145	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
146      /arm926ejs	Files specific to ARM 926 CPUs
147      /arm1136		Files specific to ARM 1136 CPUs
148      /pxa		Files specific to Intel XScale PXA CPUs
149      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
150    /lib		Architecture specific library files
151  /avr32		Files generic to AVR32 architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /blackfin		Files generic to Analog Devices Blackfin architecture
155    /cpu		CPU specific files
156    /lib		Architecture specific library files
157  /m68k			Files generic to m68k architecture
158    /cpu		CPU specific files
159      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
160      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
161      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
162      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
163      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
164    /lib		Architecture specific library files
165  /microblaze		Files generic to microblaze architecture
166    /cpu		CPU specific files
167    /lib		Architecture specific library files
168  /mips			Files generic to MIPS architecture
169    /cpu		CPU specific files
170      /mips32		Files specific to MIPS32 CPUs
171      /mips64		Files specific to MIPS64 CPUs
172    /lib		Architecture specific library files
173  /nds32		Files generic to NDS32 architecture
174    /cpu		CPU specific files
175      /n1213		Files specific to Andes Technology N1213 CPUs
176    /lib		Architecture specific library files
177  /nios2		Files generic to Altera NIOS2 architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /openrisc		Files generic to OpenRISC architecture
181    /cpu		CPU specific files
182    /lib		Architecture specific library files
183  /powerpc		Files generic to PowerPC architecture
184    /cpu		CPU specific files
185      /mpc5xx		Files specific to Freescale MPC5xx CPUs
186      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
187      /mpc8xx		Files specific to Freescale MPC8xx CPUs
188      /mpc8260		Files specific to Freescale MPC8260 CPUs
189      /mpc85xx		Files specific to Freescale MPC85xx CPUs
190      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
191    /lib		Architecture specific library files
192  /sh			Files generic to SH architecture
193    /cpu		CPU specific files
194      /sh2		Files specific to sh2 CPUs
195      /sh3		Files specific to sh3 CPUs
196      /sh4		Files specific to sh4 CPUs
197    /lib		Architecture specific library files
198  /sparc		Files generic to SPARC architecture
199    /cpu		CPU specific files
200      /leon2		Files specific to Gaisler LEON2 SPARC CPU
201      /leon3		Files specific to Gaisler LEON3 SPARC CPU
202    /lib		Architecture specific library files
203  /x86			Files generic to x86 architecture
204    /cpu		CPU specific files
205    /lib		Architecture specific library files
206/api			Machine/arch independent API for external apps
207/board			Board dependent files
208/common			Misc architecture independent functions
209/disk			Code for disk drive partition handling
210/doc			Documentation (don't expect too much)
211/drivers		Commonly used device drivers
212/dts			Contains Makefile for building internal U-Boot fdt.
213/examples		Example code for standalone applications, etc.
214/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
215/include		Header Files
216/lib			Files generic to all architectures
217  /libfdt		Library files to support flattened device trees
218  /lzma			Library files to support LZMA decompression
219  /lzo			Library files to support LZO decompression
220/net			Networking code
221/post			Power On Self Test
222/spl			Secondary Program Loader framework
223/tools			Tools to build S-Record or U-Boot images, etc.
224
225Software Configuration:
226=======================
227
228Configuration is usually done using C preprocessor defines; the
229rationale behind that is to avoid dead code whenever possible.
230
231There are two classes of configuration variables:
232
233* Configuration _OPTIONS_:
234  These are selectable by the user and have names beginning with
235  "CONFIG_".
236
237* Configuration _SETTINGS_:
238  These depend on the hardware etc. and should not be meddled with if
239  you don't know what you're doing; they have names beginning with
240  "CONFIG_SYS_".
241
242Later we will add a configuration tool - probably similar to or even
243identical to what's used for the Linux kernel. Right now, we have to
244do the configuration by hand, which means creating some symbolic
245links and editing some configuration files. We use the TQM8xxL boards
246as an example here.
247
248
249Selection of Processor Architecture and Board Type:
250---------------------------------------------------
251
252For all supported boards there are ready-to-use default
253configurations available; just type "make <board_name>_defconfig".
254
255Example: For a TQM823L module type:
256
257	cd u-boot
258	make TQM823L_defconfig
259
260For the Cogent platform, you need to specify the CPU type as well;
261e.g. "make cogent_mpc8xx_defconfig". And also configure the cogent
262directory according to the instructions in cogent/README.
263
264
265Sandbox Environment:
266--------------------
267
268U-Boot can be built natively to run on a Linux host using the 'sandbox'
269board. This allows feature development which is not board- or architecture-
270specific to be undertaken on a native platform. The sandbox is also used to
271run some of U-Boot's tests.
272
273See board/sandbox/README.sandbox for more details.
274
275
276Board Initialisation Flow:
277--------------------------
278
279This is the intended start-up flow for boards. This should apply for both
280SPL and U-Boot proper (i.e. they both follow the same rules). At present SPL
281mostly uses a separate code path, but the funtion names and roles of each
282function are the same. Some boards or architectures may not conform to this.
283At least most ARM boards which use CONFIG_SPL_FRAMEWORK conform to this.
284
285Execution starts with start.S with three functions called during init after
286that. The purpose and limitations of each is described below.
287
288lowlevel_init():
289	- purpose: essential init to permit execution to reach board_init_f()
290	- no global_data or BSS
291	- there is no stack (ARMv7 may have one but it will soon be removed)
292	- must not set up SDRAM or use console
293	- must only do the bare minimum to allow execution to continue to
294		board_init_f()
295	- this is almost never needed
296	- return normally from this function
297
298board_init_f():
299	- purpose: set up the machine ready for running board_init_r():
300		i.e. SDRAM and serial UART
301	- global_data is available
302	- stack is in SRAM
303	- BSS is not available, so you cannot use global/static variables,
304		only stack variables and global_data
305
306	Non-SPL-specific notes:
307	- dram_init() is called to set up DRAM. If already done in SPL this
308		can do nothing
309
310	SPL-specific notes:
311	- you can override the entire board_init_f() function with your own
312		version as needed.
313	- preloader_console_init() can be called here in extremis
314	- should set up SDRAM, and anything needed to make the UART work
315	- these is no need to clear BSS, it will be done by crt0.S
316	- must return normally from this function (don't call board_init_r()
317		directly)
318
319Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
320this point the stack and global_data are relocated to below
321CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
322memory.
323
324board_init_r():
325	- purpose: main execution, common code
326	- global_data is available
327	- SDRAM is available
328	- BSS is available, all static/global variables can be used
329	- execution eventually continues to main_loop()
330
331	Non-SPL-specific notes:
332	- U-Boot is relocated to the top of memory and is now running from
333		there.
334
335	SPL-specific notes:
336	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
337		CONFIG_SPL_STACK_R_ADDR points into SDRAM
338	- preloader_console_init() can be called here - typically this is
339		done by defining CONFIG_SPL_BOARD_INIT and then supplying a
340		spl_board_init() function containing this call
341	- loads U-Boot or (in falcon mode) Linux
342
343
344
345Configuration Options:
346----------------------
347
348Configuration depends on the combination of board and CPU type; all
349such information is kept in a configuration file
350"include/configs/<board_name>.h".
351
352Example: For a TQM823L module, all configuration settings are in
353"include/configs/TQM823L.h".
354
355
356Many of the options are named exactly as the corresponding Linux
357kernel configuration options. The intention is to make it easier to
358build a config tool - later.
359
360
361The following options need to be configured:
362
363- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
364
365- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
366
367- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
368		Define exactly one, e.g. CONFIG_ATSTK1002
369
370- CPU Module Type: (if CONFIG_COGENT is defined)
371		Define exactly one of
372		CONFIG_CMA286_60_OLD
373--- FIXME --- not tested yet:
374		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
375		CONFIG_CMA287_23, CONFIG_CMA287_50
376
377- Motherboard Type: (if CONFIG_COGENT is defined)
378		Define exactly one of
379		CONFIG_CMA101, CONFIG_CMA102
380
381- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
382		Define one or more of
383		CONFIG_CMA302
384
385- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
386		Define one or more of
387		CONFIG_LCD_HEARTBEAT	- update a character position on
388					  the LCD display every second with
389					  a "rotator" |\-/|\-/
390
391- Marvell Family Member
392		CONFIG_SYS_MVFS		- define it if you want to enable
393					  multiple fs option at one time
394					  for marvell soc family
395
396- 8xx CPU Options: (if using an MPC8xx CPU)
397		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
398					  get_gclk_freq() cannot work
399					  e.g. if there is no 32KHz
400					  reference PIT/RTC clock
401		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
402					  or XTAL/EXTAL)
403
404- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
405		CONFIG_SYS_8xx_CPUCLK_MIN
406		CONFIG_SYS_8xx_CPUCLK_MAX
407		CONFIG_8xx_CPUCLK_DEFAULT
408			See doc/README.MPC866
409
410		CONFIG_SYS_MEASURE_CPUCLK
411
412		Define this to measure the actual CPU clock instead
413		of relying on the correctness of the configured
414		values. Mostly useful for board bringup to make sure
415		the PLL is locked at the intended frequency. Note
416		that this requires a (stable) reference clock (32 kHz
417		RTC clock or CONFIG_SYS_8XX_XIN)
418
419		CONFIG_SYS_DELAYED_ICACHE
420
421		Define this option if you want to enable the
422		ICache only when Code runs from RAM.
423
424- 85xx CPU Options:
425		CONFIG_SYS_PPC64
426
427		Specifies that the core is a 64-bit PowerPC implementation (implements
428		the "64" category of the Power ISA). This is necessary for ePAPR
429		compliance, among other possible reasons.
430
431		CONFIG_SYS_FSL_TBCLK_DIV
432
433		Defines the core time base clock divider ratio compared to the
434		system clock.  On most PQ3 devices this is 8, on newer QorIQ
435		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
436
437		CONFIG_SYS_FSL_PCIE_COMPAT
438
439		Defines the string to utilize when trying to match PCIe device
440		tree nodes for the given platform.
441
442		CONFIG_SYS_PPC_E500_DEBUG_TLB
443
444		Enables a temporary TLB entry to be used during boot to work
445		around limitations in e500v1 and e500v2 external debugger
446		support. This reduces the portions of the boot code where
447		breakpoints and single stepping do not work.  The value of this
448		symbol should be set to the TLB1 entry to be used for this
449		purpose.
450
451		CONFIG_SYS_FSL_ERRATUM_A004510
452
453		Enables a workaround for erratum A004510.  If set,
454		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
455		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
456
457		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
458		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
459
460		Defines one or two SoC revisions (low 8 bits of SVR)
461		for which the A004510 workaround should be applied.
462
463		The rest of SVR is either not relevant to the decision
464		of whether the erratum is present (e.g. p2040 versus
465		p2041) or is implied by the build target, which controls
466		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
467
468		See Freescale App Note 4493 for more information about
469		this erratum.
470
471		CONFIG_A003399_NOR_WORKAROUND
472		Enables a workaround for IFC erratum A003399. It is only
473		required during NOR boot.
474
475		CONFIG_A008044_WORKAROUND
476		Enables a workaround for T1040/T1042 erratum A008044. It is only
477		required during NAND boot and valid for Rev 1.0 SoC revision
478
479		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
480
481		This is the value to write into CCSR offset 0x18600
482		according to the A004510 workaround.
483
484		CONFIG_SYS_FSL_DSP_DDR_ADDR
485		This value denotes start offset of DDR memory which is
486		connected exclusively to the DSP cores.
487
488		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
489		This value denotes start offset of M2 memory
490		which is directly connected to the DSP core.
491
492		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
493		This value denotes start offset of M3 memory which is directly
494		connected to the DSP core.
495
496		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
497		This value denotes start offset of DSP CCSR space.
498
499		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
500		Single Source Clock is clocking mode present in some of FSL SoC's.
501		In this mode, a single differential clock is used to supply
502		clocks to the sysclock, ddrclock and usbclock.
503
504		CONFIG_SYS_CPC_REINIT_F
505		This CONFIG is defined when the CPC is configured as SRAM at the
506		time of U-boot entry and is required to be re-initialized.
507
508		CONFIG_DEEP_SLEEP
509		Indicates this SoC supports deep sleep feature. If deep sleep is
510		supported, core will start to execute uboot when wakes up.
511
512- Generic CPU options:
513		CONFIG_SYS_GENERIC_GLOBAL_DATA
514		Defines global data is initialized in generic board board_init_f().
515		If this macro is defined, global data is created and cleared in
516		generic board board_init_f(). Without this macro, architecture/board
517		should initialize global data before calling board_init_f().
518
519		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
520
521		Defines the endianess of the CPU. Implementation of those
522		values is arch specific.
523
524		CONFIG_SYS_FSL_DDR
525		Freescale DDR driver in use. This type of DDR controller is
526		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
527		SoCs.
528
529		CONFIG_SYS_FSL_DDR_ADDR
530		Freescale DDR memory-mapped register base.
531
532		CONFIG_SYS_FSL_DDR_EMU
533		Specify emulator support for DDR. Some DDR features such as
534		deskew training are not available.
535
536		CONFIG_SYS_FSL_DDRC_GEN1
537		Freescale DDR1 controller.
538
539		CONFIG_SYS_FSL_DDRC_GEN2
540		Freescale DDR2 controller.
541
542		CONFIG_SYS_FSL_DDRC_GEN3
543		Freescale DDR3 controller.
544
545		CONFIG_SYS_FSL_DDRC_GEN4
546		Freescale DDR4 controller.
547
548		CONFIG_SYS_FSL_DDRC_ARM_GEN3
549		Freescale DDR3 controller for ARM-based SoCs.
550
551		CONFIG_SYS_FSL_DDR1
552		Board config to use DDR1. It can be enabled for SoCs with
553		Freescale DDR1 or DDR2 controllers, depending on the board
554		implemetation.
555
556		CONFIG_SYS_FSL_DDR2
557		Board config to use DDR2. It can be eanbeld for SoCs with
558		Freescale DDR2 or DDR3 controllers, depending on the board
559		implementation.
560
561		CONFIG_SYS_FSL_DDR3
562		Board config to use DDR3. It can be enabled for SoCs with
563		Freescale DDR3 or DDR3L controllers.
564
565		CONFIG_SYS_FSL_DDR3L
566		Board config to use DDR3L. It can be enabled for SoCs with
567		DDR3L controllers.
568
569		CONFIG_SYS_FSL_DDR4
570		Board config to use DDR4. It can be enabled for SoCs with
571		DDR4 controllers.
572
573		CONFIG_SYS_FSL_IFC_BE
574		Defines the IFC controller register space as Big Endian
575
576		CONFIG_SYS_FSL_IFC_LE
577		Defines the IFC controller register space as Little Endian
578
579		CONFIG_SYS_FSL_PBL_PBI
580		It enables addition of RCW (Power on reset configuration) in built image.
581		Please refer doc/README.pblimage for more details
582
583		CONFIG_SYS_FSL_PBL_RCW
584		It adds PBI(pre-boot instructions) commands in u-boot build image.
585		PBI commands can be used to configure SoC before it starts the execution.
586		Please refer doc/README.pblimage for more details
587
588		CONFIG_SPL_FSL_PBL
589		It adds a target to create boot binary having SPL binary in PBI format
590		concatenated with u-boot binary.
591
592		CONFIG_SYS_FSL_DDR_BE
593		Defines the DDR controller register space as Big Endian
594
595		CONFIG_SYS_FSL_DDR_LE
596		Defines the DDR controller register space as Little Endian
597
598		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
599		Physical address from the view of DDR controllers. It is the
600		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
601		it could be different for ARM SoCs.
602
603		CONFIG_SYS_FSL_DDR_INTLV_256B
604		DDR controller interleaving on 256-byte. This is a special
605		interleaving mode, handled by Dickens for Freescale layerscape
606		SoCs with ARM core.
607
608		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
609		Number of controllers used as main memory.
610
611		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
612		Number of controllers used for other than main memory.
613
614		CONFIG_SYS_FSL_SEC_BE
615		Defines the SEC controller register space as Big Endian
616
617		CONFIG_SYS_FSL_SEC_LE
618		Defines the SEC controller register space as Little Endian
619
620- Intel Monahans options:
621		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
622
623		Defines the Monahans run mode to oscillator
624		ratio. Valid values are 8, 16, 24, 31. The core
625		frequency is this value multiplied by 13 MHz.
626
627		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
628
629		Defines the Monahans turbo mode to oscillator
630		ratio. Valid values are 1 (default if undefined) and
631		2. The core frequency as calculated above is multiplied
632		by this value.
633
634- MIPS CPU options:
635		CONFIG_SYS_INIT_SP_OFFSET
636
637		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
638		pointer. This is needed for the temporary stack before
639		relocation.
640
641		CONFIG_SYS_MIPS_CACHE_MODE
642
643		Cache operation mode for the MIPS CPU.
644		See also arch/mips/include/asm/mipsregs.h.
645		Possible values are:
646			CONF_CM_CACHABLE_NO_WA
647			CONF_CM_CACHABLE_WA
648			CONF_CM_UNCACHED
649			CONF_CM_CACHABLE_NONCOHERENT
650			CONF_CM_CACHABLE_CE
651			CONF_CM_CACHABLE_COW
652			CONF_CM_CACHABLE_CUW
653			CONF_CM_CACHABLE_ACCELERATED
654
655		CONFIG_SYS_XWAY_EBU_BOOTCFG
656
657		Special option for Lantiq XWAY SoCs for booting from NOR flash.
658		See also arch/mips/cpu/mips32/start.S.
659
660		CONFIG_XWAY_SWAP_BYTES
661
662		Enable compilation of tools/xway-swap-bytes needed for Lantiq
663		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
664		be swapped if a flash programmer is used.
665
666- ARM options:
667		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
668
669		Select high exception vectors of the ARM core, e.g., do not
670		clear the V bit of the c1 register of CP15.
671
672		CONFIG_SYS_THUMB_BUILD
673
674		Use this flag to build U-Boot using the Thumb instruction
675		set for ARM architectures. Thumb instruction set provides
676		better code density. For ARM architectures that support
677		Thumb2 this flag will result in Thumb2 code generated by
678		GCC.
679
680		CONFIG_ARM_ERRATA_716044
681		CONFIG_ARM_ERRATA_742230
682		CONFIG_ARM_ERRATA_743622
683		CONFIG_ARM_ERRATA_751472
684		CONFIG_ARM_ERRATA_794072
685		CONFIG_ARM_ERRATA_761320
686
687		If set, the workarounds for these ARM errata are applied early
688		during U-Boot startup. Note that these options force the
689		workarounds to be applied; no CPU-type/version detection
690		exists, unlike the similar options in the Linux kernel. Do not
691		set these options unless they apply!
692
693		NOTE: The following can be machine specific errata. These
694		do have ability to provide rudimentary version and machine
695		specific checks, but expect no product checks.
696		CONFIG_ARM_ERRATA_454179
697		CONFIG_ARM_ERRATA_798870
698
699- Tegra SoC options:
700		CONFIG_TEGRA_SUPPORT_NON_SECURE
701
702		Support executing U-Boot in non-secure (NS) mode. Certain
703		impossible actions will be skipped if the CPU is in NS mode,
704		such as ARM architectural timer initialization.
705
706- Driver Model
707		Driver model is a new framework for devices in U-Boot
708		introduced in early 2014. U-Boot is being progressively
709		moved over to this. It offers a consistent device structure,
710		supports grouping devices into classes and has built-in
711		handling of platform data and device tree.
712
713		To enable transition to driver model in a relatively
714		painful fashion, each subsystem can be independently
715		switched between the legacy/ad-hoc approach and the new
716		driver model using the options below. Also, many uclass
717		interfaces include compatibility features which may be
718		removed once the conversion of that subsystem is complete.
719		As a result, the API provided by the subsystem may in fact
720		not change with driver model.
721
722		See doc/driver-model/README.txt for more information.
723
724		CONFIG_DM
725
726		Enable driver model. This brings in the core support,
727		including scanning of platform data on start-up. If
728		CONFIG_OF_CONTROL is enabled, the device tree will be
729		scanned also when available.
730
731		CONFIG_CMD_DM
732
733		Enable driver model test commands. These allow you to print
734		out the driver model tree and the uclasses.
735
736		CONFIG_DM_DEMO
737
738		Enable some demo devices and the 'demo' command. These are
739		really only useful for playing around while trying to
740		understand driver model in sandbox.
741
742		CONFIG_SPL_DM
743
744		Enable driver model in SPL. You will need to provide a
745		suitable malloc() implementation. If you are not using the
746		full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
747		consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
748		must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
749		In most cases driver model will only allocate a few uclasses
750		and devices in SPL, so 1KB should be enable. See
751		CONFIG_SYS_MALLOC_F_LEN for more details on how to enable
752		it.
753
754		CONFIG_DM_SERIAL
755
756		Enable driver model for serial. This replaces
757		drivers/serial/serial.c with the serial uclass, which
758		implements serial_putc() etc. The uclass interface is
759		defined in include/serial.h.
760
761		CONFIG_DM_GPIO
762
763		Enable driver model for GPIO access. The standard GPIO
764		interface (gpio_get_value(), etc.) is then implemented by
765		the GPIO uclass. Drivers provide methods to query the
766		particular GPIOs that they provide. The uclass interface
767		is defined in include/asm-generic/gpio.h.
768
769		CONFIG_DM_SPI
770
771		Enable driver model for SPI. The SPI slave interface
772		(spi_setup_slave(), spi_xfer(), etc.) is then implemented by
773		the SPI uclass. Drivers provide methods to access the SPI
774		buses that they control. The uclass interface is defined in
775		include/spi.h. The existing spi_slave structure is attached
776		as 'parent data' to every slave on each bus. Slaves
777		typically use driver-private data instead of extending the
778		spi_slave structure.
779
780		CONFIG_DM_SPI_FLASH
781
782		Enable driver model for SPI flash. This SPI flash interface
783		(spi_flash_probe(), spi_flash_write(), etc.) is then
784		implemented by the SPI flash uclass. There is one standard
785		SPI flash driver which knows how to probe most chips
786		supported by U-Boot. The uclass interface is defined in
787		include/spi_flash.h, but is currently fully compatible
788		with the old interface to avoid confusion and duplication
789		during the transition parent. SPI and SPI flash must be
790		enabled together (it is not possible to use driver model
791		for one and not the other).
792
793		CONFIG_DM_CROS_EC
794
795		Enable driver model for the Chrome OS EC interface. This
796		allows the cros_ec SPI driver to operate with CONFIG_DM_SPI
797		but otherwise makes few changes. Since cros_ec also supports
798		I2C and LPC (which don't support driver model yet), a full
799		conversion is not yet possible.
800
801
802		** Code size options: The following options are enabled by
803		default except in SPL. Enable them explicitly to get these
804		features in SPL.
805
806		CONFIG_DM_WARN
807
808		Enable the dm_warn() function. This can use up quite a bit
809		of space for its strings.
810
811		CONFIG_DM_STDIO
812
813		Enable registering a serial device with the stdio library.
814
815		CONFIG_DM_DEVICE_REMOVE
816
817		Enable removing of devices.
818
819- Linux Kernel Interface:
820		CONFIG_CLOCKS_IN_MHZ
821
822		U-Boot stores all clock information in Hz
823		internally. For binary compatibility with older Linux
824		kernels (which expect the clocks passed in the
825		bd_info data to be in MHz) the environment variable
826		"clocks_in_mhz" can be defined so that U-Boot
827		converts clock data to MHZ before passing it to the
828		Linux kernel.
829		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
830		"clocks_in_mhz=1" is automatically included in the
831		default environment.
832
833		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
834
835		When transferring memsize parameter to Linux, some versions
836		expect it to be in bytes, others in MB.
837		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
838
839		CONFIG_OF_LIBFDT
840
841		New kernel versions are expecting firmware settings to be
842		passed using flattened device trees (based on open firmware
843		concepts).
844
845		CONFIG_OF_LIBFDT
846		 * New libfdt-based support
847		 * Adds the "fdt" command
848		 * The bootm command automatically updates the fdt
849
850		OF_CPU - The proper name of the cpus node (only required for
851			MPC512X and MPC5xxx based boards).
852		OF_SOC - The proper name of the soc node (only required for
853			MPC512X and MPC5xxx based boards).
854		OF_TBCLK - The timebase frequency.
855		OF_STDOUT_PATH - The path to the console device
856
857		boards with QUICC Engines require OF_QE to set UCC MAC
858		addresses
859
860		CONFIG_OF_BOARD_SETUP
861
862		Board code has addition modification that it wants to make
863		to the flat device tree before handing it off to the kernel
864
865		CONFIG_OF_SYSTEM_SETUP
866
867		Other code has addition modification that it wants to make
868		to the flat device tree before handing it off to the kernel.
869		This causes ft_system_setup() to be called before booting
870		the kernel.
871
872		CONFIG_OF_BOOT_CPU
873
874		This define fills in the correct boot CPU in the boot
875		param header, the default value is zero if undefined.
876
877		CONFIG_OF_IDE_FIXUP
878
879		U-Boot can detect if an IDE device is present or not.
880		If not, and this new config option is activated, U-Boot
881		removes the ATA node from the DTS before booting Linux,
882		so the Linux IDE driver does not probe the device and
883		crash. This is needed for buggy hardware (uc101) where
884		no pull down resistor is connected to the signal IDE5V_DD7.
885
886		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
887
888		This setting is mandatory for all boards that have only one
889		machine type and must be used to specify the machine type
890		number as it appears in the ARM machine registry
891		(see http://www.arm.linux.org.uk/developer/machines/).
892		Only boards that have multiple machine types supported
893		in a single configuration file and the machine type is
894		runtime discoverable, do not have to use this setting.
895
896- vxWorks boot parameters:
897
898		bootvx constructs a valid bootline using the following
899		environments variables: bootfile, ipaddr, serverip, hostname.
900		It loads the vxWorks image pointed bootfile.
901
902		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
903		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
904		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
905		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
906
907		CONFIG_SYS_VXWORKS_ADD_PARAMS
908
909		Add it at the end of the bootline. E.g "u=username pw=secret"
910
911		Note: If a "bootargs" environment is defined, it will overwride
912		the defaults discussed just above.
913
914- Cache Configuration:
915		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
916		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
917		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
918
919- Cache Configuration for ARM:
920		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
921				      controller
922		CONFIG_SYS_PL310_BASE - Physical base address of PL310
923					controller register space
924
925- Serial Ports:
926		CONFIG_PL010_SERIAL
927
928		Define this if you want support for Amba PrimeCell PL010 UARTs.
929
930		CONFIG_PL011_SERIAL
931
932		Define this if you want support for Amba PrimeCell PL011 UARTs.
933
934		CONFIG_PL011_CLOCK
935
936		If you have Amba PrimeCell PL011 UARTs, set this variable to
937		the clock speed of the UARTs.
938
939		CONFIG_PL01x_PORTS
940
941		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
942		define this to a list of base addresses for each (supported)
943		port. See e.g. include/configs/versatile.h
944
945		CONFIG_PL011_SERIAL_RLCR
946
947		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
948		have separate receive and transmit line control registers.  Set
949		this variable to initialize the extra register.
950
951		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
952
953		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
954		boot loader that has already initialized the UART.  Define this
955		variable to flush the UART at init time.
956
957		CONFIG_SERIAL_HW_FLOW_CONTROL
958
959		Define this variable to enable hw flow control in serial driver.
960		Current user of this option is drivers/serial/nsl16550.c driver
961
962- Console Interface:
963		Depending on board, define exactly one serial port
964		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
965		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
966		console by defining CONFIG_8xx_CONS_NONE
967
968		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
969		port routines must be defined elsewhere
970		(i.e. serial_init(), serial_getc(), ...)
971
972		CONFIG_CFB_CONSOLE
973		Enables console device for a color framebuffer. Needs following
974		defines (cf. smiLynxEM, i8042)
975			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
976						(default big endian)
977			VIDEO_HW_RECTFILL	graphic chip supports
978						rectangle fill
979						(cf. smiLynxEM)
980			VIDEO_HW_BITBLT		graphic chip supports
981						bit-blit (cf. smiLynxEM)
982			VIDEO_VISIBLE_COLS	visible pixel columns
983						(cols=pitch)
984			VIDEO_VISIBLE_ROWS	visible pixel rows
985			VIDEO_PIXEL_SIZE	bytes per pixel
986			VIDEO_DATA_FORMAT	graphic data format
987						(0-5, cf. cfb_console.c)
988			VIDEO_FB_ADRS		framebuffer address
989			VIDEO_KBD_INIT_FCT	keyboard int fct
990						(i.e. i8042_kbd_init())
991			VIDEO_TSTC_FCT		test char fct
992						(i.e. i8042_tstc)
993			VIDEO_GETC_FCT		get char fct
994						(i.e. i8042_getc)
995			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
996						(requires blink timer
997						cf. i8042.c)
998			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
999			CONFIG_CONSOLE_TIME	display time/date info in
1000						upper right corner
1001						(requires CONFIG_CMD_DATE)
1002			CONFIG_VIDEO_LOGO	display Linux logo in
1003						upper left corner
1004			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
1005						linux_logo.h for logo.
1006						Requires CONFIG_VIDEO_LOGO
1007			CONFIG_CONSOLE_EXTRA_INFO
1008						additional board info beside
1009						the logo
1010
1011		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
1012		a limited number of ANSI escape sequences (cursor control,
1013		erase functions and limited graphics rendition control).
1014
1015		When CONFIG_CFB_CONSOLE is defined, video console is
1016		default i/o. Serial console can be forced with
1017		environment 'console=serial'.
1018
1019		When CONFIG_SILENT_CONSOLE is defined, all console
1020		messages (by U-Boot and Linux!) can be silenced with
1021		the "silent" environment variable. See
1022		doc/README.silent for more information.
1023
1024		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
1025			is 0x00.
1026		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
1027			is 0xa0.
1028
1029- Console Baudrate:
1030		CONFIG_BAUDRATE - in bps
1031		Select one of the baudrates listed in
1032		CONFIG_SYS_BAUDRATE_TABLE, see below.
1033		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
1034
1035- Console Rx buffer length
1036		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
1037		the maximum receive buffer length for the SMC.
1038		This option is actual only for 82xx and 8xx possible.
1039		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
1040		must be defined, to setup the maximum idle timeout for
1041		the SMC.
1042
1043- Pre-Console Buffer:
1044		Prior to the console being initialised (i.e. serial UART
1045		initialised etc) all console output is silently discarded.
1046		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
1047		buffer any console messages prior to the console being
1048		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
1049		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
1050		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
1051		bytes are output before the console is initialised, the
1052		earlier bytes are discarded.
1053
1054		'Sane' compilers will generate smaller code if
1055		CONFIG_PRE_CON_BUF_SZ is a power of 2
1056
1057- Safe printf() functions
1058		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
1059		the printf() functions. These are defined in
1060		include/vsprintf.h and include snprintf(), vsnprintf() and
1061		so on. Code size increase is approximately 300-500 bytes.
1062		If this option is not given then these functions will
1063		silently discard their buffer size argument - this means
1064		you are not getting any overflow checking in this case.
1065
1066- Boot Delay:	CONFIG_BOOTDELAY - in seconds
1067		Delay before automatically booting the default image;
1068		set to -1 to disable autoboot.
1069		set to -2 to autoboot with no delay and not check for abort
1070		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
1071
1072		See doc/README.autoboot for these options that
1073		work with CONFIG_BOOTDELAY. None are required.
1074		CONFIG_BOOT_RETRY_TIME
1075		CONFIG_BOOT_RETRY_MIN
1076		CONFIG_AUTOBOOT_KEYED
1077		CONFIG_AUTOBOOT_PROMPT
1078		CONFIG_AUTOBOOT_DELAY_STR
1079		CONFIG_AUTOBOOT_STOP_STR
1080		CONFIG_AUTOBOOT_DELAY_STR2
1081		CONFIG_AUTOBOOT_STOP_STR2
1082		CONFIG_ZERO_BOOTDELAY_CHECK
1083		CONFIG_RESET_TO_RETRY
1084
1085- Autoboot Command:
1086		CONFIG_BOOTCOMMAND
1087		Only needed when CONFIG_BOOTDELAY is enabled;
1088		define a command string that is automatically executed
1089		when no character is read on the console interface
1090		within "Boot Delay" after reset.
1091
1092		CONFIG_BOOTARGS
1093		This can be used to pass arguments to the bootm
1094		command. The value of CONFIG_BOOTARGS goes into the
1095		environment value "bootargs".
1096
1097		CONFIG_RAMBOOT and CONFIG_NFSBOOT
1098		The value of these goes into the environment as
1099		"ramboot" and "nfsboot" respectively, and can be used
1100		as a convenience, when switching between booting from
1101		RAM and NFS.
1102
1103- Bootcount:
1104		CONFIG_BOOTCOUNT_LIMIT
1105		Implements a mechanism for detecting a repeating reboot
1106		cycle, see:
1107		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
1108
1109		CONFIG_BOOTCOUNT_ENV
1110		If no softreset save registers are found on the hardware
1111		"bootcount" is stored in the environment. To prevent a
1112		saveenv on all reboots, the environment variable
1113		"upgrade_available" is used. If "upgrade_available" is
1114		0, "bootcount" is always 0, if "upgrade_available" is
1115		1 "bootcount" is incremented in the environment.
1116		So the Userspace Applikation must set the "upgrade_available"
1117		and "bootcount" variable to 0, if a boot was successfully.
1118
1119- Pre-Boot Commands:
1120		CONFIG_PREBOOT
1121
1122		When this option is #defined, the existence of the
1123		environment variable "preboot" will be checked
1124		immediately before starting the CONFIG_BOOTDELAY
1125		countdown and/or running the auto-boot command resp.
1126		entering interactive mode.
1127
1128		This feature is especially useful when "preboot" is
1129		automatically generated or modified. For an example
1130		see the LWMON board specific code: here "preboot" is
1131		modified when the user holds down a certain
1132		combination of keys on the (special) keyboard when
1133		booting the systems
1134
1135- Serial Download Echo Mode:
1136		CONFIG_LOADS_ECHO
1137		If defined to 1, all characters received during a
1138		serial download (using the "loads" command) are
1139		echoed back. This might be needed by some terminal
1140		emulations (like "cu"), but may as well just take
1141		time on others. This setting #define's the initial
1142		value of the "loads_echo" environment variable.
1143
1144- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
1145		CONFIG_KGDB_BAUDRATE
1146		Select one of the baudrates listed in
1147		CONFIG_SYS_BAUDRATE_TABLE, see below.
1148
1149- Monitor Functions:
1150		Monitor commands can be included or excluded
1151		from the build by using the #include files
1152		<config_cmd_all.h> and #undef'ing unwanted
1153		commands, or using <config_cmd_default.h>
1154		and augmenting with additional #define's
1155		for wanted commands.
1156
1157		The default command configuration includes all commands
1158		except those marked below with a "*".
1159
1160		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
1161		CONFIG_CMD_ASKENV	* ask for env variable
1162		CONFIG_CMD_BDI		  bdinfo
1163		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
1164		CONFIG_CMD_BMP		* BMP support
1165		CONFIG_CMD_BSP		* Board specific commands
1166		CONFIG_CMD_BOOTD	  bootd
1167		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
1168		CONFIG_CMD_CACHE	* icache, dcache
1169		CONFIG_CMD_CLK   	* clock command support
1170		CONFIG_CMD_CONSOLE	  coninfo
1171		CONFIG_CMD_CRC32	* crc32
1172		CONFIG_CMD_DATE		* support for RTC, date/time...
1173		CONFIG_CMD_DHCP		* DHCP support
1174		CONFIG_CMD_DIAG		* Diagnostics
1175		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
1176		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
1177		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
1178		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
1179		CONFIG_CMD_DTT		* Digital Therm and Thermostat
1180		CONFIG_CMD_ECHO		  echo arguments
1181		CONFIG_CMD_EDITENV	  edit env variable
1182		CONFIG_CMD_EEPROM	* EEPROM read/write support
1183		CONFIG_CMD_ELF		* bootelf, bootvx
1184		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
1185		CONFIG_CMD_ENV_FLAGS	* display details about env flags
1186		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
1187		CONFIG_CMD_EXPORTENV	* export the environment
1188		CONFIG_CMD_EXT2		* ext2 command support
1189		CONFIG_CMD_EXT4		* ext4 command support
1190		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
1191					  that work for multiple fs types
1192		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
1193		CONFIG_CMD_SAVEENV	  saveenv
1194		CONFIG_CMD_FDC		* Floppy Disk Support
1195		CONFIG_CMD_FAT		* FAT command support
1196		CONFIG_CMD_FLASH	  flinfo, erase, protect
1197		CONFIG_CMD_FPGA		  FPGA device initialization support
1198		CONFIG_CMD_FUSE		* Device fuse support
1199		CONFIG_CMD_GETTIME	* Get time since boot
1200		CONFIG_CMD_GO		* the 'go' command (exec code)
1201		CONFIG_CMD_GREPENV	* search environment
1202		CONFIG_CMD_HASH		* calculate hash / digest
1203		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
1204		CONFIG_CMD_I2C		* I2C serial bus support
1205		CONFIG_CMD_IDE		* IDE harddisk support
1206		CONFIG_CMD_IMI		  iminfo
1207		CONFIG_CMD_IMLS		  List all images found in NOR flash
1208		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
1209		CONFIG_CMD_IMMAP	* IMMR dump support
1210		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
1211		CONFIG_CMD_IMPORTENV	* import an environment
1212		CONFIG_CMD_INI		* import data from an ini file into the env
1213		CONFIG_CMD_IRQ		* irqinfo
1214		CONFIG_CMD_ITEST	  Integer/string test of 2 values
1215		CONFIG_CMD_JFFS2	* JFFS2 Support
1216		CONFIG_CMD_KGDB		* kgdb
1217		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
1218		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
1219					  (169.254.*.*)
1220		CONFIG_CMD_LOADB	  loadb
1221		CONFIG_CMD_LOADS	  loads
1222		CONFIG_CMD_MD5SUM	* print md5 message digest
1223					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
1224		CONFIG_CMD_MEMINFO	* Display detailed memory information
1225		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
1226					  loop, loopw
1227		CONFIG_CMD_MEMTEST	* mtest
1228		CONFIG_CMD_MISC		  Misc functions like sleep etc
1229		CONFIG_CMD_MMC		* MMC memory mapped support
1230		CONFIG_CMD_MII		* MII utility commands
1231		CONFIG_CMD_MTDPARTS	* MTD partition support
1232		CONFIG_CMD_NAND		* NAND support
1233		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
1234		CONFIG_CMD_NFS		  NFS support
1235		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1236		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1237		CONFIG_CMD_PCI		* pciinfo
1238		CONFIG_CMD_PCMCIA		* PCMCIA support
1239		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1240					  host
1241		CONFIG_CMD_PORTIO	* Port I/O
1242		CONFIG_CMD_READ		* Read raw data from partition
1243		CONFIG_CMD_REGINFO	* Register dump
1244		CONFIG_CMD_RUN		  run command in env variable
1245		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1246		CONFIG_CMD_SAVES	* save S record dump
1247		CONFIG_CMD_SCSI		* SCSI Support
1248		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1249					  (requires CONFIG_CMD_I2C)
1250		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1251					  (4xx only)
1252		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1253		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1254					  (requires CONFIG_CMD_MEMORY)
1255		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1256		CONFIG_CMD_SOURCE	  "source" command Support
1257		CONFIG_CMD_SPI		* SPI serial bus support
1258		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1259		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1260		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1261		CONFIG_CMD_TIMER	* access to the system tick timer
1262		CONFIG_CMD_USB		* USB support
1263		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1264		CONFIG_CMD_MFSL		* Microblaze FSL support
1265		CONFIG_CMD_XIMG		  Load part of Multi Image
1266		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1267
1268		EXAMPLE: If you want all functions except of network
1269		support you can write:
1270
1271		#include "config_cmd_all.h"
1272		#undef CONFIG_CMD_NET
1273
1274	Other Commands:
1275		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1276
1277	Note:	Don't enable the "icache" and "dcache" commands
1278		(configuration option CONFIG_CMD_CACHE) unless you know
1279		what you (and your U-Boot users) are doing. Data
1280		cache cannot be enabled on systems like the 8xx or
1281		8260 (where accesses to the IMMR region must be
1282		uncached), and it cannot be disabled on all other
1283		systems where we (mis-) use the data cache to hold an
1284		initial stack and some data.
1285
1286
1287		XXX - this list needs to get updated!
1288
1289- Regular expression support:
1290		CONFIG_REGEX
1291		If this variable is defined, U-Boot is linked against
1292		the SLRE (Super Light Regular Expression) library,
1293		which adds regex support to some commands, as for
1294		example "env grep" and "setexpr".
1295
1296- Device tree:
1297		CONFIG_OF_CONTROL
1298		If this variable is defined, U-Boot will use a device tree
1299		to configure its devices, instead of relying on statically
1300		compiled #defines in the board file. This option is
1301		experimental and only available on a few boards. The device
1302		tree is available in the global data as gd->fdt_blob.
1303
1304		U-Boot needs to get its device tree from somewhere. This can
1305		be done using one of the two options below:
1306
1307		CONFIG_OF_EMBED
1308		If this variable is defined, U-Boot will embed a device tree
1309		binary in its image. This device tree file should be in the
1310		board directory and called <soc>-<board>.dts. The binary file
1311		is then picked up in board_init_f() and made available through
1312		the global data structure as gd->blob.
1313
1314		CONFIG_OF_SEPARATE
1315		If this variable is defined, U-Boot will build a device tree
1316		binary. It will be called u-boot.dtb. Architecture-specific
1317		code will locate it at run-time. Generally this works by:
1318
1319			cat u-boot.bin u-boot.dtb >image.bin
1320
1321		and in fact, U-Boot does this for you, creating a file called
1322		u-boot-dtb.bin which is useful in the common case. You can
1323		still use the individual files if you need something more
1324		exotic.
1325
1326- Watchdog:
1327		CONFIG_WATCHDOG
1328		If this variable is defined, it enables watchdog
1329		support for the SoC. There must be support in the SoC
1330		specific code for a watchdog. For the 8xx and 8260
1331		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1332		register.  When supported for a specific SoC is
1333		available, then no further board specific code should
1334		be needed to use it.
1335
1336		CONFIG_HW_WATCHDOG
1337		When using a watchdog circuitry external to the used
1338		SoC, then define this variable and provide board
1339		specific code for the "hw_watchdog_reset" function.
1340
1341		CONFIG_AT91_HW_WDT_TIMEOUT
1342		specify the timeout in seconds. default 2 seconds.
1343
1344- U-Boot Version:
1345		CONFIG_VERSION_VARIABLE
1346		If this variable is defined, an environment variable
1347		named "ver" is created by U-Boot showing the U-Boot
1348		version as printed by the "version" command.
1349		Any change to this variable will be reverted at the
1350		next reset.
1351
1352- Real-Time Clock:
1353
1354		When CONFIG_CMD_DATE is selected, the type of the RTC
1355		has to be selected, too. Define exactly one of the
1356		following options:
1357
1358		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1359		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1360		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1361		CONFIG_RTC_MC146818	- use MC146818 RTC
1362		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1363		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1364		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1365		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1366		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1367		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1368		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1369		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1370		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1371					  RV3029 RTC.
1372
1373		Note that if the RTC uses I2C, then the I2C interface
1374		must also be configured. See I2C Support, below.
1375
1376- GPIO Support:
1377		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1378
1379		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1380		chip-ngpio pairs that tell the PCA953X driver the number of
1381		pins supported by a particular chip.
1382
1383		Note that if the GPIO device uses I2C, then the I2C interface
1384		must also be configured. See I2C Support, below.
1385
1386- I/O tracing:
1387		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1388		accesses and can checksum them or write a list of them out
1389		to memory. See the 'iotrace' command for details. This is
1390		useful for testing device drivers since it can confirm that
1391		the driver behaves the same way before and after a code
1392		change. Currently this is supported on sandbox and arm. To
1393		add support for your architecture, add '#include <iotrace.h>'
1394		to the bottom of arch/<arch>/include/asm/io.h and test.
1395
1396		Example output from the 'iotrace stats' command is below.
1397		Note that if the trace buffer is exhausted, the checksum will
1398		still continue to operate.
1399
1400			iotrace is enabled
1401			Start:  10000000	(buffer start address)
1402			Size:   00010000	(buffer size)
1403			Offset: 00000120	(current buffer offset)
1404			Output: 10000120	(start + offset)
1405			Count:  00000018	(number of trace records)
1406			CRC32:  9526fb66	(CRC32 of all trace records)
1407
1408- Timestamp Support:
1409
1410		When CONFIG_TIMESTAMP is selected, the timestamp
1411		(date and time) of an image is printed by image
1412		commands like bootm or iminfo. This option is
1413		automatically enabled when you select CONFIG_CMD_DATE .
1414
1415- Partition Labels (disklabels) Supported:
1416		Zero or more of the following:
1417		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1418		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1419				       Intel architecture, USB sticks, etc.
1420		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1421		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1422				       bootloader.  Note 2TB partition limit; see
1423				       disk/part_efi.c
1424		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1425
1426		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1427		CONFIG_CMD_SCSI) you must configure support for at
1428		least one non-MTD partition type as well.
1429
1430- IDE Reset method:
1431		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1432		board configurations files but used nowhere!
1433
1434		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1435		be performed by calling the function
1436			ide_set_reset(int reset)
1437		which has to be defined in a board specific file
1438
1439- ATAPI Support:
1440		CONFIG_ATAPI
1441
1442		Set this to enable ATAPI support.
1443
1444- LBA48 Support
1445		CONFIG_LBA48
1446
1447		Set this to enable support for disks larger than 137GB
1448		Also look at CONFIG_SYS_64BIT_LBA.
1449		Whithout these , LBA48 support uses 32bit variables and will 'only'
1450		support disks up to 2.1TB.
1451
1452		CONFIG_SYS_64BIT_LBA:
1453			When enabled, makes the IDE subsystem use 64bit sector addresses.
1454			Default is 32bit.
1455
1456- SCSI Support:
1457		At the moment only there is only support for the
1458		SYM53C8XX SCSI controller; define
1459		CONFIG_SCSI_SYM53C8XX to enable it.
1460
1461		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1462		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1463		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1464		maximum numbers of LUNs, SCSI ID's and target
1465		devices.
1466		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1467
1468		The environment variable 'scsidevs' is set to the number of
1469		SCSI devices found during the last scan.
1470
1471- NETWORK Support (PCI):
1472		CONFIG_E1000
1473		Support for Intel 8254x/8257x gigabit chips.
1474
1475		CONFIG_E1000_SPI
1476		Utility code for direct access to the SPI bus on Intel 8257x.
1477		This does not do anything useful unless you set at least one
1478		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1479
1480		CONFIG_E1000_SPI_GENERIC
1481		Allow generic access to the SPI bus on the Intel 8257x, for
1482		example with the "sspi" command.
1483
1484		CONFIG_CMD_E1000
1485		Management command for E1000 devices.  When used on devices
1486		with SPI support you can reprogram the EEPROM from U-Boot.
1487
1488		CONFIG_E1000_FALLBACK_MAC
1489		default MAC for empty EEPROM after production.
1490
1491		CONFIG_EEPRO100
1492		Support for Intel 82557/82559/82559ER chips.
1493		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1494		write routine for first time initialisation.
1495
1496		CONFIG_TULIP
1497		Support for Digital 2114x chips.
1498		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1499		modem chip initialisation (KS8761/QS6611).
1500
1501		CONFIG_NATSEMI
1502		Support for National dp83815 chips.
1503
1504		CONFIG_NS8382X
1505		Support for National dp8382[01] gigabit chips.
1506
1507- NETWORK Support (other):
1508
1509		CONFIG_DRIVER_AT91EMAC
1510		Support for AT91RM9200 EMAC.
1511
1512			CONFIG_RMII
1513			Define this to use reduced MII inteface
1514
1515			CONFIG_DRIVER_AT91EMAC_QUIET
1516			If this defined, the driver is quiet.
1517			The driver doen't show link status messages.
1518
1519		CONFIG_CALXEDA_XGMAC
1520		Support for the Calxeda XGMAC device
1521
1522		CONFIG_LAN91C96
1523		Support for SMSC's LAN91C96 chips.
1524
1525			CONFIG_LAN91C96_BASE
1526			Define this to hold the physical address
1527			of the LAN91C96's I/O space
1528
1529			CONFIG_LAN91C96_USE_32_BIT
1530			Define this to enable 32 bit addressing
1531
1532		CONFIG_SMC91111
1533		Support for SMSC's LAN91C111 chip
1534
1535			CONFIG_SMC91111_BASE
1536			Define this to hold the physical address
1537			of the device (I/O space)
1538
1539			CONFIG_SMC_USE_32_BIT
1540			Define this if data bus is 32 bits
1541
1542			CONFIG_SMC_USE_IOFUNCS
1543			Define this to use i/o functions instead of macros
1544			(some hardware wont work with macros)
1545
1546		CONFIG_DRIVER_TI_EMAC
1547		Support for davinci emac
1548
1549			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1550			Define this if you have more then 3 PHYs.
1551
1552		CONFIG_FTGMAC100
1553		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1554
1555			CONFIG_FTGMAC100_EGIGA
1556			Define this to use GE link update with gigabit PHY.
1557			Define this if FTGMAC100 is connected to gigabit PHY.
1558			If your system has 10/100 PHY only, it might not occur
1559			wrong behavior. Because PHY usually return timeout or
1560			useless data when polling gigabit status and gigabit
1561			control registers. This behavior won't affect the
1562			correctnessof 10/100 link speed update.
1563
1564		CONFIG_SMC911X
1565		Support for SMSC's LAN911x and LAN921x chips
1566
1567			CONFIG_SMC911X_BASE
1568			Define this to hold the physical address
1569			of the device (I/O space)
1570
1571			CONFIG_SMC911X_32_BIT
1572			Define this if data bus is 32 bits
1573
1574			CONFIG_SMC911X_16_BIT
1575			Define this if data bus is 16 bits. If your processor
1576			automatically converts one 32 bit word to two 16 bit
1577			words you may also try CONFIG_SMC911X_32_BIT.
1578
1579		CONFIG_SH_ETHER
1580		Support for Renesas on-chip Ethernet controller
1581
1582			CONFIG_SH_ETHER_USE_PORT
1583			Define the number of ports to be used
1584
1585			CONFIG_SH_ETHER_PHY_ADDR
1586			Define the ETH PHY's address
1587
1588			CONFIG_SH_ETHER_CACHE_WRITEBACK
1589			If this option is set, the driver enables cache flush.
1590
1591- PWM Support:
1592		CONFIG_PWM_IMX
1593		Support for PWM modul on the imx6.
1594
1595- TPM Support:
1596		CONFIG_TPM
1597		Support TPM devices.
1598
1599		CONFIG_TPM_TIS_I2C
1600		Support for i2c bus TPM devices. Only one device
1601		per system is supported at this time.
1602
1603			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1604			Define the the i2c bus number for the TPM device
1605
1606			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1607			Define the TPM's address on the i2c bus
1608
1609			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1610			Define the burst count bytes upper limit
1611
1612		CONFIG_TPM_ATMEL_TWI
1613		Support for Atmel TWI TPM device. Requires I2C support.
1614
1615		CONFIG_TPM_TIS_LPC
1616		Support for generic parallel port TPM devices. Only one device
1617		per system is supported at this time.
1618
1619			CONFIG_TPM_TIS_BASE_ADDRESS
1620			Base address where the generic TPM device is mapped
1621			to. Contemporary x86 systems usually map it at
1622			0xfed40000.
1623
1624		CONFIG_CMD_TPM
1625		Add tpm monitor functions.
1626		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1627		provides monitor access to authorized functions.
1628
1629		CONFIG_TPM
1630		Define this to enable the TPM support library which provides
1631		functional interfaces to some TPM commands.
1632		Requires support for a TPM device.
1633
1634		CONFIG_TPM_AUTH_SESSIONS
1635		Define this to enable authorized functions in the TPM library.
1636		Requires CONFIG_TPM and CONFIG_SHA1.
1637
1638- USB Support:
1639		At the moment only the UHCI host controller is
1640		supported (PIP405, MIP405, MPC5200); define
1641		CONFIG_USB_UHCI to enable it.
1642		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1643		and define CONFIG_USB_STORAGE to enable the USB
1644		storage devices.
1645		Note:
1646		Supported are USB Keyboards and USB Floppy drives
1647		(TEAC FD-05PUB).
1648		MPC5200 USB requires additional defines:
1649			CONFIG_USB_CLOCK
1650				for 528 MHz Clock: 0x0001bbbb
1651			CONFIG_PSC3_USB
1652				for USB on PSC3
1653			CONFIG_USB_CONFIG
1654				for differential drivers: 0x00001000
1655				for single ended drivers: 0x00005000
1656				for differential drivers on PSC3: 0x00000100
1657				for single ended drivers on PSC3: 0x00004100
1658			CONFIG_SYS_USB_EVENT_POLL
1659				May be defined to allow interrupt polling
1660				instead of using asynchronous interrupts
1661
1662		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1663		txfilltuning field in the EHCI controller on reset.
1664
1665		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1666		HW module registers.
1667
1668- USB Device:
1669		Define the below if you wish to use the USB console.
1670		Once firmware is rebuilt from a serial console issue the
1671		command "setenv stdin usbtty; setenv stdout usbtty" and
1672		attach your USB cable. The Unix command "dmesg" should print
1673		it has found a new device. The environment variable usbtty
1674		can be set to gserial or cdc_acm to enable your device to
1675		appear to a USB host as a Linux gserial device or a
1676		Common Device Class Abstract Control Model serial device.
1677		If you select usbtty = gserial you should be able to enumerate
1678		a Linux host by
1679		# modprobe usbserial vendor=0xVendorID product=0xProductID
1680		else if using cdc_acm, simply setting the environment
1681		variable usbtty to be cdc_acm should suffice. The following
1682		might be defined in YourBoardName.h
1683
1684			CONFIG_USB_DEVICE
1685			Define this to build a UDC device
1686
1687			CONFIG_USB_TTY
1688			Define this to have a tty type of device available to
1689			talk to the UDC device
1690
1691			CONFIG_USBD_HS
1692			Define this to enable the high speed support for usb
1693			device and usbtty. If this feature is enabled, a routine
1694			int is_usbd_high_speed(void)
1695			also needs to be defined by the driver to dynamically poll
1696			whether the enumeration has succeded at high speed or full
1697			speed.
1698
1699			CONFIG_SYS_CONSOLE_IS_IN_ENV
1700			Define this if you want stdin, stdout &/or stderr to
1701			be set to usbtty.
1702
1703			mpc8xx:
1704				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1705				Derive USB clock from external clock "blah"
1706				- CONFIG_SYS_USB_EXTC_CLK 0x02
1707
1708				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1709				Derive USB clock from brgclk
1710				- CONFIG_SYS_USB_BRG_CLK 0x04
1711
1712		If you have a USB-IF assigned VendorID then you may wish to
1713		define your own vendor specific values either in BoardName.h
1714		or directly in usbd_vendor_info.h. If you don't define
1715		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1716		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1717		should pretend to be a Linux device to it's target host.
1718
1719			CONFIG_USBD_MANUFACTURER
1720			Define this string as the name of your company for
1721			- CONFIG_USBD_MANUFACTURER "my company"
1722
1723			CONFIG_USBD_PRODUCT_NAME
1724			Define this string as the name of your product
1725			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1726
1727			CONFIG_USBD_VENDORID
1728			Define this as your assigned Vendor ID from the USB
1729			Implementors Forum. This *must* be a genuine Vendor ID
1730			to avoid polluting the USB namespace.
1731			- CONFIG_USBD_VENDORID 0xFFFF
1732
1733			CONFIG_USBD_PRODUCTID
1734			Define this as the unique Product ID
1735			for your device
1736			- CONFIG_USBD_PRODUCTID 0xFFFF
1737
1738- ULPI Layer Support:
1739		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1740		the generic ULPI layer. The generic layer accesses the ULPI PHY
1741		via the platform viewport, so you need both the genric layer and
1742		the viewport enabled. Currently only Chipidea/ARC based
1743		viewport is supported.
1744		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1745		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1746		If your ULPI phy needs a different reference clock than the
1747		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1748		the appropriate value in Hz.
1749
1750- MMC Support:
1751		The MMC controller on the Intel PXA is supported. To
1752		enable this define CONFIG_MMC. The MMC can be
1753		accessed from the boot prompt by mapping the device
1754		to physical memory similar to flash. Command line is
1755		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1756		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1757
1758		CONFIG_SH_MMCIF
1759		Support for Renesas on-chip MMCIF controller
1760
1761			CONFIG_SH_MMCIF_ADDR
1762			Define the base address of MMCIF registers
1763
1764			CONFIG_SH_MMCIF_CLK
1765			Define the clock frequency for MMCIF
1766
1767		CONFIG_GENERIC_MMC
1768		Enable the generic MMC driver
1769
1770		CONFIG_SUPPORT_EMMC_BOOT
1771		Enable some additional features of the eMMC boot partitions.
1772
1773		CONFIG_SUPPORT_EMMC_RPMB
1774		Enable the commands for reading, writing and programming the
1775		key for the Replay Protection Memory Block partition in eMMC.
1776
1777- USB Device Firmware Update (DFU) class support:
1778		CONFIG_DFU_FUNCTION
1779		This enables the USB portion of the DFU USB class
1780
1781		CONFIG_CMD_DFU
1782		This enables the command "dfu" which is used to have
1783		U-Boot create a DFU class device via USB.  This command
1784		requires that the "dfu_alt_info" environment variable be
1785		set and define the alt settings to expose to the host.
1786
1787		CONFIG_DFU_MMC
1788		This enables support for exposing (e)MMC devices via DFU.
1789
1790		CONFIG_DFU_NAND
1791		This enables support for exposing NAND devices via DFU.
1792
1793		CONFIG_DFU_RAM
1794		This enables support for exposing RAM via DFU.
1795		Note: DFU spec refer to non-volatile memory usage, but
1796		allow usages beyond the scope of spec - here RAM usage,
1797		one that would help mostly the developer.
1798
1799		CONFIG_SYS_DFU_DATA_BUF_SIZE
1800		Dfu transfer uses a buffer before writing data to the
1801		raw storage device. Make the size (in bytes) of this buffer
1802		configurable. The size of this buffer is also configurable
1803		through the "dfu_bufsiz" environment variable.
1804
1805		CONFIG_SYS_DFU_MAX_FILE_SIZE
1806		When updating files rather than the raw storage device,
1807		we use a static buffer to copy the file into and then write
1808		the buffer once we've been given the whole file.  Define
1809		this to the maximum filesize (in bytes) for the buffer.
1810		Default is 4 MiB if undefined.
1811
1812		DFU_DEFAULT_POLL_TIMEOUT
1813		Poll timeout [ms], is the timeout a device can send to the
1814		host. The host must wait for this timeout before sending
1815		a subsequent DFU_GET_STATUS request to the device.
1816
1817		DFU_MANIFEST_POLL_TIMEOUT
1818		Poll timeout [ms], which the device sends to the host when
1819		entering dfuMANIFEST state. Host waits this timeout, before
1820		sending again an USB request to the device.
1821
1822- USB Device Android Fastboot support:
1823		CONFIG_CMD_FASTBOOT
1824		This enables the command "fastboot" which enables the Android
1825		fastboot mode for the platform's USB device. Fastboot is a USB
1826		protocol for downloading images, flashing and device control
1827		used on Android devices.
1828		See doc/README.android-fastboot for more information.
1829
1830		CONFIG_ANDROID_BOOT_IMAGE
1831		This enables support for booting images which use the Android
1832		image format header.
1833
1834		CONFIG_USB_FASTBOOT_BUF_ADDR
1835		The fastboot protocol requires a large memory buffer for
1836		downloads. Define this to the starting RAM address to use for
1837		downloaded images.
1838
1839		CONFIG_USB_FASTBOOT_BUF_SIZE
1840		The fastboot protocol requires a large memory buffer for
1841		downloads. This buffer should be as large as possible for a
1842		platform. Define this to the size available RAM for fastboot.
1843
1844		CONFIG_FASTBOOT_FLASH
1845		The fastboot protocol includes a "flash" command for writing
1846		the downloaded image to a non-volatile storage device. Define
1847		this to enable the "fastboot flash" command.
1848
1849		CONFIG_FASTBOOT_FLASH_MMC_DEV
1850		The fastboot "flash" command requires additional information
1851		regarding the non-volatile storage device. Define this to
1852		the eMMC device that fastboot should use to store the image.
1853
1854		CONFIG_FASTBOOT_GPT_NAME
1855		The fastboot "flash" command supports writing the downloaded
1856		image to the Protective MBR and the Primary GUID Partition
1857		Table. (Additionally, this downloaded image is post-processed
1858		to generate and write the Backup GUID Partition Table.)
1859		This occurs when the specified "partition name" on the
1860		"fastboot flash" command line matches this value.
1861		Default is GPT_ENTRY_NAME (currently "gpt") if undefined.
1862
1863- Journaling Flash filesystem support:
1864		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1865		CONFIG_JFFS2_NAND_DEV
1866		Define these for a default partition on a NAND device
1867
1868		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1869		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1870		Define these for a default partition on a NOR device
1871
1872		CONFIG_SYS_JFFS_CUSTOM_PART
1873		Define this to create an own partition. You have to provide a
1874		function struct part_info* jffs2_part_info(int part_num)
1875
1876		If you define only one JFFS2 partition you may also want to
1877		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1878		to disable the command chpart. This is the default when you
1879		have not defined a custom partition
1880
1881- FAT(File Allocation Table) filesystem write function support:
1882		CONFIG_FAT_WRITE
1883
1884		Define this to enable support for saving memory data as a
1885		file in FAT formatted partition.
1886
1887		This will also enable the command "fatwrite" enabling the
1888		user to write files to FAT.
1889
1890CBFS (Coreboot Filesystem) support
1891		CONFIG_CMD_CBFS
1892
1893		Define this to enable support for reading from a Coreboot
1894		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1895		and cbfsload.
1896
1897- FAT(File Allocation Table) filesystem cluster size:
1898		CONFIG_FS_FAT_MAX_CLUSTSIZE
1899
1900		Define the max cluster size for fat operations else
1901		a default value of 65536 will be defined.
1902
1903- Keyboard Support:
1904		CONFIG_ISA_KEYBOARD
1905
1906		Define this to enable standard (PC-Style) keyboard
1907		support
1908
1909		CONFIG_I8042_KBD
1910		Standard PC keyboard driver with US (is default) and
1911		GERMAN key layout (switch via environment 'keymap=de') support.
1912		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1913		for cfb_console. Supports cursor blinking.
1914
1915		CONFIG_CROS_EC_KEYB
1916		Enables a Chrome OS keyboard using the CROS_EC interface.
1917		This uses CROS_EC to communicate with a second microcontroller
1918		which provides key scans on request.
1919
1920- Video support:
1921		CONFIG_VIDEO
1922
1923		Define this to enable video support (for output to
1924		video).
1925
1926		CONFIG_VIDEO_CT69000
1927
1928		Enable Chips & Technologies 69000 Video chip
1929
1930		CONFIG_VIDEO_SMI_LYNXEM
1931		Enable Silicon Motion SMI 712/710/810 Video chip. The
1932		video output is selected via environment 'videoout'
1933		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1934		assumed.
1935
1936		For the CT69000 and SMI_LYNXEM drivers, videomode is
1937		selected via environment 'videomode'. Two different ways
1938		are possible:
1939		- "videomode=num"   'num' is a standard LiLo mode numbers.
1940		Following standard modes are supported	(* is default):
1941
1942		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1943		-------------+---------------------------------------------
1944		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1945		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1946		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1947		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1948		-------------+---------------------------------------------
1949		(i.e. setenv videomode 317; saveenv; reset;)
1950
1951		- "videomode=bootargs" all the video parameters are parsed
1952		from the bootargs. (See drivers/video/videomodes.c)
1953
1954
1955		CONFIG_VIDEO_SED13806
1956		Enable Epson SED13806 driver. This driver supports 8bpp
1957		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1958		or CONFIG_VIDEO_SED13806_16BPP
1959
1960		CONFIG_FSL_DIU_FB
1961		Enable the Freescale DIU video driver.	Reference boards for
1962		SOCs that have a DIU should define this macro to enable DIU
1963		support, and should also define these other macros:
1964
1965			CONFIG_SYS_DIU_ADDR
1966			CONFIG_VIDEO
1967			CONFIG_CMD_BMP
1968			CONFIG_CFB_CONSOLE
1969			CONFIG_VIDEO_SW_CURSOR
1970			CONFIG_VGA_AS_SINGLE_DEVICE
1971			CONFIG_VIDEO_LOGO
1972			CONFIG_VIDEO_BMP_LOGO
1973
1974		The DIU driver will look for the 'video-mode' environment
1975		variable, and if defined, enable the DIU as a console during
1976		boot.  See the documentation file README.video for a
1977		description of this variable.
1978
1979		CONFIG_VIDEO_VGA
1980
1981		Enable the VGA video / BIOS for x86. The alternative if you
1982		are using coreboot is to use the coreboot frame buffer
1983		driver.
1984
1985
1986- Keyboard Support:
1987		CONFIG_KEYBOARD
1988
1989		Define this to enable a custom keyboard support.
1990		This simply calls drv_keyboard_init() which must be
1991		defined in your board-specific files.
1992		The only board using this so far is RBC823.
1993
1994- LCD Support:	CONFIG_LCD
1995
1996		Define this to enable LCD support (for output to LCD
1997		display); also select one of the supported displays
1998		by defining one of these:
1999
2000		CONFIG_ATMEL_LCD:
2001
2002			HITACHI TX09D70VM1CCA, 3.5", 240x320.
2003
2004		CONFIG_NEC_NL6448AC33:
2005
2006			NEC NL6448AC33-18. Active, color, single scan.
2007
2008		CONFIG_NEC_NL6448BC20
2009
2010			NEC NL6448BC20-08. 6.5", 640x480.
2011			Active, color, single scan.
2012
2013		CONFIG_NEC_NL6448BC33_54
2014
2015			NEC NL6448BC33-54. 10.4", 640x480.
2016			Active, color, single scan.
2017
2018		CONFIG_SHARP_16x9
2019
2020			Sharp 320x240. Active, color, single scan.
2021			It isn't 16x9, and I am not sure what it is.
2022
2023		CONFIG_SHARP_LQ64D341
2024
2025			Sharp LQ64D341 display, 640x480.
2026			Active, color, single scan.
2027
2028		CONFIG_HLD1045
2029
2030			HLD1045 display, 640x480.
2031			Active, color, single scan.
2032
2033		CONFIG_OPTREX_BW
2034
2035			Optrex	 CBL50840-2 NF-FW 99 22 M5
2036			or
2037			Hitachi	 LMG6912RPFC-00T
2038			or
2039			Hitachi	 SP14Q002
2040
2041			320x240. Black & white.
2042
2043		Normally display is black on white background; define
2044		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
2045
2046		CONFIG_LCD_ALIGNMENT
2047
2048		Normally the LCD is page-aligned (typically 4KB). If this is
2049		defined then the LCD will be aligned to this value instead.
2050		For ARM it is sometimes useful to use MMU_SECTION_SIZE
2051		here, since it is cheaper to change data cache settings on
2052		a per-section basis.
2053
2054		CONFIG_CONSOLE_SCROLL_LINES
2055
2056		When the console need to be scrolled, this is the number of
2057		lines to scroll by. It defaults to 1. Increasing this makes
2058		the console jump but can help speed up operation when scrolling
2059		is slow.
2060
2061		CONFIG_LCD_BMP_RLE8
2062
2063		Support drawing of RLE8-compressed bitmaps on the LCD.
2064
2065		CONFIG_I2C_EDID
2066
2067		Enables an 'i2c edid' command which can read EDID
2068		information over I2C from an attached LCD display.
2069
2070- Splash Screen Support: CONFIG_SPLASH_SCREEN
2071
2072		If this option is set, the environment is checked for
2073		a variable "splashimage". If found, the usual display
2074		of logo, copyright and system information on the LCD
2075		is suppressed and the BMP image at the address
2076		specified in "splashimage" is loaded instead. The
2077		console is redirected to the "nulldev", too. This
2078		allows for a "silent" boot where a splash screen is
2079		loaded very quickly after power-on.
2080
2081		CONFIG_SPLASHIMAGE_GUARD
2082
2083		If this option is set, then U-Boot will prevent the environment
2084		variable "splashimage" from being set to a problematic address
2085		(see README.displaying-bmps).
2086		This option is useful for targets where, due to alignment
2087		restrictions, an improperly aligned BMP image will cause a data
2088		abort. If you think you will not have problems with unaligned
2089		accesses (for example because your toolchain prevents them)
2090		there is no need to set this option.
2091
2092		CONFIG_SPLASH_SCREEN_ALIGN
2093
2094		If this option is set the splash image can be freely positioned
2095		on the screen. Environment variable "splashpos" specifies the
2096		position as "x,y". If a positive number is given it is used as
2097		number of pixel from left/top. If a negative number is given it
2098		is used as number of pixel from right/bottom. You can also
2099		specify 'm' for centering the image.
2100
2101		Example:
2102		setenv splashpos m,m
2103			=> image at center of screen
2104
2105		setenv splashpos 30,20
2106			=> image at x = 30 and y = 20
2107
2108		setenv splashpos -10,m
2109			=> vertically centered image
2110			   at x = dspWidth - bmpWidth - 9
2111
2112- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
2113
2114		If this option is set, additionally to standard BMP
2115		images, gzipped BMP images can be displayed via the
2116		splashscreen support or the bmp command.
2117
2118- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
2119
2120		If this option is set, 8-bit RLE compressed BMP images
2121		can be displayed via the splashscreen support or the
2122		bmp command.
2123
2124- Do compressing for memory range:
2125		CONFIG_CMD_ZIP
2126
2127		If this option is set, it would use zlib deflate method
2128		to compress the specified memory at its best effort.
2129
2130- Compression support:
2131		CONFIG_GZIP
2132
2133		Enabled by default to support gzip compressed images.
2134
2135		CONFIG_BZIP2
2136
2137		If this option is set, support for bzip2 compressed
2138		images is included. If not, only uncompressed and gzip
2139		compressed images are supported.
2140
2141		NOTE: the bzip2 algorithm requires a lot of RAM, so
2142		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
2143		be at least 4MB.
2144
2145		CONFIG_LZMA
2146
2147		If this option is set, support for lzma compressed
2148		images is included.
2149
2150		Note: The LZMA algorithm adds between 2 and 4KB of code and it
2151		requires an amount of dynamic memory that is given by the
2152		formula:
2153
2154			(1846 + 768 << (lc + lp)) * sizeof(uint16)
2155
2156		Where lc and lp stand for, respectively, Literal context bits
2157		and Literal pos bits.
2158
2159		This value is upper-bounded by 14MB in the worst case. Anyway,
2160		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
2161		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
2162		a very small buffer.
2163
2164		Use the lzmainfo tool to determinate the lc and lp values and
2165		then calculate the amount of needed dynamic memory (ensuring
2166		the appropriate CONFIG_SYS_MALLOC_LEN value).
2167
2168		CONFIG_LZO
2169
2170		If this option is set, support for LZO compressed images
2171		is included.
2172
2173- MII/PHY support:
2174		CONFIG_PHY_ADDR
2175
2176		The address of PHY on MII bus.
2177
2178		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
2179
2180		The clock frequency of the MII bus
2181
2182		CONFIG_PHY_GIGE
2183
2184		If this option is set, support for speed/duplex
2185		detection of gigabit PHY is included.
2186
2187		CONFIG_PHY_RESET_DELAY
2188
2189		Some PHY like Intel LXT971A need extra delay after
2190		reset before any MII register access is possible.
2191		For such PHY, set this option to the usec delay
2192		required. (minimum 300usec for LXT971A)
2193
2194		CONFIG_PHY_CMD_DELAY (ppc4xx)
2195
2196		Some PHY like Intel LXT971A need extra delay after
2197		command issued before MII status register can be read
2198
2199- Ethernet address:
2200		CONFIG_ETHADDR
2201		CONFIG_ETH1ADDR
2202		CONFIG_ETH2ADDR
2203		CONFIG_ETH3ADDR
2204		CONFIG_ETH4ADDR
2205		CONFIG_ETH5ADDR
2206
2207		Define a default value for Ethernet address to use
2208		for the respective Ethernet interface, in case this
2209		is not determined automatically.
2210
2211- IP address:
2212		CONFIG_IPADDR
2213
2214		Define a default value for the IP address to use for
2215		the default Ethernet interface, in case this is not
2216		determined through e.g. bootp.
2217		(Environment variable "ipaddr")
2218
2219- Server IP address:
2220		CONFIG_SERVERIP
2221
2222		Defines a default value for the IP address of a TFTP
2223		server to contact when using the "tftboot" command.
2224		(Environment variable "serverip")
2225
2226		CONFIG_KEEP_SERVERADDR
2227
2228		Keeps the server's MAC address, in the env 'serveraddr'
2229		for passing to bootargs (like Linux's netconsole option)
2230
2231- Gateway IP address:
2232		CONFIG_GATEWAYIP
2233
2234		Defines a default value for the IP address of the
2235		default router where packets to other networks are
2236		sent to.
2237		(Environment variable "gatewayip")
2238
2239- Subnet mask:
2240		CONFIG_NETMASK
2241
2242		Defines a default value for the subnet mask (or
2243		routing prefix) which is used to determine if an IP
2244		address belongs to the local subnet or needs to be
2245		forwarded through a router.
2246		(Environment variable "netmask")
2247
2248- Multicast TFTP Mode:
2249		CONFIG_MCAST_TFTP
2250
2251		Defines whether you want to support multicast TFTP as per
2252		rfc-2090; for example to work with atftp.  Lets lots of targets
2253		tftp down the same boot image concurrently.  Note: the Ethernet
2254		driver in use must provide a function: mcast() to join/leave a
2255		multicast group.
2256
2257- BOOTP Recovery Mode:
2258		CONFIG_BOOTP_RANDOM_DELAY
2259
2260		If you have many targets in a network that try to
2261		boot using BOOTP, you may want to avoid that all
2262		systems send out BOOTP requests at precisely the same
2263		moment (which would happen for instance at recovery
2264		from a power failure, when all systems will try to
2265		boot, thus flooding the BOOTP server. Defining
2266		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2267		inserted before sending out BOOTP requests. The
2268		following delays are inserted then:
2269
2270		1st BOOTP request:	delay 0 ... 1 sec
2271		2nd BOOTP request:	delay 0 ... 2 sec
2272		3rd BOOTP request:	delay 0 ... 4 sec
2273		4th and following
2274		BOOTP requests:		delay 0 ... 8 sec
2275
2276		CONFIG_BOOTP_ID_CACHE_SIZE
2277
2278		BOOTP packets are uniquely identified using a 32-bit ID. The
2279		server will copy the ID from client requests to responses and
2280		U-Boot will use this to determine if it is the destination of
2281		an incoming response. Some servers will check that addresses
2282		aren't in use before handing them out (usually using an ARP
2283		ping) and therefore take up to a few hundred milliseconds to
2284		respond. Network congestion may also influence the time it
2285		takes for a response to make it back to the client. If that
2286		time is too long, U-Boot will retransmit requests. In order
2287		to allow earlier responses to still be accepted after these
2288		retransmissions, U-Boot's BOOTP client keeps a small cache of
2289		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2290		cache. The default is to keep IDs for up to four outstanding
2291		requests. Increasing this will allow U-Boot to accept offers
2292		from a BOOTP client in networks with unusually high latency.
2293
2294- DHCP Advanced Options:
2295		You can fine tune the DHCP functionality by defining
2296		CONFIG_BOOTP_* symbols:
2297
2298		CONFIG_BOOTP_SUBNETMASK
2299		CONFIG_BOOTP_GATEWAY
2300		CONFIG_BOOTP_HOSTNAME
2301		CONFIG_BOOTP_NISDOMAIN
2302		CONFIG_BOOTP_BOOTPATH
2303		CONFIG_BOOTP_BOOTFILESIZE
2304		CONFIG_BOOTP_DNS
2305		CONFIG_BOOTP_DNS2
2306		CONFIG_BOOTP_SEND_HOSTNAME
2307		CONFIG_BOOTP_NTPSERVER
2308		CONFIG_BOOTP_TIMEOFFSET
2309		CONFIG_BOOTP_VENDOREX
2310		CONFIG_BOOTP_MAY_FAIL
2311
2312		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2313		environment variable, not the BOOTP server.
2314
2315		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2316		after the configured retry count, the call will fail
2317		instead of starting over.  This can be used to fail over
2318		to Link-local IP address configuration if the DHCP server
2319		is not available.
2320
2321		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2322		serverip from a DHCP server, it is possible that more
2323		than one DNS serverip is offered to the client.
2324		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2325		serverip will be stored in the additional environment
2326		variable "dnsip2". The first DNS serverip is always
2327		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2328		is defined.
2329
2330		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2331		to do a dynamic update of a DNS server. To do this, they
2332		need the hostname of the DHCP requester.
2333		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2334		of the "hostname" environment variable is passed as
2335		option 12 to the DHCP server.
2336
2337		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2338
2339		A 32bit value in microseconds for a delay between
2340		receiving a "DHCP Offer" and sending the "DHCP Request".
2341		This fixes a problem with certain DHCP servers that don't
2342		respond 100% of the time to a "DHCP request". E.g. On an
2343		AT91RM9200 processor running at 180MHz, this delay needed
2344		to be *at least* 15,000 usec before a Windows Server 2003
2345		DHCP server would reply 100% of the time. I recommend at
2346		least 50,000 usec to be safe. The alternative is to hope
2347		that one of the retries will be successful but note that
2348		the DHCP timeout and retry process takes a longer than
2349		this delay.
2350
2351 - Link-local IP address negotiation:
2352		Negotiate with other link-local clients on the local network
2353		for an address that doesn't require explicit configuration.
2354		This is especially useful if a DHCP server cannot be guaranteed
2355		to exist in all environments that the device must operate.
2356
2357		See doc/README.link-local for more information.
2358
2359 - CDP Options:
2360		CONFIG_CDP_DEVICE_ID
2361
2362		The device id used in CDP trigger frames.
2363
2364		CONFIG_CDP_DEVICE_ID_PREFIX
2365
2366		A two character string which is prefixed to the MAC address
2367		of the device.
2368
2369		CONFIG_CDP_PORT_ID
2370
2371		A printf format string which contains the ascii name of
2372		the port. Normally is set to "eth%d" which sets
2373		eth0 for the first Ethernet, eth1 for the second etc.
2374
2375		CONFIG_CDP_CAPABILITIES
2376
2377		A 32bit integer which indicates the device capabilities;
2378		0x00000010 for a normal host which does not forwards.
2379
2380		CONFIG_CDP_VERSION
2381
2382		An ascii string containing the version of the software.
2383
2384		CONFIG_CDP_PLATFORM
2385
2386		An ascii string containing the name of the platform.
2387
2388		CONFIG_CDP_TRIGGER
2389
2390		A 32bit integer sent on the trigger.
2391
2392		CONFIG_CDP_POWER_CONSUMPTION
2393
2394		A 16bit integer containing the power consumption of the
2395		device in .1 of milliwatts.
2396
2397		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2398
2399		A byte containing the id of the VLAN.
2400
2401- Status LED:	CONFIG_STATUS_LED
2402
2403		Several configurations allow to display the current
2404		status using a LED. For instance, the LED will blink
2405		fast while running U-Boot code, stop blinking as
2406		soon as a reply to a BOOTP request was received, and
2407		start blinking slow once the Linux kernel is running
2408		(supported by a status LED driver in the Linux
2409		kernel). Defining CONFIG_STATUS_LED enables this
2410		feature in U-Boot.
2411
2412		Additional options:
2413
2414		CONFIG_GPIO_LED
2415		The status LED can be connected to a GPIO pin.
2416		In such cases, the gpio_led driver can be used as a
2417		status LED backend implementation. Define CONFIG_GPIO_LED
2418		to include the gpio_led driver in the U-Boot binary.
2419
2420		CONFIG_GPIO_LED_INVERTED_TABLE
2421		Some GPIO connected LEDs may have inverted polarity in which
2422		case the GPIO high value corresponds to LED off state and
2423		GPIO low value corresponds to LED on state.
2424		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2425		with a list of GPIO LEDs that have inverted polarity.
2426
2427- CAN Support:	CONFIG_CAN_DRIVER
2428
2429		Defining CONFIG_CAN_DRIVER enables CAN driver support
2430		on those systems that support this (optional)
2431		feature, like the TQM8xxL modules.
2432
2433- I2C Support:	CONFIG_SYS_I2C
2434
2435		This enable the NEW i2c subsystem, and will allow you to use
2436		i2c commands at the u-boot command line (as long as you set
2437		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2438		based realtime clock chips or other i2c devices. See
2439		common/cmd_i2c.c for a description of the command line
2440		interface.
2441
2442		ported i2c driver to the new framework:
2443		- drivers/i2c/soft_i2c.c:
2444		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2445		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2446		    for defining speed and slave address
2447		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2448		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2449		    for defining speed and slave address
2450		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2451		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2452		    for defining speed and slave address
2453		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2454		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2455		    for defining speed and slave address
2456
2457		- drivers/i2c/fsl_i2c.c:
2458		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2459		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2460		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2461		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2462		    bus.
2463		  - If your board supports a second fsl i2c bus, define
2464		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2465		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2466		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2467		    second bus.
2468
2469		- drivers/i2c/tegra_i2c.c:
2470		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2471		  - This driver adds 4 i2c buses with a fix speed from
2472		    100000 and the slave addr 0!
2473
2474		- drivers/i2c/ppc4xx_i2c.c
2475		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2476		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2477		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2478
2479		- drivers/i2c/i2c_mxc.c
2480		  - activate this driver with CONFIG_SYS_I2C_MXC
2481		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2482		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2483		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2484		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2485		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2486		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2487		If those defines are not set, default value is 100000
2488		for speed, and 0 for slave.
2489
2490		- drivers/i2c/rcar_i2c.c:
2491		  - activate this driver with CONFIG_SYS_I2C_RCAR
2492		  - This driver adds 4 i2c buses
2493
2494		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2495		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2496		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2497		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2498		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2499		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2500		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2501		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2502		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2503
2504		- drivers/i2c/sh_i2c.c:
2505		  - activate this driver with CONFIG_SYS_I2C_SH
2506		  - This driver adds from 2 to 5 i2c buses
2507
2508		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2509		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2510		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2511		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2512		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2513		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2514		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2515		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2516		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2517		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2518		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2519		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2520		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2521
2522		- drivers/i2c/omap24xx_i2c.c
2523		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2524		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2525		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2526		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2527		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2528		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2529		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2530		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2531		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2532		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2533		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2534
2535		- drivers/i2c/zynq_i2c.c
2536		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2537		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2538		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2539
2540		- drivers/i2c/s3c24x0_i2c.c:
2541		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2542		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2543		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2544		    with a fix speed from 100000 and the slave addr 0!
2545
2546		- drivers/i2c/ihs_i2c.c
2547		  - activate this driver with CONFIG_SYS_I2C_IHS
2548		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2549		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2550		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2551		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2552		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2553		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2554		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2555		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2556		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2557		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2558		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2559		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2560
2561		additional defines:
2562
2563		CONFIG_SYS_NUM_I2C_BUSES
2564		Hold the number of i2c buses you want to use. If you
2565		don't use/have i2c muxes on your i2c bus, this
2566		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2567		omit this define.
2568
2569		CONFIG_SYS_I2C_DIRECT_BUS
2570		define this, if you don't use i2c muxes on your hardware.
2571		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2572		omit this define.
2573
2574		CONFIG_SYS_I2C_MAX_HOPS
2575		define how many muxes are maximal consecutively connected
2576		on one i2c bus. If you not use i2c muxes, omit this
2577		define.
2578
2579		CONFIG_SYS_I2C_BUSES
2580		hold a list of buses you want to use, only used if
2581		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2582		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2583		CONFIG_SYS_NUM_I2C_BUSES = 9:
2584
2585		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2586					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2587					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2588					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2589					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2590					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2591					{1, {I2C_NULL_HOP}}, \
2592					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2593					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2594					}
2595
2596		which defines
2597			bus 0 on adapter 0 without a mux
2598			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2599			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2600			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2601			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2602			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2603			bus 6 on adapter 1 without a mux
2604			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2605			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2606
2607		If you do not have i2c muxes on your board, omit this define.
2608
2609- Legacy I2C Support:	CONFIG_HARD_I2C
2610
2611		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2612		provides the following compelling advantages:
2613
2614		- more than one i2c adapter is usable
2615		- approved multibus support
2616		- better i2c mux support
2617
2618		** Please consider updating your I2C driver now. **
2619
2620		These enable legacy I2C serial bus commands. Defining
2621		CONFIG_HARD_I2C will include the appropriate I2C driver
2622		for the selected CPU.
2623
2624		This will allow you to use i2c commands at the u-boot
2625		command line (as long as you set CONFIG_CMD_I2C in
2626		CONFIG_COMMANDS) and communicate with i2c based realtime
2627		clock chips. See common/cmd_i2c.c for a description of the
2628		command line interface.
2629
2630		CONFIG_HARD_I2C selects a hardware I2C controller.
2631
2632		There are several other quantities that must also be
2633		defined when you define CONFIG_HARD_I2C.
2634
2635		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2636		to be the frequency (in Hz) at which you wish your i2c bus
2637		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2638		the CPU's i2c node address).
2639
2640		Now, the u-boot i2c code for the mpc8xx
2641		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2642		and so its address should therefore be cleared to 0 (See,
2643		eg, MPC823e User's Manual p.16-473). So, set
2644		CONFIG_SYS_I2C_SLAVE to 0.
2645
2646		CONFIG_SYS_I2C_INIT_MPC5XXX
2647
2648		When a board is reset during an i2c bus transfer
2649		chips might think that the current transfer is still
2650		in progress.  Reset the slave devices by sending start
2651		commands until the slave device responds.
2652
2653		That's all that's required for CONFIG_HARD_I2C.
2654
2655		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2656		then the following macros need to be defined (examples are
2657		from include/configs/lwmon.h):
2658
2659		I2C_INIT
2660
2661		(Optional). Any commands necessary to enable the I2C
2662		controller or configure ports.
2663
2664		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2665
2666		I2C_PORT
2667
2668		(Only for MPC8260 CPU). The I/O port to use (the code
2669		assumes both bits are on the same port). Valid values
2670		are 0..3 for ports A..D.
2671
2672		I2C_ACTIVE
2673
2674		The code necessary to make the I2C data line active
2675		(driven).  If the data line is open collector, this
2676		define can be null.
2677
2678		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2679
2680		I2C_TRISTATE
2681
2682		The code necessary to make the I2C data line tri-stated
2683		(inactive).  If the data line is open collector, this
2684		define can be null.
2685
2686		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2687
2688		I2C_READ
2689
2690		Code that returns true if the I2C data line is high,
2691		false if it is low.
2692
2693		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2694
2695		I2C_SDA(bit)
2696
2697		If <bit> is true, sets the I2C data line high. If it
2698		is false, it clears it (low).
2699
2700		eg: #define I2C_SDA(bit) \
2701			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2702			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2703
2704		I2C_SCL(bit)
2705
2706		If <bit> is true, sets the I2C clock line high. If it
2707		is false, it clears it (low).
2708
2709		eg: #define I2C_SCL(bit) \
2710			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2711			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2712
2713		I2C_DELAY
2714
2715		This delay is invoked four times per clock cycle so this
2716		controls the rate of data transfer.  The data rate thus
2717		is 1 / (I2C_DELAY * 4). Often defined to be something
2718		like:
2719
2720		#define I2C_DELAY  udelay(2)
2721
2722		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2723
2724		If your arch supports the generic GPIO framework (asm/gpio.h),
2725		then you may alternatively define the two GPIOs that are to be
2726		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2727		have GPIO-based defaults assigned to them as appropriate.
2728
2729		You should define these to the GPIO value as given directly to
2730		the generic GPIO functions.
2731
2732		CONFIG_SYS_I2C_INIT_BOARD
2733
2734		When a board is reset during an i2c bus transfer
2735		chips might think that the current transfer is still
2736		in progress. On some boards it is possible to access
2737		the i2c SCLK line directly, either by using the
2738		processor pin as a GPIO or by having a second pin
2739		connected to the bus. If this option is defined a
2740		custom i2c_init_board() routine in boards/xxx/board.c
2741		is run early in the boot sequence.
2742
2743		CONFIG_SYS_I2C_BOARD_LATE_INIT
2744
2745		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2746		defined a custom i2c_board_late_init() routine in
2747		boards/xxx/board.c is run AFTER the operations in i2c_init()
2748		is completed. This callpoint can be used to unreset i2c bus
2749		using CPU i2c controller register accesses for CPUs whose i2c
2750		controller provide such a method. It is called at the end of
2751		i2c_init() to allow i2c_init operations to setup the i2c bus
2752		controller on the CPU (e.g. setting bus speed & slave address).
2753
2754		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2755
2756		This option enables configuration of bi_iic_fast[] flags
2757		in u-boot bd_info structure based on u-boot environment
2758		variable "i2cfast". (see also i2cfast)
2759
2760		CONFIG_I2C_MULTI_BUS
2761
2762		This option allows the use of multiple I2C buses, each of which
2763		must have a controller.	 At any point in time, only one bus is
2764		active.	 To switch to a different bus, use the 'i2c dev' command.
2765		Note that bus numbering is zero-based.
2766
2767		CONFIG_SYS_I2C_NOPROBES
2768
2769		This option specifies a list of I2C devices that will be skipped
2770		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2771		is set, specify a list of bus-device pairs.  Otherwise, specify
2772		a 1D array of device addresses
2773
2774		e.g.
2775			#undef	CONFIG_I2C_MULTI_BUS
2776			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2777
2778		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2779
2780			#define CONFIG_I2C_MULTI_BUS
2781			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2782
2783		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2784
2785		CONFIG_SYS_SPD_BUS_NUM
2786
2787		If defined, then this indicates the I2C bus number for DDR SPD.
2788		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2789
2790		CONFIG_SYS_RTC_BUS_NUM
2791
2792		If defined, then this indicates the I2C bus number for the RTC.
2793		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2794
2795		CONFIG_SYS_DTT_BUS_NUM
2796
2797		If defined, then this indicates the I2C bus number for the DTT.
2798		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2799
2800		CONFIG_SYS_I2C_DTT_ADDR:
2801
2802		If defined, specifies the I2C address of the DTT device.
2803		If not defined, then U-Boot uses predefined value for
2804		specified DTT device.
2805
2806		CONFIG_SOFT_I2C_READ_REPEATED_START
2807
2808		defining this will force the i2c_read() function in
2809		the soft_i2c driver to perform an I2C repeated start
2810		between writing the address pointer and reading the
2811		data.  If this define is omitted the default behaviour
2812		of doing a stop-start sequence will be used.  Most I2C
2813		devices can use either method, but some require one or
2814		the other.
2815
2816- SPI Support:	CONFIG_SPI
2817
2818		Enables SPI driver (so far only tested with
2819		SPI EEPROM, also an instance works with Crystal A/D and
2820		D/As on the SACSng board)
2821
2822		CONFIG_SH_SPI
2823
2824		Enables the driver for SPI controller on SuperH. Currently
2825		only SH7757 is supported.
2826
2827		CONFIG_SPI_X
2828
2829		Enables extended (16-bit) SPI EEPROM addressing.
2830		(symmetrical to CONFIG_I2C_X)
2831
2832		CONFIG_SOFT_SPI
2833
2834		Enables a software (bit-bang) SPI driver rather than
2835		using hardware support. This is a general purpose
2836		driver that only requires three general I/O port pins
2837		(two outputs, one input) to function. If this is
2838		defined, the board configuration must define several
2839		SPI configuration items (port pins to use, etc). For
2840		an example, see include/configs/sacsng.h.
2841
2842		CONFIG_HARD_SPI
2843
2844		Enables a hardware SPI driver for general-purpose reads
2845		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2846		must define a list of chip-select function pointers.
2847		Currently supported on some MPC8xxx processors.	 For an
2848		example, see include/configs/mpc8349emds.h.
2849
2850		CONFIG_MXC_SPI
2851
2852		Enables the driver for the SPI controllers on i.MX and MXC
2853		SoCs. Currently i.MX31/35/51 are supported.
2854
2855		CONFIG_SYS_SPI_MXC_WAIT
2856		Timeout for waiting until spi transfer completed.
2857		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2858
2859- FPGA Support: CONFIG_FPGA
2860
2861		Enables FPGA subsystem.
2862
2863		CONFIG_FPGA_<vendor>
2864
2865		Enables support for specific chip vendors.
2866		(ALTERA, XILINX)
2867
2868		CONFIG_FPGA_<family>
2869
2870		Enables support for FPGA family.
2871		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2872
2873		CONFIG_FPGA_COUNT
2874
2875		Specify the number of FPGA devices to support.
2876
2877		CONFIG_CMD_FPGA_LOADMK
2878
2879		Enable support for fpga loadmk command
2880
2881		CONFIG_CMD_FPGA_LOADP
2882
2883		Enable support for fpga loadp command - load partial bitstream
2884
2885		CONFIG_CMD_FPGA_LOADBP
2886
2887		Enable support for fpga loadbp command - load partial bitstream
2888		(Xilinx only)
2889
2890		CONFIG_SYS_FPGA_PROG_FEEDBACK
2891
2892		Enable printing of hash marks during FPGA configuration.
2893
2894		CONFIG_SYS_FPGA_CHECK_BUSY
2895
2896		Enable checks on FPGA configuration interface busy
2897		status by the configuration function. This option
2898		will require a board or device specific function to
2899		be written.
2900
2901		CONFIG_FPGA_DELAY
2902
2903		If defined, a function that provides delays in the FPGA
2904		configuration driver.
2905
2906		CONFIG_SYS_FPGA_CHECK_CTRLC
2907		Allow Control-C to interrupt FPGA configuration
2908
2909		CONFIG_SYS_FPGA_CHECK_ERROR
2910
2911		Check for configuration errors during FPGA bitfile
2912		loading. For example, abort during Virtex II
2913		configuration if the INIT_B line goes low (which
2914		indicated a CRC error).
2915
2916		CONFIG_SYS_FPGA_WAIT_INIT
2917
2918		Maximum time to wait for the INIT_B line to de-assert
2919		after PROB_B has been de-asserted during a Virtex II
2920		FPGA configuration sequence. The default time is 500
2921		ms.
2922
2923		CONFIG_SYS_FPGA_WAIT_BUSY
2924
2925		Maximum time to wait for BUSY to de-assert during
2926		Virtex II FPGA configuration. The default is 5 ms.
2927
2928		CONFIG_SYS_FPGA_WAIT_CONFIG
2929
2930		Time to wait after FPGA configuration. The default is
2931		200 ms.
2932
2933- Configuration Management:
2934		CONFIG_BUILD_TARGET
2935
2936		Some SoCs need special image types (e.g. U-Boot binary
2937		with a special header) as build targets. By defining
2938		CONFIG_BUILD_TARGET in the SoC / board header, this
2939		special image will be automatically built upon calling
2940		make / MAKEALL.
2941
2942		CONFIG_IDENT_STRING
2943
2944		If defined, this string will be added to the U-Boot
2945		version information (U_BOOT_VERSION)
2946
2947- Vendor Parameter Protection:
2948
2949		U-Boot considers the values of the environment
2950		variables "serial#" (Board Serial Number) and
2951		"ethaddr" (Ethernet Address) to be parameters that
2952		are set once by the board vendor / manufacturer, and
2953		protects these variables from casual modification by
2954		the user. Once set, these variables are read-only,
2955		and write or delete attempts are rejected. You can
2956		change this behaviour:
2957
2958		If CONFIG_ENV_OVERWRITE is #defined in your config
2959		file, the write protection for vendor parameters is
2960		completely disabled. Anybody can change or delete
2961		these parameters.
2962
2963		Alternatively, if you #define _both_ CONFIG_ETHADDR
2964		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2965		Ethernet address is installed in the environment,
2966		which can be changed exactly ONCE by the user. [The
2967		serial# is unaffected by this, i. e. it remains
2968		read-only.]
2969
2970		The same can be accomplished in a more flexible way
2971		for any variable by configuring the type of access
2972		to allow for those variables in the ".flags" variable
2973		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2974
2975- Protected RAM:
2976		CONFIG_PRAM
2977
2978		Define this variable to enable the reservation of
2979		"protected RAM", i. e. RAM which is not overwritten
2980		by U-Boot. Define CONFIG_PRAM to hold the number of
2981		kB you want to reserve for pRAM. You can overwrite
2982		this default value by defining an environment
2983		variable "pram" to the number of kB you want to
2984		reserve. Note that the board info structure will
2985		still show the full amount of RAM. If pRAM is
2986		reserved, a new environment variable "mem" will
2987		automatically be defined to hold the amount of
2988		remaining RAM in a form that can be passed as boot
2989		argument to Linux, for instance like that:
2990
2991			setenv bootargs ... mem=\${mem}
2992			saveenv
2993
2994		This way you can tell Linux not to use this memory,
2995		either, which results in a memory region that will
2996		not be affected by reboots.
2997
2998		*WARNING* If your board configuration uses automatic
2999		detection of the RAM size, you must make sure that
3000		this memory test is non-destructive. So far, the
3001		following board configurations are known to be
3002		"pRAM-clean":
3003
3004			IVMS8, IVML24, SPD8xx, TQM8xxL,
3005			HERMES, IP860, RPXlite, LWMON,
3006			FLAGADM, TQM8260
3007
3008- Access to physical memory region (> 4GB)
3009		Some basic support is provided for operations on memory not
3010		normally accessible to U-Boot - e.g. some architectures
3011		support access to more than 4GB of memory on 32-bit
3012		machines using physical address extension or similar.
3013		Define CONFIG_PHYSMEM to access this basic support, which
3014		currently only supports clearing the memory.
3015
3016- Error Recovery:
3017		CONFIG_PANIC_HANG
3018
3019		Define this variable to stop the system in case of a
3020		fatal error, so that you have to reset it manually.
3021		This is probably NOT a good idea for an embedded
3022		system where you want the system to reboot
3023		automatically as fast as possible, but it may be
3024		useful during development since you can try to debug
3025		the conditions that lead to the situation.
3026
3027		CONFIG_NET_RETRY_COUNT
3028
3029		This variable defines the number of retries for
3030		network operations like ARP, RARP, TFTP, or BOOTP
3031		before giving up the operation. If not defined, a
3032		default value of 5 is used.
3033
3034		CONFIG_ARP_TIMEOUT
3035
3036		Timeout waiting for an ARP reply in milliseconds.
3037
3038		CONFIG_NFS_TIMEOUT
3039
3040		Timeout in milliseconds used in NFS protocol.
3041		If you encounter "ERROR: Cannot umount" in nfs command,
3042		try longer timeout such as
3043		#define CONFIG_NFS_TIMEOUT 10000UL
3044
3045- Command Interpreter:
3046		CONFIG_AUTO_COMPLETE
3047
3048		Enable auto completion of commands using TAB.
3049
3050		CONFIG_SYS_PROMPT_HUSH_PS2
3051
3052		This defines the secondary prompt string, which is
3053		printed when the command interpreter needs more input
3054		to complete a command. Usually "> ".
3055
3056	Note:
3057
3058		In the current implementation, the local variables
3059		space and global environment variables space are
3060		separated. Local variables are those you define by
3061		simply typing `name=value'. To access a local
3062		variable later on, you have write `$name' or
3063		`${name}'; to execute the contents of a variable
3064		directly type `$name' at the command prompt.
3065
3066		Global environment variables are those you use
3067		setenv/printenv to work with. To run a command stored
3068		in such a variable, you need to use the run command,
3069		and you must not use the '$' sign to access them.
3070
3071		To store commands and special characters in a
3072		variable, please use double quotation marks
3073		surrounding the whole text of the variable, instead
3074		of the backslashes before semicolons and special
3075		symbols.
3076
3077- Command Line Editing and History:
3078		CONFIG_CMDLINE_EDITING
3079
3080		Enable editing and History functions for interactive
3081		command line input operations
3082
3083- Default Environment:
3084		CONFIG_EXTRA_ENV_SETTINGS
3085
3086		Define this to contain any number of null terminated
3087		strings (variable = value pairs) that will be part of
3088		the default environment compiled into the boot image.
3089
3090		For example, place something like this in your
3091		board's config file:
3092
3093		#define CONFIG_EXTRA_ENV_SETTINGS \
3094			"myvar1=value1\0" \
3095			"myvar2=value2\0"
3096
3097		Warning: This method is based on knowledge about the
3098		internal format how the environment is stored by the
3099		U-Boot code. This is NOT an official, exported
3100		interface! Although it is unlikely that this format
3101		will change soon, there is no guarantee either.
3102		You better know what you are doing here.
3103
3104		Note: overly (ab)use of the default environment is
3105		discouraged. Make sure to check other ways to preset
3106		the environment like the "source" command or the
3107		boot command first.
3108
3109		CONFIG_ENV_VARS_UBOOT_CONFIG
3110
3111		Define this in order to add variables describing the
3112		U-Boot build configuration to the default environment.
3113		These will be named arch, cpu, board, vendor, and soc.
3114
3115		Enabling this option will cause the following to be defined:
3116
3117		- CONFIG_SYS_ARCH
3118		- CONFIG_SYS_CPU
3119		- CONFIG_SYS_BOARD
3120		- CONFIG_SYS_VENDOR
3121		- CONFIG_SYS_SOC
3122
3123		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
3124
3125		Define this in order to add variables describing certain
3126		run-time determined information about the hardware to the
3127		environment.  These will be named board_name, board_rev.
3128
3129		CONFIG_DELAY_ENVIRONMENT
3130
3131		Normally the environment is loaded when the board is
3132		initialised so that it is available to U-Boot. This inhibits
3133		that so that the environment is not available until
3134		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
3135		this is instead controlled by the value of
3136		/config/load-environment.
3137
3138- DataFlash Support:
3139		CONFIG_HAS_DATAFLASH
3140
3141		Defining this option enables DataFlash features and
3142		allows to read/write in Dataflash via the standard
3143		commands cp, md...
3144
3145- Serial Flash support
3146		CONFIG_CMD_SF
3147
3148		Defining this option enables SPI flash commands
3149		'sf probe/read/write/erase/update'.
3150
3151		Usage requires an initial 'probe' to define the serial
3152		flash parameters, followed by read/write/erase/update
3153		commands.
3154
3155		The following defaults may be provided by the platform
3156		to handle the common case when only a single serial
3157		flash is present on the system.
3158
3159		CONFIG_SF_DEFAULT_BUS		Bus identifier
3160		CONFIG_SF_DEFAULT_CS		Chip-select
3161		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
3162		CONFIG_SF_DEFAULT_SPEED		in Hz
3163
3164		CONFIG_CMD_SF_TEST
3165
3166		Define this option to include a destructive SPI flash
3167		test ('sf test').
3168
3169		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
3170
3171		Define this option to use the Bank addr/Extended addr
3172		support on SPI flashes which has size > 16Mbytes.
3173
3174		CONFIG_SF_DUAL_FLASH		Dual flash memories
3175
3176		Define this option to use dual flash support where two flash
3177		memories can be connected with a given cs line.
3178		Currently Xilinx Zynq qspi supports these type of connections.
3179
3180		CONFIG_SYS_SPI_ST_ENABLE_WP_PIN
3181		enable the W#/Vpp signal to disable writing to the status
3182		register on ST MICRON flashes like the N25Q128.
3183		The status register write enable/disable bit, combined with
3184		the W#/VPP signal provides hardware data protection for the
3185		device as follows: When the enable/disable bit is set to 1,
3186		and the W#/VPP signal is driven LOW, the status register
3187		nonvolatile bits become read-only and the WRITE STATUS REGISTER
3188		operation will not execute. The only way to exit this
3189		hardware-protected mode is to drive W#/VPP HIGH.
3190
3191- SystemACE Support:
3192		CONFIG_SYSTEMACE
3193
3194		Adding this option adds support for Xilinx SystemACE
3195		chips attached via some sort of local bus. The address
3196		of the chip must also be defined in the
3197		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
3198
3199		#define CONFIG_SYSTEMACE
3200		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
3201
3202		When SystemACE support is added, the "ace" device type
3203		becomes available to the fat commands, i.e. fatls.
3204
3205- TFTP Fixed UDP Port:
3206		CONFIG_TFTP_PORT
3207
3208		If this is defined, the environment variable tftpsrcp
3209		is used to supply the TFTP UDP source port value.
3210		If tftpsrcp isn't defined, the normal pseudo-random port
3211		number generator is used.
3212
3213		Also, the environment variable tftpdstp is used to supply
3214		the TFTP UDP destination port value.  If tftpdstp isn't
3215		defined, the normal port 69 is used.
3216
3217		The purpose for tftpsrcp is to allow a TFTP server to
3218		blindly start the TFTP transfer using the pre-configured
3219		target IP address and UDP port. This has the effect of
3220		"punching through" the (Windows XP) firewall, allowing
3221		the remainder of the TFTP transfer to proceed normally.
3222		A better solution is to properly configure the firewall,
3223		but sometimes that is not allowed.
3224
3225- Hashing support:
3226		CONFIG_CMD_HASH
3227
3228		This enables a generic 'hash' command which can produce
3229		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
3230
3231		CONFIG_HASH_VERIFY
3232
3233		Enable the hash verify command (hash -v). This adds to code
3234		size a little.
3235
3236		CONFIG_SHA1 - This option enables support of hashing using SHA1
3237		algorithm. The hash is calculated in software.
3238		CONFIG_SHA256 - This option enables support of hashing using
3239		SHA256 algorithm. The hash is calculated in software.
3240		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
3241		for SHA1/SHA256 hashing.
3242		This affects the 'hash' command and also the
3243		hash_lookup_algo() function.
3244		CONFIG_SHA_PROG_HW_ACCEL - This option enables
3245		hardware-acceleration for SHA1/SHA256 progressive hashing.
3246		Data can be streamed in a block at a time and the hashing
3247		is performed in hardware.
3248
3249		Note: There is also a sha1sum command, which should perhaps
3250		be deprecated in favour of 'hash sha1'.
3251
3252- Freescale i.MX specific commands:
3253		CONFIG_CMD_HDMIDETECT
3254		This enables 'hdmidet' command which returns true if an
3255		HDMI monitor is detected.  This command is i.MX 6 specific.
3256
3257		CONFIG_CMD_BMODE
3258		This enables the 'bmode' (bootmode) command for forcing
3259		a boot from specific media.
3260
3261		This is useful for forcing the ROM's usb downloader to
3262		activate upon a watchdog reset which is nice when iterating
3263		on U-Boot.  Using the reset button or running bmode normal
3264		will set it back to normal.  This command currently
3265		supports i.MX53 and i.MX6.
3266
3267- Signing support:
3268		CONFIG_RSA
3269
3270		This enables the RSA algorithm used for FIT image verification
3271		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
3272
3273		The Modular Exponentiation algorithm in RSA is implemented using
3274		driver model. So CONFIG_DM needs to be enabled by default for this
3275		library to function.
3276
3277		The signing part is build into mkimage regardless of this
3278		option. The software based modular exponentiation is built into
3279		mkimage irrespective of this option.
3280
3281- bootcount support:
3282		CONFIG_BOOTCOUNT_LIMIT
3283
3284		This enables the bootcounter support, see:
3285		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3286
3287		CONFIG_AT91SAM9XE
3288		enable special bootcounter support on at91sam9xe based boards.
3289		CONFIG_BLACKFIN
3290		enable special bootcounter support on blackfin based boards.
3291		CONFIG_SOC_DA8XX
3292		enable special bootcounter support on da850 based boards.
3293		CONFIG_BOOTCOUNT_RAM
3294		enable support for the bootcounter in RAM
3295		CONFIG_BOOTCOUNT_I2C
3296		enable support for the bootcounter on an i2c (like RTC) device.
3297			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3298			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3299						    the bootcounter.
3300			CONFIG_BOOTCOUNT_ALEN = address len
3301
3302- Show boot progress:
3303		CONFIG_SHOW_BOOT_PROGRESS
3304
3305		Defining this option allows to add some board-
3306		specific code (calling a user-provided function
3307		"show_boot_progress(int)") that enables you to show
3308		the system's boot progress on some display (for
3309		example, some LED's) on your board. At the moment,
3310		the following checkpoints are implemented:
3311
3312- Detailed boot stage timing
3313		CONFIG_BOOTSTAGE
3314		Define this option to get detailed timing of each stage
3315		of the boot process.
3316
3317		CONFIG_BOOTSTAGE_USER_COUNT
3318		This is the number of available user bootstage records.
3319		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
3320		a new ID will be allocated from this stash. If you exceed
3321		the limit, recording will stop.
3322
3323		CONFIG_BOOTSTAGE_REPORT
3324		Define this to print a report before boot, similar to this:
3325
3326		Timer summary in microseconds:
3327		       Mark    Elapsed  Stage
3328			  0          0  reset
3329		  3,575,678  3,575,678  board_init_f start
3330		  3,575,695         17  arch_cpu_init A9
3331		  3,575,777         82  arch_cpu_init done
3332		  3,659,598     83,821  board_init_r start
3333		  3,910,375    250,777  main_loop
3334		 29,916,167 26,005,792  bootm_start
3335		 30,361,327    445,160  start_kernel
3336
3337		CONFIG_CMD_BOOTSTAGE
3338		Add a 'bootstage' command which supports printing a report
3339		and un/stashing of bootstage data.
3340
3341		CONFIG_BOOTSTAGE_FDT
3342		Stash the bootstage information in the FDT. A root 'bootstage'
3343		node is created with each bootstage id as a child. Each child
3344		has a 'name' property and either 'mark' containing the
3345		mark time in microsecond, or 'accum' containing the
3346		accumulated time for that bootstage id in microseconds.
3347		For example:
3348
3349		bootstage {
3350			154 {
3351				name = "board_init_f";
3352				mark = <3575678>;
3353			};
3354			170 {
3355				name = "lcd";
3356				accum = <33482>;
3357			};
3358		};
3359
3360		Code in the Linux kernel can find this in /proc/devicetree.
3361
3362Legacy uImage format:
3363
3364  Arg	Where			When
3365    1	common/cmd_bootm.c	before attempting to boot an image
3366   -1	common/cmd_bootm.c	Image header has bad	 magic number
3367    2	common/cmd_bootm.c	Image header has correct magic number
3368   -2	common/cmd_bootm.c	Image header has bad	 checksum
3369    3	common/cmd_bootm.c	Image header has correct checksum
3370   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3371    4	common/cmd_bootm.c	Image data   has correct checksum
3372   -4	common/cmd_bootm.c	Image is for unsupported architecture
3373    5	common/cmd_bootm.c	Architecture check OK
3374   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3375    6	common/cmd_bootm.c	Image Type check OK
3376   -6	common/cmd_bootm.c	gunzip uncompression error
3377   -7	common/cmd_bootm.c	Unimplemented compression type
3378    7	common/cmd_bootm.c	Uncompression OK
3379    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3380   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3381
3382    9	common/image.c		Start initial ramdisk verification
3383  -10	common/image.c		Ramdisk header has bad	   magic number
3384  -11	common/image.c		Ramdisk header has bad	   checksum
3385   10	common/image.c		Ramdisk header is OK
3386  -12	common/image.c		Ramdisk data   has bad	   checksum
3387   11	common/image.c		Ramdisk data   has correct checksum
3388   12	common/image.c		Ramdisk verification complete, start loading
3389  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3390   13	common/image.c		Start multifile image verification
3391   14	common/image.c		No initial ramdisk, no multifile, continue.
3392
3393   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3394
3395  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3396  -31	post/post.c		POST test failed, detected by post_output_backlog()
3397  -32	post/post.c		POST test failed, detected by post_run_single()
3398
3399   34	common/cmd_doc.c	before loading a Image from a DOC device
3400  -35	common/cmd_doc.c	Bad usage of "doc" command
3401   35	common/cmd_doc.c	correct usage of "doc" command
3402  -36	common/cmd_doc.c	No boot device
3403   36	common/cmd_doc.c	correct boot device
3404  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3405   37	common/cmd_doc.c	correct chip ID found, device available
3406  -38	common/cmd_doc.c	Read Error on boot device
3407   38	common/cmd_doc.c	reading Image header from DOC device OK
3408  -39	common/cmd_doc.c	Image header has bad magic number
3409   39	common/cmd_doc.c	Image header has correct magic number
3410  -40	common/cmd_doc.c	Error reading Image from DOC device
3411   40	common/cmd_doc.c	Image header has correct magic number
3412   41	common/cmd_ide.c	before loading a Image from a IDE device
3413  -42	common/cmd_ide.c	Bad usage of "ide" command
3414   42	common/cmd_ide.c	correct usage of "ide" command
3415  -43	common/cmd_ide.c	No boot device
3416   43	common/cmd_ide.c	boot device found
3417  -44	common/cmd_ide.c	Device not available
3418   44	common/cmd_ide.c	Device available
3419  -45	common/cmd_ide.c	wrong partition selected
3420   45	common/cmd_ide.c	partition selected
3421  -46	common/cmd_ide.c	Unknown partition table
3422   46	common/cmd_ide.c	valid partition table found
3423  -47	common/cmd_ide.c	Invalid partition type
3424   47	common/cmd_ide.c	correct partition type
3425  -48	common/cmd_ide.c	Error reading Image Header on boot device
3426   48	common/cmd_ide.c	reading Image Header from IDE device OK
3427  -49	common/cmd_ide.c	Image header has bad magic number
3428   49	common/cmd_ide.c	Image header has correct magic number
3429  -50	common/cmd_ide.c	Image header has bad	 checksum
3430   50	common/cmd_ide.c	Image header has correct checksum
3431  -51	common/cmd_ide.c	Error reading Image from IDE device
3432   51	common/cmd_ide.c	reading Image from IDE device OK
3433   52	common/cmd_nand.c	before loading a Image from a NAND device
3434  -53	common/cmd_nand.c	Bad usage of "nand" command
3435   53	common/cmd_nand.c	correct usage of "nand" command
3436  -54	common/cmd_nand.c	No boot device
3437   54	common/cmd_nand.c	boot device found
3438  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3439   55	common/cmd_nand.c	correct chip ID found, device available
3440  -56	common/cmd_nand.c	Error reading Image Header on boot device
3441   56	common/cmd_nand.c	reading Image Header from NAND device OK
3442  -57	common/cmd_nand.c	Image header has bad magic number
3443   57	common/cmd_nand.c	Image header has correct magic number
3444  -58	common/cmd_nand.c	Error reading Image from NAND device
3445   58	common/cmd_nand.c	reading Image from NAND device OK
3446
3447  -60	common/env_common.c	Environment has a bad CRC, using default
3448
3449   64	net/eth.c		starting with Ethernet configuration.
3450  -64	net/eth.c		no Ethernet found.
3451   65	net/eth.c		Ethernet found.
3452
3453  -80	common/cmd_net.c	usage wrong
3454   80	common/cmd_net.c	before calling NetLoop()
3455  -81	common/cmd_net.c	some error in NetLoop() occurred
3456   81	common/cmd_net.c	NetLoop() back without error
3457  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3458   82	common/cmd_net.c	trying automatic boot
3459   83	common/cmd_net.c	running "source" command
3460  -83	common/cmd_net.c	some error in automatic boot or "source" command
3461   84	common/cmd_net.c	end without errors
3462
3463FIT uImage format:
3464
3465  Arg	Where			When
3466  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3467 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3468  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3469 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3470  102	common/cmd_bootm.c	Kernel unit name specified
3471 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3472  103	common/cmd_bootm.c	Found configuration node
3473  104	common/cmd_bootm.c	Got kernel subimage node offset
3474 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3475  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3476 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3477  106	common/cmd_bootm.c	Architecture check OK
3478 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3479  107	common/cmd_bootm.c	Kernel subimage type OK
3480 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3481  108	common/cmd_bootm.c	Got kernel subimage data/size
3482 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3483 -109	common/cmd_bootm.c	Can't get kernel subimage type
3484 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3485 -111	common/cmd_bootm.c	Can't get kernel subimage os
3486 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3487 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3488
3489  120	common/image.c		Start initial ramdisk verification
3490 -120	common/image.c		Ramdisk FIT image has incorrect format
3491  121	common/image.c		Ramdisk FIT image has correct format
3492  122	common/image.c		No ramdisk subimage unit name, using configuration
3493 -122	common/image.c		Can't get configuration for ramdisk subimage
3494  123	common/image.c		Ramdisk unit name specified
3495 -124	common/image.c		Can't get ramdisk subimage node offset
3496  125	common/image.c		Got ramdisk subimage node offset
3497 -125	common/image.c		Ramdisk subimage hash verification failed
3498  126	common/image.c		Ramdisk subimage hash verification OK
3499 -126	common/image.c		Ramdisk subimage for unsupported architecture
3500  127	common/image.c		Architecture check OK
3501 -127	common/image.c		Can't get ramdisk subimage data/size
3502  128	common/image.c		Got ramdisk subimage data/size
3503  129	common/image.c		Can't get ramdisk load address
3504 -129	common/image.c		Got ramdisk load address
3505
3506 -130	common/cmd_doc.c	Incorrect FIT image format
3507  131	common/cmd_doc.c	FIT image format OK
3508
3509 -140	common/cmd_ide.c	Incorrect FIT image format
3510  141	common/cmd_ide.c	FIT image format OK
3511
3512 -150	common/cmd_nand.c	Incorrect FIT image format
3513  151	common/cmd_nand.c	FIT image format OK
3514
3515- legacy image format:
3516		CONFIG_IMAGE_FORMAT_LEGACY
3517		enables the legacy image format support in U-Boot.
3518
3519		Default:
3520		enabled if CONFIG_FIT_SIGNATURE is not defined.
3521
3522		CONFIG_DISABLE_IMAGE_LEGACY
3523		disable the legacy image format
3524
3525		This define is introduced, as the legacy image format is
3526		enabled per default for backward compatibility.
3527
3528- FIT image support:
3529		CONFIG_FIT
3530		Enable support for the FIT uImage format.
3531
3532		CONFIG_FIT_BEST_MATCH
3533		When no configuration is explicitly selected, default to the
3534		one whose fdt's compatibility field best matches that of
3535		U-Boot itself. A match is considered "best" if it matches the
3536		most specific compatibility entry of U-Boot's fdt's root node.
3537		The order of entries in the configuration's fdt is ignored.
3538
3539		CONFIG_FIT_SIGNATURE
3540		This option enables signature verification of FIT uImages,
3541		using a hash signed and verified using RSA. If
3542		CONFIG_SHA_PROG_HW_ACCEL is defined, i.e support for progressive
3543		hashing is available using hardware, RSA library will use it.
3544		See doc/uImage.FIT/signature.txt for more details.
3545
3546		WARNING: When relying on signed FIT images with required
3547		signature check the legacy image format is default
3548		disabled. If a board need legacy image format support
3549		enable this through CONFIG_IMAGE_FORMAT_LEGACY
3550
3551		CONFIG_FIT_DISABLE_SHA256
3552		Supporting SHA256 hashes has quite an impact on binary size.
3553		For constrained systems sha256 hash support can be disabled
3554		with this option.
3555
3556- Standalone program support:
3557		CONFIG_STANDALONE_LOAD_ADDR
3558
3559		This option defines a board specific value for the
3560		address where standalone program gets loaded, thus
3561		overwriting the architecture dependent default
3562		settings.
3563
3564- Frame Buffer Address:
3565		CONFIG_FB_ADDR
3566
3567		Define CONFIG_FB_ADDR if you want to use specific
3568		address for frame buffer.  This is typically the case
3569		when using a graphics controller has separate video
3570		memory.  U-Boot will then place the frame buffer at
3571		the given address instead of dynamically reserving it
3572		in system RAM by calling lcd_setmem(), which grabs
3573		the memory for the frame buffer depending on the
3574		configured panel size.
3575
3576		Please see board_init_f function.
3577
3578- Automatic software updates via TFTP server
3579		CONFIG_UPDATE_TFTP
3580		CONFIG_UPDATE_TFTP_CNT_MAX
3581		CONFIG_UPDATE_TFTP_MSEC_MAX
3582
3583		These options enable and control the auto-update feature;
3584		for a more detailed description refer to doc/README.update.
3585
3586- MTD Support (mtdparts command, UBI support)
3587		CONFIG_MTD_DEVICE
3588
3589		Adds the MTD device infrastructure from the Linux kernel.
3590		Needed for mtdparts command support.
3591
3592		CONFIG_MTD_PARTITIONS
3593
3594		Adds the MTD partitioning infrastructure from the Linux
3595		kernel. Needed for UBI support.
3596
3597		CONFIG_MTD_NAND_VERIFY_WRITE
3598		verify if the written data is correct reread.
3599
3600- UBI support
3601		CONFIG_CMD_UBI
3602
3603		Adds commands for interacting with MTD partitions formatted
3604		with the UBI flash translation layer
3605
3606		Requires also defining CONFIG_RBTREE
3607
3608		CONFIG_UBI_SILENCE_MSG
3609
3610		Make the verbose messages from UBI stop printing.  This leaves
3611		warnings and errors enabled.
3612
3613
3614		CONFIG_MTD_UBI_WL_THRESHOLD
3615		This parameter defines the maximum difference between the highest
3616		erase counter value and the lowest erase counter value of eraseblocks
3617		of UBI devices. When this threshold is exceeded, UBI starts performing
3618		wear leveling by means of moving data from eraseblock with low erase
3619		counter to eraseblocks with high erase counter.
3620
3621		The default value should be OK for SLC NAND flashes, NOR flashes and
3622		other flashes which have eraseblock life-cycle 100000 or more.
3623		However, in case of MLC NAND flashes which typically have eraseblock
3624		life-cycle less than 10000, the threshold should be lessened (e.g.,
3625		to 128 or 256, although it does not have to be power of 2).
3626
3627		default: 4096
3628
3629		CONFIG_MTD_UBI_BEB_LIMIT
3630		This option specifies the maximum bad physical eraseblocks UBI
3631		expects on the MTD device (per 1024 eraseblocks). If the
3632		underlying flash does not admit of bad eraseblocks (e.g. NOR
3633		flash), this value is ignored.
3634
3635		NAND datasheets often specify the minimum and maximum NVM
3636		(Number of Valid Blocks) for the flashes' endurance lifetime.
3637		The maximum expected bad eraseblocks per 1024 eraseblocks
3638		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3639		which gives 20 for most NANDs (MaxNVB is basically the total
3640		count of eraseblocks on the chip).
3641
3642		To put it differently, if this value is 20, UBI will try to
3643		reserve about 1.9% of physical eraseblocks for bad blocks
3644		handling. And that will be 1.9% of eraseblocks on the entire
3645		NAND chip, not just the MTD partition UBI attaches. This means
3646		that if you have, say, a NAND flash chip admits maximum 40 bad
3647		eraseblocks, and it is split on two MTD partitions of the same
3648		size, UBI will reserve 40 eraseblocks when attaching a
3649		partition.
3650
3651		default: 20
3652
3653		CONFIG_MTD_UBI_FASTMAP
3654		Fastmap is a mechanism which allows attaching an UBI device
3655		in nearly constant time. Instead of scanning the whole MTD device it
3656		only has to locate a checkpoint (called fastmap) on the device.
3657		The on-flash fastmap contains all information needed to attach
3658		the device. Using fastmap makes only sense on large devices where
3659		attaching by scanning takes long. UBI will not automatically install
3660		a fastmap on old images, but you can set the UBI parameter
3661		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3662		that fastmap-enabled images are still usable with UBI implementations
3663		without	fastmap support. On typical flash devices the whole fastmap
3664		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3665
3666		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3667		Set this parameter to enable fastmap automatically on images
3668		without a fastmap.
3669		default: 0
3670
3671- UBIFS support
3672		CONFIG_CMD_UBIFS
3673
3674		Adds commands for interacting with UBI volumes formatted as
3675		UBIFS.  UBIFS is read-only in u-boot.
3676
3677		Requires UBI support as well as CONFIG_LZO
3678
3679		CONFIG_UBIFS_SILENCE_MSG
3680
3681		Make the verbose messages from UBIFS stop printing.  This leaves
3682		warnings and errors enabled.
3683
3684- SPL framework
3685		CONFIG_SPL
3686		Enable building of SPL globally.
3687
3688		CONFIG_SPL_LDSCRIPT
3689		LDSCRIPT for linking the SPL binary.
3690
3691		CONFIG_SPL_MAX_FOOTPRINT
3692		Maximum size in memory allocated to the SPL, BSS included.
3693		When defined, the linker checks that the actual memory
3694		used by SPL from _start to __bss_end does not exceed it.
3695		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3696		must not be both defined at the same time.
3697
3698		CONFIG_SPL_MAX_SIZE
3699		Maximum size of the SPL image (text, data, rodata, and
3700		linker lists sections), BSS excluded.
3701		When defined, the linker checks that the actual size does
3702		not exceed it.
3703
3704		CONFIG_SPL_TEXT_BASE
3705		TEXT_BASE for linking the SPL binary.
3706
3707		CONFIG_SPL_RELOC_TEXT_BASE
3708		Address to relocate to.  If unspecified, this is equal to
3709		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3710
3711		CONFIG_SPL_BSS_START_ADDR
3712		Link address for the BSS within the SPL binary.
3713
3714		CONFIG_SPL_BSS_MAX_SIZE
3715		Maximum size in memory allocated to the SPL BSS.
3716		When defined, the linker checks that the actual memory used
3717		by SPL from __bss_start to __bss_end does not exceed it.
3718		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3719		must not be both defined at the same time.
3720
3721		CONFIG_SPL_STACK
3722		Adress of the start of the stack SPL will use
3723
3724		CONFIG_SPL_RELOC_STACK
3725		Adress of the start of the stack SPL will use after
3726		relocation.  If unspecified, this is equal to
3727		CONFIG_SPL_STACK.
3728
3729		CONFIG_SYS_SPL_MALLOC_START
3730		Starting address of the malloc pool used in SPL.
3731
3732		CONFIG_SYS_SPL_MALLOC_SIZE
3733		The size of the malloc pool used in SPL.
3734
3735		CONFIG_SPL_FRAMEWORK
3736		Enable the SPL framework under common/.  This framework
3737		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3738		NAND loading of the Linux Kernel.
3739
3740		CONFIG_SPL_OS_BOOT
3741		Enable booting directly to an OS from SPL.
3742		See also: doc/README.falcon
3743
3744		CONFIG_SPL_DISPLAY_PRINT
3745		For ARM, enable an optional function to print more information
3746		about the running system.
3747
3748		CONFIG_SPL_INIT_MINIMAL
3749		Arch init code should be built for a very small image
3750
3751		CONFIG_SPL_LIBCOMMON_SUPPORT
3752		Support for common/libcommon.o in SPL binary
3753
3754		CONFIG_SPL_LIBDISK_SUPPORT
3755		Support for disk/libdisk.o in SPL binary
3756
3757		CONFIG_SPL_I2C_SUPPORT
3758		Support for drivers/i2c/libi2c.o in SPL binary
3759
3760		CONFIG_SPL_GPIO_SUPPORT
3761		Support for drivers/gpio/libgpio.o in SPL binary
3762
3763		CONFIG_SPL_MMC_SUPPORT
3764		Support for drivers/mmc/libmmc.o in SPL binary
3765
3766		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3767		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3768		Address and partition on the MMC to load U-Boot from
3769		when the MMC is being used in raw mode.
3770
3771		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3772		Partition on the MMC to load U-Boot from when the MMC is being
3773		used in raw mode
3774
3775		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3776		Sector to load kernel uImage from when MMC is being
3777		used in raw mode (for Falcon mode)
3778
3779		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3780		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3781		Sector and number of sectors to load kernel argument
3782		parameters from when MMC is being used in raw mode
3783		(for falcon mode)
3784
3785		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3786		Partition on the MMC to load U-Boot from when the MMC is being
3787		used in fs mode
3788
3789		CONFIG_SPL_FAT_SUPPORT
3790		Support for fs/fat/libfat.o in SPL binary
3791
3792		CONFIG_SPL_EXT_SUPPORT
3793		Support for EXT filesystem in SPL binary
3794
3795		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3796		Filename to read to load U-Boot when reading from filesystem
3797
3798		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3799		Filename to read to load kernel uImage when reading
3800		from filesystem (for Falcon mode)
3801
3802		CONFIG_SPL_FS_LOAD_ARGS_NAME
3803		Filename to read to load kernel argument parameters
3804		when reading from filesystem (for Falcon mode)
3805
3806		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3807		Set this for NAND SPL on PPC mpc83xx targets, so that
3808		start.S waits for the rest of the SPL to load before
3809		continuing (the hardware starts execution after just
3810		loading the first page rather than the full 4K).
3811
3812		CONFIG_SPL_SKIP_RELOCATE
3813		Avoid SPL relocation
3814
3815		CONFIG_SPL_NAND_BASE
3816		Include nand_base.c in the SPL.  Requires
3817		CONFIG_SPL_NAND_DRIVERS.
3818
3819		CONFIG_SPL_NAND_DRIVERS
3820		SPL uses normal NAND drivers, not minimal drivers.
3821
3822		CONFIG_SPL_NAND_ECC
3823		Include standard software ECC in the SPL
3824
3825		CONFIG_SPL_NAND_SIMPLE
3826		Support for NAND boot using simple NAND drivers that
3827		expose the cmd_ctrl() interface.
3828
3829		CONFIG_SPL_MTD_SUPPORT
3830		Support for the MTD subsystem within SPL.  Useful for
3831		environment on NAND support within SPL.
3832
3833		CONFIG_SPL_NAND_RAW_ONLY
3834		Support to boot only raw u-boot.bin images. Use this only
3835		if you need to save space.
3836
3837		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3838		Set for the SPL on PPC mpc8xxx targets, support for
3839		drivers/ddr/fsl/libddr.o in SPL binary.
3840
3841		CONFIG_SPL_COMMON_INIT_DDR
3842		Set for common ddr init with serial presence detect in
3843		SPL binary.
3844
3845		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3846		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3847		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3848		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3849		CONFIG_SYS_NAND_ECCBYTES
3850		Defines the size and behavior of the NAND that SPL uses
3851		to read U-Boot
3852
3853		CONFIG_SPL_NAND_BOOT
3854		Add support NAND boot
3855
3856		CONFIG_SYS_NAND_U_BOOT_OFFS
3857		Location in NAND to read U-Boot from
3858
3859		CONFIG_SYS_NAND_U_BOOT_DST
3860		Location in memory to load U-Boot to
3861
3862		CONFIG_SYS_NAND_U_BOOT_SIZE
3863		Size of image to load
3864
3865		CONFIG_SYS_NAND_U_BOOT_START
3866		Entry point in loaded image to jump to
3867
3868		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3869		Define this if you need to first read the OOB and then the
3870		data. This is used, for example, on davinci platforms.
3871
3872		CONFIG_SPL_OMAP3_ID_NAND
3873		Support for an OMAP3-specific set of functions to return the
3874		ID and MFR of the first attached NAND chip, if present.
3875
3876		CONFIG_SPL_SERIAL_SUPPORT
3877		Support for drivers/serial/libserial.o in SPL binary
3878
3879		CONFIG_SPL_SPI_FLASH_SUPPORT
3880		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3881
3882		CONFIG_SPL_SPI_SUPPORT
3883		Support for drivers/spi/libspi.o in SPL binary
3884
3885		CONFIG_SPL_RAM_DEVICE
3886		Support for running image already present in ram, in SPL binary
3887
3888		CONFIG_SPL_LIBGENERIC_SUPPORT
3889		Support for lib/libgeneric.o in SPL binary
3890
3891		CONFIG_SPL_ENV_SUPPORT
3892		Support for the environment operating in SPL binary
3893
3894		CONFIG_SPL_NET_SUPPORT
3895		Support for the net/libnet.o in SPL binary.
3896		It conflicts with SPL env from storage medium specified by
3897		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3898
3899		CONFIG_SPL_PAD_TO
3900		Image offset to which the SPL should be padded before appending
3901		the SPL payload. By default, this is defined as
3902		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3903		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3904		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3905
3906		CONFIG_SPL_TARGET
3907		Final target image containing SPL and payload.  Some SPLs
3908		use an arch-specific makefile fragment instead, for
3909		example if more than one image needs to be produced.
3910
3911		CONFIG_FIT_SPL_PRINT
3912		Printing information about a FIT image adds quite a bit of
3913		code to SPL. So this is normally disabled in SPL. Use this
3914		option to re-enable it. This will affect the output of the
3915		bootm command when booting a FIT image.
3916
3917- TPL framework
3918		CONFIG_TPL
3919		Enable building of TPL globally.
3920
3921		CONFIG_TPL_PAD_TO
3922		Image offset to which the TPL should be padded before appending
3923		the TPL payload. By default, this is defined as
3924		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3925		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3926		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3927
3928Modem Support:
3929--------------
3930
3931[so far only for SMDK2400 boards]
3932
3933- Modem support enable:
3934		CONFIG_MODEM_SUPPORT
3935
3936- RTS/CTS Flow control enable:
3937		CONFIG_HWFLOW
3938
3939- Modem debug support:
3940		CONFIG_MODEM_SUPPORT_DEBUG
3941
3942		Enables debugging stuff (char screen[1024], dbg())
3943		for modem support. Useful only with BDI2000.
3944
3945- Interrupt support (PPC):
3946
3947		There are common interrupt_init() and timer_interrupt()
3948		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3949		for CPU specific initialization. interrupt_init_cpu()
3950		should set decrementer_count to appropriate value. If
3951		CPU resets decrementer automatically after interrupt
3952		(ppc4xx) it should set decrementer_count to zero.
3953		timer_interrupt() calls timer_interrupt_cpu() for CPU
3954		specific handling. If board has watchdog / status_led
3955		/ other_activity_monitor it works automatically from
3956		general timer_interrupt().
3957
3958- General:
3959
3960		In the target system modem support is enabled when a
3961		specific key (key combination) is pressed during
3962		power-on. Otherwise U-Boot will boot normally
3963		(autoboot). The key_pressed() function is called from
3964		board_init(). Currently key_pressed() is a dummy
3965		function, returning 1 and thus enabling modem
3966		initialization.
3967
3968		If there are no modem init strings in the
3969		environment, U-Boot proceed to autoboot; the
3970		previous output (banner, info printfs) will be
3971		suppressed, though.
3972
3973		See also: doc/README.Modem
3974
3975Board initialization settings:
3976------------------------------
3977
3978During Initialization u-boot calls a number of board specific functions
3979to allow the preparation of board specific prerequisites, e.g. pin setup
3980before drivers are initialized. To enable these callbacks the
3981following configuration macros have to be defined. Currently this is
3982architecture specific, so please check arch/your_architecture/lib/board.c
3983typically in board_init_f() and board_init_r().
3984
3985- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3986- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3987- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3988- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3989
3990Configuration Settings:
3991-----------------------
3992
3993- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3994		Optionally it can be defined to support 64-bit memory commands.
3995
3996- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3997		undefine this when you're short of memory.
3998
3999- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
4000		width of the commands listed in the 'help' command output.
4001
4002- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
4003		prompt for user input.
4004
4005- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
4006
4007- CONFIG_SYS_PBSIZE:	Buffer size for Console output
4008
4009- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
4010
4011- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
4012		the application (usually a Linux kernel) when it is
4013		booted
4014
4015- CONFIG_SYS_BAUDRATE_TABLE:
4016		List of legal baudrate settings for this board.
4017
4018- CONFIG_SYS_CONSOLE_INFO_QUIET
4019		Suppress display of console information at boot.
4020
4021- CONFIG_SYS_CONSOLE_IS_IN_ENV
4022		If the board specific function
4023			extern int overwrite_console (void);
4024		returns 1, the stdin, stderr and stdout are switched to the
4025		serial port, else the settings in the environment are used.
4026
4027- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
4028		Enable the call to overwrite_console().
4029
4030- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
4031		Enable overwrite of previous console environment settings.
4032
4033- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
4034		Begin and End addresses of the area used by the
4035		simple memory test.
4036
4037- CONFIG_SYS_ALT_MEMTEST:
4038		Enable an alternate, more extensive memory test.
4039
4040- CONFIG_SYS_MEMTEST_SCRATCH:
4041		Scratch address used by the alternate memory test
4042		You only need to set this if address zero isn't writeable
4043
4044- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
4045		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
4046		this specified memory area will get subtracted from the top
4047		(end) of RAM and won't get "touched" at all by U-Boot. By
4048		fixing up gd->ram_size the Linux kernel should gets passed
4049		the now "corrected" memory size and won't touch it either.
4050		This should work for arch/ppc and arch/powerpc. Only Linux
4051		board ports in arch/powerpc with bootwrapper support that
4052		recalculate the memory size from the SDRAM controller setup
4053		will have to get fixed in Linux additionally.
4054
4055		This option can be used as a workaround for the 440EPx/GRx
4056		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
4057		be touched.
4058
4059		WARNING: Please make sure that this value is a multiple of
4060		the Linux page size (normally 4k). If this is not the case,
4061		then the end address of the Linux memory will be located at a
4062		non page size aligned address and this could cause major
4063		problems.
4064
4065- CONFIG_SYS_LOADS_BAUD_CHANGE:
4066		Enable temporary baudrate change while serial download
4067
4068- CONFIG_SYS_SDRAM_BASE:
4069		Physical start address of SDRAM. _Must_ be 0 here.
4070
4071- CONFIG_SYS_MBIO_BASE:
4072		Physical start address of Motherboard I/O (if using a
4073		Cogent motherboard)
4074
4075- CONFIG_SYS_FLASH_BASE:
4076		Physical start address of Flash memory.
4077
4078- CONFIG_SYS_MONITOR_BASE:
4079		Physical start address of boot monitor code (set by
4080		make config files to be same as the text base address
4081		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
4082		CONFIG_SYS_FLASH_BASE when booting from flash.
4083
4084- CONFIG_SYS_MONITOR_LEN:
4085		Size of memory reserved for monitor code, used to
4086		determine _at_compile_time_ (!) if the environment is
4087		embedded within the U-Boot image, or in a separate
4088		flash sector.
4089
4090- CONFIG_SYS_MALLOC_LEN:
4091		Size of DRAM reserved for malloc() use.
4092
4093- CONFIG_SYS_MALLOC_F_LEN
4094		Size of the malloc() pool for use before relocation. If
4095		this is defined, then a very simple malloc() implementation
4096		will become available before relocation. The address is just
4097		below the global data, and the stack is moved down to make
4098		space.
4099
4100		This feature allocates regions with increasing addresses
4101		within the region. calloc() is supported, but realloc()
4102		is not available. free() is supported but does nothing.
4103		The memory will be freed (or in fact just forgotten) when
4104		U-Boot relocates itself.
4105
4106		Pre-relocation malloc() is only supported on ARM and sandbox
4107		at present but is fairly easy to enable for other archs.
4108
4109- CONFIG_SYS_MALLOC_SIMPLE
4110		Provides a simple and small malloc() and calloc() for those
4111		boards which do not use the full malloc in SPL (which is
4112		enabled with CONFIG_SYS_SPL_MALLOC_START).
4113
4114- CONFIG_SYS_NONCACHED_MEMORY:
4115		Size of non-cached memory area. This area of memory will be
4116		typically located right below the malloc() area and mapped
4117		uncached in the MMU. This is useful for drivers that would
4118		otherwise require a lot of explicit cache maintenance. For
4119		some drivers it's also impossible to properly maintain the
4120		cache. For example if the regions that need to be flushed
4121		are not a multiple of the cache-line size, *and* padding
4122		cannot be allocated between the regions to align them (i.e.
4123		if the HW requires a contiguous array of regions, and the
4124		size of each region is not cache-aligned), then a flush of
4125		one region may result in overwriting data that hardware has
4126		written to another region in the same cache-line. This can
4127		happen for example in network drivers where descriptors for
4128		buffers are typically smaller than the CPU cache-line (e.g.
4129		16 bytes vs. 32 or 64 bytes).
4130
4131		Non-cached memory is only supported on 32-bit ARM at present.
4132
4133- CONFIG_SYS_BOOTM_LEN:
4134		Normally compressed uImages are limited to an
4135		uncompressed size of 8 MBytes. If this is not enough,
4136		you can define CONFIG_SYS_BOOTM_LEN in your board config file
4137		to adjust this setting to your needs.
4138
4139- CONFIG_SYS_BOOTMAPSZ:
4140		Maximum size of memory mapped by the startup code of
4141		the Linux kernel; all data that must be processed by
4142		the Linux kernel (bd_info, boot arguments, FDT blob if
4143		used) must be put below this limit, unless "bootm_low"
4144		environment variable is defined and non-zero. In such case
4145		all data for the Linux kernel must be between "bootm_low"
4146		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
4147		variable "bootm_mapsize" will override the value of
4148		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
4149		then the value in "bootm_size" will be used instead.
4150
4151- CONFIG_SYS_BOOT_RAMDISK_HIGH:
4152		Enable initrd_high functionality.  If defined then the
4153		initrd_high feature is enabled and the bootm ramdisk subcommand
4154		is enabled.
4155
4156- CONFIG_SYS_BOOT_GET_CMDLINE:
4157		Enables allocating and saving kernel cmdline in space between
4158		"bootm_low" and "bootm_low" + BOOTMAPSZ.
4159
4160- CONFIG_SYS_BOOT_GET_KBD:
4161		Enables allocating and saving a kernel copy of the bd_info in
4162		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
4163
4164- CONFIG_SYS_MAX_FLASH_BANKS:
4165		Max number of Flash memory banks
4166
4167- CONFIG_SYS_MAX_FLASH_SECT:
4168		Max number of sectors on a Flash chip
4169
4170- CONFIG_SYS_FLASH_ERASE_TOUT:
4171		Timeout for Flash erase operations (in ms)
4172
4173- CONFIG_SYS_FLASH_WRITE_TOUT:
4174		Timeout for Flash write operations (in ms)
4175
4176- CONFIG_SYS_FLASH_LOCK_TOUT
4177		Timeout for Flash set sector lock bit operation (in ms)
4178
4179- CONFIG_SYS_FLASH_UNLOCK_TOUT
4180		Timeout for Flash clear lock bits operation (in ms)
4181
4182- CONFIG_SYS_FLASH_PROTECTION
4183		If defined, hardware flash sectors protection is used
4184		instead of U-Boot software protection.
4185
4186- CONFIG_SYS_DIRECT_FLASH_TFTP:
4187
4188		Enable TFTP transfers directly to flash memory;
4189		without this option such a download has to be
4190		performed in two steps: (1) download to RAM, and (2)
4191		copy from RAM to flash.
4192
4193		The two-step approach is usually more reliable, since
4194		you can check if the download worked before you erase
4195		the flash, but in some situations (when system RAM is
4196		too limited to allow for a temporary copy of the
4197		downloaded image) this option may be very useful.
4198
4199- CONFIG_SYS_FLASH_CFI:
4200		Define if the flash driver uses extra elements in the
4201		common flash structure for storing flash geometry.
4202
4203- CONFIG_FLASH_CFI_DRIVER
4204		This option also enables the building of the cfi_flash driver
4205		in the drivers directory
4206
4207- CONFIG_FLASH_CFI_MTD
4208		This option enables the building of the cfi_mtd driver
4209		in the drivers directory. The driver exports CFI flash
4210		to the MTD layer.
4211
4212- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
4213		Use buffered writes to flash.
4214
4215- CONFIG_FLASH_SPANSION_S29WS_N
4216		s29ws-n MirrorBit flash has non-standard addresses for buffered
4217		write commands.
4218
4219- CONFIG_SYS_FLASH_QUIET_TEST
4220		If this option is defined, the common CFI flash doesn't
4221		print it's warning upon not recognized FLASH banks. This
4222		is useful, if some of the configured banks are only
4223		optionally available.
4224
4225- CONFIG_FLASH_SHOW_PROGRESS
4226		If defined (must be an integer), print out countdown
4227		digits and dots.  Recommended value: 45 (9..1) for 80
4228		column displays, 15 (3..1) for 40 column displays.
4229
4230- CONFIG_FLASH_VERIFY
4231		If defined, the content of the flash (destination) is compared
4232		against the source after the write operation. An error message
4233		will be printed when the contents are not identical.
4234		Please note that this option is useless in nearly all cases,
4235		since such flash programming errors usually are detected earlier
4236		while unprotecting/erasing/programming. Please only enable
4237		this option if you really know what you are doing.
4238
4239- CONFIG_SYS_RX_ETH_BUFFER:
4240		Defines the number of Ethernet receive buffers. On some
4241		Ethernet controllers it is recommended to set this value
4242		to 8 or even higher (EEPRO100 or 405 EMAC), since all
4243		buffers can be full shortly after enabling the interface
4244		on high Ethernet traffic.
4245		Defaults to 4 if not defined.
4246
4247- CONFIG_ENV_MAX_ENTRIES
4248
4249	Maximum number of entries in the hash table that is used
4250	internally to store the environment settings. The default
4251	setting is supposed to be generous and should work in most
4252	cases. This setting can be used to tune behaviour; see
4253	lib/hashtable.c for details.
4254
4255- CONFIG_ENV_FLAGS_LIST_DEFAULT
4256- CONFIG_ENV_FLAGS_LIST_STATIC
4257	Enable validation of the values given to environment variables when
4258	calling env set.  Variables can be restricted to only decimal,
4259	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
4260	the variables can also be restricted to IP address or MAC address.
4261
4262	The format of the list is:
4263		type_attribute = [s|d|x|b|i|m]
4264		access_attribute = [a|r|o|c]
4265		attributes = type_attribute[access_attribute]
4266		entry = variable_name[:attributes]
4267		list = entry[,list]
4268
4269	The type attributes are:
4270		s - String (default)
4271		d - Decimal
4272		x - Hexadecimal
4273		b - Boolean ([1yYtT|0nNfF])
4274		i - IP address
4275		m - MAC address
4276
4277	The access attributes are:
4278		a - Any (default)
4279		r - Read-only
4280		o - Write-once
4281		c - Change-default
4282
4283	- CONFIG_ENV_FLAGS_LIST_DEFAULT
4284		Define this to a list (string) to define the ".flags"
4285		environment variable in the default or embedded environment.
4286
4287	- CONFIG_ENV_FLAGS_LIST_STATIC
4288		Define this to a list (string) to define validation that
4289		should be done if an entry is not found in the ".flags"
4290		environment variable.  To override a setting in the static
4291		list, simply add an entry for the same variable name to the
4292		".flags" variable.
4293
4294- CONFIG_ENV_ACCESS_IGNORE_FORCE
4295	If defined, don't allow the -f switch to env set override variable
4296	access flags.
4297
4298- CONFIG_SYS_GENERIC_BOARD
4299	This selects the architecture-generic board system instead of the
4300	architecture-specific board files. It is intended to move boards
4301	to this new framework over time. Defining this will disable the
4302	arch/foo/lib/board.c file and use common/board_f.c and
4303	common/board_r.c instead. To use this option your architecture
4304	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
4305	its config.mk file). If you find problems enabling this option on
4306	your board please report the problem and send patches!
4307
4308- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
4309	This is set by OMAP boards for the max time that reset should
4310	be asserted. See doc/README.omap-reset-time for details on how
4311	the value can be calculated on a given board.
4312
4313- CONFIG_USE_STDINT
4314	If stdint.h is available with your toolchain you can define this
4315	option to enable it. You can provide option 'USE_STDINT=1' when
4316	building U-Boot to enable this.
4317
4318The following definitions that deal with the placement and management
4319of environment data (variable area); in general, we support the
4320following configurations:
4321
4322- CONFIG_BUILD_ENVCRC:
4323
4324	Builds up envcrc with the target environment so that external utils
4325	may easily extract it and embed it in final U-Boot images.
4326
4327- CONFIG_ENV_IS_IN_FLASH:
4328
4329	Define this if the environment is in flash memory.
4330
4331	a) The environment occupies one whole flash sector, which is
4332	   "embedded" in the text segment with the U-Boot code. This
4333	   happens usually with "bottom boot sector" or "top boot
4334	   sector" type flash chips, which have several smaller
4335	   sectors at the start or the end. For instance, such a
4336	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
4337	   such a case you would place the environment in one of the
4338	   4 kB sectors - with U-Boot code before and after it. With
4339	   "top boot sector" type flash chips, you would put the
4340	   environment in one of the last sectors, leaving a gap
4341	   between U-Boot and the environment.
4342
4343	- CONFIG_ENV_OFFSET:
4344
4345	   Offset of environment data (variable area) to the
4346	   beginning of flash memory; for instance, with bottom boot
4347	   type flash chips the second sector can be used: the offset
4348	   for this sector is given here.
4349
4350	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
4351
4352	- CONFIG_ENV_ADDR:
4353
4354	   This is just another way to specify the start address of
4355	   the flash sector containing the environment (instead of
4356	   CONFIG_ENV_OFFSET).
4357
4358	- CONFIG_ENV_SECT_SIZE:
4359
4360	   Size of the sector containing the environment.
4361
4362
4363	b) Sometimes flash chips have few, equal sized, BIG sectors.
4364	   In such a case you don't want to spend a whole sector for
4365	   the environment.
4366
4367	- CONFIG_ENV_SIZE:
4368
4369	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
4370	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
4371	   of this flash sector for the environment. This saves
4372	   memory for the RAM copy of the environment.
4373
4374	   It may also save flash memory if you decide to use this
4375	   when your environment is "embedded" within U-Boot code,
4376	   since then the remainder of the flash sector could be used
4377	   for U-Boot code. It should be pointed out that this is
4378	   STRONGLY DISCOURAGED from a robustness point of view:
4379	   updating the environment in flash makes it always
4380	   necessary to erase the WHOLE sector. If something goes
4381	   wrong before the contents has been restored from a copy in
4382	   RAM, your target system will be dead.
4383
4384	- CONFIG_ENV_ADDR_REDUND
4385	  CONFIG_ENV_SIZE_REDUND
4386
4387	   These settings describe a second storage area used to hold
4388	   a redundant copy of the environment data, so that there is
4389	   a valid backup copy in case there is a power failure during
4390	   a "saveenv" operation.
4391
4392BE CAREFUL! Any changes to the flash layout, and some changes to the
4393source code will make it necessary to adapt <board>/u-boot.lds*
4394accordingly!
4395
4396
4397- CONFIG_ENV_IS_IN_NVRAM:
4398
4399	Define this if you have some non-volatile memory device
4400	(NVRAM, battery buffered SRAM) which you want to use for the
4401	environment.
4402
4403	- CONFIG_ENV_ADDR:
4404	- CONFIG_ENV_SIZE:
4405
4406	  These two #defines are used to determine the memory area you
4407	  want to use for environment. It is assumed that this memory
4408	  can just be read and written to, without any special
4409	  provision.
4410
4411BE CAREFUL! The first access to the environment happens quite early
4412in U-Boot initialization (when we try to get the setting of for the
4413console baudrate). You *MUST* have mapped your NVRAM area then, or
4414U-Boot will hang.
4415
4416Please note that even with NVRAM we still use a copy of the
4417environment in RAM: we could work on NVRAM directly, but we want to
4418keep settings there always unmodified except somebody uses "saveenv"
4419to save the current settings.
4420
4421
4422- CONFIG_ENV_IS_IN_EEPROM:
4423
4424	Use this if you have an EEPROM or similar serial access
4425	device and a driver for it.
4426
4427	- CONFIG_ENV_OFFSET:
4428	- CONFIG_ENV_SIZE:
4429
4430	  These two #defines specify the offset and size of the
4431	  environment area within the total memory of your EEPROM.
4432
4433	- CONFIG_SYS_I2C_EEPROM_ADDR:
4434	  If defined, specified the chip address of the EEPROM device.
4435	  The default address is zero.
4436
4437	- CONFIG_SYS_I2C_EEPROM_BUS:
4438	  If defined, specified the i2c bus of the EEPROM device.
4439
4440	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4441	  If defined, the number of bits used to address bytes in a
4442	  single page in the EEPROM device.  A 64 byte page, for example
4443	  would require six bits.
4444
4445	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4446	  If defined, the number of milliseconds to delay between
4447	  page writes.	The default is zero milliseconds.
4448
4449	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4450	  The length in bytes of the EEPROM memory array address.  Note
4451	  that this is NOT the chip address length!
4452
4453	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4454	  EEPROM chips that implement "address overflow" are ones
4455	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4456	  address and the extra bits end up in the "chip address" bit
4457	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4458	  byte chips.
4459
4460	  Note that we consider the length of the address field to
4461	  still be one byte because the extra address bits are hidden
4462	  in the chip address.
4463
4464	- CONFIG_SYS_EEPROM_SIZE:
4465	  The size in bytes of the EEPROM device.
4466
4467	- CONFIG_ENV_EEPROM_IS_ON_I2C
4468	  define this, if you have I2C and SPI activated, and your
4469	  EEPROM, which holds the environment, is on the I2C bus.
4470
4471	- CONFIG_I2C_ENV_EEPROM_BUS
4472	  if you have an Environment on an EEPROM reached over
4473	  I2C muxes, you can define here, how to reach this
4474	  EEPROM. For example:
4475
4476	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4477
4478	  EEPROM which holds the environment, is reached over
4479	  a pca9547 i2c mux with address 0x70, channel 3.
4480
4481- CONFIG_ENV_IS_IN_DATAFLASH:
4482
4483	Define this if you have a DataFlash memory device which you
4484	want to use for the environment.
4485
4486	- CONFIG_ENV_OFFSET:
4487	- CONFIG_ENV_ADDR:
4488	- CONFIG_ENV_SIZE:
4489
4490	  These three #defines specify the offset and size of the
4491	  environment area within the total memory of your DataFlash placed
4492	  at the specified address.
4493
4494- CONFIG_ENV_IS_IN_SPI_FLASH:
4495
4496	Define this if you have a SPI Flash memory device which you
4497	want to use for the environment.
4498
4499	- CONFIG_ENV_OFFSET:
4500	- CONFIG_ENV_SIZE:
4501
4502	  These two #defines specify the offset and size of the
4503	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4504	  aligned to an erase sector boundary.
4505
4506	- CONFIG_ENV_SECT_SIZE:
4507
4508	  Define the SPI flash's sector size.
4509
4510	- CONFIG_ENV_OFFSET_REDUND (optional):
4511
4512	  This setting describes a second storage area of CONFIG_ENV_SIZE
4513	  size used to hold a redundant copy of the environment data, so
4514	  that there is a valid backup copy in case there is a power failure
4515	  during a "saveenv" operation. CONFIG_ENV_OFFSET_RENDUND must be
4516	  aligned to an erase sector boundary.
4517
4518	- CONFIG_ENV_SPI_BUS (optional):
4519	- CONFIG_ENV_SPI_CS (optional):
4520
4521	  Define the SPI bus and chip select. If not defined they will be 0.
4522
4523	- CONFIG_ENV_SPI_MAX_HZ (optional):
4524
4525	  Define the SPI max work clock. If not defined then use 1MHz.
4526
4527	- CONFIG_ENV_SPI_MODE (optional):
4528
4529	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4530
4531- CONFIG_ENV_IS_IN_REMOTE:
4532
4533	Define this if you have a remote memory space which you
4534	want to use for the local device's environment.
4535
4536	- CONFIG_ENV_ADDR:
4537	- CONFIG_ENV_SIZE:
4538
4539	  These two #defines specify the address and size of the
4540	  environment area within the remote memory space. The
4541	  local device can get the environment from remote memory
4542	  space by SRIO or PCIE links.
4543
4544BE CAREFUL! For some special cases, the local device can not use
4545"saveenv" command. For example, the local device will get the
4546environment stored in a remote NOR flash by SRIO or PCIE link,
4547but it can not erase, write this NOR flash by SRIO or PCIE interface.
4548
4549- CONFIG_ENV_IS_IN_NAND:
4550
4551	Define this if you have a NAND device which you want to use
4552	for the environment.
4553
4554	- CONFIG_ENV_OFFSET:
4555	- CONFIG_ENV_SIZE:
4556
4557	  These two #defines specify the offset and size of the environment
4558	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4559	  aligned to an erase block boundary.
4560
4561	- CONFIG_ENV_OFFSET_REDUND (optional):
4562
4563	  This setting describes a second storage area of CONFIG_ENV_SIZE
4564	  size used to hold a redundant copy of the environment data, so
4565	  that there is a valid backup copy in case there is a power failure
4566	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4567	  aligned to an erase block boundary.
4568
4569	- CONFIG_ENV_RANGE (optional):
4570
4571	  Specifies the length of the region in which the environment
4572	  can be written.  This should be a multiple of the NAND device's
4573	  block size.  Specifying a range with more erase blocks than
4574	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4575	  the range to be avoided.
4576
4577	- CONFIG_ENV_OFFSET_OOB (optional):
4578
4579	  Enables support for dynamically retrieving the offset of the
4580	  environment from block zero's out-of-band data.  The
4581	  "nand env.oob" command can be used to record this offset.
4582	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4583	  using CONFIG_ENV_OFFSET_OOB.
4584
4585- CONFIG_NAND_ENV_DST
4586
4587	Defines address in RAM to which the nand_spl code should copy the
4588	environment. If redundant environment is used, it will be copied to
4589	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4590
4591- CONFIG_ENV_IS_IN_UBI:
4592
4593	Define this if you have an UBI volume that you want to use for the
4594	environment.  This has the benefit of wear-leveling the environment
4595	accesses, which is important on NAND.
4596
4597	- CONFIG_ENV_UBI_PART:
4598
4599	  Define this to a string that is the mtd partition containing the UBI.
4600
4601	- CONFIG_ENV_UBI_VOLUME:
4602
4603	  Define this to the name of the volume that you want to store the
4604	  environment in.
4605
4606	- CONFIG_ENV_UBI_VOLUME_REDUND:
4607
4608	  Define this to the name of another volume to store a second copy of
4609	  the environment in.  This will enable redundant environments in UBI.
4610	  It is assumed that both volumes are in the same MTD partition.
4611
4612	- CONFIG_UBI_SILENCE_MSG
4613	- CONFIG_UBIFS_SILENCE_MSG
4614
4615	  You will probably want to define these to avoid a really noisy system
4616	  when storing the env in UBI.
4617
4618- CONFIG_ENV_IS_IN_FAT:
4619       Define this if you want to use the FAT file system for the environment.
4620
4621       - FAT_ENV_INTERFACE:
4622
4623         Define this to a string that is the name of the block device.
4624
4625       - FAT_ENV_DEV_AND_PART:
4626
4627         Define this to a string to specify the partition of the device. It can
4628         be as following:
4629
4630           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4631               - "D:P": device D partition P. Error occurs if device D has no
4632                        partition table.
4633               - "D:0": device D.
4634               - "D" or "D:": device D partition 1 if device D has partition
4635                              table, or the whole device D if has no partition
4636                              table.
4637               - "D:auto": first partition in device D with bootable flag set.
4638                           If none, first valid partition in device D. If no
4639                           partition table then means device D.
4640
4641       - FAT_ENV_FILE:
4642
4643         It's a string of the FAT file name. This file use to store the
4644         environment.
4645
4646       - CONFIG_FAT_WRITE:
4647         This should be defined. Otherwise it cannot save the environment file.
4648
4649- CONFIG_ENV_IS_IN_MMC:
4650
4651	Define this if you have an MMC device which you want to use for the
4652	environment.
4653
4654	- CONFIG_SYS_MMC_ENV_DEV:
4655
4656	  Specifies which MMC device the environment is stored in.
4657
4658	- CONFIG_SYS_MMC_ENV_PART (optional):
4659
4660	  Specifies which MMC partition the environment is stored in. If not
4661	  set, defaults to partition 0, the user area. Common values might be
4662	  1 (first MMC boot partition), 2 (second MMC boot partition).
4663
4664	- CONFIG_ENV_OFFSET:
4665	- CONFIG_ENV_SIZE:
4666
4667	  These two #defines specify the offset and size of the environment
4668	  area within the specified MMC device.
4669
4670	  If offset is positive (the usual case), it is treated as relative to
4671	  the start of the MMC partition. If offset is negative, it is treated
4672	  as relative to the end of the MMC partition. This can be useful if
4673	  your board may be fitted with different MMC devices, which have
4674	  different sizes for the MMC partitions, and you always want the
4675	  environment placed at the very end of the partition, to leave the
4676	  maximum possible space before it, to store other data.
4677
4678	  These two values are in units of bytes, but must be aligned to an
4679	  MMC sector boundary.
4680
4681	- CONFIG_ENV_OFFSET_REDUND (optional):
4682
4683	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4684	  hold a redundant copy of the environment data. This provides a
4685	  valid backup copy in case the other copy is corrupted, e.g. due
4686	  to a power failure during a "saveenv" operation.
4687
4688	  This value may also be positive or negative; this is handled in the
4689	  same way as CONFIG_ENV_OFFSET.
4690
4691	  This value is also in units of bytes, but must also be aligned to
4692	  an MMC sector boundary.
4693
4694	- CONFIG_ENV_SIZE_REDUND (optional):
4695
4696	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4697	  set. If this value is set, it must be set to the same value as
4698	  CONFIG_ENV_SIZE.
4699
4700- CONFIG_SYS_SPI_INIT_OFFSET
4701
4702	Defines offset to the initial SPI buffer area in DPRAM. The
4703	area is used at an early stage (ROM part) if the environment
4704	is configured to reside in the SPI EEPROM: We need a 520 byte
4705	scratch DPRAM area. It is used between the two initialization
4706	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4707	to be a good choice since it makes it far enough from the
4708	start of the data area as well as from the stack pointer.
4709
4710Please note that the environment is read-only until the monitor
4711has been relocated to RAM and a RAM copy of the environment has been
4712created; also, when using EEPROM you will have to use getenv_f()
4713until then to read environment variables.
4714
4715The environment is protected by a CRC32 checksum. Before the monitor
4716is relocated into RAM, as a result of a bad CRC you will be working
4717with the compiled-in default environment - *silently*!!! [This is
4718necessary, because the first environment variable we need is the
4719"baudrate" setting for the console - if we have a bad CRC, we don't
4720have any device yet where we could complain.]
4721
4722Note: once the monitor has been relocated, then it will complain if
4723the default environment is used; a new CRC is computed as soon as you
4724use the "saveenv" command to store a valid environment.
4725
4726- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4727		Echo the inverted Ethernet link state to the fault LED.
4728
4729		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4730		      also needs to be defined.
4731
4732- CONFIG_SYS_FAULT_MII_ADDR:
4733		MII address of the PHY to check for the Ethernet link state.
4734
4735- CONFIG_NS16550_MIN_FUNCTIONS:
4736		Define this if you desire to only have use of the NS16550_init
4737		and NS16550_putc functions for the serial driver located at
4738		drivers/serial/ns16550.c.  This option is useful for saving
4739		space for already greatly restricted images, including but not
4740		limited to NAND_SPL configurations.
4741
4742- CONFIG_DISPLAY_BOARDINFO
4743		Display information about the board that U-Boot is running on
4744		when U-Boot starts up. The board function checkboard() is called
4745		to do this.
4746
4747- CONFIG_DISPLAY_BOARDINFO_LATE
4748		Similar to the previous option, but display this information
4749		later, once stdio is running and output goes to the LCD, if
4750		present.
4751
4752- CONFIG_BOARD_SIZE_LIMIT:
4753		Maximum size of the U-Boot image. When defined, the
4754		build system checks that the actual size does not
4755		exceed it.
4756
4757Low Level (hardware related) configuration options:
4758---------------------------------------------------
4759
4760- CONFIG_SYS_CACHELINE_SIZE:
4761		Cache Line Size of the CPU.
4762
4763- CONFIG_SYS_DEFAULT_IMMR:
4764		Default address of the IMMR after system reset.
4765
4766		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4767		and RPXsuper) to be able to adjust the position of
4768		the IMMR register after a reset.
4769
4770- CONFIG_SYS_CCSRBAR_DEFAULT:
4771		Default (power-on reset) physical address of CCSR on Freescale
4772		PowerPC SOCs.
4773
4774- CONFIG_SYS_CCSRBAR:
4775		Virtual address of CCSR.  On a 32-bit build, this is typically
4776		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4777
4778		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4779		for cross-platform code that uses that macro instead.
4780
4781- CONFIG_SYS_CCSRBAR_PHYS:
4782		Physical address of CCSR.  CCSR can be relocated to a new
4783		physical address, if desired.  In this case, this macro should
4784		be set to that address.	 Otherwise, it should be set to the
4785		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4786		is typically relocated on 36-bit builds.  It is recommended
4787		that this macro be defined via the _HIGH and _LOW macros:
4788
4789		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4790			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4791
4792- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4793		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4794		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4795		used in assembly code, so it must not contain typecasts or
4796		integer size suffixes (e.g. "ULL").
4797
4798- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4799		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4800		used in assembly code, so it must not contain typecasts or
4801		integer size suffixes (e.g. "ULL").
4802
4803- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4804		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4805		forced to a value that ensures that CCSR is not relocated.
4806
4807- Floppy Disk Support:
4808		CONFIG_SYS_FDC_DRIVE_NUMBER
4809
4810		the default drive number (default value 0)
4811
4812		CONFIG_SYS_ISA_IO_STRIDE
4813
4814		defines the spacing between FDC chipset registers
4815		(default value 1)
4816
4817		CONFIG_SYS_ISA_IO_OFFSET
4818
4819		defines the offset of register from address. It
4820		depends on which part of the data bus is connected to
4821		the FDC chipset. (default value 0)
4822
4823		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4824		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4825		default value.
4826
4827		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4828		fdc_hw_init() is called at the beginning of the FDC
4829		setup. fdc_hw_init() must be provided by the board
4830		source code. It is used to make hardware-dependent
4831		initializations.
4832
4833- CONFIG_IDE_AHB:
4834		Most IDE controllers were designed to be connected with PCI
4835		interface. Only few of them were designed for AHB interface.
4836		When software is doing ATA command and data transfer to
4837		IDE devices through IDE-AHB controller, some additional
4838		registers accessing to these kind of IDE-AHB controller
4839		is required.
4840
4841- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4842		DO NOT CHANGE unless you know exactly what you're
4843		doing! (11-4) [MPC8xx/82xx systems only]
4844
4845- CONFIG_SYS_INIT_RAM_ADDR:
4846
4847		Start address of memory area that can be used for
4848		initial data and stack; please note that this must be
4849		writable memory that is working WITHOUT special
4850		initialization, i. e. you CANNOT use normal RAM which
4851		will become available only after programming the
4852		memory controller and running certain initialization
4853		sequences.
4854
4855		U-Boot uses the following memory types:
4856		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4857		- MPC824X: data cache
4858		- PPC4xx:  data cache
4859
4860- CONFIG_SYS_GBL_DATA_OFFSET:
4861
4862		Offset of the initial data structure in the memory
4863		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4864		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4865		data is located at the end of the available space
4866		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4867		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4868		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4869		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4870
4871	Note:
4872		On the MPC824X (or other systems that use the data
4873		cache for initial memory) the address chosen for
4874		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4875		point to an otherwise UNUSED address space between
4876		the top of RAM and the start of the PCI space.
4877
4878- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4879
4880- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4881
4882- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4883
4884- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4885
4886- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4887
4888- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4889
4890- CONFIG_SYS_OR_TIMING_SDRAM:
4891		SDRAM timing
4892
4893- CONFIG_SYS_MAMR_PTA:
4894		periodic timer for refresh
4895
4896- CONFIG_SYS_DER:	Debug Event Register (37-47)
4897
4898- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4899  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4900  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4901  CONFIG_SYS_BR1_PRELIM:
4902		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4903
4904- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4905  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4906  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4907		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4908
4909- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4910  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4911		Machine Mode Register and Memory Periodic Timer
4912		Prescaler definitions (SDRAM timing)
4913
4914- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4915		enable I2C microcode relocation patch (MPC8xx);
4916		define relocation offset in DPRAM [DSP2]
4917
4918- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4919		enable SMC microcode relocation patch (MPC8xx);
4920		define relocation offset in DPRAM [SMC1]
4921
4922- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4923		enable SPI microcode relocation patch (MPC8xx);
4924		define relocation offset in DPRAM [SCC4]
4925
4926- CONFIG_SYS_USE_OSCCLK:
4927		Use OSCM clock mode on MBX8xx board. Be careful,
4928		wrong setting might damage your board. Read
4929		doc/README.MBX before setting this variable!
4930
4931- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4932		Offset of the bootmode word in DPRAM used by post
4933		(Power On Self Tests). This definition overrides
4934		#define'd default value in commproc.h resp.
4935		cpm_8260.h.
4936
4937- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4938  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4939  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4940  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4941  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4942  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4943  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4944  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4945		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4946
4947- CONFIG_PCI_DISABLE_PCIE:
4948		Disable PCI-Express on systems where it is supported but not
4949		required.
4950
4951- CONFIG_PCI_ENUM_ONLY
4952		Only scan through and get the devices on the buses.
4953		Don't do any setup work, presumably because someone or
4954		something has already done it, and we don't need to do it
4955		a second time.	Useful for platforms that are pre-booted
4956		by coreboot or similar.
4957
4958- CONFIG_PCI_INDIRECT_BRIDGE:
4959		Enable support for indirect PCI bridges.
4960
4961- CONFIG_SYS_SRIO:
4962		Chip has SRIO or not
4963
4964- CONFIG_SRIO1:
4965		Board has SRIO 1 port available
4966
4967- CONFIG_SRIO2:
4968		Board has SRIO 2 port available
4969
4970- CONFIG_SRIO_PCIE_BOOT_MASTER
4971		Board can support master function for Boot from SRIO and PCIE
4972
4973- CONFIG_SYS_SRIOn_MEM_VIRT:
4974		Virtual Address of SRIO port 'n' memory region
4975
4976- CONFIG_SYS_SRIOn_MEM_PHYS:
4977		Physical Address of SRIO port 'n' memory region
4978
4979- CONFIG_SYS_SRIOn_MEM_SIZE:
4980		Size of SRIO port 'n' memory region
4981
4982- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4983		Defined to tell the NAND controller that the NAND chip is using
4984		a 16 bit bus.
4985		Not all NAND drivers use this symbol.
4986		Example of drivers that use it:
4987		- drivers/mtd/nand/ndfc.c
4988		- drivers/mtd/nand/mxc_nand.c
4989
4990- CONFIG_SYS_NDFC_EBC0_CFG
4991		Sets the EBC0_CFG register for the NDFC. If not defined
4992		a default value will be used.
4993
4994- CONFIG_SPD_EEPROM
4995		Get DDR timing information from an I2C EEPROM. Common
4996		with pluggable memory modules such as SODIMMs
4997
4998  SPD_EEPROM_ADDRESS
4999		I2C address of the SPD EEPROM
5000
5001- CONFIG_SYS_SPD_BUS_NUM
5002		If SPD EEPROM is on an I2C bus other than the first
5003		one, specify here. Note that the value must resolve
5004		to something your driver can deal with.
5005
5006- CONFIG_SYS_DDR_RAW_TIMING
5007		Get DDR timing information from other than SPD. Common with
5008		soldered DDR chips onboard without SPD. DDR raw timing
5009		parameters are extracted from datasheet and hard-coded into
5010		header files or board specific files.
5011
5012- CONFIG_FSL_DDR_INTERACTIVE
5013		Enable interactive DDR debugging. See doc/README.fsl-ddr.
5014
5015- CONFIG_FSL_DDR_SYNC_REFRESH
5016		Enable sync of refresh for multiple controllers.
5017
5018- CONFIG_SYS_83XX_DDR_USES_CS0
5019		Only for 83xx systems. If specified, then DDR should
5020		be configured using CS0 and CS1 instead of CS2 and CS3.
5021
5022- CONFIG_ETHER_ON_FEC[12]
5023		Define to enable FEC[12] on a 8xx series processor.
5024
5025- CONFIG_FEC[12]_PHY
5026		Define to the hardcoded PHY address which corresponds
5027		to the given FEC; i. e.
5028			#define CONFIG_FEC1_PHY 4
5029		means that the PHY with address 4 is connected to FEC1
5030
5031		When set to -1, means to probe for first available.
5032
5033- CONFIG_FEC[12]_PHY_NORXERR
5034		The PHY does not have a RXERR line (RMII only).
5035		(so program the FEC to ignore it).
5036
5037- CONFIG_RMII
5038		Enable RMII mode for all FECs.
5039		Note that this is a global option, we can't
5040		have one FEC in standard MII mode and another in RMII mode.
5041
5042- CONFIG_CRC32_VERIFY
5043		Add a verify option to the crc32 command.
5044		The syntax is:
5045
5046		=> crc32 -v <address> <count> <crc32>
5047
5048		Where address/count indicate a memory area
5049		and crc32 is the correct crc32 which the
5050		area should have.
5051
5052- CONFIG_LOOPW
5053		Add the "loopw" memory command. This only takes effect if
5054		the memory commands are activated globally (CONFIG_CMD_MEM).
5055
5056- CONFIG_MX_CYCLIC
5057		Add the "mdc" and "mwc" memory commands. These are cyclic
5058		"md/mw" commands.
5059		Examples:
5060
5061		=> mdc.b 10 4 500
5062		This command will print 4 bytes (10,11,12,13) each 500 ms.
5063
5064		=> mwc.l 100 12345678 10
5065		This command will write 12345678 to address 100 all 10 ms.
5066
5067		This only takes effect if the memory commands are activated
5068		globally (CONFIG_CMD_MEM).
5069
5070- CONFIG_SKIP_LOWLEVEL_INIT
5071		[ARM, NDS32, MIPS only] If this variable is defined, then certain
5072		low level initializations (like setting up the memory
5073		controller) are omitted and/or U-Boot does not
5074		relocate itself into RAM.
5075
5076		Normally this variable MUST NOT be defined. The only
5077		exception is when U-Boot is loaded (to RAM) by some
5078		other boot loader or by a debugger which performs
5079		these initializations itself.
5080
5081- CONFIG_SPL_BUILD
5082		Modifies the behaviour of start.S when compiling a loader
5083		that is executed before the actual U-Boot. E.g. when
5084		compiling a NAND SPL.
5085
5086- CONFIG_TPL_BUILD
5087		Modifies the behaviour of start.S  when compiling a loader
5088		that is executed after the SPL and before the actual U-Boot.
5089		It is loaded by the SPL.
5090
5091- CONFIG_SYS_MPC85XX_NO_RESETVEC
5092		Only for 85xx systems. If this variable is specified, the section
5093		.resetvec is not kept and the section .bootpg is placed in the
5094		previous 4k of the .text section.
5095
5096- CONFIG_ARCH_MAP_SYSMEM
5097		Generally U-Boot (and in particular the md command) uses
5098		effective address. It is therefore not necessary to regard
5099		U-Boot address as virtual addresses that need to be translated
5100		to physical addresses. However, sandbox requires this, since
5101		it maintains its own little RAM buffer which contains all
5102		addressable memory. This option causes some memory accesses
5103		to be mapped through map_sysmem() / unmap_sysmem().
5104
5105- CONFIG_USE_ARCH_MEMCPY
5106  CONFIG_USE_ARCH_MEMSET
5107		If these options are used a optimized version of memcpy/memset will
5108		be used if available. These functions may be faster under some
5109		conditions but may increase the binary size.
5110
5111- CONFIG_X86_RESET_VECTOR
5112		If defined, the x86 reset vector code is included. This is not
5113		needed when U-Boot is running from Coreboot.
5114
5115- CONFIG_SYS_MPUCLK
5116		Defines the MPU clock speed (in MHz).
5117
5118		NOTE : currently only supported on AM335x platforms.
5119
5120- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
5121		Enables the RTC32K OSC on AM33xx based plattforms
5122
5123- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
5124		Option to disable subpage write in NAND driver
5125		driver that uses this:
5126		drivers/mtd/nand/davinci_nand.c
5127
5128Freescale QE/FMAN Firmware Support:
5129-----------------------------------
5130
5131The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
5132loading of "firmware", which is encoded in the QE firmware binary format.
5133This firmware often needs to be loaded during U-Boot booting, so macros
5134are used to identify the storage device (NOR flash, SPI, etc) and the address
5135within that device.
5136
5137- CONFIG_SYS_FMAN_FW_ADDR
5138	The address in the storage device where the FMAN microcode is located.  The
5139	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
5140	is also specified.
5141
5142- CONFIG_SYS_QE_FW_ADDR
5143	The address in the storage device where the QE microcode is located.  The
5144	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
5145	is also specified.
5146
5147- CONFIG_SYS_QE_FMAN_FW_LENGTH
5148	The maximum possible size of the firmware.  The firmware binary format
5149	has a field that specifies the actual size of the firmware, but it
5150	might not be possible to read any part of the firmware unless some
5151	local storage is allocated to hold the entire firmware first.
5152
5153- CONFIG_SYS_QE_FMAN_FW_IN_NOR
5154	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
5155	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
5156	virtual address in NOR flash.
5157
5158- CONFIG_SYS_QE_FMAN_FW_IN_NAND
5159	Specifies that QE/FMAN firmware is located in NAND flash.
5160	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
5161
5162- CONFIG_SYS_QE_FMAN_FW_IN_MMC
5163	Specifies that QE/FMAN firmware is located on the primary SD/MMC
5164	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5165
5166- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
5167	Specifies that QE/FMAN firmware is located on the primary SPI
5168	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5169
5170- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
5171	Specifies that QE/FMAN firmware is located in the remote (master)
5172	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
5173	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
5174	window->master inbound window->master LAW->the ucode address in
5175	master's memory space.
5176
5177Freescale Layerscape Management Complex Firmware Support:
5178---------------------------------------------------------
5179The Freescale Layerscape Management Complex (MC) supports the loading of
5180"firmware".
5181This firmware often needs to be loaded during U-Boot booting, so macros
5182are used to identify the storage device (NOR flash, SPI, etc) and the address
5183within that device.
5184
5185- CONFIG_FSL_MC_ENET
5186	Enable the MC driver for Layerscape SoCs.
5187
5188- CONFIG_SYS_LS_MC_FW_ADDR
5189	The address in the storage device where the firmware is located.  The
5190	meaning of this address depends on which CONFIG_SYS_LS_MC_FW_IN_xxx macro
5191	is also specified.
5192
5193- CONFIG_SYS_LS_MC_FW_LENGTH
5194	The maximum possible size of the firmware.  The firmware binary format
5195	has a field that specifies the actual size of the firmware, but it
5196	might not be possible to read any part of the firmware unless some
5197	local storage is allocated to hold the entire firmware first.
5198
5199- CONFIG_SYS_LS_MC_FW_IN_NOR
5200	Specifies that MC firmware is located in NOR flash, mapped as
5201	normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
5202	virtual address in NOR flash.
5203
5204Building the Software:
5205======================
5206
5207Building U-Boot has been tested in several native build environments
5208and in many different cross environments. Of course we cannot support
5209all possibly existing versions of cross development tools in all
5210(potentially obsolete) versions. In case of tool chain problems we
5211recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
5212which is extensively used to build and test U-Boot.
5213
5214If you are not using a native environment, it is assumed that you
5215have GNU cross compiling tools available in your path. In this case,
5216you must set the environment variable CROSS_COMPILE in your shell.
5217Note that no changes to the Makefile or any other source files are
5218necessary. For example using the ELDK on a 4xx CPU, please enter:
5219
5220	$ CROSS_COMPILE=ppc_4xx-
5221	$ export CROSS_COMPILE
5222
5223Note: If you wish to generate Windows versions of the utilities in
5224      the tools directory you can use the MinGW toolchain
5225      (http://www.mingw.org).  Set your HOST tools to the MinGW
5226      toolchain and execute 'make tools'.  For example:
5227
5228       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
5229
5230      Binaries such as tools/mkimage.exe will be created which can
5231      be executed on computers running Windows.
5232
5233U-Boot is intended to be simple to build. After installing the
5234sources you must configure U-Boot for one specific board type. This
5235is done by typing:
5236
5237	make NAME_defconfig
5238
5239where "NAME_defconfig" is the name of one of the existing configu-
5240rations; see boards.cfg for supported names.
5241
5242Note: for some board special configuration names may exist; check if
5243      additional information is available from the board vendor; for
5244      instance, the TQM823L systems are available without (standard)
5245      or with LCD support. You can select such additional "features"
5246      when choosing the configuration, i. e.
5247
5248      make TQM823L_defconfig
5249	- will configure for a plain TQM823L, i. e. no LCD support
5250
5251      make TQM823L_LCD_defconfig
5252	- will configure for a TQM823L with U-Boot console on LCD
5253
5254      etc.
5255
5256
5257Finally, type "make all", and you should get some working U-Boot
5258images ready for download to / installation on your system:
5259
5260- "u-boot.bin" is a raw binary image
5261- "u-boot" is an image in ELF binary format
5262- "u-boot.srec" is in Motorola S-Record format
5263
5264By default the build is performed locally and the objects are saved
5265in the source directory. One of the two methods can be used to change
5266this behavior and build U-Boot to some external directory:
5267
52681. Add O= to the make command line invocations:
5269
5270	make O=/tmp/build distclean
5271	make O=/tmp/build NAME_defconfig
5272	make O=/tmp/build all
5273
52742. Set environment variable KBUILD_OUTPUT to point to the desired location:
5275
5276	export KBUILD_OUTPUT=/tmp/build
5277	make distclean
5278	make NAME_defconfig
5279	make all
5280
5281Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
5282variable.
5283
5284
5285Please be aware that the Makefiles assume you are using GNU make, so
5286for instance on NetBSD you might need to use "gmake" instead of
5287native "make".
5288
5289
5290If the system board that you have is not listed, then you will need
5291to port U-Boot to your hardware platform. To do this, follow these
5292steps:
5293
52941.  Add a new configuration option for your board to the toplevel
5295    "boards.cfg" file, using the existing entries as examples.
5296    Follow the instructions there to keep the boards in order.
52972.  Create a new directory to hold your board specific code. Add any
5298    files you need. In your board directory, you will need at least
5299    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
53003.  Create a new configuration file "include/configs/<board>.h" for
5301    your board
53023.  If you're porting U-Boot to a new CPU, then also create a new
5303    directory to hold your CPU specific code. Add any files you need.
53044.  Run "make <board>_defconfig" with your new name.
53055.  Type "make", and you should get a working "u-boot.srec" file
5306    to be installed on your target system.
53076.  Debug and solve any problems that might arise.
5308    [Of course, this last step is much harder than it sounds.]
5309
5310
5311Testing of U-Boot Modifications, Ports to New Hardware, etc.:
5312==============================================================
5313
5314If you have modified U-Boot sources (for instance added a new board
5315or support for new devices, a new CPU, etc.) you are expected to
5316provide feedback to the other developers. The feedback normally takes
5317the form of a "patch", i. e. a context diff against a certain (latest
5318official or latest in the git repository) version of U-Boot sources.
5319
5320But before you submit such a patch, please verify that your modifi-
5321cation did not break existing code. At least make sure that *ALL* of
5322the supported boards compile WITHOUT ANY compiler warnings. To do so,
5323just run the "MAKEALL" script, which will configure and build U-Boot
5324for ALL supported system. Be warned, this will take a while. You can
5325select which (cross) compiler to use by passing a `CROSS_COMPILE'
5326environment variable to the script, i. e. to use the ELDK cross tools
5327you can type
5328
5329	CROSS_COMPILE=ppc_8xx- MAKEALL
5330
5331or to build on a native PowerPC system you can type
5332
5333	CROSS_COMPILE=' ' MAKEALL
5334
5335When using the MAKEALL script, the default behaviour is to build
5336U-Boot in the source directory. This location can be changed by
5337setting the BUILD_DIR environment variable. Also, for each target
5338built, the MAKEALL script saves two log files (<target>.ERR and
5339<target>.MAKEALL) in the <source dir>/LOG directory. This default
5340location can be changed by setting the MAKEALL_LOGDIR environment
5341variable. For example:
5342
5343	export BUILD_DIR=/tmp/build
5344	export MAKEALL_LOGDIR=/tmp/log
5345	CROSS_COMPILE=ppc_8xx- MAKEALL
5346
5347With the above settings build objects are saved in the /tmp/build,
5348log files are saved in the /tmp/log and the source tree remains clean
5349during the whole build process.
5350
5351
5352See also "U-Boot Porting Guide" below.
5353
5354
5355Monitor Commands - Overview:
5356============================
5357
5358go	- start application at address 'addr'
5359run	- run commands in an environment variable
5360bootm	- boot application image from memory
5361bootp	- boot image via network using BootP/TFTP protocol
5362bootz   - boot zImage from memory
5363tftpboot- boot image via network using TFTP protocol
5364	       and env variables "ipaddr" and "serverip"
5365	       (and eventually "gatewayip")
5366tftpput - upload a file via network using TFTP protocol
5367rarpboot- boot image via network using RARP/TFTP protocol
5368diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
5369loads	- load S-Record file over serial line
5370loadb	- load binary file over serial line (kermit mode)
5371md	- memory display
5372mm	- memory modify (auto-incrementing)
5373nm	- memory modify (constant address)
5374mw	- memory write (fill)
5375cp	- memory copy
5376cmp	- memory compare
5377crc32	- checksum calculation
5378i2c	- I2C sub-system
5379sspi	- SPI utility commands
5380base	- print or set address offset
5381printenv- print environment variables
5382setenv	- set environment variables
5383saveenv - save environment variables to persistent storage
5384protect - enable or disable FLASH write protection
5385erase	- erase FLASH memory
5386flinfo	- print FLASH memory information
5387nand	- NAND memory operations (see doc/README.nand)
5388bdinfo	- print Board Info structure
5389iminfo	- print header information for application image
5390coninfo - print console devices and informations
5391ide	- IDE sub-system
5392loop	- infinite loop on address range
5393loopw	- infinite write loop on address range
5394mtest	- simple RAM test
5395icache	- enable or disable instruction cache
5396dcache	- enable or disable data cache
5397reset	- Perform RESET of the CPU
5398echo	- echo args to console
5399version - print monitor version
5400help	- print online help
5401?	- alias for 'help'
5402
5403
5404Monitor Commands - Detailed Description:
5405========================================
5406
5407TODO.
5408
5409For now: just type "help <command>".
5410
5411
5412Environment Variables:
5413======================
5414
5415U-Boot supports user configuration using Environment Variables which
5416can be made persistent by saving to Flash memory.
5417
5418Environment Variables are set using "setenv", printed using
5419"printenv", and saved to Flash using "saveenv". Using "setenv"
5420without a value can be used to delete a variable from the
5421environment. As long as you don't save the environment you are
5422working with an in-memory copy. In case the Flash area containing the
5423environment is erased by accident, a default environment is provided.
5424
5425Some configuration options can be set using Environment Variables.
5426
5427List of environment variables (most likely not complete):
5428
5429  baudrate	- see CONFIG_BAUDRATE
5430
5431  bootdelay	- see CONFIG_BOOTDELAY
5432
5433  bootcmd	- see CONFIG_BOOTCOMMAND
5434
5435  bootargs	- Boot arguments when booting an RTOS image
5436
5437  bootfile	- Name of the image to load with TFTP
5438
5439  bootm_low	- Memory range available for image processing in the bootm
5440		  command can be restricted. This variable is given as
5441		  a hexadecimal number and defines lowest address allowed
5442		  for use by the bootm command. See also "bootm_size"
5443		  environment variable. Address defined by "bootm_low" is
5444		  also the base of the initial memory mapping for the Linux
5445		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5446		  bootm_mapsize.
5447
5448  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5449		  This variable is given as a hexadecimal number and it
5450		  defines the size of the memory region starting at base
5451		  address bootm_low that is accessible by the Linux kernel
5452		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5453		  as the default value if it is defined, and bootm_size is
5454		  used otherwise.
5455
5456  bootm_size	- Memory range available for image processing in the bootm
5457		  command can be restricted. This variable is given as
5458		  a hexadecimal number and defines the size of the region
5459		  allowed for use by the bootm command. See also "bootm_low"
5460		  environment variable.
5461
5462  updatefile	- Location of the software update file on a TFTP server, used
5463		  by the automatic software update feature. Please refer to
5464		  documentation in doc/README.update for more details.
5465
5466  autoload	- if set to "no" (any string beginning with 'n'),
5467		  "bootp" will just load perform a lookup of the
5468		  configuration from the BOOTP server, but not try to
5469		  load any image using TFTP
5470
5471  autostart	- if set to "yes", an image loaded using the "bootp",
5472		  "rarpboot", "tftpboot" or "diskboot" commands will
5473		  be automatically started (by internally calling
5474		  "bootm")
5475
5476		  If set to "no", a standalone image passed to the
5477		  "bootm" command will be copied to the load address
5478		  (and eventually uncompressed), but NOT be started.
5479		  This can be used to load and uncompress arbitrary
5480		  data.
5481
5482  fdt_high	- if set this restricts the maximum address that the
5483		  flattened device tree will be copied into upon boot.
5484		  For example, if you have a system with 1 GB memory
5485		  at physical address 0x10000000, while Linux kernel
5486		  only recognizes the first 704 MB as low memory, you
5487		  may need to set fdt_high as 0x3C000000 to have the
5488		  device tree blob be copied to the maximum address
5489		  of the 704 MB low memory, so that Linux kernel can
5490		  access it during the boot procedure.
5491
5492		  If this is set to the special value 0xFFFFFFFF then
5493		  the fdt will not be copied at all on boot.  For this
5494		  to work it must reside in writable memory, have
5495		  sufficient padding on the end of it for u-boot to
5496		  add the information it needs into it, and the memory
5497		  must be accessible by the kernel.
5498
5499  fdtcontroladdr- if set this is the address of the control flattened
5500		  device tree used by U-Boot when CONFIG_OF_CONTROL is
5501		  defined.
5502
5503  i2cfast	- (PPC405GP|PPC405EP only)
5504		  if set to 'y' configures Linux I2C driver for fast
5505		  mode (400kHZ). This environment variable is used in
5506		  initialization code. So, for changes to be effective
5507		  it must be saved and board must be reset.
5508
5509  initrd_high	- restrict positioning of initrd images:
5510		  If this variable is not set, initrd images will be
5511		  copied to the highest possible address in RAM; this
5512		  is usually what you want since it allows for
5513		  maximum initrd size. If for some reason you want to
5514		  make sure that the initrd image is loaded below the
5515		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5516		  variable to a value of "no" or "off" or "0".
5517		  Alternatively, you can set it to a maximum upper
5518		  address to use (U-Boot will still check that it
5519		  does not overwrite the U-Boot stack and data).
5520
5521		  For instance, when you have a system with 16 MB
5522		  RAM, and want to reserve 4 MB from use by Linux,
5523		  you can do this by adding "mem=12M" to the value of
5524		  the "bootargs" variable. However, now you must make
5525		  sure that the initrd image is placed in the first
5526		  12 MB as well - this can be done with
5527
5528		  setenv initrd_high 00c00000
5529
5530		  If you set initrd_high to 0xFFFFFFFF, this is an
5531		  indication to U-Boot that all addresses are legal
5532		  for the Linux kernel, including addresses in flash
5533		  memory. In this case U-Boot will NOT COPY the
5534		  ramdisk at all. This may be useful to reduce the
5535		  boot time on your system, but requires that this
5536		  feature is supported by your Linux kernel.
5537
5538  ipaddr	- IP address; needed for tftpboot command
5539
5540  loadaddr	- Default load address for commands like "bootp",
5541		  "rarpboot", "tftpboot", "loadb" or "diskboot"
5542
5543  loads_echo	- see CONFIG_LOADS_ECHO
5544
5545  serverip	- TFTP server IP address; needed for tftpboot command
5546
5547  bootretry	- see CONFIG_BOOT_RETRY_TIME
5548
5549  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5550
5551  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5552
5553  ethprime	- controls which interface is used first.
5554
5555  ethact	- controls which interface is currently active.
5556		  For example you can do the following
5557
5558		  => setenv ethact FEC
5559		  => ping 192.168.0.1 # traffic sent on FEC
5560		  => setenv ethact SCC
5561		  => ping 10.0.0.1 # traffic sent on SCC
5562
5563  ethrotate	- When set to "no" U-Boot does not go through all
5564		  available network interfaces.
5565		  It just stays at the currently selected interface.
5566
5567  netretry	- When set to "no" each network operation will
5568		  either succeed or fail without retrying.
5569		  When set to "once" the network operation will
5570		  fail when all the available network interfaces
5571		  are tried once without success.
5572		  Useful on scripts which control the retry operation
5573		  themselves.
5574
5575  npe_ucode	- set load address for the NPE microcode
5576
5577  silent_linux  - If set then Linux will be told to boot silently, by
5578		  changing the console to be empty. If "yes" it will be
5579		  made silent. If "no" it will not be made silent. If
5580		  unset, then it will be made silent if the U-Boot console
5581		  is silent.
5582
5583  tftpsrcport	- If this is set, the value is used for TFTP's
5584		  UDP source port.
5585
5586  tftpdstport	- If this is set, the value is used for TFTP's UDP
5587		  destination port instead of the Well Know Port 69.
5588
5589  tftpblocksize - Block size to use for TFTP transfers; if not set,
5590		  we use the TFTP server's default block size
5591
5592  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5593		  seconds, minimum value is 1000 = 1 second). Defines
5594		  when a packet is considered to be lost so it has to
5595		  be retransmitted. The default is 5000 = 5 seconds.
5596		  Lowering this value may make downloads succeed
5597		  faster in networks with high packet loss rates or
5598		  with unreliable TFTP servers.
5599
5600  vlan		- When set to a value < 4095 the traffic over
5601		  Ethernet is encapsulated/received over 802.1q
5602		  VLAN tagged frames.
5603
5604The following image location variables contain the location of images
5605used in booting. The "Image" column gives the role of the image and is
5606not an environment variable name. The other columns are environment
5607variable names. "File Name" gives the name of the file on a TFTP
5608server, "RAM Address" gives the location in RAM the image will be
5609loaded to, and "Flash Location" gives the image's address in NOR
5610flash or offset in NAND flash.
5611
5612*Note* - these variables don't have to be defined for all boards, some
5613boards currenlty use other variables for these purposes, and some
5614boards use these variables for other purposes.
5615
5616Image		    File Name	     RAM Address       Flash Location
5617-----		    ---------	     -----------       --------------
5618u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5619Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5620device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5621ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5622
5623The following environment variables may be used and automatically
5624updated by the network boot commands ("bootp" and "rarpboot"),
5625depending the information provided by your boot server:
5626
5627  bootfile	- see above
5628  dnsip		- IP address of your Domain Name Server
5629  dnsip2	- IP address of your secondary Domain Name Server
5630  gatewayip	- IP address of the Gateway (Router) to use
5631  hostname	- Target hostname
5632  ipaddr	- see above
5633  netmask	- Subnet Mask
5634  rootpath	- Pathname of the root filesystem on the NFS server
5635  serverip	- see above
5636
5637
5638There are two special Environment Variables:
5639
5640  serial#	- contains hardware identification information such
5641		  as type string and/or serial number
5642  ethaddr	- Ethernet address
5643
5644These variables can be set only once (usually during manufacturing of
5645the board). U-Boot refuses to delete or overwrite these variables
5646once they have been set once.
5647
5648
5649Further special Environment Variables:
5650
5651  ver		- Contains the U-Boot version string as printed
5652		  with the "version" command. This variable is
5653		  readonly (see CONFIG_VERSION_VARIABLE).
5654
5655
5656Please note that changes to some configuration parameters may take
5657only effect after the next boot (yes, that's just like Windoze :-).
5658
5659
5660Callback functions for environment variables:
5661---------------------------------------------
5662
5663For some environment variables, the behavior of u-boot needs to change
5664when their values are changed.  This functionality allows functions to
5665be associated with arbitrary variables.  On creation, overwrite, or
5666deletion, the callback will provide the opportunity for some side
5667effect to happen or for the change to be rejected.
5668
5669The callbacks are named and associated with a function using the
5670U_BOOT_ENV_CALLBACK macro in your board or driver code.
5671
5672These callbacks are associated with variables in one of two ways.  The
5673static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5674in the board configuration to a string that defines a list of
5675associations.  The list must be in the following format:
5676
5677	entry = variable_name[:callback_name]
5678	list = entry[,list]
5679
5680If the callback name is not specified, then the callback is deleted.
5681Spaces are also allowed anywhere in the list.
5682
5683Callbacks can also be associated by defining the ".callbacks" variable
5684with the same list format above.  Any association in ".callbacks" will
5685override any association in the static list. You can define
5686CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5687".callbacks" environment variable in the default or embedded environment.
5688
5689
5690Command Line Parsing:
5691=====================
5692
5693There are two different command line parsers available with U-Boot:
5694the old "simple" one, and the much more powerful "hush" shell:
5695
5696Old, simple command line parser:
5697--------------------------------
5698
5699- supports environment variables (through setenv / saveenv commands)
5700- several commands on one line, separated by ';'
5701- variable substitution using "... ${name} ..." syntax
5702- special characters ('$', ';') can be escaped by prefixing with '\',
5703  for example:
5704	setenv bootcmd bootm \${address}
5705- You can also escape text by enclosing in single apostrophes, for example:
5706	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5707
5708Hush shell:
5709-----------
5710
5711- similar to Bourne shell, with control structures like
5712  if...then...else...fi, for...do...done; while...do...done,
5713  until...do...done, ...
5714- supports environment ("global") variables (through setenv / saveenv
5715  commands) and local shell variables (through standard shell syntax
5716  "name=value"); only environment variables can be used with "run"
5717  command
5718
5719General rules:
5720--------------
5721
5722(1) If a command line (or an environment variable executed by a "run"
5723    command) contains several commands separated by semicolon, and
5724    one of these commands fails, then the remaining commands will be
5725    executed anyway.
5726
5727(2) If you execute several variables with one call to run (i. e.
5728    calling run with a list of variables as arguments), any failing
5729    command will cause "run" to terminate, i. e. the remaining
5730    variables are not executed.
5731
5732Note for Redundant Ethernet Interfaces:
5733=======================================
5734
5735Some boards come with redundant Ethernet interfaces; U-Boot supports
5736such configurations and is capable of automatic selection of a
5737"working" interface when needed. MAC assignment works as follows:
5738
5739Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5740MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5741"eth1addr" (=>eth1), "eth2addr", ...
5742
5743If the network interface stores some valid MAC address (for instance
5744in SROM), this is used as default address if there is NO correspon-
5745ding setting in the environment; if the corresponding environment
5746variable is set, this overrides the settings in the card; that means:
5747
5748o If the SROM has a valid MAC address, and there is no address in the
5749  environment, the SROM's address is used.
5750
5751o If there is no valid address in the SROM, and a definition in the
5752  environment exists, then the value from the environment variable is
5753  used.
5754
5755o If both the SROM and the environment contain a MAC address, and
5756  both addresses are the same, this MAC address is used.
5757
5758o If both the SROM and the environment contain a MAC address, and the
5759  addresses differ, the value from the environment is used and a
5760  warning is printed.
5761
5762o If neither SROM nor the environment contain a MAC address, an error
5763  is raised.
5764
5765If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5766will be programmed into hardware as part of the initialization process.	 This
5767may be skipped by setting the appropriate 'ethmacskip' environment variable.
5768The naming convention is as follows:
5769"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5770
5771Image Formats:
5772==============
5773
5774U-Boot is capable of booting (and performing other auxiliary operations on)
5775images in two formats:
5776
5777New uImage format (FIT)
5778-----------------------
5779
5780Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5781to Flattened Device Tree). It allows the use of images with multiple
5782components (several kernels, ramdisks, etc.), with contents protected by
5783SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5784
5785
5786Old uImage format
5787-----------------
5788
5789Old image format is based on binary files which can be basically anything,
5790preceded by a special header; see the definitions in include/image.h for
5791details; basically, the header defines the following image properties:
5792
5793* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5794  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5795  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5796  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5797  INTEGRITY).
5798* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5799  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5800  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5801* Compression Type (uncompressed, gzip, bzip2)
5802* Load Address
5803* Entry Point
5804* Image Name
5805* Image Timestamp
5806
5807The header is marked by a special Magic Number, and both the header
5808and the data portions of the image are secured against corruption by
5809CRC32 checksums.
5810
5811
5812Linux Support:
5813==============
5814
5815Although U-Boot should support any OS or standalone application
5816easily, the main focus has always been on Linux during the design of
5817U-Boot.
5818
5819U-Boot includes many features that so far have been part of some
5820special "boot loader" code within the Linux kernel. Also, any
5821"initrd" images to be used are no longer part of one big Linux image;
5822instead, kernel and "initrd" are separate images. This implementation
5823serves several purposes:
5824
5825- the same features can be used for other OS or standalone
5826  applications (for instance: using compressed images to reduce the
5827  Flash memory footprint)
5828
5829- it becomes much easier to port new Linux kernel versions because
5830  lots of low-level, hardware dependent stuff are done by U-Boot
5831
5832- the same Linux kernel image can now be used with different "initrd"
5833  images; of course this also means that different kernel images can
5834  be run with the same "initrd". This makes testing easier (you don't
5835  have to build a new "zImage.initrd" Linux image when you just
5836  change a file in your "initrd"). Also, a field-upgrade of the
5837  software is easier now.
5838
5839
5840Linux HOWTO:
5841============
5842
5843Porting Linux to U-Boot based systems:
5844---------------------------------------
5845
5846U-Boot cannot save you from doing all the necessary modifications to
5847configure the Linux device drivers for use with your target hardware
5848(no, we don't intend to provide a full virtual machine interface to
5849Linux :-).
5850
5851But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5852
5853Just make sure your machine specific header file (for instance
5854include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5855Information structure as we define in include/asm-<arch>/u-boot.h,
5856and make sure that your definition of IMAP_ADDR uses the same value
5857as your U-Boot configuration in CONFIG_SYS_IMMR.
5858
5859Note that U-Boot now has a driver model, a unified model for drivers.
5860If you are adding a new driver, plumb it into driver model. If there
5861is no uclass available, you are encouraged to create one. See
5862doc/driver-model.
5863
5864
5865Configuring the Linux kernel:
5866-----------------------------
5867
5868No specific requirements for U-Boot. Make sure you have some root
5869device (initial ramdisk, NFS) for your target system.
5870
5871
5872Building a Linux Image:
5873-----------------------
5874
5875With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5876not used. If you use recent kernel source, a new build target
5877"uImage" will exist which automatically builds an image usable by
5878U-Boot. Most older kernels also have support for a "pImage" target,
5879which was introduced for our predecessor project PPCBoot and uses a
5880100% compatible format.
5881
5882Example:
5883
5884	make TQM850L_defconfig
5885	make oldconfig
5886	make dep
5887	make uImage
5888
5889The "uImage" build target uses a special tool (in 'tools/mkimage') to
5890encapsulate a compressed Linux kernel image with header	 information,
5891CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5892
5893* build a standard "vmlinux" kernel image (in ELF binary format):
5894
5895* convert the kernel into a raw binary image:
5896
5897	${CROSS_COMPILE}-objcopy -O binary \
5898				 -R .note -R .comment \
5899				 -S vmlinux linux.bin
5900
5901* compress the binary image:
5902
5903	gzip -9 linux.bin
5904
5905* package compressed binary image for U-Boot:
5906
5907	mkimage -A ppc -O linux -T kernel -C gzip \
5908		-a 0 -e 0 -n "Linux Kernel Image" \
5909		-d linux.bin.gz uImage
5910
5911
5912The "mkimage" tool can also be used to create ramdisk images for use
5913with U-Boot, either separated from the Linux kernel image, or
5914combined into one file. "mkimage" encapsulates the images with a 64
5915byte header containing information about target architecture,
5916operating system, image type, compression method, entry points, time
5917stamp, CRC32 checksums, etc.
5918
5919"mkimage" can be called in two ways: to verify existing images and
5920print the header information, or to build new images.
5921
5922In the first form (with "-l" option) mkimage lists the information
5923contained in the header of an existing U-Boot image; this includes
5924checksum verification:
5925
5926	tools/mkimage -l image
5927	  -l ==> list image header information
5928
5929The second form (with "-d" option) is used to build a U-Boot image
5930from a "data file" which is used as image payload:
5931
5932	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5933		      -n name -d data_file image
5934	  -A ==> set architecture to 'arch'
5935	  -O ==> set operating system to 'os'
5936	  -T ==> set image type to 'type'
5937	  -C ==> set compression type 'comp'
5938	  -a ==> set load address to 'addr' (hex)
5939	  -e ==> set entry point to 'ep' (hex)
5940	  -n ==> set image name to 'name'
5941	  -d ==> use image data from 'datafile'
5942
5943Right now, all Linux kernels for PowerPC systems use the same load
5944address (0x00000000), but the entry point address depends on the
5945kernel version:
5946
5947- 2.2.x kernels have the entry point at 0x0000000C,
5948- 2.3.x and later kernels have the entry point at 0x00000000.
5949
5950So a typical call to build a U-Boot image would read:
5951
5952	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5953	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5954	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5955	> examples/uImage.TQM850L
5956	Image Name:   2.4.4 kernel for TQM850L
5957	Created:      Wed Jul 19 02:34:59 2000
5958	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5959	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5960	Load Address: 0x00000000
5961	Entry Point:  0x00000000
5962
5963To verify the contents of the image (or check for corruption):
5964
5965	-> tools/mkimage -l examples/uImage.TQM850L
5966	Image Name:   2.4.4 kernel for TQM850L
5967	Created:      Wed Jul 19 02:34:59 2000
5968	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5969	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5970	Load Address: 0x00000000
5971	Entry Point:  0x00000000
5972
5973NOTE: for embedded systems where boot time is critical you can trade
5974speed for memory and install an UNCOMPRESSED image instead: this
5975needs more space in Flash, but boots much faster since it does not
5976need to be uncompressed:
5977
5978	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5979	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5980	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5981	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5982	> examples/uImage.TQM850L-uncompressed
5983	Image Name:   2.4.4 kernel for TQM850L
5984	Created:      Wed Jul 19 02:34:59 2000
5985	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5986	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5987	Load Address: 0x00000000
5988	Entry Point:  0x00000000
5989
5990
5991Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5992when your kernel is intended to use an initial ramdisk:
5993
5994	-> tools/mkimage -n 'Simple Ramdisk Image' \
5995	> -A ppc -O linux -T ramdisk -C gzip \
5996	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5997	Image Name:   Simple Ramdisk Image
5998	Created:      Wed Jan 12 14:01:50 2000
5999	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
6000	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
6001	Load Address: 0x00000000
6002	Entry Point:  0x00000000
6003
6004The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
6005option performs the converse operation of the mkimage's second form (the "-d"
6006option). Given an image built by mkimage, the dumpimage extracts a "data file"
6007from the image:
6008
6009	tools/dumpimage -i image -T type -p position data_file
6010	  -i ==> extract from the 'image' a specific 'data_file'
6011	  -T ==> set image type to 'type'
6012	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
6013
6014
6015Installing a Linux Image:
6016-------------------------
6017
6018To downloading a U-Boot image over the serial (console) interface,
6019you must convert the image to S-Record format:
6020
6021	objcopy -I binary -O srec examples/image examples/image.srec
6022
6023The 'objcopy' does not understand the information in the U-Boot
6024image header, so the resulting S-Record file will be relative to
6025address 0x00000000. To load it to a given address, you need to
6026specify the target address as 'offset' parameter with the 'loads'
6027command.
6028
6029Example: install the image to address 0x40100000 (which on the
6030TQM8xxL is in the first Flash bank):
6031
6032	=> erase 40100000 401FFFFF
6033
6034	.......... done
6035	Erased 8 sectors
6036
6037	=> loads 40100000
6038	## Ready for S-Record download ...
6039	~>examples/image.srec
6040	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
6041	...
6042	15989 15990 15991 15992
6043	[file transfer complete]
6044	[connected]
6045	## Start Addr = 0x00000000
6046
6047
6048You can check the success of the download using the 'iminfo' command;
6049this includes a checksum verification so you can be sure no data
6050corruption happened:
6051
6052	=> imi 40100000
6053
6054	## Checking Image at 40100000 ...
6055	   Image Name:	 2.2.13 for initrd on TQM850L
6056	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
6057	   Data Size:	 335725 Bytes = 327 kB = 0 MB
6058	   Load Address: 00000000
6059	   Entry Point:	 0000000c
6060	   Verifying Checksum ... OK
6061
6062
6063Boot Linux:
6064-----------
6065
6066The "bootm" command is used to boot an application that is stored in
6067memory (RAM or Flash). In case of a Linux kernel image, the contents
6068of the "bootargs" environment variable is passed to the kernel as
6069parameters. You can check and modify this variable using the
6070"printenv" and "setenv" commands:
6071
6072
6073	=> printenv bootargs
6074	bootargs=root=/dev/ram
6075
6076	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
6077
6078	=> printenv bootargs
6079	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
6080
6081	=> bootm 40020000
6082	## Booting Linux kernel at 40020000 ...
6083	   Image Name:	 2.2.13 for NFS on TQM850L
6084	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
6085	   Data Size:	 381681 Bytes = 372 kB = 0 MB
6086	   Load Address: 00000000
6087	   Entry Point:	 0000000c
6088	   Verifying Checksum ... OK
6089	   Uncompressing Kernel Image ... OK
6090	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
6091	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
6092	time_init: decrementer frequency = 187500000/60
6093	Calibrating delay loop... 49.77 BogoMIPS
6094	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
6095	...
6096
6097If you want to boot a Linux kernel with initial RAM disk, you pass
6098the memory addresses of both the kernel and the initrd image (PPBCOOT
6099format!) to the "bootm" command:
6100
6101	=> imi 40100000 40200000
6102
6103	## Checking Image at 40100000 ...
6104	   Image Name:	 2.2.13 for initrd on TQM850L
6105	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
6106	   Data Size:	 335725 Bytes = 327 kB = 0 MB
6107	   Load Address: 00000000
6108	   Entry Point:	 0000000c
6109	   Verifying Checksum ... OK
6110
6111	## Checking Image at 40200000 ...
6112	   Image Name:	 Simple Ramdisk Image
6113	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
6114	   Data Size:	 566530 Bytes = 553 kB = 0 MB
6115	   Load Address: 00000000
6116	   Entry Point:	 00000000
6117	   Verifying Checksum ... OK
6118
6119	=> bootm 40100000 40200000
6120	## Booting Linux kernel at 40100000 ...
6121	   Image Name:	 2.2.13 for initrd on TQM850L
6122	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
6123	   Data Size:	 335725 Bytes = 327 kB = 0 MB
6124	   Load Address: 00000000
6125	   Entry Point:	 0000000c
6126	   Verifying Checksum ... OK
6127	   Uncompressing Kernel Image ... OK
6128	## Loading RAMDisk Image at 40200000 ...
6129	   Image Name:	 Simple Ramdisk Image
6130	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
6131	   Data Size:	 566530 Bytes = 553 kB = 0 MB
6132	   Load Address: 00000000
6133	   Entry Point:	 00000000
6134	   Verifying Checksum ... OK
6135	   Loading Ramdisk ... OK
6136	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
6137	Boot arguments: root=/dev/ram
6138	time_init: decrementer frequency = 187500000/60
6139	Calibrating delay loop... 49.77 BogoMIPS
6140	...
6141	RAMDISK: Compressed image found at block 0
6142	VFS: Mounted root (ext2 filesystem).
6143
6144	bash#
6145
6146Boot Linux and pass a flat device tree:
6147-----------
6148
6149First, U-Boot must be compiled with the appropriate defines. See the section
6150titled "Linux Kernel Interface" above for a more in depth explanation. The
6151following is an example of how to start a kernel and pass an updated
6152flat device tree:
6153
6154=> print oftaddr
6155oftaddr=0x300000
6156=> print oft
6157oft=oftrees/mpc8540ads.dtb
6158=> tftp $oftaddr $oft
6159Speed: 1000, full duplex
6160Using TSEC0 device
6161TFTP from server 192.168.1.1; our IP address is 192.168.1.101
6162Filename 'oftrees/mpc8540ads.dtb'.
6163Load address: 0x300000
6164Loading: #
6165done
6166Bytes transferred = 4106 (100a hex)
6167=> tftp $loadaddr $bootfile
6168Speed: 1000, full duplex
6169Using TSEC0 device
6170TFTP from server 192.168.1.1; our IP address is 192.168.1.2
6171Filename 'uImage'.
6172Load address: 0x200000
6173Loading:############
6174done
6175Bytes transferred = 1029407 (fb51f hex)
6176=> print loadaddr
6177loadaddr=200000
6178=> print oftaddr
6179oftaddr=0x300000
6180=> bootm $loadaddr - $oftaddr
6181## Booting image at 00200000 ...
6182   Image Name:	 Linux-2.6.17-dirty
6183   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
6184   Data Size:	 1029343 Bytes = 1005.2 kB
6185   Load Address: 00000000
6186   Entry Point:	 00000000
6187   Verifying Checksum ... OK
6188   Uncompressing Kernel Image ... OK
6189Booting using flat device tree at 0x300000
6190Using MPC85xx ADS machine description
6191Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
6192[snip]
6193
6194
6195More About U-Boot Image Types:
6196------------------------------
6197
6198U-Boot supports the following image types:
6199
6200   "Standalone Programs" are directly runnable in the environment
6201	provided by U-Boot; it is expected that (if they behave
6202	well) you can continue to work in U-Boot after return from
6203	the Standalone Program.
6204   "OS Kernel Images" are usually images of some Embedded OS which
6205	will take over control completely. Usually these programs
6206	will install their own set of exception handlers, device
6207	drivers, set up the MMU, etc. - this means, that you cannot
6208	expect to re-enter U-Boot except by resetting the CPU.
6209   "RAMDisk Images" are more or less just data blocks, and their
6210	parameters (address, size) are passed to an OS kernel that is
6211	being started.
6212   "Multi-File Images" contain several images, typically an OS
6213	(Linux) kernel image and one or more data images like
6214	RAMDisks. This construct is useful for instance when you want
6215	to boot over the network using BOOTP etc., where the boot
6216	server provides just a single image file, but you want to get
6217	for instance an OS kernel and a RAMDisk image.
6218
6219	"Multi-File Images" start with a list of image sizes, each
6220	image size (in bytes) specified by an "uint32_t" in network
6221	byte order. This list is terminated by an "(uint32_t)0".
6222	Immediately after the terminating 0 follow the images, one by
6223	one, all aligned on "uint32_t" boundaries (size rounded up to
6224	a multiple of 4 bytes).
6225
6226   "Firmware Images" are binary images containing firmware (like
6227	U-Boot or FPGA images) which usually will be programmed to
6228	flash memory.
6229
6230   "Script files" are command sequences that will be executed by
6231	U-Boot's command interpreter; this feature is especially
6232	useful when you configure U-Boot to use a real shell (hush)
6233	as command interpreter.
6234
6235Booting the Linux zImage:
6236-------------------------
6237
6238On some platforms, it's possible to boot Linux zImage. This is done
6239using the "bootz" command. The syntax of "bootz" command is the same
6240as the syntax of "bootm" command.
6241
6242Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
6243kernel with raw initrd images. The syntax is slightly different, the
6244address of the initrd must be augmented by it's size, in the following
6245format: "<initrd addres>:<initrd size>".
6246
6247
6248Standalone HOWTO:
6249=================
6250
6251One of the features of U-Boot is that you can dynamically load and
6252run "standalone" applications, which can use some resources of
6253U-Boot like console I/O functions or interrupt services.
6254
6255Two simple examples are included with the sources:
6256
6257"Hello World" Demo:
6258-------------------
6259
6260'examples/hello_world.c' contains a small "Hello World" Demo
6261application; it is automatically compiled when you build U-Boot.
6262It's configured to run at address 0x00040004, so you can play with it
6263like that:
6264
6265	=> loads
6266	## Ready for S-Record download ...
6267	~>examples/hello_world.srec
6268	1 2 3 4 5 6 7 8 9 10 11 ...
6269	[file transfer complete]
6270	[connected]
6271	## Start Addr = 0x00040004
6272
6273	=> go 40004 Hello World! This is a test.
6274	## Starting application at 0x00040004 ...
6275	Hello World
6276	argc = 7
6277	argv[0] = "40004"
6278	argv[1] = "Hello"
6279	argv[2] = "World!"
6280	argv[3] = "This"
6281	argv[4] = "is"
6282	argv[5] = "a"
6283	argv[6] = "test."
6284	argv[7] = "<NULL>"
6285	Hit any key to exit ...
6286
6287	## Application terminated, rc = 0x0
6288
6289Another example, which demonstrates how to register a CPM interrupt
6290handler with the U-Boot code, can be found in 'examples/timer.c'.
6291Here, a CPM timer is set up to generate an interrupt every second.
6292The interrupt service routine is trivial, just printing a '.'
6293character, but this is just a demo program. The application can be
6294controlled by the following keys:
6295
6296	? - print current values og the CPM Timer registers
6297	b - enable interrupts and start timer
6298	e - stop timer and disable interrupts
6299	q - quit application
6300
6301	=> loads
6302	## Ready for S-Record download ...
6303	~>examples/timer.srec
6304	1 2 3 4 5 6 7 8 9 10 11 ...
6305	[file transfer complete]
6306	[connected]
6307	## Start Addr = 0x00040004
6308
6309	=> go 40004
6310	## Starting application at 0x00040004 ...
6311	TIMERS=0xfff00980
6312	Using timer 1
6313	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
6314
6315Hit 'b':
6316	[q, b, e, ?] Set interval 1000000 us
6317	Enabling timer
6318Hit '?':
6319	[q, b, e, ?] ........
6320	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
6321Hit '?':
6322	[q, b, e, ?] .
6323	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
6324Hit '?':
6325	[q, b, e, ?] .
6326	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
6327Hit '?':
6328	[q, b, e, ?] .
6329	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
6330Hit 'e':
6331	[q, b, e, ?] ...Stopping timer
6332Hit 'q':
6333	[q, b, e, ?] ## Application terminated, rc = 0x0
6334
6335
6336Minicom warning:
6337================
6338
6339Over time, many people have reported problems when trying to use the
6340"minicom" terminal emulation program for serial download. I (wd)
6341consider minicom to be broken, and recommend not to use it. Under
6342Unix, I recommend to use C-Kermit for general purpose use (and
6343especially for kermit binary protocol download ("loadb" command), and
6344use "cu" for S-Record download ("loads" command).  See
6345http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
6346for help with kermit.
6347
6348
6349Nevertheless, if you absolutely want to use it try adding this
6350configuration to your "File transfer protocols" section:
6351
6352	   Name	   Program			Name U/D FullScr IO-Red. Multi
6353	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
6354	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
6355
6356
6357NetBSD Notes:
6358=============
6359
6360Starting at version 0.9.2, U-Boot supports NetBSD both as host
6361(build U-Boot) and target system (boots NetBSD/mpc8xx).
6362
6363Building requires a cross environment; it is known to work on
6364NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
6365need gmake since the Makefiles are not compatible with BSD make).
6366Note that the cross-powerpc package does not install include files;
6367attempting to build U-Boot will fail because <machine/ansi.h> is
6368missing.  This file has to be installed and patched manually:
6369
6370	# cd /usr/pkg/cross/powerpc-netbsd/include
6371	# mkdir powerpc
6372	# ln -s powerpc machine
6373	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
6374	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
6375
6376Native builds *don't* work due to incompatibilities between native
6377and U-Boot include files.
6378
6379Booting assumes that (the first part of) the image booted is a
6380stage-2 loader which in turn loads and then invokes the kernel
6381proper. Loader sources will eventually appear in the NetBSD source
6382tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
6383meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
6384
6385
6386Implementation Internals:
6387=========================
6388
6389The following is not intended to be a complete description of every
6390implementation detail. However, it should help to understand the
6391inner workings of U-Boot and make it easier to port it to custom
6392hardware.
6393
6394
6395Initial Stack, Global Data:
6396---------------------------
6397
6398The implementation of U-Boot is complicated by the fact that U-Boot
6399starts running out of ROM (flash memory), usually without access to
6400system RAM (because the memory controller is not initialized yet).
6401This means that we don't have writable Data or BSS segments, and BSS
6402is not initialized as zero. To be able to get a C environment working
6403at all, we have to allocate at least a minimal stack. Implementation
6404options for this are defined and restricted by the CPU used: Some CPU
6405models provide on-chip memory (like the IMMR area on MPC8xx and
6406MPC826x processors), on others (parts of) the data cache can be
6407locked as (mis-) used as memory, etc.
6408
6409	Chris Hallinan posted a good summary of these issues to the
6410	U-Boot mailing list:
6411
6412	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6413	From: "Chris Hallinan" <clh@net1plus.com>
6414	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6415	...
6416
6417	Correct me if I'm wrong, folks, but the way I understand it
6418	is this: Using DCACHE as initial RAM for Stack, etc, does not
6419	require any physical RAM backing up the cache. The cleverness
6420	is that the cache is being used as a temporary supply of
6421	necessary storage before the SDRAM controller is setup. It's
6422	beyond the scope of this list to explain the details, but you
6423	can see how this works by studying the cache architecture and
6424	operation in the architecture and processor-specific manuals.
6425
6426	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6427	is another option for the system designer to use as an
6428	initial stack/RAM area prior to SDRAM being available. Either
6429	option should work for you. Using CS 4 should be fine if your
6430	board designers haven't used it for something that would
6431	cause you grief during the initial boot! It is frequently not
6432	used.
6433
6434	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6435	with your processor/board/system design. The default value
6436	you will find in any recent u-boot distribution in
6437	walnut.h should work for you. I'd set it to a value larger
6438	than your SDRAM module. If you have a 64MB SDRAM module, set
6439	it above 400_0000. Just make sure your board has no resources
6440	that are supposed to respond to that address! That code in
6441	start.S has been around a while and should work as is when
6442	you get the config right.
6443
6444	-Chris Hallinan
6445	DS4.COM, Inc.
6446
6447It is essential to remember this, since it has some impact on the C
6448code for the initialization procedures:
6449
6450* Initialized global data (data segment) is read-only. Do not attempt
6451  to write it.
6452
6453* Do not use any uninitialized global data (or implicitly initialized
6454  as zero data - BSS segment) at all - this is undefined, initiali-
6455  zation is performed later (when relocating to RAM).
6456
6457* Stack space is very limited. Avoid big data buffers or things like
6458  that.
6459
6460Having only the stack as writable memory limits means we cannot use
6461normal global data to share information between the code. But it
6462turned out that the implementation of U-Boot can be greatly
6463simplified by making a global data structure (gd_t) available to all
6464functions. We could pass a pointer to this data as argument to _all_
6465functions, but this would bloat the code. Instead we use a feature of
6466the GCC compiler (Global Register Variables) to share the data: we
6467place a pointer (gd) to the global data into a register which we
6468reserve for this purpose.
6469
6470When choosing a register for such a purpose we are restricted by the
6471relevant  (E)ABI  specifications for the current architecture, and by
6472GCC's implementation.
6473
6474For PowerPC, the following registers have specific use:
6475	R1:	stack pointer
6476	R2:	reserved for system use
6477	R3-R4:	parameter passing and return values
6478	R5-R10: parameter passing
6479	R13:	small data area pointer
6480	R30:	GOT pointer
6481	R31:	frame pointer
6482
6483	(U-Boot also uses R12 as internal GOT pointer. r12
6484	is a volatile register so r12 needs to be reset when
6485	going back and forth between asm and C)
6486
6487    ==> U-Boot will use R2 to hold a pointer to the global data
6488
6489    Note: on PPC, we could use a static initializer (since the
6490    address of the global data structure is known at compile time),
6491    but it turned out that reserving a register results in somewhat
6492    smaller code - although the code savings are not that big (on
6493    average for all boards 752 bytes for the whole U-Boot image,
6494    624 text + 127 data).
6495
6496On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6497	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6498
6499    ==> U-Boot will use P3 to hold a pointer to the global data
6500
6501On ARM, the following registers are used:
6502
6503	R0:	function argument word/integer result
6504	R1-R3:	function argument word
6505	R9:	platform specific
6506	R10:	stack limit (used only if stack checking is enabled)
6507	R11:	argument (frame) pointer
6508	R12:	temporary workspace
6509	R13:	stack pointer
6510	R14:	link register
6511	R15:	program counter
6512
6513    ==> U-Boot will use R9 to hold a pointer to the global data
6514
6515    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6516
6517On Nios II, the ABI is documented here:
6518	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6519
6520    ==> U-Boot will use gp to hold a pointer to the global data
6521
6522    Note: on Nios II, we give "-G0" option to gcc and don't use gp
6523    to access small data sections, so gp is free.
6524
6525On NDS32, the following registers are used:
6526
6527	R0-R1:	argument/return
6528	R2-R5:	argument
6529	R15:	temporary register for assembler
6530	R16:	trampoline register
6531	R28:	frame pointer (FP)
6532	R29:	global pointer (GP)
6533	R30:	link register (LP)
6534	R31:	stack pointer (SP)
6535	PC:	program counter (PC)
6536
6537    ==> U-Boot will use R10 to hold a pointer to the global data
6538
6539NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6540or current versions of GCC may "optimize" the code too much.
6541
6542Memory Management:
6543------------------
6544
6545U-Boot runs in system state and uses physical addresses, i.e. the
6546MMU is not used either for address mapping nor for memory protection.
6547
6548The available memory is mapped to fixed addresses using the memory
6549controller. In this process, a contiguous block is formed for each
6550memory type (Flash, SDRAM, SRAM), even when it consists of several
6551physical memory banks.
6552
6553U-Boot is installed in the first 128 kB of the first Flash bank (on
6554TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6555booting and sizing and initializing DRAM, the code relocates itself
6556to the upper end of DRAM. Immediately below the U-Boot code some
6557memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6558configuration setting]. Below that, a structure with global Board
6559Info data is placed, followed by the stack (growing downward).
6560
6561Additionally, some exception handler code is copied to the low 8 kB
6562of DRAM (0x00000000 ... 0x00001FFF).
6563
6564So a typical memory configuration with 16 MB of DRAM could look like
6565this:
6566
6567	0x0000 0000	Exception Vector code
6568	      :
6569	0x0000 1FFF
6570	0x0000 2000	Free for Application Use
6571	      :
6572	      :
6573
6574	      :
6575	      :
6576	0x00FB FF20	Monitor Stack (Growing downward)
6577	0x00FB FFAC	Board Info Data and permanent copy of global data
6578	0x00FC 0000	Malloc Arena
6579	      :
6580	0x00FD FFFF
6581	0x00FE 0000	RAM Copy of Monitor Code
6582	...		eventually: LCD or video framebuffer
6583	...		eventually: pRAM (Protected RAM - unchanged by reset)
6584	0x00FF FFFF	[End of RAM]
6585
6586
6587System Initialization:
6588----------------------
6589
6590In the reset configuration, U-Boot starts at the reset entry point
6591(on most PowerPC systems at address 0x00000100). Because of the reset
6592configuration for CS0# this is a mirror of the on board Flash memory.
6593To be able to re-map memory U-Boot then jumps to its link address.
6594To be able to implement the initialization code in C, a (small!)
6595initial stack is set up in the internal Dual Ported RAM (in case CPUs
6596which provide such a feature like MPC8xx or MPC8260), or in a locked
6597part of the data cache. After that, U-Boot initializes the CPU core,
6598the caches and the SIU.
6599
6600Next, all (potentially) available memory banks are mapped using a
6601preliminary mapping. For example, we put them on 512 MB boundaries
6602(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6603on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6604programmed for SDRAM access. Using the temporary configuration, a
6605simple memory test is run that determines the size of the SDRAM
6606banks.
6607
6608When there is more than one SDRAM bank, and the banks are of
6609different size, the largest is mapped first. For equal size, the first
6610bank (CS2#) is mapped first. The first mapping is always for address
66110x00000000, with any additional banks following immediately to create
6612contiguous memory starting from 0.
6613
6614Then, the monitor installs itself at the upper end of the SDRAM area
6615and allocates memory for use by malloc() and for the global Board
6616Info data; also, the exception vector code is copied to the low RAM
6617pages, and the final stack is set up.
6618
6619Only after this relocation will you have a "normal" C environment;
6620until that you are restricted in several ways, mostly because you are
6621running from ROM, and because the code will have to be relocated to a
6622new address in RAM.
6623
6624
6625U-Boot Porting Guide:
6626----------------------
6627
6628[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6629list, October 2002]
6630
6631
6632int main(int argc, char *argv[])
6633{
6634	sighandler_t no_more_time;
6635
6636	signal(SIGALRM, no_more_time);
6637	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6638
6639	if (available_money > available_manpower) {
6640		Pay consultant to port U-Boot;
6641		return 0;
6642	}
6643
6644	Download latest U-Boot source;
6645
6646	Subscribe to u-boot mailing list;
6647
6648	if (clueless)
6649		email("Hi, I am new to U-Boot, how do I get started?");
6650
6651	while (learning) {
6652		Read the README file in the top level directory;
6653		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6654		Read applicable doc/*.README;
6655		Read the source, Luke;
6656		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6657	}
6658
6659	if (available_money > toLocalCurrency ($2500))
6660		Buy a BDI3000;
6661	else
6662		Add a lot of aggravation and time;
6663
6664	if (a similar board exists) {	/* hopefully... */
6665		cp -a board/<similar> board/<myboard>
6666		cp include/configs/<similar>.h include/configs/<myboard>.h
6667	} else {
6668		Create your own board support subdirectory;
6669		Create your own board include/configs/<myboard>.h file;
6670	}
6671	Edit new board/<myboard> files
6672	Edit new include/configs/<myboard>.h
6673
6674	while (!accepted) {
6675		while (!running) {
6676			do {
6677				Add / modify source code;
6678			} until (compiles);
6679			Debug;
6680			if (clueless)
6681				email("Hi, I am having problems...");
6682		}
6683		Send patch file to the U-Boot email list;
6684		if (reasonable critiques)
6685			Incorporate improvements from email list code review;
6686		else
6687			Defend code as written;
6688	}
6689
6690	return 0;
6691}
6692
6693void no_more_time (int sig)
6694{
6695      hire_a_guru();
6696}
6697
6698
6699Coding Standards:
6700-----------------
6701
6702All contributions to U-Boot should conform to the Linux kernel
6703coding style; see the file "Documentation/CodingStyle" and the script
6704"scripts/Lindent" in your Linux kernel source directory.
6705
6706Source files originating from a different project (for example the
6707MTD subsystem) are generally exempt from these guidelines and are not
6708reformatted to ease subsequent migration to newer versions of those
6709sources.
6710
6711Please note that U-Boot is implemented in C (and to some small parts in
6712Assembler); no C++ is used, so please do not use C++ style comments (//)
6713in your code.
6714
6715Please also stick to the following formatting rules:
6716- remove any trailing white space
6717- use TAB characters for indentation and vertical alignment, not spaces
6718- make sure NOT to use DOS '\r\n' line feeds
6719- do not add more than 2 consecutive empty lines to source files
6720- do not add trailing empty lines to source files
6721
6722Submissions which do not conform to the standards may be returned
6723with a request to reformat the changes.
6724
6725
6726Submitting Patches:
6727-------------------
6728
6729Since the number of patches for U-Boot is growing, we need to
6730establish some rules. Submissions which do not conform to these rules
6731may be rejected, even when they contain important and valuable stuff.
6732
6733Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6734
6735Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6736see http://lists.denx.de/mailman/listinfo/u-boot
6737
6738When you send a patch, please include the following information with
6739it:
6740
6741* For bug fixes: a description of the bug and how your patch fixes
6742  this bug. Please try to include a way of demonstrating that the
6743  patch actually fixes something.
6744
6745* For new features: a description of the feature and your
6746  implementation.
6747
6748* A CHANGELOG entry as plaintext (separate from the patch)
6749
6750* For major contributions, your entry to the CREDITS file
6751
6752* When you add support for a new board, don't forget to add a
6753  maintainer e-mail address to the boards.cfg file, too.
6754
6755* If your patch adds new configuration options, don't forget to
6756  document these in the README file.
6757
6758* The patch itself. If you are using git (which is *strongly*
6759  recommended) you can easily generate the patch using the
6760  "git format-patch". If you then use "git send-email" to send it to
6761  the U-Boot mailing list, you will avoid most of the common problems
6762  with some other mail clients.
6763
6764  If you cannot use git, use "diff -purN OLD NEW". If your version of
6765  diff does not support these options, then get the latest version of
6766  GNU diff.
6767
6768  The current directory when running this command shall be the parent
6769  directory of the U-Boot source tree (i. e. please make sure that
6770  your patch includes sufficient directory information for the
6771  affected files).
6772
6773  We prefer patches as plain text. MIME attachments are discouraged,
6774  and compressed attachments must not be used.
6775
6776* If one logical set of modifications affects or creates several
6777  files, all these changes shall be submitted in a SINGLE patch file.
6778
6779* Changesets that contain different, unrelated modifications shall be
6780  submitted as SEPARATE patches, one patch per changeset.
6781
6782
6783Notes:
6784
6785* Before sending the patch, run the MAKEALL script on your patched
6786  source tree and make sure that no errors or warnings are reported
6787  for any of the boards.
6788
6789* Keep your modifications to the necessary minimum: A patch
6790  containing several unrelated changes or arbitrary reformats will be
6791  returned with a request to re-formatting / split it.
6792
6793* If you modify existing code, make sure that your new code does not
6794  add to the memory footprint of the code ;-) Small is beautiful!
6795  When adding new features, these should compile conditionally only
6796  (using #ifdef), and the resulting code with the new feature
6797  disabled must not need more memory than the old code without your
6798  modification.
6799
6800* Remember that there is a size limit of 100 kB per message on the
6801  u-boot mailing list. Bigger patches will be moderated. If they are
6802  reasonable and not too big, they will be acknowledged. But patches
6803  bigger than the size limit should be avoided.
6804