xref: /rk3399_rockchip-uboot/README (revision c9afa7cea84c9b7346fcd2710577bcc386631aba)
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      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
186      /mpc5xx		Files specific to Freescale MPC5xx CPUs
187      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
188      /mpc8xx		Files specific to Freescale MPC8xx CPUs
189      /mpc824x		Files specific to Freescale MPC824x CPUs
190      /mpc8260		Files specific to Freescale MPC8260 CPUs
191      /mpc85xx		Files specific to Freescale MPC85xx CPUs
192      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
193    /lib		Architecture specific library files
194  /sh			Files generic to SH architecture
195    /cpu		CPU specific files
196      /sh2		Files specific to sh2 CPUs
197      /sh3		Files specific to sh3 CPUs
198      /sh4		Files specific to sh4 CPUs
199    /lib		Architecture specific library files
200  /sparc		Files generic to SPARC architecture
201    /cpu		CPU specific files
202      /leon2		Files specific to Gaisler LEON2 SPARC CPU
203      /leon3		Files specific to Gaisler LEON3 SPARC CPU
204    /lib		Architecture specific library files
205  /x86			Files generic to x86 architecture
206    /cpu		CPU specific files
207    /lib		Architecture specific library files
208/api			Machine/arch independent API for external apps
209/board			Board dependent files
210/common			Misc architecture independent functions
211/disk			Code for disk drive partition handling
212/doc			Documentation (don't expect too much)
213/drivers		Commonly used device drivers
214/dts			Contains Makefile for building internal U-Boot fdt.
215/examples		Example code for standalone applications, etc.
216/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
217/include		Header Files
218/lib			Files generic to all architectures
219  /libfdt		Library files to support flattened device trees
220  /lzma			Library files to support LZMA decompression
221  /lzo			Library files to support LZO decompression
222/net			Networking code
223/post			Power On Self Test
224/spl			Secondary Program Loader framework
225/tools			Tools to build S-Record or U-Boot images, etc.
226
227Software Configuration:
228=======================
229
230Configuration is usually done using C preprocessor defines; the
231rationale behind that is to avoid dead code whenever possible.
232
233There are two classes of configuration variables:
234
235* Configuration _OPTIONS_:
236  These are selectable by the user and have names beginning with
237  "CONFIG_".
238
239* Configuration _SETTINGS_:
240  These depend on the hardware etc. and should not be meddled with if
241  you don't know what you're doing; they have names beginning with
242  "CONFIG_SYS_".
243
244Later we will add a configuration tool - probably similar to or even
245identical to what's used for the Linux kernel. Right now, we have to
246do the configuration by hand, which means creating some symbolic
247links and editing some configuration files. We use the TQM8xxL boards
248as an example here.
249
250
251Selection of Processor Architecture and Board Type:
252---------------------------------------------------
253
254For all supported boards there are ready-to-use default
255configurations available; just type "make <board_name>_config".
256
257Example: For a TQM823L module type:
258
259	cd u-boot
260	make TQM823L_config
261
262For the Cogent platform, you need to specify the CPU type as well;
263e.g. "make cogent_mpc8xx_config". And also configure the cogent
264directory according to the instructions in cogent/README.
265
266
267Sandbox Environment:
268--------------------
269
270U-Boot can be built natively to run on a Linux host using the 'sandbox'
271board. This allows feature development which is not board- or architecture-
272specific to be undertaken on a native platform. The sandbox is also used to
273run some of U-Boot's tests.
274
275See board/sandbox/sandbox/README.sandbox for more details.
276
277
278Configuration Options:
279----------------------
280
281Configuration depends on the combination of board and CPU type; all
282such information is kept in a configuration file
283"include/configs/<board_name>.h".
284
285Example: For a TQM823L module, all configuration settings are in
286"include/configs/TQM823L.h".
287
288
289Many of the options are named exactly as the corresponding Linux
290kernel configuration options. The intention is to make it easier to
291build a config tool - later.
292
293
294The following options need to be configured:
295
296- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
297
298- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
299
300- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
301		Define exactly one, e.g. CONFIG_ATSTK1002
302
303- CPU Module Type: (if CONFIG_COGENT is defined)
304		Define exactly one of
305		CONFIG_CMA286_60_OLD
306--- FIXME --- not tested yet:
307		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
308		CONFIG_CMA287_23, CONFIG_CMA287_50
309
310- Motherboard Type: (if CONFIG_COGENT is defined)
311		Define exactly one of
312		CONFIG_CMA101, CONFIG_CMA102
313
314- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
315		Define one or more of
316		CONFIG_CMA302
317
318- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
319		Define one or more of
320		CONFIG_LCD_HEARTBEAT	- update a character position on
321					  the LCD display every second with
322					  a "rotator" |\-/|\-/
323
324- Board flavour: (if CONFIG_MPC8260ADS is defined)
325		CONFIG_ADSTYPE
326		Possible values are:
327			CONFIG_SYS_8260ADS	- original MPC8260ADS
328			CONFIG_SYS_8266ADS	- MPC8266ADS
329			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
330			CONFIG_SYS_8272ADS	- MPC8272ADS
331
332- Marvell Family Member
333		CONFIG_SYS_MVFS		- define it if you want to enable
334					  multiple fs option at one time
335					  for marvell soc family
336
337- MPC824X Family Member (if CONFIG_MPC824X is defined)
338		Define exactly one of
339		CONFIG_MPC8240, CONFIG_MPC8245
340
341- 8xx CPU Options: (if using an MPC8xx CPU)
342		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
343					  get_gclk_freq() cannot work
344					  e.g. if there is no 32KHz
345					  reference PIT/RTC clock
346		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
347					  or XTAL/EXTAL)
348
349- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
350		CONFIG_SYS_8xx_CPUCLK_MIN
351		CONFIG_SYS_8xx_CPUCLK_MAX
352		CONFIG_8xx_CPUCLK_DEFAULT
353			See doc/README.MPC866
354
355		CONFIG_SYS_MEASURE_CPUCLK
356
357		Define this to measure the actual CPU clock instead
358		of relying on the correctness of the configured
359		values. Mostly useful for board bringup to make sure
360		the PLL is locked at the intended frequency. Note
361		that this requires a (stable) reference clock (32 kHz
362		RTC clock or CONFIG_SYS_8XX_XIN)
363
364		CONFIG_SYS_DELAYED_ICACHE
365
366		Define this option if you want to enable the
367		ICache only when Code runs from RAM.
368
369- 85xx CPU Options:
370		CONFIG_SYS_PPC64
371
372		Specifies that the core is a 64-bit PowerPC implementation (implements
373		the "64" category of the Power ISA). This is necessary for ePAPR
374		compliance, among other possible reasons.
375
376		CONFIG_SYS_FSL_TBCLK_DIV
377
378		Defines the core time base clock divider ratio compared to the
379		system clock.  On most PQ3 devices this is 8, on newer QorIQ
380		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
381
382		CONFIG_SYS_FSL_PCIE_COMPAT
383
384		Defines the string to utilize when trying to match PCIe device
385		tree nodes for the given platform.
386
387		CONFIG_SYS_PPC_E500_DEBUG_TLB
388
389		Enables a temporary TLB entry to be used during boot to work
390		around limitations in e500v1 and e500v2 external debugger
391		support. This reduces the portions of the boot code where
392		breakpoints and single stepping do not work.  The value of this
393		symbol should be set to the TLB1 entry to be used for this
394		purpose.
395
396		CONFIG_SYS_FSL_ERRATUM_A004510
397
398		Enables a workaround for erratum A004510.  If set,
399		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
400		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
401
402		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
403		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
404
405		Defines one or two SoC revisions (low 8 bits of SVR)
406		for which the A004510 workaround should be applied.
407
408		The rest of SVR is either not relevant to the decision
409		of whether the erratum is present (e.g. p2040 versus
410		p2041) or is implied by the build target, which controls
411		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
412
413		See Freescale App Note 4493 for more information about
414		this erratum.
415
416		CONFIG_A003399_NOR_WORKAROUND
417		Enables a workaround for IFC erratum A003399. It is only
418		requred during NOR boot.
419
420		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
421
422		This is the value to write into CCSR offset 0x18600
423		according to the A004510 workaround.
424
425		CONFIG_SYS_FSL_DSP_DDR_ADDR
426		This value denotes start offset of DDR memory which is
427		connected exclusively to the DSP cores.
428
429		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
430		This value denotes start offset of M2 memory
431		which is directly connected to the DSP core.
432
433		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
434		This value denotes start offset of M3 memory which is directly
435		connected to the DSP core.
436
437		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
438		This value denotes start offset of DSP CCSR space.
439
440		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
441		Single Source Clock is clocking mode present in some of FSL SoC's.
442		In this mode, a single differential clock is used to supply
443		clocks to the sysclock, ddrclock and usbclock.
444
445		CONFIG_SYS_CPC_REINIT_F
446		This CONFIG is defined when the CPC is configured as SRAM at the
447		time of U-boot entry and is required to be re-initialized.
448
449		CONFIG_DEEP_SLEEP
450		Inidcates this SoC supports deep sleep feature. If deep sleep is
451		supported, core will start to execute uboot when wakes up.
452
453- Generic CPU options:
454		CONFIG_SYS_GENERIC_GLOBAL_DATA
455		Defines global data is initialized in generic board board_init_f().
456		If this macro is defined, global data is created and cleared in
457		generic board board_init_f(). Without this macro, architecture/board
458		should initialize global data before calling board_init_f().
459
460		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
461
462		Defines the endianess of the CPU. Implementation of those
463		values is arch specific.
464
465		CONFIG_SYS_FSL_DDR
466		Freescale DDR driver in use. This type of DDR controller is
467		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
468		SoCs.
469
470		CONFIG_SYS_FSL_DDR_ADDR
471		Freescale DDR memory-mapped register base.
472
473		CONFIG_SYS_FSL_DDR_EMU
474		Specify emulator support for DDR. Some DDR features such as
475		deskew training are not available.
476
477		CONFIG_SYS_FSL_DDRC_GEN1
478		Freescale DDR1 controller.
479
480		CONFIG_SYS_FSL_DDRC_GEN2
481		Freescale DDR2 controller.
482
483		CONFIG_SYS_FSL_DDRC_GEN3
484		Freescale DDR3 controller.
485
486		CONFIG_SYS_FSL_DDRC_GEN4
487		Freescale DDR4 controller.
488
489		CONFIG_SYS_FSL_DDRC_ARM_GEN3
490		Freescale DDR3 controller for ARM-based SoCs.
491
492		CONFIG_SYS_FSL_DDR1
493		Board config to use DDR1. It can be enabled for SoCs with
494		Freescale DDR1 or DDR2 controllers, depending on the board
495		implemetation.
496
497		CONFIG_SYS_FSL_DDR2
498		Board config to use DDR2. It can be eanbeld for SoCs with
499		Freescale DDR2 or DDR3 controllers, depending on the board
500		implementation.
501
502		CONFIG_SYS_FSL_DDR3
503		Board config to use DDR3. It can be enabled for SoCs with
504		Freescale DDR3 or DDR3L controllers.
505
506		CONFIG_SYS_FSL_DDR3L
507		Board config to use DDR3L. It can be enabled for SoCs with
508		DDR3L controllers.
509
510		CONFIG_SYS_FSL_DDR4
511		Board config to use DDR4. It can be enabled for SoCs with
512		DDR4 controllers.
513
514		CONFIG_SYS_FSL_IFC_BE
515		Defines the IFC controller register space as Big Endian
516
517		CONFIG_SYS_FSL_IFC_LE
518		Defines the IFC controller register space as Little Endian
519
520		CONFIG_SYS_FSL_PBL_PBI
521		It enables addition of RCW (Power on reset configuration) in built image.
522		Please refer doc/README.pblimage for more details
523
524		CONFIG_SYS_FSL_PBL_RCW
525		It adds PBI(pre-boot instructions) commands in u-boot build image.
526		PBI commands can be used to configure SoC before it starts the execution.
527		Please refer doc/README.pblimage for more details
528
529		CONFIG_SPL_FSL_PBL
530		It adds a target to create boot binary having SPL binary in PBI format
531		concatenated with u-boot binary.
532
533		CONFIG_SYS_FSL_DDR_BE
534		Defines the DDR controller register space as Big Endian
535
536		CONFIG_SYS_FSL_DDR_LE
537		Defines the DDR controller register space as Little Endian
538
539		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
540		Physical address from the view of DDR controllers. It is the
541		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
542		it could be different for ARM SoCs.
543
544		CONFIG_SYS_FSL_DDR_INTLV_256B
545		DDR controller interleaving on 256-byte. This is a special
546		interleaving mode, handled by Dickens for Freescale layerscape
547		SoCs with ARM core.
548
549- Intel Monahans options:
550		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
551
552		Defines the Monahans run mode to oscillator
553		ratio. Valid values are 8, 16, 24, 31. The core
554		frequency is this value multiplied by 13 MHz.
555
556		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
557
558		Defines the Monahans turbo mode to oscillator
559		ratio. Valid values are 1 (default if undefined) and
560		2. The core frequency as calculated above is multiplied
561		by this value.
562
563- MIPS CPU options:
564		CONFIG_SYS_INIT_SP_OFFSET
565
566		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
567		pointer. This is needed for the temporary stack before
568		relocation.
569
570		CONFIG_SYS_MIPS_CACHE_MODE
571
572		Cache operation mode for the MIPS CPU.
573		See also arch/mips/include/asm/mipsregs.h.
574		Possible values are:
575			CONF_CM_CACHABLE_NO_WA
576			CONF_CM_CACHABLE_WA
577			CONF_CM_UNCACHED
578			CONF_CM_CACHABLE_NONCOHERENT
579			CONF_CM_CACHABLE_CE
580			CONF_CM_CACHABLE_COW
581			CONF_CM_CACHABLE_CUW
582			CONF_CM_CACHABLE_ACCELERATED
583
584		CONFIG_SYS_XWAY_EBU_BOOTCFG
585
586		Special option for Lantiq XWAY SoCs for booting from NOR flash.
587		See also arch/mips/cpu/mips32/start.S.
588
589		CONFIG_XWAY_SWAP_BYTES
590
591		Enable compilation of tools/xway-swap-bytes needed for Lantiq
592		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
593		be swapped if a flash programmer is used.
594
595- ARM options:
596		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
597
598		Select high exception vectors of the ARM core, e.g., do not
599		clear the V bit of the c1 register of CP15.
600
601		CONFIG_SYS_THUMB_BUILD
602
603		Use this flag to build U-Boot using the Thumb instruction
604		set for ARM architectures. Thumb instruction set provides
605		better code density. For ARM architectures that support
606		Thumb2 this flag will result in Thumb2 code generated by
607		GCC.
608
609		CONFIG_ARM_ERRATA_716044
610		CONFIG_ARM_ERRATA_742230
611		CONFIG_ARM_ERRATA_743622
612		CONFIG_ARM_ERRATA_751472
613		CONFIG_ARM_ERRATA_794072
614		CONFIG_ARM_ERRATA_761320
615
616		If set, the workarounds for these ARM errata are applied early
617		during U-Boot startup. Note that these options force the
618		workarounds to be applied; no CPU-type/version detection
619		exists, unlike the similar options in the Linux kernel. Do not
620		set these options unless they apply!
621
622- CPU timer options:
623		CONFIG_SYS_HZ
624
625		The frequency of the timer returned by get_timer().
626		get_timer() must operate in milliseconds and this CONFIG
627		option must be set to 1000.
628
629- Linux Kernel Interface:
630		CONFIG_CLOCKS_IN_MHZ
631
632		U-Boot stores all clock information in Hz
633		internally. For binary compatibility with older Linux
634		kernels (which expect the clocks passed in the
635		bd_info data to be in MHz) the environment variable
636		"clocks_in_mhz" can be defined so that U-Boot
637		converts clock data to MHZ before passing it to the
638		Linux kernel.
639		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
640		"clocks_in_mhz=1" is automatically included in the
641		default environment.
642
643		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
644
645		When transferring memsize parameter to linux, some versions
646		expect it to be in bytes, others in MB.
647		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
648
649		CONFIG_OF_LIBFDT
650
651		New kernel versions are expecting firmware settings to be
652		passed using flattened device trees (based on open firmware
653		concepts).
654
655		CONFIG_OF_LIBFDT
656		 * New libfdt-based support
657		 * Adds the "fdt" command
658		 * The bootm command automatically updates the fdt
659
660		OF_CPU - The proper name of the cpus node (only required for
661			MPC512X and MPC5xxx based boards).
662		OF_SOC - The proper name of the soc node (only required for
663			MPC512X and MPC5xxx based boards).
664		OF_TBCLK - The timebase frequency.
665		OF_STDOUT_PATH - The path to the console device
666
667		boards with QUICC Engines require OF_QE to set UCC MAC
668		addresses
669
670		CONFIG_OF_BOARD_SETUP
671
672		Board code has addition modification that it wants to make
673		to the flat device tree before handing it off to the kernel
674
675		CONFIG_OF_BOOT_CPU
676
677		This define fills in the correct boot CPU in the boot
678		param header, the default value is zero if undefined.
679
680		CONFIG_OF_IDE_FIXUP
681
682		U-Boot can detect if an IDE device is present or not.
683		If not, and this new config option is activated, U-Boot
684		removes the ATA node from the DTS before booting Linux,
685		so the Linux IDE driver does not probe the device and
686		crash. This is needed for buggy hardware (uc101) where
687		no pull down resistor is connected to the signal IDE5V_DD7.
688
689		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
690
691		This setting is mandatory for all boards that have only one
692		machine type and must be used to specify the machine type
693		number as it appears in the ARM machine registry
694		(see http://www.arm.linux.org.uk/developer/machines/).
695		Only boards that have multiple machine types supported
696		in a single configuration file and the machine type is
697		runtime discoverable, do not have to use this setting.
698
699- vxWorks boot parameters:
700
701		bootvx constructs a valid bootline using the following
702		environments variables: bootfile, ipaddr, serverip, hostname.
703		It loads the vxWorks image pointed bootfile.
704
705		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
706		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
707		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
708		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
709
710		CONFIG_SYS_VXWORKS_ADD_PARAMS
711
712		Add it at the end of the bootline. E.g "u=username pw=secret"
713
714		Note: If a "bootargs" environment is defined, it will overwride
715		the defaults discussed just above.
716
717- Cache Configuration:
718		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
719		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
720		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
721
722- Cache Configuration for ARM:
723		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
724				      controller
725		CONFIG_SYS_PL310_BASE - Physical base address of PL310
726					controller register space
727
728- Serial Ports:
729		CONFIG_PL010_SERIAL
730
731		Define this if you want support for Amba PrimeCell PL010 UARTs.
732
733		CONFIG_PL011_SERIAL
734
735		Define this if you want support for Amba PrimeCell PL011 UARTs.
736
737		CONFIG_PL011_CLOCK
738
739		If you have Amba PrimeCell PL011 UARTs, set this variable to
740		the clock speed of the UARTs.
741
742		CONFIG_PL01x_PORTS
743
744		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
745		define this to a list of base addresses for each (supported)
746		port. See e.g. include/configs/versatile.h
747
748		CONFIG_PL011_SERIAL_RLCR
749
750		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
751		have separate receive and transmit line control registers.  Set
752		this variable to initialize the extra register.
753
754		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
755
756		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
757		boot loader that has already initialized the UART.  Define this
758		variable to flush the UART at init time.
759
760		CONFIG_SERIAL_HW_FLOW_CONTROL
761
762		Define this variable to enable hw flow control in serial driver.
763		Current user of this option is drivers/serial/nsl16550.c driver
764
765- Console Interface:
766		Depending on board, define exactly one serial port
767		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
768		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
769		console by defining CONFIG_8xx_CONS_NONE
770
771		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
772		port routines must be defined elsewhere
773		(i.e. serial_init(), serial_getc(), ...)
774
775		CONFIG_CFB_CONSOLE
776		Enables console device for a color framebuffer. Needs following
777		defines (cf. smiLynxEM, i8042)
778			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
779						(default big endian)
780			VIDEO_HW_RECTFILL	graphic chip supports
781						rectangle fill
782						(cf. smiLynxEM)
783			VIDEO_HW_BITBLT		graphic chip supports
784						bit-blit (cf. smiLynxEM)
785			VIDEO_VISIBLE_COLS	visible pixel columns
786						(cols=pitch)
787			VIDEO_VISIBLE_ROWS	visible pixel rows
788			VIDEO_PIXEL_SIZE	bytes per pixel
789			VIDEO_DATA_FORMAT	graphic data format
790						(0-5, cf. cfb_console.c)
791			VIDEO_FB_ADRS		framebuffer address
792			VIDEO_KBD_INIT_FCT	keyboard int fct
793						(i.e. i8042_kbd_init())
794			VIDEO_TSTC_FCT		test char fct
795						(i.e. i8042_tstc)
796			VIDEO_GETC_FCT		get char fct
797						(i.e. i8042_getc)
798			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
799						(requires blink timer
800						cf. i8042.c)
801			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
802			CONFIG_CONSOLE_TIME	display time/date info in
803						upper right corner
804						(requires CONFIG_CMD_DATE)
805			CONFIG_VIDEO_LOGO	display Linux logo in
806						upper left corner
807			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
808						linux_logo.h for logo.
809						Requires CONFIG_VIDEO_LOGO
810			CONFIG_CONSOLE_EXTRA_INFO
811						additional board info beside
812						the logo
813
814		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
815		a limited number of ANSI escape sequences (cursor control,
816		erase functions and limited graphics rendition control).
817
818		When CONFIG_CFB_CONSOLE is defined, video console is
819		default i/o. Serial console can be forced with
820		environment 'console=serial'.
821
822		When CONFIG_SILENT_CONSOLE is defined, all console
823		messages (by U-Boot and Linux!) can be silenced with
824		the "silent" environment variable. See
825		doc/README.silent for more information.
826
827		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
828			is 0x00.
829		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
830			is 0xa0.
831
832- Console Baudrate:
833		CONFIG_BAUDRATE - in bps
834		Select one of the baudrates listed in
835		CONFIG_SYS_BAUDRATE_TABLE, see below.
836		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
837
838- Console Rx buffer length
839		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
840		the maximum receive buffer length for the SMC.
841		This option is actual only for 82xx and 8xx possible.
842		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
843		must be defined, to setup the maximum idle timeout for
844		the SMC.
845
846- Pre-Console Buffer:
847		Prior to the console being initialised (i.e. serial UART
848		initialised etc) all console output is silently discarded.
849		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
850		buffer any console messages prior to the console being
851		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
852		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
853		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
854		bytes are output before the console is initialised, the
855		earlier bytes are discarded.
856
857		'Sane' compilers will generate smaller code if
858		CONFIG_PRE_CON_BUF_SZ is a power of 2
859
860- Safe printf() functions
861		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
862		the printf() functions. These are defined in
863		include/vsprintf.h and include snprintf(), vsnprintf() and
864		so on. Code size increase is approximately 300-500 bytes.
865		If this option is not given then these functions will
866		silently discard their buffer size argument - this means
867		you are not getting any overflow checking in this case.
868
869- Boot Delay:	CONFIG_BOOTDELAY - in seconds
870		Delay before automatically booting the default image;
871		set to -1 to disable autoboot.
872		set to -2 to autoboot with no delay and not check for abort
873		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
874
875		See doc/README.autoboot for these options that
876		work with CONFIG_BOOTDELAY. None are required.
877		CONFIG_BOOT_RETRY_TIME
878		CONFIG_BOOT_RETRY_MIN
879		CONFIG_AUTOBOOT_KEYED
880		CONFIG_AUTOBOOT_PROMPT
881		CONFIG_AUTOBOOT_DELAY_STR
882		CONFIG_AUTOBOOT_STOP_STR
883		CONFIG_AUTOBOOT_DELAY_STR2
884		CONFIG_AUTOBOOT_STOP_STR2
885		CONFIG_ZERO_BOOTDELAY_CHECK
886		CONFIG_RESET_TO_RETRY
887
888- Autoboot Command:
889		CONFIG_BOOTCOMMAND
890		Only needed when CONFIG_BOOTDELAY is enabled;
891		define a command string that is automatically executed
892		when no character is read on the console interface
893		within "Boot Delay" after reset.
894
895		CONFIG_BOOTARGS
896		This can be used to pass arguments to the bootm
897		command. The value of CONFIG_BOOTARGS goes into the
898		environment value "bootargs".
899
900		CONFIG_RAMBOOT and CONFIG_NFSBOOT
901		The value of these goes into the environment as
902		"ramboot" and "nfsboot" respectively, and can be used
903		as a convenience, when switching between booting from
904		RAM and NFS.
905
906- Bootcount:
907		CONFIG_BOOTCOUNT_LIMIT
908		Implements a mechanism for detecting a repeating reboot
909		cycle, see:
910		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
911
912		CONFIG_BOOTCOUNT_ENV
913		If no softreset save registers are found on the hardware
914		"bootcount" is stored in the environment. To prevent a
915		saveenv on all reboots, the environment variable
916		"upgrade_available" is used. If "upgrade_available" is
917		0, "bootcount" is always 0, if "upgrade_available" is
918		1 "bootcount" is incremented in the environment.
919		So the Userspace Applikation must set the "upgrade_available"
920		and "bootcount" variable to 0, if a boot was successfully.
921
922- Pre-Boot Commands:
923		CONFIG_PREBOOT
924
925		When this option is #defined, the existence of the
926		environment variable "preboot" will be checked
927		immediately before starting the CONFIG_BOOTDELAY
928		countdown and/or running the auto-boot command resp.
929		entering interactive mode.
930
931		This feature is especially useful when "preboot" is
932		automatically generated or modified. For an example
933		see the LWMON board specific code: here "preboot" is
934		modified when the user holds down a certain
935		combination of keys on the (special) keyboard when
936		booting the systems
937
938- Serial Download Echo Mode:
939		CONFIG_LOADS_ECHO
940		If defined to 1, all characters received during a
941		serial download (using the "loads" command) are
942		echoed back. This might be needed by some terminal
943		emulations (like "cu"), but may as well just take
944		time on others. This setting #define's the initial
945		value of the "loads_echo" environment variable.
946
947- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
948		CONFIG_KGDB_BAUDRATE
949		Select one of the baudrates listed in
950		CONFIG_SYS_BAUDRATE_TABLE, see below.
951
952- Monitor Functions:
953		Monitor commands can be included or excluded
954		from the build by using the #include files
955		<config_cmd_all.h> and #undef'ing unwanted
956		commands, or using <config_cmd_default.h>
957		and augmenting with additional #define's
958		for wanted commands.
959
960		The default command configuration includes all commands
961		except those marked below with a "*".
962
963		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
964		CONFIG_CMD_ASKENV	* ask for env variable
965		CONFIG_CMD_BDI		  bdinfo
966		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
967		CONFIG_CMD_BMP		* BMP support
968		CONFIG_CMD_BSP		* Board specific commands
969		CONFIG_CMD_BOOTD	  bootd
970		CONFIG_CMD_CACHE	* icache, dcache
971		CONFIG_CMD_CLK   	* clock command support
972		CONFIG_CMD_CONSOLE	  coninfo
973		CONFIG_CMD_CRC32	* crc32
974		CONFIG_CMD_DATE		* support for RTC, date/time...
975		CONFIG_CMD_DHCP		* DHCP support
976		CONFIG_CMD_DIAG		* Diagnostics
977		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
978		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
979		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
980		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
981		CONFIG_CMD_DTT		* Digital Therm and Thermostat
982		CONFIG_CMD_ECHO		  echo arguments
983		CONFIG_CMD_EDITENV	  edit env variable
984		CONFIG_CMD_EEPROM	* EEPROM read/write support
985		CONFIG_CMD_ELF		* bootelf, bootvx
986		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
987		CONFIG_CMD_ENV_FLAGS	* display details about env flags
988		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
989		CONFIG_CMD_EXPORTENV	* export the environment
990		CONFIG_CMD_EXT2		* ext2 command support
991		CONFIG_CMD_EXT4		* ext4 command support
992		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
993					  that work for multiple fs types
994		CONFIG_CMD_SAVEENV	  saveenv
995		CONFIG_CMD_FDC		* Floppy Disk Support
996		CONFIG_CMD_FAT		* FAT command support
997		CONFIG_CMD_FLASH	  flinfo, erase, protect
998		CONFIG_CMD_FPGA		  FPGA device initialization support
999		CONFIG_CMD_FUSE		* Device fuse support
1000		CONFIG_CMD_GETTIME	* Get time since boot
1001		CONFIG_CMD_GO		* the 'go' command (exec code)
1002		CONFIG_CMD_GREPENV	* search environment
1003		CONFIG_CMD_HASH		* calculate hash / digest
1004		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
1005		CONFIG_CMD_I2C		* I2C serial bus support
1006		CONFIG_CMD_IDE		* IDE harddisk support
1007		CONFIG_CMD_IMI		  iminfo
1008		CONFIG_CMD_IMLS		  List all images found in NOR flash
1009		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
1010		CONFIG_CMD_IMMAP	* IMMR dump support
1011		CONFIG_CMD_IMPORTENV	* import an environment
1012		CONFIG_CMD_INI		* import data from an ini file into the env
1013		CONFIG_CMD_IRQ		* irqinfo
1014		CONFIG_CMD_ITEST	  Integer/string test of 2 values
1015		CONFIG_CMD_JFFS2	* JFFS2 Support
1016		CONFIG_CMD_KGDB		* kgdb
1017		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
1018		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
1019					  (169.254.*.*)
1020		CONFIG_CMD_LOADB	  loadb
1021		CONFIG_CMD_LOADS	  loads
1022		CONFIG_CMD_MD5SUM	* print md5 message digest
1023					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
1024		CONFIG_CMD_MEMINFO	* Display detailed memory information
1025		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
1026					  loop, loopw
1027		CONFIG_CMD_MEMTEST	* mtest
1028		CONFIG_CMD_MISC		  Misc functions like sleep etc
1029		CONFIG_CMD_MMC		* MMC memory mapped support
1030		CONFIG_CMD_MII		* MII utility commands
1031		CONFIG_CMD_MTDPARTS	* MTD partition support
1032		CONFIG_CMD_NAND		* NAND support
1033		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
1034		CONFIG_CMD_NFS		  NFS support
1035		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1036		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1037		CONFIG_CMD_PCI		* pciinfo
1038		CONFIG_CMD_PCMCIA		* PCMCIA support
1039		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1040					  host
1041		CONFIG_CMD_PORTIO	* Port I/O
1042		CONFIG_CMD_READ		* Read raw data from partition
1043		CONFIG_CMD_REGINFO	* Register dump
1044		CONFIG_CMD_RUN		  run command in env variable
1045		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1046		CONFIG_CMD_SAVES	* save S record dump
1047		CONFIG_CMD_SCSI		* SCSI Support
1048		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1049					  (requires CONFIG_CMD_I2C)
1050		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1051					  (4xx only)
1052		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1053		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1054					  (requires CONFIG_CMD_MEMORY)
1055		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1056		CONFIG_CMD_SOURCE	  "source" command Support
1057		CONFIG_CMD_SPI		* SPI serial bus support
1058		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1059		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1060		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1061		CONFIG_CMD_TIMER	* access to the system tick timer
1062		CONFIG_CMD_USB		* USB support
1063		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1064		CONFIG_CMD_MFSL		* Microblaze FSL support
1065		CONFIG_CMD_XIMG		  Load part of Multi Image
1066		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1067
1068		EXAMPLE: If you want all functions except of network
1069		support you can write:
1070
1071		#include "config_cmd_all.h"
1072		#undef CONFIG_CMD_NET
1073
1074	Other Commands:
1075		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1076
1077	Note:	Don't enable the "icache" and "dcache" commands
1078		(configuration option CONFIG_CMD_CACHE) unless you know
1079		what you (and your U-Boot users) are doing. Data
1080		cache cannot be enabled on systems like the 8xx or
1081		8260 (where accesses to the IMMR region must be
1082		uncached), and it cannot be disabled on all other
1083		systems where we (mis-) use the data cache to hold an
1084		initial stack and some data.
1085
1086
1087		XXX - this list needs to get updated!
1088
1089- Regular expression support:
1090		CONFIG_REGEX
1091		If this variable is defined, U-Boot is linked against
1092		the SLRE (Super Light Regular Expression) library,
1093		which adds regex support to some commands, as for
1094		example "env grep" and "setexpr".
1095
1096- Device tree:
1097		CONFIG_OF_CONTROL
1098		If this variable is defined, U-Boot will use a device tree
1099		to configure its devices, instead of relying on statically
1100		compiled #defines in the board file. This option is
1101		experimental and only available on a few boards. The device
1102		tree is available in the global data as gd->fdt_blob.
1103
1104		U-Boot needs to get its device tree from somewhere. This can
1105		be done using one of the two options below:
1106
1107		CONFIG_OF_EMBED
1108		If this variable is defined, U-Boot will embed a device tree
1109		binary in its image. This device tree file should be in the
1110		board directory and called <soc>-<board>.dts. The binary file
1111		is then picked up in board_init_f() and made available through
1112		the global data structure as gd->blob.
1113
1114		CONFIG_OF_SEPARATE
1115		If this variable is defined, U-Boot will build a device tree
1116		binary. It will be called u-boot.dtb. Architecture-specific
1117		code will locate it at run-time. Generally this works by:
1118
1119			cat u-boot.bin u-boot.dtb >image.bin
1120
1121		and in fact, U-Boot does this for you, creating a file called
1122		u-boot-dtb.bin which is useful in the common case. You can
1123		still use the individual files if you need something more
1124		exotic.
1125
1126- Watchdog:
1127		CONFIG_WATCHDOG
1128		If this variable is defined, it enables watchdog
1129		support for the SoC. There must be support in the SoC
1130		specific code for a watchdog. For the 8xx and 8260
1131		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1132		register.  When supported for a specific SoC is
1133		available, then no further board specific code should
1134		be needed to use it.
1135
1136		CONFIG_HW_WATCHDOG
1137		When using a watchdog circuitry external to the used
1138		SoC, then define this variable and provide board
1139		specific code for the "hw_watchdog_reset" function.
1140
1141- U-Boot Version:
1142		CONFIG_VERSION_VARIABLE
1143		If this variable is defined, an environment variable
1144		named "ver" is created by U-Boot showing the U-Boot
1145		version as printed by the "version" command.
1146		Any change to this variable will be reverted at the
1147		next reset.
1148
1149- Real-Time Clock:
1150
1151		When CONFIG_CMD_DATE is selected, the type of the RTC
1152		has to be selected, too. Define exactly one of the
1153		following options:
1154
1155		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1156		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1157		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1158		CONFIG_RTC_MC146818	- use MC146818 RTC
1159		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1160		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1161		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1162		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1163		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1164		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1165		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1166		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1167					  RV3029 RTC.
1168
1169		Note that if the RTC uses I2C, then the I2C interface
1170		must also be configured. See I2C Support, below.
1171
1172- GPIO Support:
1173		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1174
1175		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1176		chip-ngpio pairs that tell the PCA953X driver the number of
1177		pins supported by a particular chip.
1178
1179		Note that if the GPIO device uses I2C, then the I2C interface
1180		must also be configured. See I2C Support, below.
1181
1182- Timestamp Support:
1183
1184		When CONFIG_TIMESTAMP is selected, the timestamp
1185		(date and time) of an image is printed by image
1186		commands like bootm or iminfo. This option is
1187		automatically enabled when you select CONFIG_CMD_DATE .
1188
1189- Partition Labels (disklabels) Supported:
1190		Zero or more of the following:
1191		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1192		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1193				       Intel architecture, USB sticks, etc.
1194		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1195		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1196				       bootloader.  Note 2TB partition limit; see
1197				       disk/part_efi.c
1198		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1199
1200		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1201		CONFIG_CMD_SCSI) you must configure support for at
1202		least one non-MTD partition type as well.
1203
1204- IDE Reset method:
1205		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1206		board configurations files but used nowhere!
1207
1208		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1209		be performed by calling the function
1210			ide_set_reset(int reset)
1211		which has to be defined in a board specific file
1212
1213- ATAPI Support:
1214		CONFIG_ATAPI
1215
1216		Set this to enable ATAPI support.
1217
1218- LBA48 Support
1219		CONFIG_LBA48
1220
1221		Set this to enable support for disks larger than 137GB
1222		Also look at CONFIG_SYS_64BIT_LBA.
1223		Whithout these , LBA48 support uses 32bit variables and will 'only'
1224		support disks up to 2.1TB.
1225
1226		CONFIG_SYS_64BIT_LBA:
1227			When enabled, makes the IDE subsystem use 64bit sector addresses.
1228			Default is 32bit.
1229
1230- SCSI Support:
1231		At the moment only there is only support for the
1232		SYM53C8XX SCSI controller; define
1233		CONFIG_SCSI_SYM53C8XX to enable it.
1234
1235		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1236		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1237		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1238		maximum numbers of LUNs, SCSI ID's and target
1239		devices.
1240		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1241
1242		The environment variable 'scsidevs' is set to the number of
1243		SCSI devices found during the last scan.
1244
1245- NETWORK Support (PCI):
1246		CONFIG_E1000
1247		Support for Intel 8254x/8257x gigabit chips.
1248
1249		CONFIG_E1000_SPI
1250		Utility code for direct access to the SPI bus on Intel 8257x.
1251		This does not do anything useful unless you set at least one
1252		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1253
1254		CONFIG_E1000_SPI_GENERIC
1255		Allow generic access to the SPI bus on the Intel 8257x, for
1256		example with the "sspi" command.
1257
1258		CONFIG_CMD_E1000
1259		Management command for E1000 devices.  When used on devices
1260		with SPI support you can reprogram the EEPROM from U-Boot.
1261
1262		CONFIG_E1000_FALLBACK_MAC
1263		default MAC for empty EEPROM after production.
1264
1265		CONFIG_EEPRO100
1266		Support for Intel 82557/82559/82559ER chips.
1267		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1268		write routine for first time initialisation.
1269
1270		CONFIG_TULIP
1271		Support for Digital 2114x chips.
1272		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1273		modem chip initialisation (KS8761/QS6611).
1274
1275		CONFIG_NATSEMI
1276		Support for National dp83815 chips.
1277
1278		CONFIG_NS8382X
1279		Support for National dp8382[01] gigabit chips.
1280
1281- NETWORK Support (other):
1282
1283		CONFIG_DRIVER_AT91EMAC
1284		Support for AT91RM9200 EMAC.
1285
1286			CONFIG_RMII
1287			Define this to use reduced MII inteface
1288
1289			CONFIG_DRIVER_AT91EMAC_QUIET
1290			If this defined, the driver is quiet.
1291			The driver doen't show link status messages.
1292
1293		CONFIG_CALXEDA_XGMAC
1294		Support for the Calxeda XGMAC device
1295
1296		CONFIG_LAN91C96
1297		Support for SMSC's LAN91C96 chips.
1298
1299			CONFIG_LAN91C96_BASE
1300			Define this to hold the physical address
1301			of the LAN91C96's I/O space
1302
1303			CONFIG_LAN91C96_USE_32_BIT
1304			Define this to enable 32 bit addressing
1305
1306		CONFIG_SMC91111
1307		Support for SMSC's LAN91C111 chip
1308
1309			CONFIG_SMC91111_BASE
1310			Define this to hold the physical address
1311			of the device (I/O space)
1312
1313			CONFIG_SMC_USE_32_BIT
1314			Define this if data bus is 32 bits
1315
1316			CONFIG_SMC_USE_IOFUNCS
1317			Define this to use i/o functions instead of macros
1318			(some hardware wont work with macros)
1319
1320		CONFIG_DRIVER_TI_EMAC
1321		Support for davinci emac
1322
1323			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1324			Define this if you have more then 3 PHYs.
1325
1326		CONFIG_FTGMAC100
1327		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1328
1329			CONFIG_FTGMAC100_EGIGA
1330			Define this to use GE link update with gigabit PHY.
1331			Define this if FTGMAC100 is connected to gigabit PHY.
1332			If your system has 10/100 PHY only, it might not occur
1333			wrong behavior. Because PHY usually return timeout or
1334			useless data when polling gigabit status and gigabit
1335			control registers. This behavior won't affect the
1336			correctnessof 10/100 link speed update.
1337
1338		CONFIG_SMC911X
1339		Support for SMSC's LAN911x and LAN921x chips
1340
1341			CONFIG_SMC911X_BASE
1342			Define this to hold the physical address
1343			of the device (I/O space)
1344
1345			CONFIG_SMC911X_32_BIT
1346			Define this if data bus is 32 bits
1347
1348			CONFIG_SMC911X_16_BIT
1349			Define this if data bus is 16 bits. If your processor
1350			automatically converts one 32 bit word to two 16 bit
1351			words you may also try CONFIG_SMC911X_32_BIT.
1352
1353		CONFIG_SH_ETHER
1354		Support for Renesas on-chip Ethernet controller
1355
1356			CONFIG_SH_ETHER_USE_PORT
1357			Define the number of ports to be used
1358
1359			CONFIG_SH_ETHER_PHY_ADDR
1360			Define the ETH PHY's address
1361
1362			CONFIG_SH_ETHER_CACHE_WRITEBACK
1363			If this option is set, the driver enables cache flush.
1364
1365- TPM Support:
1366		CONFIG_TPM
1367		Support TPM devices.
1368
1369		CONFIG_TPM_TIS_I2C
1370		Support for i2c bus TPM devices. Only one device
1371		per system is supported at this time.
1372
1373			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1374			Define the the i2c bus number for the TPM device
1375
1376			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1377			Define the TPM's address on the i2c bus
1378
1379			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1380			Define the burst count bytes upper limit
1381
1382		CONFIG_TPM_ATMEL_TWI
1383		Support for Atmel TWI TPM device. Requires I2C support.
1384
1385		CONFIG_TPM_TIS_LPC
1386		Support for generic parallel port TPM devices. Only one device
1387		per system is supported at this time.
1388
1389			CONFIG_TPM_TIS_BASE_ADDRESS
1390			Base address where the generic TPM device is mapped
1391			to. Contemporary x86 systems usually map it at
1392			0xfed40000.
1393
1394		CONFIG_CMD_TPM
1395		Add tpm monitor functions.
1396		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1397		provides monitor access to authorized functions.
1398
1399		CONFIG_TPM
1400		Define this to enable the TPM support library which provides
1401		functional interfaces to some TPM commands.
1402		Requires support for a TPM device.
1403
1404		CONFIG_TPM_AUTH_SESSIONS
1405		Define this to enable authorized functions in the TPM library.
1406		Requires CONFIG_TPM and CONFIG_SHA1.
1407
1408- USB Support:
1409		At the moment only the UHCI host controller is
1410		supported (PIP405, MIP405, MPC5200); define
1411		CONFIG_USB_UHCI to enable it.
1412		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1413		and define CONFIG_USB_STORAGE to enable the USB
1414		storage devices.
1415		Note:
1416		Supported are USB Keyboards and USB Floppy drives
1417		(TEAC FD-05PUB).
1418		MPC5200 USB requires additional defines:
1419			CONFIG_USB_CLOCK
1420				for 528 MHz Clock: 0x0001bbbb
1421			CONFIG_PSC3_USB
1422				for USB on PSC3
1423			CONFIG_USB_CONFIG
1424				for differential drivers: 0x00001000
1425				for single ended drivers: 0x00005000
1426				for differential drivers on PSC3: 0x00000100
1427				for single ended drivers on PSC3: 0x00004100
1428			CONFIG_SYS_USB_EVENT_POLL
1429				May be defined to allow interrupt polling
1430				instead of using asynchronous interrupts
1431
1432		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1433		txfilltuning field in the EHCI controller on reset.
1434
1435		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1436		interval for usb hub power-on delay.(minimum 100msec)
1437
1438- USB Device:
1439		Define the below if you wish to use the USB console.
1440		Once firmware is rebuilt from a serial console issue the
1441		command "setenv stdin usbtty; setenv stdout usbtty" and
1442		attach your USB cable. The Unix command "dmesg" should print
1443		it has found a new device. The environment variable usbtty
1444		can be set to gserial or cdc_acm to enable your device to
1445		appear to a USB host as a Linux gserial device or a
1446		Common Device Class Abstract Control Model serial device.
1447		If you select usbtty = gserial you should be able to enumerate
1448		a Linux host by
1449		# modprobe usbserial vendor=0xVendorID product=0xProductID
1450		else if using cdc_acm, simply setting the environment
1451		variable usbtty to be cdc_acm should suffice. The following
1452		might be defined in YourBoardName.h
1453
1454			CONFIG_USB_DEVICE
1455			Define this to build a UDC device
1456
1457			CONFIG_USB_TTY
1458			Define this to have a tty type of device available to
1459			talk to the UDC device
1460
1461			CONFIG_USBD_HS
1462			Define this to enable the high speed support for usb
1463			device and usbtty. If this feature is enabled, a routine
1464			int is_usbd_high_speed(void)
1465			also needs to be defined by the driver to dynamically poll
1466			whether the enumeration has succeded at high speed or full
1467			speed.
1468
1469			CONFIG_SYS_CONSOLE_IS_IN_ENV
1470			Define this if you want stdin, stdout &/or stderr to
1471			be set to usbtty.
1472
1473			mpc8xx:
1474				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1475				Derive USB clock from external clock "blah"
1476				- CONFIG_SYS_USB_EXTC_CLK 0x02
1477
1478				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1479				Derive USB clock from brgclk
1480				- CONFIG_SYS_USB_BRG_CLK 0x04
1481
1482		If you have a USB-IF assigned VendorID then you may wish to
1483		define your own vendor specific values either in BoardName.h
1484		or directly in usbd_vendor_info.h. If you don't define
1485		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1486		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1487		should pretend to be a Linux device to it's target host.
1488
1489			CONFIG_USBD_MANUFACTURER
1490			Define this string as the name of your company for
1491			- CONFIG_USBD_MANUFACTURER "my company"
1492
1493			CONFIG_USBD_PRODUCT_NAME
1494			Define this string as the name of your product
1495			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1496
1497			CONFIG_USBD_VENDORID
1498			Define this as your assigned Vendor ID from the USB
1499			Implementors Forum. This *must* be a genuine Vendor ID
1500			to avoid polluting the USB namespace.
1501			- CONFIG_USBD_VENDORID 0xFFFF
1502
1503			CONFIG_USBD_PRODUCTID
1504			Define this as the unique Product ID
1505			for your device
1506			- CONFIG_USBD_PRODUCTID 0xFFFF
1507
1508- ULPI Layer Support:
1509		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1510		the generic ULPI layer. The generic layer accesses the ULPI PHY
1511		via the platform viewport, so you need both the genric layer and
1512		the viewport enabled. Currently only Chipidea/ARC based
1513		viewport is supported.
1514		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1515		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1516		If your ULPI phy needs a different reference clock than the
1517		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1518		the appropriate value in Hz.
1519
1520- MMC Support:
1521		The MMC controller on the Intel PXA is supported. To
1522		enable this define CONFIG_MMC. The MMC can be
1523		accessed from the boot prompt by mapping the device
1524		to physical memory similar to flash. Command line is
1525		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1526		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1527
1528		CONFIG_SH_MMCIF
1529		Support for Renesas on-chip MMCIF controller
1530
1531			CONFIG_SH_MMCIF_ADDR
1532			Define the base address of MMCIF registers
1533
1534			CONFIG_SH_MMCIF_CLK
1535			Define the clock frequency for MMCIF
1536
1537- USB Device Firmware Update (DFU) class support:
1538		CONFIG_DFU_FUNCTION
1539		This enables the USB portion of the DFU USB class
1540
1541		CONFIG_CMD_DFU
1542		This enables the command "dfu" which is used to have
1543		U-Boot create a DFU class device via USB.  This command
1544		requires that the "dfu_alt_info" environment variable be
1545		set and define the alt settings to expose to the host.
1546
1547		CONFIG_DFU_MMC
1548		This enables support for exposing (e)MMC devices via DFU.
1549
1550		CONFIG_DFU_NAND
1551		This enables support for exposing NAND devices via DFU.
1552
1553		CONFIG_DFU_RAM
1554		This enables support for exposing RAM via DFU.
1555		Note: DFU spec refer to non-volatile memory usage, but
1556		allow usages beyond the scope of spec - here RAM usage,
1557		one that would help mostly the developer.
1558
1559		CONFIG_SYS_DFU_DATA_BUF_SIZE
1560		Dfu transfer uses a buffer before writing data to the
1561		raw storage device. Make the size (in bytes) of this buffer
1562		configurable. The size of this buffer is also configurable
1563		through the "dfu_bufsiz" environment variable.
1564
1565		CONFIG_SYS_DFU_MAX_FILE_SIZE
1566		When updating files rather than the raw storage device,
1567		we use a static buffer to copy the file into and then write
1568		the buffer once we've been given the whole file.  Define
1569		this to the maximum filesize (in bytes) for the buffer.
1570		Default is 4 MiB if undefined.
1571
1572		DFU_DEFAULT_POLL_TIMEOUT
1573		Poll timeout [ms], is the timeout a device can send to the
1574		host. The host must wait for this timeout before sending
1575		a subsequent DFU_GET_STATUS request to the device.
1576
1577		DFU_MANIFEST_POLL_TIMEOUT
1578		Poll timeout [ms], which the device sends to the host when
1579		entering dfuMANIFEST state. Host waits this timeout, before
1580		sending again an USB request to the device.
1581
1582- USB Device Android Fastboot support:
1583		CONFIG_CMD_FASTBOOT
1584		This enables the command "fastboot" which enables the Android
1585		fastboot mode for the platform's USB device. Fastboot is a USB
1586		protocol for downloading images, flashing and device control
1587		used on Android devices.
1588		See doc/README.android-fastboot for more information.
1589
1590		CONFIG_ANDROID_BOOT_IMAGE
1591		This enables support for booting images which use the Android
1592		image format header.
1593
1594		CONFIG_USB_FASTBOOT_BUF_ADDR
1595		The fastboot protocol requires a large memory buffer for
1596		downloads. Define this to the starting RAM address to use for
1597		downloaded images.
1598
1599		CONFIG_USB_FASTBOOT_BUF_SIZE
1600		The fastboot protocol requires a large memory buffer for
1601		downloads. This buffer should be as large as possible for a
1602		platform. Define this to the size available RAM for fastboot.
1603
1604- Journaling Flash filesystem support:
1605		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1606		CONFIG_JFFS2_NAND_DEV
1607		Define these for a default partition on a NAND device
1608
1609		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1610		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1611		Define these for a default partition on a NOR device
1612
1613		CONFIG_SYS_JFFS_CUSTOM_PART
1614		Define this to create an own partition. You have to provide a
1615		function struct part_info* jffs2_part_info(int part_num)
1616
1617		If you define only one JFFS2 partition you may also want to
1618		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1619		to disable the command chpart. This is the default when you
1620		have not defined a custom partition
1621
1622- FAT(File Allocation Table) filesystem write function support:
1623		CONFIG_FAT_WRITE
1624
1625		Define this to enable support for saving memory data as a
1626		file in FAT formatted partition.
1627
1628		This will also enable the command "fatwrite" enabling the
1629		user to write files to FAT.
1630
1631CBFS (Coreboot Filesystem) support
1632		CONFIG_CMD_CBFS
1633
1634		Define this to enable support for reading from a Coreboot
1635		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1636		and cbfsload.
1637
1638- Keyboard Support:
1639		CONFIG_ISA_KEYBOARD
1640
1641		Define this to enable standard (PC-Style) keyboard
1642		support
1643
1644		CONFIG_I8042_KBD
1645		Standard PC keyboard driver with US (is default) and
1646		GERMAN key layout (switch via environment 'keymap=de') support.
1647		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1648		for cfb_console. Supports cursor blinking.
1649
1650		CONFIG_CROS_EC_KEYB
1651		Enables a Chrome OS keyboard using the CROS_EC interface.
1652		This uses CROS_EC to communicate with a second microcontroller
1653		which provides key scans on request.
1654
1655- Video support:
1656		CONFIG_VIDEO
1657
1658		Define this to enable video support (for output to
1659		video).
1660
1661		CONFIG_VIDEO_CT69000
1662
1663		Enable Chips & Technologies 69000 Video chip
1664
1665		CONFIG_VIDEO_SMI_LYNXEM
1666		Enable Silicon Motion SMI 712/710/810 Video chip. The
1667		video output is selected via environment 'videoout'
1668		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1669		assumed.
1670
1671		For the CT69000 and SMI_LYNXEM drivers, videomode is
1672		selected via environment 'videomode'. Two different ways
1673		are possible:
1674		- "videomode=num"   'num' is a standard LiLo mode numbers.
1675		Following standard modes are supported	(* is default):
1676
1677		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1678		-------------+---------------------------------------------
1679		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1680		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1681		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1682		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1683		-------------+---------------------------------------------
1684		(i.e. setenv videomode 317; saveenv; reset;)
1685
1686		- "videomode=bootargs" all the video parameters are parsed
1687		from the bootargs. (See drivers/video/videomodes.c)
1688
1689
1690		CONFIG_VIDEO_SED13806
1691		Enable Epson SED13806 driver. This driver supports 8bpp
1692		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1693		or CONFIG_VIDEO_SED13806_16BPP
1694
1695		CONFIG_FSL_DIU_FB
1696		Enable the Freescale DIU video driver.	Reference boards for
1697		SOCs that have a DIU should define this macro to enable DIU
1698		support, and should also define these other macros:
1699
1700			CONFIG_SYS_DIU_ADDR
1701			CONFIG_VIDEO
1702			CONFIG_CMD_BMP
1703			CONFIG_CFB_CONSOLE
1704			CONFIG_VIDEO_SW_CURSOR
1705			CONFIG_VGA_AS_SINGLE_DEVICE
1706			CONFIG_VIDEO_LOGO
1707			CONFIG_VIDEO_BMP_LOGO
1708
1709		The DIU driver will look for the 'video-mode' environment
1710		variable, and if defined, enable the DIU as a console during
1711		boot.  See the documentation file README.video for a
1712		description of this variable.
1713
1714		CONFIG_VIDEO_VGA
1715
1716		Enable the VGA video / BIOS for x86. The alternative if you
1717		are using coreboot is to use the coreboot frame buffer
1718		driver.
1719
1720
1721- Keyboard Support:
1722		CONFIG_KEYBOARD
1723
1724		Define this to enable a custom keyboard support.
1725		This simply calls drv_keyboard_init() which must be
1726		defined in your board-specific files.
1727		The only board using this so far is RBC823.
1728
1729- LCD Support:	CONFIG_LCD
1730
1731		Define this to enable LCD support (for output to LCD
1732		display); also select one of the supported displays
1733		by defining one of these:
1734
1735		CONFIG_ATMEL_LCD:
1736
1737			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1738
1739		CONFIG_NEC_NL6448AC33:
1740
1741			NEC NL6448AC33-18. Active, color, single scan.
1742
1743		CONFIG_NEC_NL6448BC20
1744
1745			NEC NL6448BC20-08. 6.5", 640x480.
1746			Active, color, single scan.
1747
1748		CONFIG_NEC_NL6448BC33_54
1749
1750			NEC NL6448BC33-54. 10.4", 640x480.
1751			Active, color, single scan.
1752
1753		CONFIG_SHARP_16x9
1754
1755			Sharp 320x240. Active, color, single scan.
1756			It isn't 16x9, and I am not sure what it is.
1757
1758		CONFIG_SHARP_LQ64D341
1759
1760			Sharp LQ64D341 display, 640x480.
1761			Active, color, single scan.
1762
1763		CONFIG_HLD1045
1764
1765			HLD1045 display, 640x480.
1766			Active, color, single scan.
1767
1768		CONFIG_OPTREX_BW
1769
1770			Optrex	 CBL50840-2 NF-FW 99 22 M5
1771			or
1772			Hitachi	 LMG6912RPFC-00T
1773			or
1774			Hitachi	 SP14Q002
1775
1776			320x240. Black & white.
1777
1778		Normally display is black on white background; define
1779		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1780
1781		CONFIG_LCD_ALIGNMENT
1782
1783		Normally the LCD is page-aligned (tyically 4KB). If this is
1784		defined then the LCD will be aligned to this value instead.
1785		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1786		here, since it is cheaper to change data cache settings on
1787		a per-section basis.
1788
1789		CONFIG_CONSOLE_SCROLL_LINES
1790
1791		When the console need to be scrolled, this is the number of
1792		lines to scroll by. It defaults to 1. Increasing this makes
1793		the console jump but can help speed up operation when scrolling
1794		is slow.
1795
1796		CONFIG_LCD_BMP_RLE8
1797
1798		Support drawing of RLE8-compressed bitmaps on the LCD.
1799
1800		CONFIG_I2C_EDID
1801
1802		Enables an 'i2c edid' command which can read EDID
1803		information over I2C from an attached LCD display.
1804
1805- Splash Screen Support: CONFIG_SPLASH_SCREEN
1806
1807		If this option is set, the environment is checked for
1808		a variable "splashimage". If found, the usual display
1809		of logo, copyright and system information on the LCD
1810		is suppressed and the BMP image at the address
1811		specified in "splashimage" is loaded instead. The
1812		console is redirected to the "nulldev", too. This
1813		allows for a "silent" boot where a splash screen is
1814		loaded very quickly after power-on.
1815
1816		CONFIG_SPLASHIMAGE_GUARD
1817
1818		If this option is set, then U-Boot will prevent the environment
1819		variable "splashimage" from being set to a problematic address
1820		(see README.displaying-bmps).
1821		This option is useful for targets where, due to alignment
1822		restrictions, an improperly aligned BMP image will cause a data
1823		abort. If you think you will not have problems with unaligned
1824		accesses (for example because your toolchain prevents them)
1825		there is no need to set this option.
1826
1827		CONFIG_SPLASH_SCREEN_ALIGN
1828
1829		If this option is set the splash image can be freely positioned
1830		on the screen. Environment variable "splashpos" specifies the
1831		position as "x,y". If a positive number is given it is used as
1832		number of pixel from left/top. If a negative number is given it
1833		is used as number of pixel from right/bottom. You can also
1834		specify 'm' for centering the image.
1835
1836		Example:
1837		setenv splashpos m,m
1838			=> image at center of screen
1839
1840		setenv splashpos 30,20
1841			=> image at x = 30 and y = 20
1842
1843		setenv splashpos -10,m
1844			=> vertically centered image
1845			   at x = dspWidth - bmpWidth - 9
1846
1847- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1848
1849		If this option is set, additionally to standard BMP
1850		images, gzipped BMP images can be displayed via the
1851		splashscreen support or the bmp command.
1852
1853- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1854
1855		If this option is set, 8-bit RLE compressed BMP images
1856		can be displayed via the splashscreen support or the
1857		bmp command.
1858
1859- Do compresssing for memory range:
1860		CONFIG_CMD_ZIP
1861
1862		If this option is set, it would use zlib deflate method
1863		to compress the specified memory at its best effort.
1864
1865- Compression support:
1866		CONFIG_GZIP
1867
1868		Enabled by default to support gzip compressed images.
1869
1870		CONFIG_BZIP2
1871
1872		If this option is set, support for bzip2 compressed
1873		images is included. If not, only uncompressed and gzip
1874		compressed images are supported.
1875
1876		NOTE: the bzip2 algorithm requires a lot of RAM, so
1877		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1878		be at least 4MB.
1879
1880		CONFIG_LZMA
1881
1882		If this option is set, support for lzma compressed
1883		images is included.
1884
1885		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1886		requires an amount of dynamic memory that is given by the
1887		formula:
1888
1889			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1890
1891		Where lc and lp stand for, respectively, Literal context bits
1892		and Literal pos bits.
1893
1894		This value is upper-bounded by 14MB in the worst case. Anyway,
1895		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1896		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1897		a very small buffer.
1898
1899		Use the lzmainfo tool to determinate the lc and lp values and
1900		then calculate the amount of needed dynamic memory (ensuring
1901		the appropriate CONFIG_SYS_MALLOC_LEN value).
1902
1903		CONFIG_LZO
1904
1905		If this option is set, support for LZO compressed images
1906		is included.
1907
1908- MII/PHY support:
1909		CONFIG_PHY_ADDR
1910
1911		The address of PHY on MII bus.
1912
1913		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1914
1915		The clock frequency of the MII bus
1916
1917		CONFIG_PHY_GIGE
1918
1919		If this option is set, support for speed/duplex
1920		detection of gigabit PHY is included.
1921
1922		CONFIG_PHY_RESET_DELAY
1923
1924		Some PHY like Intel LXT971A need extra delay after
1925		reset before any MII register access is possible.
1926		For such PHY, set this option to the usec delay
1927		required. (minimum 300usec for LXT971A)
1928
1929		CONFIG_PHY_CMD_DELAY (ppc4xx)
1930
1931		Some PHY like Intel LXT971A need extra delay after
1932		command issued before MII status register can be read
1933
1934- Ethernet address:
1935		CONFIG_ETHADDR
1936		CONFIG_ETH1ADDR
1937		CONFIG_ETH2ADDR
1938		CONFIG_ETH3ADDR
1939		CONFIG_ETH4ADDR
1940		CONFIG_ETH5ADDR
1941
1942		Define a default value for Ethernet address to use
1943		for the respective Ethernet interface, in case this
1944		is not determined automatically.
1945
1946- IP address:
1947		CONFIG_IPADDR
1948
1949		Define a default value for the IP address to use for
1950		the default Ethernet interface, in case this is not
1951		determined through e.g. bootp.
1952		(Environment variable "ipaddr")
1953
1954- Server IP address:
1955		CONFIG_SERVERIP
1956
1957		Defines a default value for the IP address of a TFTP
1958		server to contact when using the "tftboot" command.
1959		(Environment variable "serverip")
1960
1961		CONFIG_KEEP_SERVERADDR
1962
1963		Keeps the server's MAC address, in the env 'serveraddr'
1964		for passing to bootargs (like Linux's netconsole option)
1965
1966- Gateway IP address:
1967		CONFIG_GATEWAYIP
1968
1969		Defines a default value for the IP address of the
1970		default router where packets to other networks are
1971		sent to.
1972		(Environment variable "gatewayip")
1973
1974- Subnet mask:
1975		CONFIG_NETMASK
1976
1977		Defines a default value for the subnet mask (or
1978		routing prefix) which is used to determine if an IP
1979		address belongs to the local subnet or needs to be
1980		forwarded through a router.
1981		(Environment variable "netmask")
1982
1983- Multicast TFTP Mode:
1984		CONFIG_MCAST_TFTP
1985
1986		Defines whether you want to support multicast TFTP as per
1987		rfc-2090; for example to work with atftp.  Lets lots of targets
1988		tftp down the same boot image concurrently.  Note: the Ethernet
1989		driver in use must provide a function: mcast() to join/leave a
1990		multicast group.
1991
1992- BOOTP Recovery Mode:
1993		CONFIG_BOOTP_RANDOM_DELAY
1994
1995		If you have many targets in a network that try to
1996		boot using BOOTP, you may want to avoid that all
1997		systems send out BOOTP requests at precisely the same
1998		moment (which would happen for instance at recovery
1999		from a power failure, when all systems will try to
2000		boot, thus flooding the BOOTP server. Defining
2001		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2002		inserted before sending out BOOTP requests. The
2003		following delays are inserted then:
2004
2005		1st BOOTP request:	delay 0 ... 1 sec
2006		2nd BOOTP request:	delay 0 ... 2 sec
2007		3rd BOOTP request:	delay 0 ... 4 sec
2008		4th and following
2009		BOOTP requests:		delay 0 ... 8 sec
2010
2011- DHCP Advanced Options:
2012		You can fine tune the DHCP functionality by defining
2013		CONFIG_BOOTP_* symbols:
2014
2015		CONFIG_BOOTP_SUBNETMASK
2016		CONFIG_BOOTP_GATEWAY
2017		CONFIG_BOOTP_HOSTNAME
2018		CONFIG_BOOTP_NISDOMAIN
2019		CONFIG_BOOTP_BOOTPATH
2020		CONFIG_BOOTP_BOOTFILESIZE
2021		CONFIG_BOOTP_DNS
2022		CONFIG_BOOTP_DNS2
2023		CONFIG_BOOTP_SEND_HOSTNAME
2024		CONFIG_BOOTP_NTPSERVER
2025		CONFIG_BOOTP_TIMEOFFSET
2026		CONFIG_BOOTP_VENDOREX
2027		CONFIG_BOOTP_MAY_FAIL
2028
2029		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2030		environment variable, not the BOOTP server.
2031
2032		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2033		after the configured retry count, the call will fail
2034		instead of starting over.  This can be used to fail over
2035		to Link-local IP address configuration if the DHCP server
2036		is not available.
2037
2038		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2039		serverip from a DHCP server, it is possible that more
2040		than one DNS serverip is offered to the client.
2041		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2042		serverip will be stored in the additional environment
2043		variable "dnsip2". The first DNS serverip is always
2044		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2045		is defined.
2046
2047		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2048		to do a dynamic update of a DNS server. To do this, they
2049		need the hostname of the DHCP requester.
2050		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2051		of the "hostname" environment variable is passed as
2052		option 12 to the DHCP server.
2053
2054		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2055
2056		A 32bit value in microseconds for a delay between
2057		receiving a "DHCP Offer" and sending the "DHCP Request".
2058		This fixes a problem with certain DHCP servers that don't
2059		respond 100% of the time to a "DHCP request". E.g. On an
2060		AT91RM9200 processor running at 180MHz, this delay needed
2061		to be *at least* 15,000 usec before a Windows Server 2003
2062		DHCP server would reply 100% of the time. I recommend at
2063		least 50,000 usec to be safe. The alternative is to hope
2064		that one of the retries will be successful but note that
2065		the DHCP timeout and retry process takes a longer than
2066		this delay.
2067
2068 - Link-local IP address negotiation:
2069		Negotiate with other link-local clients on the local network
2070		for an address that doesn't require explicit configuration.
2071		This is especially useful if a DHCP server cannot be guaranteed
2072		to exist in all environments that the device must operate.
2073
2074		See doc/README.link-local for more information.
2075
2076 - CDP Options:
2077		CONFIG_CDP_DEVICE_ID
2078
2079		The device id used in CDP trigger frames.
2080
2081		CONFIG_CDP_DEVICE_ID_PREFIX
2082
2083		A two character string which is prefixed to the MAC address
2084		of the device.
2085
2086		CONFIG_CDP_PORT_ID
2087
2088		A printf format string which contains the ascii name of
2089		the port. Normally is set to "eth%d" which sets
2090		eth0 for the first Ethernet, eth1 for the second etc.
2091
2092		CONFIG_CDP_CAPABILITIES
2093
2094		A 32bit integer which indicates the device capabilities;
2095		0x00000010 for a normal host which does not forwards.
2096
2097		CONFIG_CDP_VERSION
2098
2099		An ascii string containing the version of the software.
2100
2101		CONFIG_CDP_PLATFORM
2102
2103		An ascii string containing the name of the platform.
2104
2105		CONFIG_CDP_TRIGGER
2106
2107		A 32bit integer sent on the trigger.
2108
2109		CONFIG_CDP_POWER_CONSUMPTION
2110
2111		A 16bit integer containing the power consumption of the
2112		device in .1 of milliwatts.
2113
2114		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2115
2116		A byte containing the id of the VLAN.
2117
2118- Status LED:	CONFIG_STATUS_LED
2119
2120		Several configurations allow to display the current
2121		status using a LED. For instance, the LED will blink
2122		fast while running U-Boot code, stop blinking as
2123		soon as a reply to a BOOTP request was received, and
2124		start blinking slow once the Linux kernel is running
2125		(supported by a status LED driver in the Linux
2126		kernel). Defining CONFIG_STATUS_LED enables this
2127		feature in U-Boot.
2128
2129		Additional options:
2130
2131		CONFIG_GPIO_LED
2132		The status LED can be connected to a GPIO pin.
2133		In such cases, the gpio_led driver can be used as a
2134		status LED backend implementation. Define CONFIG_GPIO_LED
2135		to include the gpio_led driver in the U-Boot binary.
2136
2137		CONFIG_GPIO_LED_INVERTED_TABLE
2138		Some GPIO connected LEDs may have inverted polarity in which
2139		case the GPIO high value corresponds to LED off state and
2140		GPIO low value corresponds to LED on state.
2141		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2142		with a list of GPIO LEDs that have inverted polarity.
2143
2144- CAN Support:	CONFIG_CAN_DRIVER
2145
2146		Defining CONFIG_CAN_DRIVER enables CAN driver support
2147		on those systems that support this (optional)
2148		feature, like the TQM8xxL modules.
2149
2150- I2C Support:	CONFIG_SYS_I2C
2151
2152		This enable the NEW i2c subsystem, and will allow you to use
2153		i2c commands at the u-boot command line (as long as you set
2154		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2155		based realtime clock chips or other i2c devices. See
2156		common/cmd_i2c.c for a description of the command line
2157		interface.
2158
2159		ported i2c driver to the new framework:
2160		- drivers/i2c/soft_i2c.c:
2161		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2162		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2163		    for defining speed and slave address
2164		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2165		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2166		    for defining speed and slave address
2167		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2168		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2169		    for defining speed and slave address
2170		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2171		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2172		    for defining speed and slave address
2173
2174		- drivers/i2c/fsl_i2c.c:
2175		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2176		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2177		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2178		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2179		    bus.
2180		  - If your board supports a second fsl i2c bus, define
2181		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2182		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2183		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2184		    second bus.
2185
2186		- drivers/i2c/tegra_i2c.c:
2187		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2188		  - This driver adds 4 i2c buses with a fix speed from
2189		    100000 and the slave addr 0!
2190
2191		- drivers/i2c/ppc4xx_i2c.c
2192		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2193		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2194		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2195
2196		- drivers/i2c/i2c_mxc.c
2197		  - activate this driver with CONFIG_SYS_I2C_MXC
2198		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2199		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2200		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2201		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2202		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2203		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2204		If thoses defines are not set, default value is 100000
2205		for speed, and 0 for slave.
2206
2207		- drivers/i2c/rcar_i2c.c:
2208		  - activate this driver with CONFIG_SYS_I2C_RCAR
2209		  - This driver adds 4 i2c buses
2210
2211		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2212		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2213		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2214		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2215		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2216		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2217		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2218		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2219		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2220
2221		- drivers/i2c/sh_i2c.c:
2222		  - activate this driver with CONFIG_SYS_I2C_SH
2223		  - This driver adds from 2 to 5 i2c buses
2224
2225		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2226		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2227		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2228		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2229		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2230		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2231		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2232		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2233		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2234		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2235		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2236		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2237		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2238
2239		- drivers/i2c/omap24xx_i2c.c
2240		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2241		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2242		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2243		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2244		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2245		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2246		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2247		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2248		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2249		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2250		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2251
2252		- drivers/i2c/zynq_i2c.c
2253		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2254		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2255		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2256
2257		- drivers/i2c/s3c24x0_i2c.c:
2258		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2259		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2260		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2261		    with a fix speed from 100000 and the slave addr 0!
2262
2263		additional defines:
2264
2265		CONFIG_SYS_NUM_I2C_BUSES
2266		Hold the number of i2c busses you want to use. If you
2267		don't use/have i2c muxes on your i2c bus, this
2268		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2269		omit this define.
2270
2271		CONFIG_SYS_I2C_DIRECT_BUS
2272		define this, if you don't use i2c muxes on your hardware.
2273		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2274		omit this define.
2275
2276		CONFIG_SYS_I2C_MAX_HOPS
2277		define how many muxes are maximal consecutively connected
2278		on one i2c bus. If you not use i2c muxes, omit this
2279		define.
2280
2281		CONFIG_SYS_I2C_BUSES
2282		hold a list of busses you want to use, only used if
2283		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2284		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2285		CONFIG_SYS_NUM_I2C_BUSES = 9:
2286
2287		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2288					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2289					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2290					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2291					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2292					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2293					{1, {I2C_NULL_HOP}}, \
2294					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2295					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2296					}
2297
2298		which defines
2299			bus 0 on adapter 0 without a mux
2300			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2301			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2302			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2303			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2304			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2305			bus 6 on adapter 1 without a mux
2306			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2307			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2308
2309		If you do not have i2c muxes on your board, omit this define.
2310
2311- Legacy I2C Support:	CONFIG_HARD_I2C
2312
2313		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2314		provides the following compelling advantages:
2315
2316		- more than one i2c adapter is usable
2317		- approved multibus support
2318		- better i2c mux support
2319
2320		** Please consider updating your I2C driver now. **
2321
2322		These enable legacy I2C serial bus commands. Defining
2323		CONFIG_HARD_I2C will include the appropriate I2C driver
2324		for the selected CPU.
2325
2326		This will allow you to use i2c commands at the u-boot
2327		command line (as long as you set CONFIG_CMD_I2C in
2328		CONFIG_COMMANDS) and communicate with i2c based realtime
2329		clock chips. See common/cmd_i2c.c for a description of the
2330		command line interface.
2331
2332		CONFIG_HARD_I2C selects a hardware I2C controller.
2333
2334		There are several other quantities that must also be
2335		defined when you define CONFIG_HARD_I2C.
2336
2337		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2338		to be the frequency (in Hz) at which you wish your i2c bus
2339		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2340		the CPU's i2c node address).
2341
2342		Now, the u-boot i2c code for the mpc8xx
2343		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2344		and so its address should therefore be cleared to 0 (See,
2345		eg, MPC823e User's Manual p.16-473). So, set
2346		CONFIG_SYS_I2C_SLAVE to 0.
2347
2348		CONFIG_SYS_I2C_INIT_MPC5XXX
2349
2350		When a board is reset during an i2c bus transfer
2351		chips might think that the current transfer is still
2352		in progress.  Reset the slave devices by sending start
2353		commands until the slave device responds.
2354
2355		That's all that's required for CONFIG_HARD_I2C.
2356
2357		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2358		then the following macros need to be defined (examples are
2359		from include/configs/lwmon.h):
2360
2361		I2C_INIT
2362
2363		(Optional). Any commands necessary to enable the I2C
2364		controller or configure ports.
2365
2366		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2367
2368		I2C_PORT
2369
2370		(Only for MPC8260 CPU). The I/O port to use (the code
2371		assumes both bits are on the same port). Valid values
2372		are 0..3 for ports A..D.
2373
2374		I2C_ACTIVE
2375
2376		The code necessary to make the I2C data line active
2377		(driven).  If the data line is open collector, this
2378		define can be null.
2379
2380		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2381
2382		I2C_TRISTATE
2383
2384		The code necessary to make the I2C data line tri-stated
2385		(inactive).  If the data line is open collector, this
2386		define can be null.
2387
2388		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2389
2390		I2C_READ
2391
2392		Code that returns true if the I2C data line is high,
2393		false if it is low.
2394
2395		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2396
2397		I2C_SDA(bit)
2398
2399		If <bit> is true, sets the I2C data line high. If it
2400		is false, it clears it (low).
2401
2402		eg: #define I2C_SDA(bit) \
2403			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2404			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2405
2406		I2C_SCL(bit)
2407
2408		If <bit> is true, sets the I2C clock line high. If it
2409		is false, it clears it (low).
2410
2411		eg: #define I2C_SCL(bit) \
2412			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2413			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2414
2415		I2C_DELAY
2416
2417		This delay is invoked four times per clock cycle so this
2418		controls the rate of data transfer.  The data rate thus
2419		is 1 / (I2C_DELAY * 4). Often defined to be something
2420		like:
2421
2422		#define I2C_DELAY  udelay(2)
2423
2424		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2425
2426		If your arch supports the generic GPIO framework (asm/gpio.h),
2427		then you may alternatively define the two GPIOs that are to be
2428		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2429		have GPIO-based defaults assigned to them as appropriate.
2430
2431		You should define these to the GPIO value as given directly to
2432		the generic GPIO functions.
2433
2434		CONFIG_SYS_I2C_INIT_BOARD
2435
2436		When a board is reset during an i2c bus transfer
2437		chips might think that the current transfer is still
2438		in progress. On some boards it is possible to access
2439		the i2c SCLK line directly, either by using the
2440		processor pin as a GPIO or by having a second pin
2441		connected to the bus. If this option is defined a
2442		custom i2c_init_board() routine in boards/xxx/board.c
2443		is run early in the boot sequence.
2444
2445		CONFIG_SYS_I2C_BOARD_LATE_INIT
2446
2447		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2448		defined a custom i2c_board_late_init() routine in
2449		boards/xxx/board.c is run AFTER the operations in i2c_init()
2450		is completed. This callpoint can be used to unreset i2c bus
2451		using CPU i2c controller register accesses for CPUs whose i2c
2452		controller provide such a method. It is called at the end of
2453		i2c_init() to allow i2c_init operations to setup the i2c bus
2454		controller on the CPU (e.g. setting bus speed & slave address).
2455
2456		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2457
2458		This option enables configuration of bi_iic_fast[] flags
2459		in u-boot bd_info structure based on u-boot environment
2460		variable "i2cfast". (see also i2cfast)
2461
2462		CONFIG_I2C_MULTI_BUS
2463
2464		This option allows the use of multiple I2C buses, each of which
2465		must have a controller.	 At any point in time, only one bus is
2466		active.	 To switch to a different bus, use the 'i2c dev' command.
2467		Note that bus numbering is zero-based.
2468
2469		CONFIG_SYS_I2C_NOPROBES
2470
2471		This option specifies a list of I2C devices that will be skipped
2472		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2473		is set, specify a list of bus-device pairs.  Otherwise, specify
2474		a 1D array of device addresses
2475
2476		e.g.
2477			#undef	CONFIG_I2C_MULTI_BUS
2478			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2479
2480		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2481
2482			#define CONFIG_I2C_MULTI_BUS
2483			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2484
2485		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2486
2487		CONFIG_SYS_SPD_BUS_NUM
2488
2489		If defined, then this indicates the I2C bus number for DDR SPD.
2490		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2491
2492		CONFIG_SYS_RTC_BUS_NUM
2493
2494		If defined, then this indicates the I2C bus number for the RTC.
2495		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2496
2497		CONFIG_SYS_DTT_BUS_NUM
2498
2499		If defined, then this indicates the I2C bus number for the DTT.
2500		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2501
2502		CONFIG_SYS_I2C_DTT_ADDR:
2503
2504		If defined, specifies the I2C address of the DTT device.
2505		If not defined, then U-Boot uses predefined value for
2506		specified DTT device.
2507
2508		CONFIG_SOFT_I2C_READ_REPEATED_START
2509
2510		defining this will force the i2c_read() function in
2511		the soft_i2c driver to perform an I2C repeated start
2512		between writing the address pointer and reading the
2513		data.  If this define is omitted the default behaviour
2514		of doing a stop-start sequence will be used.  Most I2C
2515		devices can use either method, but some require one or
2516		the other.
2517
2518- SPI Support:	CONFIG_SPI
2519
2520		Enables SPI driver (so far only tested with
2521		SPI EEPROM, also an instance works with Crystal A/D and
2522		D/As on the SACSng board)
2523
2524		CONFIG_SH_SPI
2525
2526		Enables the driver for SPI controller on SuperH. Currently
2527		only SH7757 is supported.
2528
2529		CONFIG_SPI_X
2530
2531		Enables extended (16-bit) SPI EEPROM addressing.
2532		(symmetrical to CONFIG_I2C_X)
2533
2534		CONFIG_SOFT_SPI
2535
2536		Enables a software (bit-bang) SPI driver rather than
2537		using hardware support. This is a general purpose
2538		driver that only requires three general I/O port pins
2539		(two outputs, one input) to function. If this is
2540		defined, the board configuration must define several
2541		SPI configuration items (port pins to use, etc). For
2542		an example, see include/configs/sacsng.h.
2543
2544		CONFIG_HARD_SPI
2545
2546		Enables a hardware SPI driver for general-purpose reads
2547		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2548		must define a list of chip-select function pointers.
2549		Currently supported on some MPC8xxx processors.	 For an
2550		example, see include/configs/mpc8349emds.h.
2551
2552		CONFIG_MXC_SPI
2553
2554		Enables the driver for the SPI controllers on i.MX and MXC
2555		SoCs. Currently i.MX31/35/51 are supported.
2556
2557- FPGA Support: CONFIG_FPGA
2558
2559		Enables FPGA subsystem.
2560
2561		CONFIG_FPGA_<vendor>
2562
2563		Enables support for specific chip vendors.
2564		(ALTERA, XILINX)
2565
2566		CONFIG_FPGA_<family>
2567
2568		Enables support for FPGA family.
2569		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2570
2571		CONFIG_FPGA_COUNT
2572
2573		Specify the number of FPGA devices to support.
2574
2575		CONFIG_SYS_FPGA_PROG_FEEDBACK
2576
2577		Enable printing of hash marks during FPGA configuration.
2578
2579		CONFIG_SYS_FPGA_CHECK_BUSY
2580
2581		Enable checks on FPGA configuration interface busy
2582		status by the configuration function. This option
2583		will require a board or device specific function to
2584		be written.
2585
2586		CONFIG_FPGA_DELAY
2587
2588		If defined, a function that provides delays in the FPGA
2589		configuration driver.
2590
2591		CONFIG_SYS_FPGA_CHECK_CTRLC
2592		Allow Control-C to interrupt FPGA configuration
2593
2594		CONFIG_SYS_FPGA_CHECK_ERROR
2595
2596		Check for configuration errors during FPGA bitfile
2597		loading. For example, abort during Virtex II
2598		configuration if the INIT_B line goes low (which
2599		indicated a CRC error).
2600
2601		CONFIG_SYS_FPGA_WAIT_INIT
2602
2603		Maximum time to wait for the INIT_B line to deassert
2604		after PROB_B has been deasserted during a Virtex II
2605		FPGA configuration sequence. The default time is 500
2606		ms.
2607
2608		CONFIG_SYS_FPGA_WAIT_BUSY
2609
2610		Maximum time to wait for BUSY to deassert during
2611		Virtex II FPGA configuration. The default is 5 ms.
2612
2613		CONFIG_SYS_FPGA_WAIT_CONFIG
2614
2615		Time to wait after FPGA configuration. The default is
2616		200 ms.
2617
2618- Configuration Management:
2619		CONFIG_IDENT_STRING
2620
2621		If defined, this string will be added to the U-Boot
2622		version information (U_BOOT_VERSION)
2623
2624- Vendor Parameter Protection:
2625
2626		U-Boot considers the values of the environment
2627		variables "serial#" (Board Serial Number) and
2628		"ethaddr" (Ethernet Address) to be parameters that
2629		are set once by the board vendor / manufacturer, and
2630		protects these variables from casual modification by
2631		the user. Once set, these variables are read-only,
2632		and write or delete attempts are rejected. You can
2633		change this behaviour:
2634
2635		If CONFIG_ENV_OVERWRITE is #defined in your config
2636		file, the write protection for vendor parameters is
2637		completely disabled. Anybody can change or delete
2638		these parameters.
2639
2640		Alternatively, if you #define _both_ CONFIG_ETHADDR
2641		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2642		Ethernet address is installed in the environment,
2643		which can be changed exactly ONCE by the user. [The
2644		serial# is unaffected by this, i. e. it remains
2645		read-only.]
2646
2647		The same can be accomplished in a more flexible way
2648		for any variable by configuring the type of access
2649		to allow for those variables in the ".flags" variable
2650		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2651
2652- Protected RAM:
2653		CONFIG_PRAM
2654
2655		Define this variable to enable the reservation of
2656		"protected RAM", i. e. RAM which is not overwritten
2657		by U-Boot. Define CONFIG_PRAM to hold the number of
2658		kB you want to reserve for pRAM. You can overwrite
2659		this default value by defining an environment
2660		variable "pram" to the number of kB you want to
2661		reserve. Note that the board info structure will
2662		still show the full amount of RAM. If pRAM is
2663		reserved, a new environment variable "mem" will
2664		automatically be defined to hold the amount of
2665		remaining RAM in a form that can be passed as boot
2666		argument to Linux, for instance like that:
2667
2668			setenv bootargs ... mem=\${mem}
2669			saveenv
2670
2671		This way you can tell Linux not to use this memory,
2672		either, which results in a memory region that will
2673		not be affected by reboots.
2674
2675		*WARNING* If your board configuration uses automatic
2676		detection of the RAM size, you must make sure that
2677		this memory test is non-destructive. So far, the
2678		following board configurations are known to be
2679		"pRAM-clean":
2680
2681			IVMS8, IVML24, SPD8xx, TQM8xxL,
2682			HERMES, IP860, RPXlite, LWMON,
2683			FLAGADM, TQM8260
2684
2685- Access to physical memory region (> 4GB)
2686		Some basic support is provided for operations on memory not
2687		normally accessible to U-Boot - e.g. some architectures
2688		support access to more than 4GB of memory on 32-bit
2689		machines using physical address extension or similar.
2690		Define CONFIG_PHYSMEM to access this basic support, which
2691		currently only supports clearing the memory.
2692
2693- Error Recovery:
2694		CONFIG_PANIC_HANG
2695
2696		Define this variable to stop the system in case of a
2697		fatal error, so that you have to reset it manually.
2698		This is probably NOT a good idea for an embedded
2699		system where you want the system to reboot
2700		automatically as fast as possible, but it may be
2701		useful during development since you can try to debug
2702		the conditions that lead to the situation.
2703
2704		CONFIG_NET_RETRY_COUNT
2705
2706		This variable defines the number of retries for
2707		network operations like ARP, RARP, TFTP, or BOOTP
2708		before giving up the operation. If not defined, a
2709		default value of 5 is used.
2710
2711		CONFIG_ARP_TIMEOUT
2712
2713		Timeout waiting for an ARP reply in milliseconds.
2714
2715		CONFIG_NFS_TIMEOUT
2716
2717		Timeout in milliseconds used in NFS protocol.
2718		If you encounter "ERROR: Cannot umount" in nfs command,
2719		try longer timeout such as
2720		#define CONFIG_NFS_TIMEOUT 10000UL
2721
2722- Command Interpreter:
2723		CONFIG_AUTO_COMPLETE
2724
2725		Enable auto completion of commands using TAB.
2726
2727		Note that this feature has NOT been implemented yet
2728		for the "hush" shell.
2729
2730
2731		CONFIG_SYS_HUSH_PARSER
2732
2733		Define this variable to enable the "hush" shell (from
2734		Busybox) as command line interpreter, thus enabling
2735		powerful command line syntax like
2736		if...then...else...fi conditionals or `&&' and '||'
2737		constructs ("shell scripts").
2738
2739		If undefined, you get the old, much simpler behaviour
2740		with a somewhat smaller memory footprint.
2741
2742
2743		CONFIG_SYS_PROMPT_HUSH_PS2
2744
2745		This defines the secondary prompt string, which is
2746		printed when the command interpreter needs more input
2747		to complete a command. Usually "> ".
2748
2749	Note:
2750
2751		In the current implementation, the local variables
2752		space and global environment variables space are
2753		separated. Local variables are those you define by
2754		simply typing `name=value'. To access a local
2755		variable later on, you have write `$name' or
2756		`${name}'; to execute the contents of a variable
2757		directly type `$name' at the command prompt.
2758
2759		Global environment variables are those you use
2760		setenv/printenv to work with. To run a command stored
2761		in such a variable, you need to use the run command,
2762		and you must not use the '$' sign to access them.
2763
2764		To store commands and special characters in a
2765		variable, please use double quotation marks
2766		surrounding the whole text of the variable, instead
2767		of the backslashes before semicolons and special
2768		symbols.
2769
2770- Commandline Editing and History:
2771		CONFIG_CMDLINE_EDITING
2772
2773		Enable editing and History functions for interactive
2774		commandline input operations
2775
2776- Default Environment:
2777		CONFIG_EXTRA_ENV_SETTINGS
2778
2779		Define this to contain any number of null terminated
2780		strings (variable = value pairs) that will be part of
2781		the default environment compiled into the boot image.
2782
2783		For example, place something like this in your
2784		board's config file:
2785
2786		#define CONFIG_EXTRA_ENV_SETTINGS \
2787			"myvar1=value1\0" \
2788			"myvar2=value2\0"
2789
2790		Warning: This method is based on knowledge about the
2791		internal format how the environment is stored by the
2792		U-Boot code. This is NOT an official, exported
2793		interface! Although it is unlikely that this format
2794		will change soon, there is no guarantee either.
2795		You better know what you are doing here.
2796
2797		Note: overly (ab)use of the default environment is
2798		discouraged. Make sure to check other ways to preset
2799		the environment like the "source" command or the
2800		boot command first.
2801
2802		CONFIG_ENV_VARS_UBOOT_CONFIG
2803
2804		Define this in order to add variables describing the
2805		U-Boot build configuration to the default environment.
2806		These will be named arch, cpu, board, vendor, and soc.
2807
2808		Enabling this option will cause the following to be defined:
2809
2810		- CONFIG_SYS_ARCH
2811		- CONFIG_SYS_CPU
2812		- CONFIG_SYS_BOARD
2813		- CONFIG_SYS_VENDOR
2814		- CONFIG_SYS_SOC
2815
2816		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2817
2818		Define this in order to add variables describing certain
2819		run-time determined information about the hardware to the
2820		environment.  These will be named board_name, board_rev.
2821
2822		CONFIG_DELAY_ENVIRONMENT
2823
2824		Normally the environment is loaded when the board is
2825		intialised so that it is available to U-Boot. This inhibits
2826		that so that the environment is not available until
2827		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2828		this is instead controlled by the value of
2829		/config/load-environment.
2830
2831- DataFlash Support:
2832		CONFIG_HAS_DATAFLASH
2833
2834		Defining this option enables DataFlash features and
2835		allows to read/write in Dataflash via the standard
2836		commands cp, md...
2837
2838- Serial Flash support
2839		CONFIG_CMD_SF
2840
2841		Defining this option enables SPI flash commands
2842		'sf probe/read/write/erase/update'.
2843
2844		Usage requires an initial 'probe' to define the serial
2845		flash parameters, followed by read/write/erase/update
2846		commands.
2847
2848		The following defaults may be provided by the platform
2849		to handle the common case when only a single serial
2850		flash is present on the system.
2851
2852		CONFIG_SF_DEFAULT_BUS		Bus identifier
2853		CONFIG_SF_DEFAULT_CS		Chip-select
2854		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2855		CONFIG_SF_DEFAULT_SPEED		in Hz
2856
2857		CONFIG_CMD_SF_TEST
2858
2859		Define this option to include a destructive SPI flash
2860		test ('sf test').
2861
2862		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2863
2864		Define this option to use the Bank addr/Extended addr
2865		support on SPI flashes which has size > 16Mbytes.
2866
2867		CONFIG_SF_DUAL_FLASH		Dual flash memories
2868
2869		Define this option to use dual flash support where two flash
2870		memories can be connected with a given cs line.
2871		currently Xilinx Zynq qspi support these type of connections.
2872
2873- SystemACE Support:
2874		CONFIG_SYSTEMACE
2875
2876		Adding this option adds support for Xilinx SystemACE
2877		chips attached via some sort of local bus. The address
2878		of the chip must also be defined in the
2879		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2880
2881		#define CONFIG_SYSTEMACE
2882		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2883
2884		When SystemACE support is added, the "ace" device type
2885		becomes available to the fat commands, i.e. fatls.
2886
2887- TFTP Fixed UDP Port:
2888		CONFIG_TFTP_PORT
2889
2890		If this is defined, the environment variable tftpsrcp
2891		is used to supply the TFTP UDP source port value.
2892		If tftpsrcp isn't defined, the normal pseudo-random port
2893		number generator is used.
2894
2895		Also, the environment variable tftpdstp is used to supply
2896		the TFTP UDP destination port value.  If tftpdstp isn't
2897		defined, the normal port 69 is used.
2898
2899		The purpose for tftpsrcp is to allow a TFTP server to
2900		blindly start the TFTP transfer using the pre-configured
2901		target IP address and UDP port. This has the effect of
2902		"punching through" the (Windows XP) firewall, allowing
2903		the remainder of the TFTP transfer to proceed normally.
2904		A better solution is to properly configure the firewall,
2905		but sometimes that is not allowed.
2906
2907- Hashing support:
2908		CONFIG_CMD_HASH
2909
2910		This enables a generic 'hash' command which can produce
2911		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2912
2913		CONFIG_HASH_VERIFY
2914
2915		Enable the hash verify command (hash -v). This adds to code
2916		size a little.
2917
2918		CONFIG_SHA1 - support SHA1 hashing
2919		CONFIG_SHA256 - support SHA256 hashing
2920
2921		Note: There is also a sha1sum command, which should perhaps
2922		be deprecated in favour of 'hash sha1'.
2923
2924- Freescale i.MX specific commands:
2925		CONFIG_CMD_HDMIDETECT
2926		This enables 'hdmidet' command which returns true if an
2927		HDMI monitor is detected.  This command is i.MX 6 specific.
2928
2929		CONFIG_CMD_BMODE
2930		This enables the 'bmode' (bootmode) command for forcing
2931		a boot from specific media.
2932
2933		This is useful for forcing the ROM's usb downloader to
2934		activate upon a watchdog reset which is nice when iterating
2935		on U-Boot.  Using the reset button or running bmode normal
2936		will set it back to normal.  This command currently
2937		supports i.MX53 and i.MX6.
2938
2939- Signing support:
2940		CONFIG_RSA
2941
2942		This enables the RSA algorithm used for FIT image verification
2943		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2944
2945		The signing part is build into mkimage regardless of this
2946		option.
2947
2948- bootcount support:
2949		CONFIG_BOOTCOUNT_LIMIT
2950
2951		This enables the bootcounter support, see:
2952		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2953
2954		CONFIG_AT91SAM9XE
2955		enable special bootcounter support on at91sam9xe based boards.
2956		CONFIG_BLACKFIN
2957		enable special bootcounter support on blackfin based boards.
2958		CONFIG_SOC_DA8XX
2959		enable special bootcounter support on da850 based boards.
2960		CONFIG_BOOTCOUNT_RAM
2961		enable support for the bootcounter in RAM
2962		CONFIG_BOOTCOUNT_I2C
2963		enable support for the bootcounter on an i2c (like RTC) device.
2964			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2965			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2966						    the bootcounter.
2967			CONFIG_BOOTCOUNT_ALEN = address len
2968
2969- Show boot progress:
2970		CONFIG_SHOW_BOOT_PROGRESS
2971
2972		Defining this option allows to add some board-
2973		specific code (calling a user-provided function
2974		"show_boot_progress(int)") that enables you to show
2975		the system's boot progress on some display (for
2976		example, some LED's) on your board. At the moment,
2977		the following checkpoints are implemented:
2978
2979- Detailed boot stage timing
2980		CONFIG_BOOTSTAGE
2981		Define this option to get detailed timing of each stage
2982		of the boot process.
2983
2984		CONFIG_BOOTSTAGE_USER_COUNT
2985		This is the number of available user bootstage records.
2986		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2987		a new ID will be allocated from this stash. If you exceed
2988		the limit, recording will stop.
2989
2990		CONFIG_BOOTSTAGE_REPORT
2991		Define this to print a report before boot, similar to this:
2992
2993		Timer summary in microseconds:
2994		       Mark    Elapsed  Stage
2995			  0          0  reset
2996		  3,575,678  3,575,678  board_init_f start
2997		  3,575,695         17  arch_cpu_init A9
2998		  3,575,777         82  arch_cpu_init done
2999		  3,659,598     83,821  board_init_r start
3000		  3,910,375    250,777  main_loop
3001		 29,916,167 26,005,792  bootm_start
3002		 30,361,327    445,160  start_kernel
3003
3004		CONFIG_CMD_BOOTSTAGE
3005		Add a 'bootstage' command which supports printing a report
3006		and un/stashing of bootstage data.
3007
3008		CONFIG_BOOTSTAGE_FDT
3009		Stash the bootstage information in the FDT. A root 'bootstage'
3010		node is created with each bootstage id as a child. Each child
3011		has a 'name' property and either 'mark' containing the
3012		mark time in microsecond, or 'accum' containing the
3013		accumulated time for that bootstage id in microseconds.
3014		For example:
3015
3016		bootstage {
3017			154 {
3018				name = "board_init_f";
3019				mark = <3575678>;
3020			};
3021			170 {
3022				name = "lcd";
3023				accum = <33482>;
3024			};
3025		};
3026
3027		Code in the Linux kernel can find this in /proc/devicetree.
3028
3029Legacy uImage format:
3030
3031  Arg	Where			When
3032    1	common/cmd_bootm.c	before attempting to boot an image
3033   -1	common/cmd_bootm.c	Image header has bad	 magic number
3034    2	common/cmd_bootm.c	Image header has correct magic number
3035   -2	common/cmd_bootm.c	Image header has bad	 checksum
3036    3	common/cmd_bootm.c	Image header has correct checksum
3037   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3038    4	common/cmd_bootm.c	Image data   has correct checksum
3039   -4	common/cmd_bootm.c	Image is for unsupported architecture
3040    5	common/cmd_bootm.c	Architecture check OK
3041   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3042    6	common/cmd_bootm.c	Image Type check OK
3043   -6	common/cmd_bootm.c	gunzip uncompression error
3044   -7	common/cmd_bootm.c	Unimplemented compression type
3045    7	common/cmd_bootm.c	Uncompression OK
3046    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3047   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3048
3049    9	common/image.c		Start initial ramdisk verification
3050  -10	common/image.c		Ramdisk header has bad	   magic number
3051  -11	common/image.c		Ramdisk header has bad	   checksum
3052   10	common/image.c		Ramdisk header is OK
3053  -12	common/image.c		Ramdisk data   has bad	   checksum
3054   11	common/image.c		Ramdisk data   has correct checksum
3055   12	common/image.c		Ramdisk verification complete, start loading
3056  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3057   13	common/image.c		Start multifile image verification
3058   14	common/image.c		No initial ramdisk, no multifile, continue.
3059
3060   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3061
3062  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3063  -31	post/post.c		POST test failed, detected by post_output_backlog()
3064  -32	post/post.c		POST test failed, detected by post_run_single()
3065
3066   34	common/cmd_doc.c	before loading a Image from a DOC device
3067  -35	common/cmd_doc.c	Bad usage of "doc" command
3068   35	common/cmd_doc.c	correct usage of "doc" command
3069  -36	common/cmd_doc.c	No boot device
3070   36	common/cmd_doc.c	correct boot device
3071  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3072   37	common/cmd_doc.c	correct chip ID found, device available
3073  -38	common/cmd_doc.c	Read Error on boot device
3074   38	common/cmd_doc.c	reading Image header from DOC device OK
3075  -39	common/cmd_doc.c	Image header has bad magic number
3076   39	common/cmd_doc.c	Image header has correct magic number
3077  -40	common/cmd_doc.c	Error reading Image from DOC device
3078   40	common/cmd_doc.c	Image header has correct magic number
3079   41	common/cmd_ide.c	before loading a Image from a IDE device
3080  -42	common/cmd_ide.c	Bad usage of "ide" command
3081   42	common/cmd_ide.c	correct usage of "ide" command
3082  -43	common/cmd_ide.c	No boot device
3083   43	common/cmd_ide.c	boot device found
3084  -44	common/cmd_ide.c	Device not available
3085   44	common/cmd_ide.c	Device available
3086  -45	common/cmd_ide.c	wrong partition selected
3087   45	common/cmd_ide.c	partition selected
3088  -46	common/cmd_ide.c	Unknown partition table
3089   46	common/cmd_ide.c	valid partition table found
3090  -47	common/cmd_ide.c	Invalid partition type
3091   47	common/cmd_ide.c	correct partition type
3092  -48	common/cmd_ide.c	Error reading Image Header on boot device
3093   48	common/cmd_ide.c	reading Image Header from IDE device OK
3094  -49	common/cmd_ide.c	Image header has bad magic number
3095   49	common/cmd_ide.c	Image header has correct magic number
3096  -50	common/cmd_ide.c	Image header has bad	 checksum
3097   50	common/cmd_ide.c	Image header has correct checksum
3098  -51	common/cmd_ide.c	Error reading Image from IDE device
3099   51	common/cmd_ide.c	reading Image from IDE device OK
3100   52	common/cmd_nand.c	before loading a Image from a NAND device
3101  -53	common/cmd_nand.c	Bad usage of "nand" command
3102   53	common/cmd_nand.c	correct usage of "nand" command
3103  -54	common/cmd_nand.c	No boot device
3104   54	common/cmd_nand.c	boot device found
3105  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3106   55	common/cmd_nand.c	correct chip ID found, device available
3107  -56	common/cmd_nand.c	Error reading Image Header on boot device
3108   56	common/cmd_nand.c	reading Image Header from NAND device OK
3109  -57	common/cmd_nand.c	Image header has bad magic number
3110   57	common/cmd_nand.c	Image header has correct magic number
3111  -58	common/cmd_nand.c	Error reading Image from NAND device
3112   58	common/cmd_nand.c	reading Image from NAND device OK
3113
3114  -60	common/env_common.c	Environment has a bad CRC, using default
3115
3116   64	net/eth.c		starting with Ethernet configuration.
3117  -64	net/eth.c		no Ethernet found.
3118   65	net/eth.c		Ethernet found.
3119
3120  -80	common/cmd_net.c	usage wrong
3121   80	common/cmd_net.c	before calling NetLoop()
3122  -81	common/cmd_net.c	some error in NetLoop() occurred
3123   81	common/cmd_net.c	NetLoop() back without error
3124  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3125   82	common/cmd_net.c	trying automatic boot
3126   83	common/cmd_net.c	running "source" command
3127  -83	common/cmd_net.c	some error in automatic boot or "source" command
3128   84	common/cmd_net.c	end without errors
3129
3130FIT uImage format:
3131
3132  Arg	Where			When
3133  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3134 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3135  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3136 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3137  102	common/cmd_bootm.c	Kernel unit name specified
3138 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3139  103	common/cmd_bootm.c	Found configuration node
3140  104	common/cmd_bootm.c	Got kernel subimage node offset
3141 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3142  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3143 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3144  106	common/cmd_bootm.c	Architecture check OK
3145 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3146  107	common/cmd_bootm.c	Kernel subimage type OK
3147 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3148  108	common/cmd_bootm.c	Got kernel subimage data/size
3149 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3150 -109	common/cmd_bootm.c	Can't get kernel subimage type
3151 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3152 -111	common/cmd_bootm.c	Can't get kernel subimage os
3153 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3154 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3155
3156  120	common/image.c		Start initial ramdisk verification
3157 -120	common/image.c		Ramdisk FIT image has incorrect format
3158  121	common/image.c		Ramdisk FIT image has correct format
3159  122	common/image.c		No ramdisk subimage unit name, using configuration
3160 -122	common/image.c		Can't get configuration for ramdisk subimage
3161  123	common/image.c		Ramdisk unit name specified
3162 -124	common/image.c		Can't get ramdisk subimage node offset
3163  125	common/image.c		Got ramdisk subimage node offset
3164 -125	common/image.c		Ramdisk subimage hash verification failed
3165  126	common/image.c		Ramdisk subimage hash verification OK
3166 -126	common/image.c		Ramdisk subimage for unsupported architecture
3167  127	common/image.c		Architecture check OK
3168 -127	common/image.c		Can't get ramdisk subimage data/size
3169  128	common/image.c		Got ramdisk subimage data/size
3170  129	common/image.c		Can't get ramdisk load address
3171 -129	common/image.c		Got ramdisk load address
3172
3173 -130	common/cmd_doc.c	Incorrect FIT image format
3174  131	common/cmd_doc.c	FIT image format OK
3175
3176 -140	common/cmd_ide.c	Incorrect FIT image format
3177  141	common/cmd_ide.c	FIT image format OK
3178
3179 -150	common/cmd_nand.c	Incorrect FIT image format
3180  151	common/cmd_nand.c	FIT image format OK
3181
3182- FIT image support:
3183		CONFIG_FIT
3184		Enable support for the FIT uImage format.
3185
3186		CONFIG_FIT_BEST_MATCH
3187		When no configuration is explicitly selected, default to the
3188		one whose fdt's compatibility field best matches that of
3189		U-Boot itself. A match is considered "best" if it matches the
3190		most specific compatibility entry of U-Boot's fdt's root node.
3191		The order of entries in the configuration's fdt is ignored.
3192
3193		CONFIG_FIT_SIGNATURE
3194		This option enables signature verification of FIT uImages,
3195		using a hash signed and verified using RSA. See
3196		doc/uImage.FIT/signature.txt for more details.
3197
3198- Standalone program support:
3199		CONFIG_STANDALONE_LOAD_ADDR
3200
3201		This option defines a board specific value for the
3202		address where standalone program gets loaded, thus
3203		overwriting the architecture dependent default
3204		settings.
3205
3206- Frame Buffer Address:
3207		CONFIG_FB_ADDR
3208
3209		Define CONFIG_FB_ADDR if you want to use specific
3210		address for frame buffer.  This is typically the case
3211		when using a graphics controller has separate video
3212		memory.  U-Boot will then place the frame buffer at
3213		the given address instead of dynamically reserving it
3214		in system RAM by calling lcd_setmem(), which grabs
3215		the memory for the frame buffer depending on the
3216		configured panel size.
3217
3218		Please see board_init_f function.
3219
3220- Automatic software updates via TFTP server
3221		CONFIG_UPDATE_TFTP
3222		CONFIG_UPDATE_TFTP_CNT_MAX
3223		CONFIG_UPDATE_TFTP_MSEC_MAX
3224
3225		These options enable and control the auto-update feature;
3226		for a more detailed description refer to doc/README.update.
3227
3228- MTD Support (mtdparts command, UBI support)
3229		CONFIG_MTD_DEVICE
3230
3231		Adds the MTD device infrastructure from the Linux kernel.
3232		Needed for mtdparts command support.
3233
3234		CONFIG_MTD_PARTITIONS
3235
3236		Adds the MTD partitioning infrastructure from the Linux
3237		kernel. Needed for UBI support.
3238
3239- UBI support
3240		CONFIG_CMD_UBI
3241
3242		Adds commands for interacting with MTD partitions formatted
3243		with the UBI flash translation layer
3244
3245		Requires also defining CONFIG_RBTREE
3246
3247		CONFIG_UBI_SILENCE_MSG
3248
3249		Make the verbose messages from UBI stop printing.  This leaves
3250		warnings and errors enabled.
3251
3252- UBIFS support
3253		CONFIG_CMD_UBIFS
3254
3255		Adds commands for interacting with UBI volumes formatted as
3256		UBIFS.  UBIFS is read-only in u-boot.
3257
3258		Requires UBI support as well as CONFIG_LZO
3259
3260		CONFIG_UBIFS_SILENCE_MSG
3261
3262		Make the verbose messages from UBIFS stop printing.  This leaves
3263		warnings and errors enabled.
3264
3265- SPL framework
3266		CONFIG_SPL
3267		Enable building of SPL globally.
3268
3269		CONFIG_SPL_LDSCRIPT
3270		LDSCRIPT for linking the SPL binary.
3271
3272		CONFIG_SPL_MAX_FOOTPRINT
3273		Maximum size in memory allocated to the SPL, BSS included.
3274		When defined, the linker checks that the actual memory
3275		used by SPL from _start to __bss_end does not exceed it.
3276		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3277		must not be both defined at the same time.
3278
3279		CONFIG_SPL_MAX_SIZE
3280		Maximum size of the SPL image (text, data, rodata, and
3281		linker lists sections), BSS excluded.
3282		When defined, the linker checks that the actual size does
3283		not exceed it.
3284
3285		CONFIG_SPL_TEXT_BASE
3286		TEXT_BASE for linking the SPL binary.
3287
3288		CONFIG_SPL_RELOC_TEXT_BASE
3289		Address to relocate to.  If unspecified, this is equal to
3290		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3291
3292		CONFIG_SPL_BSS_START_ADDR
3293		Link address for the BSS within the SPL binary.
3294
3295		CONFIG_SPL_BSS_MAX_SIZE
3296		Maximum size in memory allocated to the SPL BSS.
3297		When defined, the linker checks that the actual memory used
3298		by SPL from __bss_start to __bss_end does not exceed it.
3299		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3300		must not be both defined at the same time.
3301
3302		CONFIG_SPL_STACK
3303		Adress of the start of the stack SPL will use
3304
3305		CONFIG_SPL_RELOC_STACK
3306		Adress of the start of the stack SPL will use after
3307		relocation.  If unspecified, this is equal to
3308		CONFIG_SPL_STACK.
3309
3310		CONFIG_SYS_SPL_MALLOC_START
3311		Starting address of the malloc pool used in SPL.
3312
3313		CONFIG_SYS_SPL_MALLOC_SIZE
3314		The size of the malloc pool used in SPL.
3315
3316		CONFIG_SPL_FRAMEWORK
3317		Enable the SPL framework under common/.  This framework
3318		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3319		NAND loading of the Linux Kernel.
3320
3321		CONFIG_SPL_OS_BOOT
3322		Enable booting directly to an OS from SPL.
3323		See also: doc/README.falcon
3324
3325		CONFIG_SPL_DISPLAY_PRINT
3326		For ARM, enable an optional function to print more information
3327		about the running system.
3328
3329		CONFIG_SPL_INIT_MINIMAL
3330		Arch init code should be built for a very small image
3331
3332		CONFIG_SPL_LIBCOMMON_SUPPORT
3333		Support for common/libcommon.o in SPL binary
3334
3335		CONFIG_SPL_LIBDISK_SUPPORT
3336		Support for disk/libdisk.o in SPL binary
3337
3338		CONFIG_SPL_I2C_SUPPORT
3339		Support for drivers/i2c/libi2c.o in SPL binary
3340
3341		CONFIG_SPL_GPIO_SUPPORT
3342		Support for drivers/gpio/libgpio.o in SPL binary
3343
3344		CONFIG_SPL_MMC_SUPPORT
3345		Support for drivers/mmc/libmmc.o in SPL binary
3346
3347		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3348		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3349		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3350		Address, size and partition on the MMC to load U-Boot from
3351		when the MMC is being used in raw mode.
3352
3353		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3354		Sector to load kernel uImage from when MMC is being
3355		used in raw mode (for Falcon mode)
3356
3357		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3358		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3359		Sector and number of sectors to load kernel argument
3360		parameters from when MMC is being used in raw mode
3361		(for falcon mode)
3362
3363		CONFIG_SPL_FAT_SUPPORT
3364		Support for fs/fat/libfat.o in SPL binary
3365
3366		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3367		Filename to read to load U-Boot when reading from FAT
3368
3369		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3370		Filename to read to load kernel uImage when reading
3371		from FAT (for Falcon mode)
3372
3373		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3374		Filename to read to load kernel argument parameters
3375		when reading from FAT (for Falcon mode)
3376
3377		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3378		Set this for NAND SPL on PPC mpc83xx targets, so that
3379		start.S waits for the rest of the SPL to load before
3380		continuing (the hardware starts execution after just
3381		loading the first page rather than the full 4K).
3382
3383		CONFIG_SPL_SKIP_RELOCATE
3384		Avoid SPL relocation
3385
3386		CONFIG_SPL_NAND_BASE
3387		Include nand_base.c in the SPL.  Requires
3388		CONFIG_SPL_NAND_DRIVERS.
3389
3390		CONFIG_SPL_NAND_DRIVERS
3391		SPL uses normal NAND drivers, not minimal drivers.
3392
3393		CONFIG_SPL_NAND_ECC
3394		Include standard software ECC in the SPL
3395
3396		CONFIG_SPL_NAND_SIMPLE
3397		Support for NAND boot using simple NAND drivers that
3398		expose the cmd_ctrl() interface.
3399
3400		CONFIG_SPL_MTD_SUPPORT
3401		Support for the MTD subsystem within SPL.  Useful for
3402		environment on NAND support within SPL.
3403
3404		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3405		Set for the SPL on PPC mpc8xxx targets, support for
3406		drivers/ddr/fsl/libddr.o in SPL binary.
3407
3408		CONFIG_SPL_COMMON_INIT_DDR
3409		Set for common ddr init with serial presence detect in
3410		SPL binary.
3411
3412		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3413		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3414		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3415		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3416		CONFIG_SYS_NAND_ECCBYTES
3417		Defines the size and behavior of the NAND that SPL uses
3418		to read U-Boot
3419
3420		CONFIG_SPL_NAND_BOOT
3421		Add support NAND boot
3422
3423		CONFIG_SYS_NAND_U_BOOT_OFFS
3424		Location in NAND to read U-Boot from
3425
3426		CONFIG_SYS_NAND_U_BOOT_DST
3427		Location in memory to load U-Boot to
3428
3429		CONFIG_SYS_NAND_U_BOOT_SIZE
3430		Size of image to load
3431
3432		CONFIG_SYS_NAND_U_BOOT_START
3433		Entry point in loaded image to jump to
3434
3435		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3436		Define this if you need to first read the OOB and then the
3437		data. This is used for example on davinci plattforms.
3438
3439		CONFIG_SPL_OMAP3_ID_NAND
3440		Support for an OMAP3-specific set of functions to return the
3441		ID and MFR of the first attached NAND chip, if present.
3442
3443		CONFIG_SPL_SERIAL_SUPPORT
3444		Support for drivers/serial/libserial.o in SPL binary
3445
3446		CONFIG_SPL_SPI_FLASH_SUPPORT
3447		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3448
3449		CONFIG_SPL_SPI_SUPPORT
3450		Support for drivers/spi/libspi.o in SPL binary
3451
3452		CONFIG_SPL_RAM_DEVICE
3453		Support for running image already present in ram, in SPL binary
3454
3455		CONFIG_SPL_LIBGENERIC_SUPPORT
3456		Support for lib/libgeneric.o in SPL binary
3457
3458		CONFIG_SPL_ENV_SUPPORT
3459		Support for the environment operating in SPL binary
3460
3461		CONFIG_SPL_NET_SUPPORT
3462		Support for the net/libnet.o in SPL binary.
3463		It conflicts with SPL env from storage medium specified by
3464		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3465
3466		CONFIG_SPL_PAD_TO
3467		Image offset to which the SPL should be padded before appending
3468		the SPL payload. By default, this is defined as
3469		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3470		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3471		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3472
3473		CONFIG_SPL_TARGET
3474		Final target image containing SPL and payload.  Some SPLs
3475		use an arch-specific makefile fragment instead, for
3476		example if more than one image needs to be produced.
3477
3478		CONFIG_FIT_SPL_PRINT
3479		Printing information about a FIT image adds quite a bit of
3480		code to SPL. So this is normally disabled in SPL. Use this
3481		option to re-enable it. This will affect the output of the
3482		bootm command when booting a FIT image.
3483
3484- TPL framework
3485		CONFIG_TPL
3486		Enable building of TPL globally.
3487
3488		CONFIG_TPL_PAD_TO
3489		Image offset to which the TPL should be padded before appending
3490		the TPL payload. By default, this is defined as
3491		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3492		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3493		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3494
3495Modem Support:
3496--------------
3497
3498[so far only for SMDK2400 boards]
3499
3500- Modem support enable:
3501		CONFIG_MODEM_SUPPORT
3502
3503- RTS/CTS Flow control enable:
3504		CONFIG_HWFLOW
3505
3506- Modem debug support:
3507		CONFIG_MODEM_SUPPORT_DEBUG
3508
3509		Enables debugging stuff (char screen[1024], dbg())
3510		for modem support. Useful only with BDI2000.
3511
3512- Interrupt support (PPC):
3513
3514		There are common interrupt_init() and timer_interrupt()
3515		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3516		for CPU specific initialization. interrupt_init_cpu()
3517		should set decrementer_count to appropriate value. If
3518		CPU resets decrementer automatically after interrupt
3519		(ppc4xx) it should set decrementer_count to zero.
3520		timer_interrupt() calls timer_interrupt_cpu() for CPU
3521		specific handling. If board has watchdog / status_led
3522		/ other_activity_monitor it works automatically from
3523		general timer_interrupt().
3524
3525- General:
3526
3527		In the target system modem support is enabled when a
3528		specific key (key combination) is pressed during
3529		power-on. Otherwise U-Boot will boot normally
3530		(autoboot). The key_pressed() function is called from
3531		board_init(). Currently key_pressed() is a dummy
3532		function, returning 1 and thus enabling modem
3533		initialization.
3534
3535		If there are no modem init strings in the
3536		environment, U-Boot proceed to autoboot; the
3537		previous output (banner, info printfs) will be
3538		suppressed, though.
3539
3540		See also: doc/README.Modem
3541
3542Board initialization settings:
3543------------------------------
3544
3545During Initialization u-boot calls a number of board specific functions
3546to allow the preparation of board specific prerequisites, e.g. pin setup
3547before drivers are initialized. To enable these callbacks the
3548following configuration macros have to be defined. Currently this is
3549architecture specific, so please check arch/your_architecture/lib/board.c
3550typically in board_init_f() and board_init_r().
3551
3552- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3553- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3554- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3555- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3556
3557Configuration Settings:
3558-----------------------
3559
3560- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3561		Optionally it can be defined to support 64-bit memory commands.
3562
3563- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3564		undefine this when you're short of memory.
3565
3566- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3567		width of the commands listed in the 'help' command output.
3568
3569- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3570		prompt for user input.
3571
3572- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3573
3574- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3575
3576- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3577
3578- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3579		the application (usually a Linux kernel) when it is
3580		booted
3581
3582- CONFIG_SYS_BAUDRATE_TABLE:
3583		List of legal baudrate settings for this board.
3584
3585- CONFIG_SYS_CONSOLE_INFO_QUIET
3586		Suppress display of console information at boot.
3587
3588- CONFIG_SYS_CONSOLE_IS_IN_ENV
3589		If the board specific function
3590			extern int overwrite_console (void);
3591		returns 1, the stdin, stderr and stdout are switched to the
3592		serial port, else the settings in the environment are used.
3593
3594- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3595		Enable the call to overwrite_console().
3596
3597- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3598		Enable overwrite of previous console environment settings.
3599
3600- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3601		Begin and End addresses of the area used by the
3602		simple memory test.
3603
3604- CONFIG_SYS_ALT_MEMTEST:
3605		Enable an alternate, more extensive memory test.
3606
3607- CONFIG_SYS_MEMTEST_SCRATCH:
3608		Scratch address used by the alternate memory test
3609		You only need to set this if address zero isn't writeable
3610
3611- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3612		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3613		this specified memory area will get subtracted from the top
3614		(end) of RAM and won't get "touched" at all by U-Boot. By
3615		fixing up gd->ram_size the Linux kernel should gets passed
3616		the now "corrected" memory size and won't touch it either.
3617		This should work for arch/ppc and arch/powerpc. Only Linux
3618		board ports in arch/powerpc with bootwrapper support that
3619		recalculate the memory size from the SDRAM controller setup
3620		will have to get fixed in Linux additionally.
3621
3622		This option can be used as a workaround for the 440EPx/GRx
3623		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3624		be touched.
3625
3626		WARNING: Please make sure that this value is a multiple of
3627		the Linux page size (normally 4k). If this is not the case,
3628		then the end address of the Linux memory will be located at a
3629		non page size aligned address and this could cause major
3630		problems.
3631
3632- CONFIG_SYS_LOADS_BAUD_CHANGE:
3633		Enable temporary baudrate change while serial download
3634
3635- CONFIG_SYS_SDRAM_BASE:
3636		Physical start address of SDRAM. _Must_ be 0 here.
3637
3638- CONFIG_SYS_MBIO_BASE:
3639		Physical start address of Motherboard I/O (if using a
3640		Cogent motherboard)
3641
3642- CONFIG_SYS_FLASH_BASE:
3643		Physical start address of Flash memory.
3644
3645- CONFIG_SYS_MONITOR_BASE:
3646		Physical start address of boot monitor code (set by
3647		make config files to be same as the text base address
3648		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3649		CONFIG_SYS_FLASH_BASE when booting from flash.
3650
3651- CONFIG_SYS_MONITOR_LEN:
3652		Size of memory reserved for monitor code, used to
3653		determine _at_compile_time_ (!) if the environment is
3654		embedded within the U-Boot image, or in a separate
3655		flash sector.
3656
3657- CONFIG_SYS_MALLOC_LEN:
3658		Size of DRAM reserved for malloc() use.
3659
3660- CONFIG_SYS_BOOTM_LEN:
3661		Normally compressed uImages are limited to an
3662		uncompressed size of 8 MBytes. If this is not enough,
3663		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3664		to adjust this setting to your needs.
3665
3666- CONFIG_SYS_BOOTMAPSZ:
3667		Maximum size of memory mapped by the startup code of
3668		the Linux kernel; all data that must be processed by
3669		the Linux kernel (bd_info, boot arguments, FDT blob if
3670		used) must be put below this limit, unless "bootm_low"
3671		environment variable is defined and non-zero. In such case
3672		all data for the Linux kernel must be between "bootm_low"
3673		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3674		variable "bootm_mapsize" will override the value of
3675		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3676		then the value in "bootm_size" will be used instead.
3677
3678- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3679		Enable initrd_high functionality.  If defined then the
3680		initrd_high feature is enabled and the bootm ramdisk subcommand
3681		is enabled.
3682
3683- CONFIG_SYS_BOOT_GET_CMDLINE:
3684		Enables allocating and saving kernel cmdline in space between
3685		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3686
3687- CONFIG_SYS_BOOT_GET_KBD:
3688		Enables allocating and saving a kernel copy of the bd_info in
3689		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3690
3691- CONFIG_SYS_MAX_FLASH_BANKS:
3692		Max number of Flash memory banks
3693
3694- CONFIG_SYS_MAX_FLASH_SECT:
3695		Max number of sectors on a Flash chip
3696
3697- CONFIG_SYS_FLASH_ERASE_TOUT:
3698		Timeout for Flash erase operations (in ms)
3699
3700- CONFIG_SYS_FLASH_WRITE_TOUT:
3701		Timeout for Flash write operations (in ms)
3702
3703- CONFIG_SYS_FLASH_LOCK_TOUT
3704		Timeout for Flash set sector lock bit operation (in ms)
3705
3706- CONFIG_SYS_FLASH_UNLOCK_TOUT
3707		Timeout for Flash clear lock bits operation (in ms)
3708
3709- CONFIG_SYS_FLASH_PROTECTION
3710		If defined, hardware flash sectors protection is used
3711		instead of U-Boot software protection.
3712
3713- CONFIG_SYS_DIRECT_FLASH_TFTP:
3714
3715		Enable TFTP transfers directly to flash memory;
3716		without this option such a download has to be
3717		performed in two steps: (1) download to RAM, and (2)
3718		copy from RAM to flash.
3719
3720		The two-step approach is usually more reliable, since
3721		you can check if the download worked before you erase
3722		the flash, but in some situations (when system RAM is
3723		too limited to allow for a temporary copy of the
3724		downloaded image) this option may be very useful.
3725
3726- CONFIG_SYS_FLASH_CFI:
3727		Define if the flash driver uses extra elements in the
3728		common flash structure for storing flash geometry.
3729
3730- CONFIG_FLASH_CFI_DRIVER
3731		This option also enables the building of the cfi_flash driver
3732		in the drivers directory
3733
3734- CONFIG_FLASH_CFI_MTD
3735		This option enables the building of the cfi_mtd driver
3736		in the drivers directory. The driver exports CFI flash
3737		to the MTD layer.
3738
3739- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3740		Use buffered writes to flash.
3741
3742- CONFIG_FLASH_SPANSION_S29WS_N
3743		s29ws-n MirrorBit flash has non-standard addresses for buffered
3744		write commands.
3745
3746- CONFIG_SYS_FLASH_QUIET_TEST
3747		If this option is defined, the common CFI flash doesn't
3748		print it's warning upon not recognized FLASH banks. This
3749		is useful, if some of the configured banks are only
3750		optionally available.
3751
3752- CONFIG_FLASH_SHOW_PROGRESS
3753		If defined (must be an integer), print out countdown
3754		digits and dots.  Recommended value: 45 (9..1) for 80
3755		column displays, 15 (3..1) for 40 column displays.
3756
3757- CONFIG_FLASH_VERIFY
3758		If defined, the content of the flash (destination) is compared
3759		against the source after the write operation. An error message
3760		will be printed when the contents are not identical.
3761		Please note that this option is useless in nearly all cases,
3762		since such flash programming errors usually are detected earlier
3763		while unprotecting/erasing/programming. Please only enable
3764		this option if you really know what you are doing.
3765
3766- CONFIG_SYS_RX_ETH_BUFFER:
3767		Defines the number of Ethernet receive buffers. On some
3768		Ethernet controllers it is recommended to set this value
3769		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3770		buffers can be full shortly after enabling the interface
3771		on high Ethernet traffic.
3772		Defaults to 4 if not defined.
3773
3774- CONFIG_ENV_MAX_ENTRIES
3775
3776	Maximum number of entries in the hash table that is used
3777	internally to store the environment settings. The default
3778	setting is supposed to be generous and should work in most
3779	cases. This setting can be used to tune behaviour; see
3780	lib/hashtable.c for details.
3781
3782- CONFIG_ENV_FLAGS_LIST_DEFAULT
3783- CONFIG_ENV_FLAGS_LIST_STATIC
3784	Enable validation of the values given to environment variables when
3785	calling env set.  Variables can be restricted to only decimal,
3786	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3787	the variables can also be restricted to IP address or MAC address.
3788
3789	The format of the list is:
3790		type_attribute = [s|d|x|b|i|m]
3791		access_atribute = [a|r|o|c]
3792		attributes = type_attribute[access_atribute]
3793		entry = variable_name[:attributes]
3794		list = entry[,list]
3795
3796	The type attributes are:
3797		s - String (default)
3798		d - Decimal
3799		x - Hexadecimal
3800		b - Boolean ([1yYtT|0nNfF])
3801		i - IP address
3802		m - MAC address
3803
3804	The access attributes are:
3805		a - Any (default)
3806		r - Read-only
3807		o - Write-once
3808		c - Change-default
3809
3810	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3811		Define this to a list (string) to define the ".flags"
3812		envirnoment variable in the default or embedded environment.
3813
3814	- CONFIG_ENV_FLAGS_LIST_STATIC
3815		Define this to a list (string) to define validation that
3816		should be done if an entry is not found in the ".flags"
3817		environment variable.  To override a setting in the static
3818		list, simply add an entry for the same variable name to the
3819		".flags" variable.
3820
3821- CONFIG_ENV_ACCESS_IGNORE_FORCE
3822	If defined, don't allow the -f switch to env set override variable
3823	access flags.
3824
3825- CONFIG_SYS_GENERIC_BOARD
3826	This selects the architecture-generic board system instead of the
3827	architecture-specific board files. It is intended to move boards
3828	to this new framework over time. Defining this will disable the
3829	arch/foo/lib/board.c file and use common/board_f.c and
3830	common/board_r.c instead. To use this option your architecture
3831	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3832	its config.mk file). If you find problems enabling this option on
3833	your board please report the problem and send patches!
3834
3835- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3836	This is set by OMAP boards for the max time that reset should
3837	be asserted. See doc/README.omap-reset-time for details on how
3838	the value can be calulated on a given board.
3839
3840The following definitions that deal with the placement and management
3841of environment data (variable area); in general, we support the
3842following configurations:
3843
3844- CONFIG_BUILD_ENVCRC:
3845
3846	Builds up envcrc with the target environment so that external utils
3847	may easily extract it and embed it in final U-Boot images.
3848
3849- CONFIG_ENV_IS_IN_FLASH:
3850
3851	Define this if the environment is in flash memory.
3852
3853	a) The environment occupies one whole flash sector, which is
3854	   "embedded" in the text segment with the U-Boot code. This
3855	   happens usually with "bottom boot sector" or "top boot
3856	   sector" type flash chips, which have several smaller
3857	   sectors at the start or the end. For instance, such a
3858	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3859	   such a case you would place the environment in one of the
3860	   4 kB sectors - with U-Boot code before and after it. With
3861	   "top boot sector" type flash chips, you would put the
3862	   environment in one of the last sectors, leaving a gap
3863	   between U-Boot and the environment.
3864
3865	- CONFIG_ENV_OFFSET:
3866
3867	   Offset of environment data (variable area) to the
3868	   beginning of flash memory; for instance, with bottom boot
3869	   type flash chips the second sector can be used: the offset
3870	   for this sector is given here.
3871
3872	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3873
3874	- CONFIG_ENV_ADDR:
3875
3876	   This is just another way to specify the start address of
3877	   the flash sector containing the environment (instead of
3878	   CONFIG_ENV_OFFSET).
3879
3880	- CONFIG_ENV_SECT_SIZE:
3881
3882	   Size of the sector containing the environment.
3883
3884
3885	b) Sometimes flash chips have few, equal sized, BIG sectors.
3886	   In such a case you don't want to spend a whole sector for
3887	   the environment.
3888
3889	- CONFIG_ENV_SIZE:
3890
3891	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3892	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3893	   of this flash sector for the environment. This saves
3894	   memory for the RAM copy of the environment.
3895
3896	   It may also save flash memory if you decide to use this
3897	   when your environment is "embedded" within U-Boot code,
3898	   since then the remainder of the flash sector could be used
3899	   for U-Boot code. It should be pointed out that this is
3900	   STRONGLY DISCOURAGED from a robustness point of view:
3901	   updating the environment in flash makes it always
3902	   necessary to erase the WHOLE sector. If something goes
3903	   wrong before the contents has been restored from a copy in
3904	   RAM, your target system will be dead.
3905
3906	- CONFIG_ENV_ADDR_REDUND
3907	  CONFIG_ENV_SIZE_REDUND
3908
3909	   These settings describe a second storage area used to hold
3910	   a redundant copy of the environment data, so that there is
3911	   a valid backup copy in case there is a power failure during
3912	   a "saveenv" operation.
3913
3914BE CAREFUL! Any changes to the flash layout, and some changes to the
3915source code will make it necessary to adapt <board>/u-boot.lds*
3916accordingly!
3917
3918
3919- CONFIG_ENV_IS_IN_NVRAM:
3920
3921	Define this if you have some non-volatile memory device
3922	(NVRAM, battery buffered SRAM) which you want to use for the
3923	environment.
3924
3925	- CONFIG_ENV_ADDR:
3926	- CONFIG_ENV_SIZE:
3927
3928	  These two #defines are used to determine the memory area you
3929	  want to use for environment. It is assumed that this memory
3930	  can just be read and written to, without any special
3931	  provision.
3932
3933BE CAREFUL! The first access to the environment happens quite early
3934in U-Boot initalization (when we try to get the setting of for the
3935console baudrate). You *MUST* have mapped your NVRAM area then, or
3936U-Boot will hang.
3937
3938Please note that even with NVRAM we still use a copy of the
3939environment in RAM: we could work on NVRAM directly, but we want to
3940keep settings there always unmodified except somebody uses "saveenv"
3941to save the current settings.
3942
3943
3944- CONFIG_ENV_IS_IN_EEPROM:
3945
3946	Use this if you have an EEPROM or similar serial access
3947	device and a driver for it.
3948
3949	- CONFIG_ENV_OFFSET:
3950	- CONFIG_ENV_SIZE:
3951
3952	  These two #defines specify the offset and size of the
3953	  environment area within the total memory of your EEPROM.
3954
3955	- CONFIG_SYS_I2C_EEPROM_ADDR:
3956	  If defined, specified the chip address of the EEPROM device.
3957	  The default address is zero.
3958
3959	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3960	  If defined, the number of bits used to address bytes in a
3961	  single page in the EEPROM device.  A 64 byte page, for example
3962	  would require six bits.
3963
3964	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3965	  If defined, the number of milliseconds to delay between
3966	  page writes.	The default is zero milliseconds.
3967
3968	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3969	  The length in bytes of the EEPROM memory array address.  Note
3970	  that this is NOT the chip address length!
3971
3972	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3973	  EEPROM chips that implement "address overflow" are ones
3974	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3975	  address and the extra bits end up in the "chip address" bit
3976	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3977	  byte chips.
3978
3979	  Note that we consider the length of the address field to
3980	  still be one byte because the extra address bits are hidden
3981	  in the chip address.
3982
3983	- CONFIG_SYS_EEPROM_SIZE:
3984	  The size in bytes of the EEPROM device.
3985
3986	- CONFIG_ENV_EEPROM_IS_ON_I2C
3987	  define this, if you have I2C and SPI activated, and your
3988	  EEPROM, which holds the environment, is on the I2C bus.
3989
3990	- CONFIG_I2C_ENV_EEPROM_BUS
3991	  if you have an Environment on an EEPROM reached over
3992	  I2C muxes, you can define here, how to reach this
3993	  EEPROM. For example:
3994
3995	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3996
3997	  EEPROM which holds the environment, is reached over
3998	  a pca9547 i2c mux with address 0x70, channel 3.
3999
4000- CONFIG_ENV_IS_IN_DATAFLASH:
4001
4002	Define this if you have a DataFlash memory device which you
4003	want to use for the environment.
4004
4005	- CONFIG_ENV_OFFSET:
4006	- CONFIG_ENV_ADDR:
4007	- CONFIG_ENV_SIZE:
4008
4009	  These three #defines specify the offset and size of the
4010	  environment area within the total memory of your DataFlash placed
4011	  at the specified address.
4012
4013- CONFIG_ENV_IS_IN_REMOTE:
4014
4015	Define this if you have a remote memory space which you
4016	want to use for the local device's environment.
4017
4018	- CONFIG_ENV_ADDR:
4019	- CONFIG_ENV_SIZE:
4020
4021	  These two #defines specify the address and size of the
4022	  environment area within the remote memory space. The
4023	  local device can get the environment from remote memory
4024	  space by SRIO or PCIE links.
4025
4026BE CAREFUL! For some special cases, the local device can not use
4027"saveenv" command. For example, the local device will get the
4028environment stored in a remote NOR flash by SRIO or PCIE link,
4029but it can not erase, write this NOR flash by SRIO or PCIE interface.
4030
4031- CONFIG_ENV_IS_IN_NAND:
4032
4033	Define this if you have a NAND device which you want to use
4034	for the environment.
4035
4036	- CONFIG_ENV_OFFSET:
4037	- CONFIG_ENV_SIZE:
4038
4039	  These two #defines specify the offset and size of the environment
4040	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4041	  aligned to an erase block boundary.
4042
4043	- CONFIG_ENV_OFFSET_REDUND (optional):
4044
4045	  This setting describes a second storage area of CONFIG_ENV_SIZE
4046	  size used to hold a redundant copy of the environment data, so
4047	  that there is a valid backup copy in case there is a power failure
4048	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4049	  aligned to an erase block boundary.
4050
4051	- CONFIG_ENV_RANGE (optional):
4052
4053	  Specifies the length of the region in which the environment
4054	  can be written.  This should be a multiple of the NAND device's
4055	  block size.  Specifying a range with more erase blocks than
4056	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4057	  the range to be avoided.
4058
4059	- CONFIG_ENV_OFFSET_OOB (optional):
4060
4061	  Enables support for dynamically retrieving the offset of the
4062	  environment from block zero's out-of-band data.  The
4063	  "nand env.oob" command can be used to record this offset.
4064	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4065	  using CONFIG_ENV_OFFSET_OOB.
4066
4067- CONFIG_NAND_ENV_DST
4068
4069	Defines address in RAM to which the nand_spl code should copy the
4070	environment. If redundant environment is used, it will be copied to
4071	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4072
4073- CONFIG_ENV_IS_IN_UBI:
4074
4075	Define this if you have an UBI volume that you want to use for the
4076	environment.  This has the benefit of wear-leveling the environment
4077	accesses, which is important on NAND.
4078
4079	- CONFIG_ENV_UBI_PART:
4080
4081	  Define this to a string that is the mtd partition containing the UBI.
4082
4083	- CONFIG_ENV_UBI_VOLUME:
4084
4085	  Define this to the name of the volume that you want to store the
4086	  environment in.
4087
4088	- CONFIG_ENV_UBI_VOLUME_REDUND:
4089
4090	  Define this to the name of another volume to store a second copy of
4091	  the environment in.  This will enable redundant environments in UBI.
4092	  It is assumed that both volumes are in the same MTD partition.
4093
4094	- CONFIG_UBI_SILENCE_MSG
4095	- CONFIG_UBIFS_SILENCE_MSG
4096
4097	  You will probably want to define these to avoid a really noisy system
4098	  when storing the env in UBI.
4099
4100- CONFIG_ENV_IS_IN_MMC:
4101
4102	Define this if you have an MMC device which you want to use for the
4103	environment.
4104
4105	- CONFIG_SYS_MMC_ENV_DEV:
4106
4107	  Specifies which MMC device the environment is stored in.
4108
4109	- CONFIG_SYS_MMC_ENV_PART (optional):
4110
4111	  Specifies which MMC partition the environment is stored in. If not
4112	  set, defaults to partition 0, the user area. Common values might be
4113	  1 (first MMC boot partition), 2 (second MMC boot partition).
4114
4115	- CONFIG_ENV_OFFSET:
4116	- CONFIG_ENV_SIZE:
4117
4118	  These two #defines specify the offset and size of the environment
4119	  area within the specified MMC device.
4120
4121	  If offset is positive (the usual case), it is treated as relative to
4122	  the start of the MMC partition. If offset is negative, it is treated
4123	  as relative to the end of the MMC partition. This can be useful if
4124	  your board may be fitted with different MMC devices, which have
4125	  different sizes for the MMC partitions, and you always want the
4126	  environment placed at the very end of the partition, to leave the
4127	  maximum possible space before it, to store other data.
4128
4129	  These two values are in units of bytes, but must be aligned to an
4130	  MMC sector boundary.
4131
4132	- CONFIG_ENV_OFFSET_REDUND (optional):
4133
4134	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4135	  hold a redundant copy of the environment data. This provides a
4136	  valid backup copy in case the other copy is corrupted, e.g. due
4137	  to a power failure during a "saveenv" operation.
4138
4139	  This value may also be positive or negative; this is handled in the
4140	  same way as CONFIG_ENV_OFFSET.
4141
4142	  This value is also in units of bytes, but must also be aligned to
4143	  an MMC sector boundary.
4144
4145	- CONFIG_ENV_SIZE_REDUND (optional):
4146
4147	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4148	  set. If this value is set, it must be set to the same value as
4149	  CONFIG_ENV_SIZE.
4150
4151- CONFIG_SYS_SPI_INIT_OFFSET
4152
4153	Defines offset to the initial SPI buffer area in DPRAM. The
4154	area is used at an early stage (ROM part) if the environment
4155	is configured to reside in the SPI EEPROM: We need a 520 byte
4156	scratch DPRAM area. It is used between the two initialization
4157	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4158	to be a good choice since it makes it far enough from the
4159	start of the data area as well as from the stack pointer.
4160
4161Please note that the environment is read-only until the monitor
4162has been relocated to RAM and a RAM copy of the environment has been
4163created; also, when using EEPROM you will have to use getenv_f()
4164until then to read environment variables.
4165
4166The environment is protected by a CRC32 checksum. Before the monitor
4167is relocated into RAM, as a result of a bad CRC you will be working
4168with the compiled-in default environment - *silently*!!! [This is
4169necessary, because the first environment variable we need is the
4170"baudrate" setting for the console - if we have a bad CRC, we don't
4171have any device yet where we could complain.]
4172
4173Note: once the monitor has been relocated, then it will complain if
4174the default environment is used; a new CRC is computed as soon as you
4175use the "saveenv" command to store a valid environment.
4176
4177- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4178		Echo the inverted Ethernet link state to the fault LED.
4179
4180		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4181		      also needs to be defined.
4182
4183- CONFIG_SYS_FAULT_MII_ADDR:
4184		MII address of the PHY to check for the Ethernet link state.
4185
4186- CONFIG_NS16550_MIN_FUNCTIONS:
4187		Define this if you desire to only have use of the NS16550_init
4188		and NS16550_putc functions for the serial driver located at
4189		drivers/serial/ns16550.c.  This option is useful for saving
4190		space for already greatly restricted images, including but not
4191		limited to NAND_SPL configurations.
4192
4193- CONFIG_DISPLAY_BOARDINFO
4194		Display information about the board that U-Boot is running on
4195		when U-Boot starts up. The board function checkboard() is called
4196		to do this.
4197
4198- CONFIG_DISPLAY_BOARDINFO_LATE
4199		Similar to the previous option, but display this information
4200		later, once stdio is running and output goes to the LCD, if
4201		present.
4202
4203Low Level (hardware related) configuration options:
4204---------------------------------------------------
4205
4206- CONFIG_SYS_CACHELINE_SIZE:
4207		Cache Line Size of the CPU.
4208
4209- CONFIG_SYS_DEFAULT_IMMR:
4210		Default address of the IMMR after system reset.
4211
4212		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4213		and RPXsuper) to be able to adjust the position of
4214		the IMMR register after a reset.
4215
4216- CONFIG_SYS_CCSRBAR_DEFAULT:
4217		Default (power-on reset) physical address of CCSR on Freescale
4218		PowerPC SOCs.
4219
4220- CONFIG_SYS_CCSRBAR:
4221		Virtual address of CCSR.  On a 32-bit build, this is typically
4222		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4223
4224		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4225		for cross-platform code that uses that macro instead.
4226
4227- CONFIG_SYS_CCSRBAR_PHYS:
4228		Physical address of CCSR.  CCSR can be relocated to a new
4229		physical address, if desired.  In this case, this macro should
4230		be set to that address.	 Otherwise, it should be set to the
4231		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4232		is typically relocated on 36-bit builds.  It is recommended
4233		that this macro be defined via the _HIGH and _LOW macros:
4234
4235		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4236			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4237
4238- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4239		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4240		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4241		used in assembly code, so it must not contain typecasts or
4242		integer size suffixes (e.g. "ULL").
4243
4244- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4245		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4246		used in assembly code, so it must not contain typecasts or
4247		integer size suffixes (e.g. "ULL").
4248
4249- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4250		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4251		forced to a value that ensures that CCSR is not relocated.
4252
4253- Floppy Disk Support:
4254		CONFIG_SYS_FDC_DRIVE_NUMBER
4255
4256		the default drive number (default value 0)
4257
4258		CONFIG_SYS_ISA_IO_STRIDE
4259
4260		defines the spacing between FDC chipset registers
4261		(default value 1)
4262
4263		CONFIG_SYS_ISA_IO_OFFSET
4264
4265		defines the offset of register from address. It
4266		depends on which part of the data bus is connected to
4267		the FDC chipset. (default value 0)
4268
4269		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4270		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4271		default value.
4272
4273		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4274		fdc_hw_init() is called at the beginning of the FDC
4275		setup. fdc_hw_init() must be provided by the board
4276		source code. It is used to make hardware dependant
4277		initializations.
4278
4279- CONFIG_IDE_AHB:
4280		Most IDE controllers were designed to be connected with PCI
4281		interface. Only few of them were designed for AHB interface.
4282		When software is doing ATA command and data transfer to
4283		IDE devices through IDE-AHB controller, some additional
4284		registers accessing to these kind of IDE-AHB controller
4285		is requierd.
4286
4287- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4288		DO NOT CHANGE unless you know exactly what you're
4289		doing! (11-4) [MPC8xx/82xx systems only]
4290
4291- CONFIG_SYS_INIT_RAM_ADDR:
4292
4293		Start address of memory area that can be used for
4294		initial data and stack; please note that this must be
4295		writable memory that is working WITHOUT special
4296		initialization, i. e. you CANNOT use normal RAM which
4297		will become available only after programming the
4298		memory controller and running certain initialization
4299		sequences.
4300
4301		U-Boot uses the following memory types:
4302		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4303		- MPC824X: data cache
4304		- PPC4xx:  data cache
4305
4306- CONFIG_SYS_GBL_DATA_OFFSET:
4307
4308		Offset of the initial data structure in the memory
4309		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4310		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4311		data is located at the end of the available space
4312		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4313		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4314		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4315		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4316
4317	Note:
4318		On the MPC824X (or other systems that use the data
4319		cache for initial memory) the address chosen for
4320		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4321		point to an otherwise UNUSED address space between
4322		the top of RAM and the start of the PCI space.
4323
4324- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4325
4326- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4327
4328- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4329
4330- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4331
4332- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4333
4334- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4335
4336- CONFIG_SYS_OR_TIMING_SDRAM:
4337		SDRAM timing
4338
4339- CONFIG_SYS_MAMR_PTA:
4340		periodic timer for refresh
4341
4342- CONFIG_SYS_DER:	Debug Event Register (37-47)
4343
4344- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4345  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4346  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4347  CONFIG_SYS_BR1_PRELIM:
4348		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4349
4350- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4351  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4352  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4353		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4354
4355- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4356  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4357		Machine Mode Register and Memory Periodic Timer
4358		Prescaler definitions (SDRAM timing)
4359
4360- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4361		enable I2C microcode relocation patch (MPC8xx);
4362		define relocation offset in DPRAM [DSP2]
4363
4364- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4365		enable SMC microcode relocation patch (MPC8xx);
4366		define relocation offset in DPRAM [SMC1]
4367
4368- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4369		enable SPI microcode relocation patch (MPC8xx);
4370		define relocation offset in DPRAM [SCC4]
4371
4372- CONFIG_SYS_USE_OSCCLK:
4373		Use OSCM clock mode on MBX8xx board. Be careful,
4374		wrong setting might damage your board. Read
4375		doc/README.MBX before setting this variable!
4376
4377- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4378		Offset of the bootmode word in DPRAM used by post
4379		(Power On Self Tests). This definition overrides
4380		#define'd default value in commproc.h resp.
4381		cpm_8260.h.
4382
4383- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4384  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4385  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4386  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4387  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4388  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4389  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4390  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4391		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4392
4393- CONFIG_PCI_DISABLE_PCIE:
4394		Disable PCI-Express on systems where it is supported but not
4395		required.
4396
4397- CONFIG_PCI_ENUM_ONLY
4398		Only scan through and get the devices on the busses.
4399		Don't do any setup work, presumably because someone or
4400		something has already done it, and we don't need to do it
4401		a second time.	Useful for platforms that are pre-booted
4402		by coreboot or similar.
4403
4404- CONFIG_PCI_INDIRECT_BRIDGE:
4405		Enable support for indirect PCI bridges.
4406
4407- CONFIG_SYS_SRIO:
4408		Chip has SRIO or not
4409
4410- CONFIG_SRIO1:
4411		Board has SRIO 1 port available
4412
4413- CONFIG_SRIO2:
4414		Board has SRIO 2 port available
4415
4416- CONFIG_SRIO_PCIE_BOOT_MASTER
4417		Board can support master function for Boot from SRIO and PCIE
4418
4419- CONFIG_SYS_SRIOn_MEM_VIRT:
4420		Virtual Address of SRIO port 'n' memory region
4421
4422- CONFIG_SYS_SRIOn_MEM_PHYS:
4423		Physical Address of SRIO port 'n' memory region
4424
4425- CONFIG_SYS_SRIOn_MEM_SIZE:
4426		Size of SRIO port 'n' memory region
4427
4428- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4429		Defined to tell the NAND controller that the NAND chip is using
4430		a 16 bit bus.
4431		Not all NAND drivers use this symbol.
4432		Example of drivers that use it:
4433		- drivers/mtd/nand/ndfc.c
4434		- drivers/mtd/nand/mxc_nand.c
4435
4436- CONFIG_SYS_NDFC_EBC0_CFG
4437		Sets the EBC0_CFG register for the NDFC. If not defined
4438		a default value will be used.
4439
4440- CONFIG_SPD_EEPROM
4441		Get DDR timing information from an I2C EEPROM. Common
4442		with pluggable memory modules such as SODIMMs
4443
4444  SPD_EEPROM_ADDRESS
4445		I2C address of the SPD EEPROM
4446
4447- CONFIG_SYS_SPD_BUS_NUM
4448		If SPD EEPROM is on an I2C bus other than the first
4449		one, specify here. Note that the value must resolve
4450		to something your driver can deal with.
4451
4452- CONFIG_SYS_DDR_RAW_TIMING
4453		Get DDR timing information from other than SPD. Common with
4454		soldered DDR chips onboard without SPD. DDR raw timing
4455		parameters are extracted from datasheet and hard-coded into
4456		header files or board specific files.
4457
4458- CONFIG_FSL_DDR_INTERACTIVE
4459		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4460
4461- CONFIG_SYS_83XX_DDR_USES_CS0
4462		Only for 83xx systems. If specified, then DDR should
4463		be configured using CS0 and CS1 instead of CS2 and CS3.
4464
4465- CONFIG_ETHER_ON_FEC[12]
4466		Define to enable FEC[12] on a 8xx series processor.
4467
4468- CONFIG_FEC[12]_PHY
4469		Define to the hardcoded PHY address which corresponds
4470		to the given FEC; i. e.
4471			#define CONFIG_FEC1_PHY 4
4472		means that the PHY with address 4 is connected to FEC1
4473
4474		When set to -1, means to probe for first available.
4475
4476- CONFIG_FEC[12]_PHY_NORXERR
4477		The PHY does not have a RXERR line (RMII only).
4478		(so program the FEC to ignore it).
4479
4480- CONFIG_RMII
4481		Enable RMII mode for all FECs.
4482		Note that this is a global option, we can't
4483		have one FEC in standard MII mode and another in RMII mode.
4484
4485- CONFIG_CRC32_VERIFY
4486		Add a verify option to the crc32 command.
4487		The syntax is:
4488
4489		=> crc32 -v <address> <count> <crc32>
4490
4491		Where address/count indicate a memory area
4492		and crc32 is the correct crc32 which the
4493		area should have.
4494
4495- CONFIG_LOOPW
4496		Add the "loopw" memory command. This only takes effect if
4497		the memory commands are activated globally (CONFIG_CMD_MEM).
4498
4499- CONFIG_MX_CYCLIC
4500		Add the "mdc" and "mwc" memory commands. These are cyclic
4501		"md/mw" commands.
4502		Examples:
4503
4504		=> mdc.b 10 4 500
4505		This command will print 4 bytes (10,11,12,13) each 500 ms.
4506
4507		=> mwc.l 100 12345678 10
4508		This command will write 12345678 to address 100 all 10 ms.
4509
4510		This only takes effect if the memory commands are activated
4511		globally (CONFIG_CMD_MEM).
4512
4513- CONFIG_SKIP_LOWLEVEL_INIT
4514		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4515		low level initializations (like setting up the memory
4516		controller) are omitted and/or U-Boot does not
4517		relocate itself into RAM.
4518
4519		Normally this variable MUST NOT be defined. The only
4520		exception is when U-Boot is loaded (to RAM) by some
4521		other boot loader or by a debugger which performs
4522		these initializations itself.
4523
4524- CONFIG_SPL_BUILD
4525		Modifies the behaviour of start.S when compiling a loader
4526		that is executed before the actual U-Boot. E.g. when
4527		compiling a NAND SPL.
4528
4529- CONFIG_TPL_BUILD
4530		Modifies the behaviour of start.S  when compiling a loader
4531		that is executed after the SPL and before the actual U-Boot.
4532		It is loaded by the SPL.
4533
4534- CONFIG_SYS_MPC85XX_NO_RESETVEC
4535		Only for 85xx systems. If this variable is specified, the section
4536		.resetvec is not kept and the section .bootpg is placed in the
4537		previous 4k of the .text section.
4538
4539- CONFIG_ARCH_MAP_SYSMEM
4540		Generally U-Boot (and in particular the md command) uses
4541		effective address. It is therefore not necessary to regard
4542		U-Boot address as virtual addresses that need to be translated
4543		to physical addresses. However, sandbox requires this, since
4544		it maintains its own little RAM buffer which contains all
4545		addressable memory. This option causes some memory accesses
4546		to be mapped through map_sysmem() / unmap_sysmem().
4547
4548- CONFIG_USE_ARCH_MEMCPY
4549  CONFIG_USE_ARCH_MEMSET
4550		If these options are used a optimized version of memcpy/memset will
4551		be used if available. These functions may be faster under some
4552		conditions but may increase the binary size.
4553
4554- CONFIG_X86_RESET_VECTOR
4555		If defined, the x86 reset vector code is included. This is not
4556		needed when U-Boot is running from Coreboot.
4557
4558- CONFIG_SYS_MPUCLK
4559		Defines the MPU clock speed (in MHz).
4560
4561		NOTE : currently only supported on AM335x platforms.
4562
4563- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4564		Enables the RTC32K OSC on AM33xx based plattforms
4565
4566- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4567		Option to disable subpage write in NAND driver
4568		driver that uses this:
4569		drivers/mtd/nand/davinci_nand.c
4570
4571Freescale QE/FMAN Firmware Support:
4572-----------------------------------
4573
4574The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4575loading of "firmware", which is encoded in the QE firmware binary format.
4576This firmware often needs to be loaded during U-Boot booting, so macros
4577are used to identify the storage device (NOR flash, SPI, etc) and the address
4578within that device.
4579
4580- CONFIG_SYS_FMAN_FW_ADDR
4581	The address in the storage device where the FMAN microcode is located.  The
4582	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4583	is also specified.
4584
4585- CONFIG_SYS_QE_FW_ADDR
4586	The address in the storage device where the QE microcode is located.  The
4587	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4588	is also specified.
4589
4590- CONFIG_SYS_QE_FMAN_FW_LENGTH
4591	The maximum possible size of the firmware.  The firmware binary format
4592	has a field that specifies the actual size of the firmware, but it
4593	might not be possible to read any part of the firmware unless some
4594	local storage is allocated to hold the entire firmware first.
4595
4596- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4597	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4598	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4599	virtual address in NOR flash.
4600
4601- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4602	Specifies that QE/FMAN firmware is located in NAND flash.
4603	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4604
4605- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4606	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4607	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4608
4609- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4610	Specifies that QE/FMAN firmware is located on the primary SPI
4611	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4612
4613- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4614	Specifies that QE/FMAN firmware is located in the remote (master)
4615	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4616	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4617	window->master inbound window->master LAW->the ucode address in
4618	master's memory space.
4619
4620Building the Software:
4621======================
4622
4623Building U-Boot has been tested in several native build environments
4624and in many different cross environments. Of course we cannot support
4625all possibly existing versions of cross development tools in all
4626(potentially obsolete) versions. In case of tool chain problems we
4627recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4628which is extensively used to build and test U-Boot.
4629
4630If you are not using a native environment, it is assumed that you
4631have GNU cross compiling tools available in your path. In this case,
4632you must set the environment variable CROSS_COMPILE in your shell.
4633Note that no changes to the Makefile or any other source files are
4634necessary. For example using the ELDK on a 4xx CPU, please enter:
4635
4636	$ CROSS_COMPILE=ppc_4xx-
4637	$ export CROSS_COMPILE
4638
4639Note: If you wish to generate Windows versions of the utilities in
4640      the tools directory you can use the MinGW toolchain
4641      (http://www.mingw.org).  Set your HOST tools to the MinGW
4642      toolchain and execute 'make tools'.  For example:
4643
4644       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4645
4646      Binaries such as tools/mkimage.exe will be created which can
4647      be executed on computers running Windows.
4648
4649U-Boot is intended to be simple to build. After installing the
4650sources you must configure U-Boot for one specific board type. This
4651is done by typing:
4652
4653	make NAME_config
4654
4655where "NAME_config" is the name of one of the existing configu-
4656rations; see boards.cfg for supported names.
4657
4658Note: for some board special configuration names may exist; check if
4659      additional information is available from the board vendor; for
4660      instance, the TQM823L systems are available without (standard)
4661      or with LCD support. You can select such additional "features"
4662      when choosing the configuration, i. e.
4663
4664      make TQM823L_config
4665	- will configure for a plain TQM823L, i. e. no LCD support
4666
4667      make TQM823L_LCD_config
4668	- will configure for a TQM823L with U-Boot console on LCD
4669
4670      etc.
4671
4672
4673Finally, type "make all", and you should get some working U-Boot
4674images ready for download to / installation on your system:
4675
4676- "u-boot.bin" is a raw binary image
4677- "u-boot" is an image in ELF binary format
4678- "u-boot.srec" is in Motorola S-Record format
4679
4680By default the build is performed locally and the objects are saved
4681in the source directory. One of the two methods can be used to change
4682this behavior and build U-Boot to some external directory:
4683
46841. Add O= to the make command line invocations:
4685
4686	make O=/tmp/build distclean
4687	make O=/tmp/build NAME_config
4688	make O=/tmp/build all
4689
46902. Set environment variable BUILD_DIR to point to the desired location:
4691
4692	export BUILD_DIR=/tmp/build
4693	make distclean
4694	make NAME_config
4695	make all
4696
4697Note that the command line "O=" setting overrides the BUILD_DIR environment
4698variable.
4699
4700
4701Please be aware that the Makefiles assume you are using GNU make, so
4702for instance on NetBSD you might need to use "gmake" instead of
4703native "make".
4704
4705
4706If the system board that you have is not listed, then you will need
4707to port U-Boot to your hardware platform. To do this, follow these
4708steps:
4709
47101.  Add a new configuration option for your board to the toplevel
4711    "boards.cfg" file, using the existing entries as examples.
4712    Follow the instructions there to keep the boards in order.
47132.  Create a new directory to hold your board specific code. Add any
4714    files you need. In your board directory, you will need at least
4715    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
47163.  Create a new configuration file "include/configs/<board>.h" for
4717    your board
47183.  If you're porting U-Boot to a new CPU, then also create a new
4719    directory to hold your CPU specific code. Add any files you need.
47204.  Run "make <board>_config" with your new name.
47215.  Type "make", and you should get a working "u-boot.srec" file
4722    to be installed on your target system.
47236.  Debug and solve any problems that might arise.
4724    [Of course, this last step is much harder than it sounds.]
4725
4726
4727Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4728==============================================================
4729
4730If you have modified U-Boot sources (for instance added a new board
4731or support for new devices, a new CPU, etc.) you are expected to
4732provide feedback to the other developers. The feedback normally takes
4733the form of a "patch", i. e. a context diff against a certain (latest
4734official or latest in the git repository) version of U-Boot sources.
4735
4736But before you submit such a patch, please verify that your modifi-
4737cation did not break existing code. At least make sure that *ALL* of
4738the supported boards compile WITHOUT ANY compiler warnings. To do so,
4739just run the "MAKEALL" script, which will configure and build U-Boot
4740for ALL supported system. Be warned, this will take a while. You can
4741select which (cross) compiler to use by passing a `CROSS_COMPILE'
4742environment variable to the script, i. e. to use the ELDK cross tools
4743you can type
4744
4745	CROSS_COMPILE=ppc_8xx- MAKEALL
4746
4747or to build on a native PowerPC system you can type
4748
4749	CROSS_COMPILE=' ' MAKEALL
4750
4751When using the MAKEALL script, the default behaviour is to build
4752U-Boot in the source directory. This location can be changed by
4753setting the BUILD_DIR environment variable. Also, for each target
4754built, the MAKEALL script saves two log files (<target>.ERR and
4755<target>.MAKEALL) in the <source dir>/LOG directory. This default
4756location can be changed by setting the MAKEALL_LOGDIR environment
4757variable. For example:
4758
4759	export BUILD_DIR=/tmp/build
4760	export MAKEALL_LOGDIR=/tmp/log
4761	CROSS_COMPILE=ppc_8xx- MAKEALL
4762
4763With the above settings build objects are saved in the /tmp/build,
4764log files are saved in the /tmp/log and the source tree remains clean
4765during the whole build process.
4766
4767
4768See also "U-Boot Porting Guide" below.
4769
4770
4771Monitor Commands - Overview:
4772============================
4773
4774go	- start application at address 'addr'
4775run	- run commands in an environment variable
4776bootm	- boot application image from memory
4777bootp	- boot image via network using BootP/TFTP protocol
4778bootz   - boot zImage from memory
4779tftpboot- boot image via network using TFTP protocol
4780	       and env variables "ipaddr" and "serverip"
4781	       (and eventually "gatewayip")
4782tftpput - upload a file via network using TFTP protocol
4783rarpboot- boot image via network using RARP/TFTP protocol
4784diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4785loads	- load S-Record file over serial line
4786loadb	- load binary file over serial line (kermit mode)
4787md	- memory display
4788mm	- memory modify (auto-incrementing)
4789nm	- memory modify (constant address)
4790mw	- memory write (fill)
4791cp	- memory copy
4792cmp	- memory compare
4793crc32	- checksum calculation
4794i2c	- I2C sub-system
4795sspi	- SPI utility commands
4796base	- print or set address offset
4797printenv- print environment variables
4798setenv	- set environment variables
4799saveenv - save environment variables to persistent storage
4800protect - enable or disable FLASH write protection
4801erase	- erase FLASH memory
4802flinfo	- print FLASH memory information
4803nand	- NAND memory operations (see doc/README.nand)
4804bdinfo	- print Board Info structure
4805iminfo	- print header information for application image
4806coninfo - print console devices and informations
4807ide	- IDE sub-system
4808loop	- infinite loop on address range
4809loopw	- infinite write loop on address range
4810mtest	- simple RAM test
4811icache	- enable or disable instruction cache
4812dcache	- enable or disable data cache
4813reset	- Perform RESET of the CPU
4814echo	- echo args to console
4815version - print monitor version
4816help	- print online help
4817?	- alias for 'help'
4818
4819
4820Monitor Commands - Detailed Description:
4821========================================
4822
4823TODO.
4824
4825For now: just type "help <command>".
4826
4827
4828Environment Variables:
4829======================
4830
4831U-Boot supports user configuration using Environment Variables which
4832can be made persistent by saving to Flash memory.
4833
4834Environment Variables are set using "setenv", printed using
4835"printenv", and saved to Flash using "saveenv". Using "setenv"
4836without a value can be used to delete a variable from the
4837environment. As long as you don't save the environment you are
4838working with an in-memory copy. In case the Flash area containing the
4839environment is erased by accident, a default environment is provided.
4840
4841Some configuration options can be set using Environment Variables.
4842
4843List of environment variables (most likely not complete):
4844
4845  baudrate	- see CONFIG_BAUDRATE
4846
4847  bootdelay	- see CONFIG_BOOTDELAY
4848
4849  bootcmd	- see CONFIG_BOOTCOMMAND
4850
4851  bootargs	- Boot arguments when booting an RTOS image
4852
4853  bootfile	- Name of the image to load with TFTP
4854
4855  bootm_low	- Memory range available for image processing in the bootm
4856		  command can be restricted. This variable is given as
4857		  a hexadecimal number and defines lowest address allowed
4858		  for use by the bootm command. See also "bootm_size"
4859		  environment variable. Address defined by "bootm_low" is
4860		  also the base of the initial memory mapping for the Linux
4861		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4862		  bootm_mapsize.
4863
4864  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4865		  This variable is given as a hexadecimal number and it
4866		  defines the size of the memory region starting at base
4867		  address bootm_low that is accessible by the Linux kernel
4868		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4869		  as the default value if it is defined, and bootm_size is
4870		  used otherwise.
4871
4872  bootm_size	- Memory range available for image processing in the bootm
4873		  command can be restricted. This variable is given as
4874		  a hexadecimal number and defines the size of the region
4875		  allowed for use by the bootm command. See also "bootm_low"
4876		  environment variable.
4877
4878  updatefile	- Location of the software update file on a TFTP server, used
4879		  by the automatic software update feature. Please refer to
4880		  documentation in doc/README.update for more details.
4881
4882  autoload	- if set to "no" (any string beginning with 'n'),
4883		  "bootp" will just load perform a lookup of the
4884		  configuration from the BOOTP server, but not try to
4885		  load any image using TFTP
4886
4887  autostart	- if set to "yes", an image loaded using the "bootp",
4888		  "rarpboot", "tftpboot" or "diskboot" commands will
4889		  be automatically started (by internally calling
4890		  "bootm")
4891
4892		  If set to "no", a standalone image passed to the
4893		  "bootm" command will be copied to the load address
4894		  (and eventually uncompressed), but NOT be started.
4895		  This can be used to load and uncompress arbitrary
4896		  data.
4897
4898  fdt_high	- if set this restricts the maximum address that the
4899		  flattened device tree will be copied into upon boot.
4900		  For example, if you have a system with 1 GB memory
4901		  at physical address 0x10000000, while Linux kernel
4902		  only recognizes the first 704 MB as low memory, you
4903		  may need to set fdt_high as 0x3C000000 to have the
4904		  device tree blob be copied to the maximum address
4905		  of the 704 MB low memory, so that Linux kernel can
4906		  access it during the boot procedure.
4907
4908		  If this is set to the special value 0xFFFFFFFF then
4909		  the fdt will not be copied at all on boot.  For this
4910		  to work it must reside in writable memory, have
4911		  sufficient padding on the end of it for u-boot to
4912		  add the information it needs into it, and the memory
4913		  must be accessible by the kernel.
4914
4915  fdtcontroladdr- if set this is the address of the control flattened
4916		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4917		  defined.
4918
4919  i2cfast	- (PPC405GP|PPC405EP only)
4920		  if set to 'y' configures Linux I2C driver for fast
4921		  mode (400kHZ). This environment variable is used in
4922		  initialization code. So, for changes to be effective
4923		  it must be saved and board must be reset.
4924
4925  initrd_high	- restrict positioning of initrd images:
4926		  If this variable is not set, initrd images will be
4927		  copied to the highest possible address in RAM; this
4928		  is usually what you want since it allows for
4929		  maximum initrd size. If for some reason you want to
4930		  make sure that the initrd image is loaded below the
4931		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4932		  variable to a value of "no" or "off" or "0".
4933		  Alternatively, you can set it to a maximum upper
4934		  address to use (U-Boot will still check that it
4935		  does not overwrite the U-Boot stack and data).
4936
4937		  For instance, when you have a system with 16 MB
4938		  RAM, and want to reserve 4 MB from use by Linux,
4939		  you can do this by adding "mem=12M" to the value of
4940		  the "bootargs" variable. However, now you must make
4941		  sure that the initrd image is placed in the first
4942		  12 MB as well - this can be done with
4943
4944		  setenv initrd_high 00c00000
4945
4946		  If you set initrd_high to 0xFFFFFFFF, this is an
4947		  indication to U-Boot that all addresses are legal
4948		  for the Linux kernel, including addresses in flash
4949		  memory. In this case U-Boot will NOT COPY the
4950		  ramdisk at all. This may be useful to reduce the
4951		  boot time on your system, but requires that this
4952		  feature is supported by your Linux kernel.
4953
4954  ipaddr	- IP address; needed for tftpboot command
4955
4956  loadaddr	- Default load address for commands like "bootp",
4957		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4958
4959  loads_echo	- see CONFIG_LOADS_ECHO
4960
4961  serverip	- TFTP server IP address; needed for tftpboot command
4962
4963  bootretry	- see CONFIG_BOOT_RETRY_TIME
4964
4965  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4966
4967  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4968
4969  ethprime	- controls which interface is used first.
4970
4971  ethact	- controls which interface is currently active.
4972		  For example you can do the following
4973
4974		  => setenv ethact FEC
4975		  => ping 192.168.0.1 # traffic sent on FEC
4976		  => setenv ethact SCC
4977		  => ping 10.0.0.1 # traffic sent on SCC
4978
4979  ethrotate	- When set to "no" U-Boot does not go through all
4980		  available network interfaces.
4981		  It just stays at the currently selected interface.
4982
4983  netretry	- When set to "no" each network operation will
4984		  either succeed or fail without retrying.
4985		  When set to "once" the network operation will
4986		  fail when all the available network interfaces
4987		  are tried once without success.
4988		  Useful on scripts which control the retry operation
4989		  themselves.
4990
4991  npe_ucode	- set load address for the NPE microcode
4992
4993  silent_linux  - If set then linux will be told to boot silently, by
4994		  changing the console to be empty. If "yes" it will be
4995		  made silent. If "no" it will not be made silent. If
4996		  unset, then it will be made silent if the U-Boot console
4997		  is silent.
4998
4999  tftpsrcport	- If this is set, the value is used for TFTP's
5000		  UDP source port.
5001
5002  tftpdstport	- If this is set, the value is used for TFTP's UDP
5003		  destination port instead of the Well Know Port 69.
5004
5005  tftpblocksize - Block size to use for TFTP transfers; if not set,
5006		  we use the TFTP server's default block size
5007
5008  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5009		  seconds, minimum value is 1000 = 1 second). Defines
5010		  when a packet is considered to be lost so it has to
5011		  be retransmitted. The default is 5000 = 5 seconds.
5012		  Lowering this value may make downloads succeed
5013		  faster in networks with high packet loss rates or
5014		  with unreliable TFTP servers.
5015
5016  vlan		- When set to a value < 4095 the traffic over
5017		  Ethernet is encapsulated/received over 802.1q
5018		  VLAN tagged frames.
5019
5020The following image location variables contain the location of images
5021used in booting. The "Image" column gives the role of the image and is
5022not an environment variable name. The other columns are environment
5023variable names. "File Name" gives the name of the file on a TFTP
5024server, "RAM Address" gives the location in RAM the image will be
5025loaded to, and "Flash Location" gives the image's address in NOR
5026flash or offset in NAND flash.
5027
5028*Note* - these variables don't have to be defined for all boards, some
5029boards currenlty use other variables for these purposes, and some
5030boards use these variables for other purposes.
5031
5032Image		    File Name	     RAM Address       Flash Location
5033-----		    ---------	     -----------       --------------
5034u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5035Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5036device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5037ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5038
5039The following environment variables may be used and automatically
5040updated by the network boot commands ("bootp" and "rarpboot"),
5041depending the information provided by your boot server:
5042
5043  bootfile	- see above
5044  dnsip		- IP address of your Domain Name Server
5045  dnsip2	- IP address of your secondary Domain Name Server
5046  gatewayip	- IP address of the Gateway (Router) to use
5047  hostname	- Target hostname
5048  ipaddr	- see above
5049  netmask	- Subnet Mask
5050  rootpath	- Pathname of the root filesystem on the NFS server
5051  serverip	- see above
5052
5053
5054There are two special Environment Variables:
5055
5056  serial#	- contains hardware identification information such
5057		  as type string and/or serial number
5058  ethaddr	- Ethernet address
5059
5060These variables can be set only once (usually during manufacturing of
5061the board). U-Boot refuses to delete or overwrite these variables
5062once they have been set once.
5063
5064
5065Further special Environment Variables:
5066
5067  ver		- Contains the U-Boot version string as printed
5068		  with the "version" command. This variable is
5069		  readonly (see CONFIG_VERSION_VARIABLE).
5070
5071
5072Please note that changes to some configuration parameters may take
5073only effect after the next boot (yes, that's just like Windoze :-).
5074
5075
5076Callback functions for environment variables:
5077---------------------------------------------
5078
5079For some environment variables, the behavior of u-boot needs to change
5080when their values are changed.  This functionailty allows functions to
5081be associated with arbitrary variables.  On creation, overwrite, or
5082deletion, the callback will provide the opportunity for some side
5083effect to happen or for the change to be rejected.
5084
5085The callbacks are named and associated with a function using the
5086U_BOOT_ENV_CALLBACK macro in your board or driver code.
5087
5088These callbacks are associated with variables in one of two ways.  The
5089static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5090in the board configuration to a string that defines a list of
5091associations.  The list must be in the following format:
5092
5093	entry = variable_name[:callback_name]
5094	list = entry[,list]
5095
5096If the callback name is not specified, then the callback is deleted.
5097Spaces are also allowed anywhere in the list.
5098
5099Callbacks can also be associated by defining the ".callbacks" variable
5100with the same list format above.  Any association in ".callbacks" will
5101override any association in the static list. You can define
5102CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5103".callbacks" envirnoment variable in the default or embedded environment.
5104
5105
5106Command Line Parsing:
5107=====================
5108
5109There are two different command line parsers available with U-Boot:
5110the old "simple" one, and the much more powerful "hush" shell:
5111
5112Old, simple command line parser:
5113--------------------------------
5114
5115- supports environment variables (through setenv / saveenv commands)
5116- several commands on one line, separated by ';'
5117- variable substitution using "... ${name} ..." syntax
5118- special characters ('$', ';') can be escaped by prefixing with '\',
5119  for example:
5120	setenv bootcmd bootm \${address}
5121- You can also escape text by enclosing in single apostrophes, for example:
5122	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5123
5124Hush shell:
5125-----------
5126
5127- similar to Bourne shell, with control structures like
5128  if...then...else...fi, for...do...done; while...do...done,
5129  until...do...done, ...
5130- supports environment ("global") variables (through setenv / saveenv
5131  commands) and local shell variables (through standard shell syntax
5132  "name=value"); only environment variables can be used with "run"
5133  command
5134
5135General rules:
5136--------------
5137
5138(1) If a command line (or an environment variable executed by a "run"
5139    command) contains several commands separated by semicolon, and
5140    one of these commands fails, then the remaining commands will be
5141    executed anyway.
5142
5143(2) If you execute several variables with one call to run (i. e.
5144    calling run with a list of variables as arguments), any failing
5145    command will cause "run" to terminate, i. e. the remaining
5146    variables are not executed.
5147
5148Note for Redundant Ethernet Interfaces:
5149=======================================
5150
5151Some boards come with redundant Ethernet interfaces; U-Boot supports
5152such configurations and is capable of automatic selection of a
5153"working" interface when needed. MAC assignment works as follows:
5154
5155Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5156MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5157"eth1addr" (=>eth1), "eth2addr", ...
5158
5159If the network interface stores some valid MAC address (for instance
5160in SROM), this is used as default address if there is NO correspon-
5161ding setting in the environment; if the corresponding environment
5162variable is set, this overrides the settings in the card; that means:
5163
5164o If the SROM has a valid MAC address, and there is no address in the
5165  environment, the SROM's address is used.
5166
5167o If there is no valid address in the SROM, and a definition in the
5168  environment exists, then the value from the environment variable is
5169  used.
5170
5171o If both the SROM and the environment contain a MAC address, and
5172  both addresses are the same, this MAC address is used.
5173
5174o If both the SROM and the environment contain a MAC address, and the
5175  addresses differ, the value from the environment is used and a
5176  warning is printed.
5177
5178o If neither SROM nor the environment contain a MAC address, an error
5179  is raised.
5180
5181If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5182will be programmed into hardware as part of the initialization process.	 This
5183may be skipped by setting the appropriate 'ethmacskip' environment variable.
5184The naming convention is as follows:
5185"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5186
5187Image Formats:
5188==============
5189
5190U-Boot is capable of booting (and performing other auxiliary operations on)
5191images in two formats:
5192
5193New uImage format (FIT)
5194-----------------------
5195
5196Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5197to Flattened Device Tree). It allows the use of images with multiple
5198components (several kernels, ramdisks, etc.), with contents protected by
5199SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5200
5201
5202Old uImage format
5203-----------------
5204
5205Old image format is based on binary files which can be basically anything,
5206preceded by a special header; see the definitions in include/image.h for
5207details; basically, the header defines the following image properties:
5208
5209* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5210  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5211  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5212  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5213  INTEGRITY).
5214* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5215  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5216  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5217* Compression Type (uncompressed, gzip, bzip2)
5218* Load Address
5219* Entry Point
5220* Image Name
5221* Image Timestamp
5222
5223The header is marked by a special Magic Number, and both the header
5224and the data portions of the image are secured against corruption by
5225CRC32 checksums.
5226
5227
5228Linux Support:
5229==============
5230
5231Although U-Boot should support any OS or standalone application
5232easily, the main focus has always been on Linux during the design of
5233U-Boot.
5234
5235U-Boot includes many features that so far have been part of some
5236special "boot loader" code within the Linux kernel. Also, any
5237"initrd" images to be used are no longer part of one big Linux image;
5238instead, kernel and "initrd" are separate images. This implementation
5239serves several purposes:
5240
5241- the same features can be used for other OS or standalone
5242  applications (for instance: using compressed images to reduce the
5243  Flash memory footprint)
5244
5245- it becomes much easier to port new Linux kernel versions because
5246  lots of low-level, hardware dependent stuff are done by U-Boot
5247
5248- the same Linux kernel image can now be used with different "initrd"
5249  images; of course this also means that different kernel images can
5250  be run with the same "initrd". This makes testing easier (you don't
5251  have to build a new "zImage.initrd" Linux image when you just
5252  change a file in your "initrd"). Also, a field-upgrade of the
5253  software is easier now.
5254
5255
5256Linux HOWTO:
5257============
5258
5259Porting Linux to U-Boot based systems:
5260---------------------------------------
5261
5262U-Boot cannot save you from doing all the necessary modifications to
5263configure the Linux device drivers for use with your target hardware
5264(no, we don't intend to provide a full virtual machine interface to
5265Linux :-).
5266
5267But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5268
5269Just make sure your machine specific header file (for instance
5270include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5271Information structure as we define in include/asm-<arch>/u-boot.h,
5272and make sure that your definition of IMAP_ADDR uses the same value
5273as your U-Boot configuration in CONFIG_SYS_IMMR.
5274
5275
5276Configuring the Linux kernel:
5277-----------------------------
5278
5279No specific requirements for U-Boot. Make sure you have some root
5280device (initial ramdisk, NFS) for your target system.
5281
5282
5283Building a Linux Image:
5284-----------------------
5285
5286With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5287not used. If you use recent kernel source, a new build target
5288"uImage" will exist which automatically builds an image usable by
5289U-Boot. Most older kernels also have support for a "pImage" target,
5290which was introduced for our predecessor project PPCBoot and uses a
5291100% compatible format.
5292
5293Example:
5294
5295	make TQM850L_config
5296	make oldconfig
5297	make dep
5298	make uImage
5299
5300The "uImage" build target uses a special tool (in 'tools/mkimage') to
5301encapsulate a compressed Linux kernel image with header	 information,
5302CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5303
5304* build a standard "vmlinux" kernel image (in ELF binary format):
5305
5306* convert the kernel into a raw binary image:
5307
5308	${CROSS_COMPILE}-objcopy -O binary \
5309				 -R .note -R .comment \
5310				 -S vmlinux linux.bin
5311
5312* compress the binary image:
5313
5314	gzip -9 linux.bin
5315
5316* package compressed binary image for U-Boot:
5317
5318	mkimage -A ppc -O linux -T kernel -C gzip \
5319		-a 0 -e 0 -n "Linux Kernel Image" \
5320		-d linux.bin.gz uImage
5321
5322
5323The "mkimage" tool can also be used to create ramdisk images for use
5324with U-Boot, either separated from the Linux kernel image, or
5325combined into one file. "mkimage" encapsulates the images with a 64
5326byte header containing information about target architecture,
5327operating system, image type, compression method, entry points, time
5328stamp, CRC32 checksums, etc.
5329
5330"mkimage" can be called in two ways: to verify existing images and
5331print the header information, or to build new images.
5332
5333In the first form (with "-l" option) mkimage lists the information
5334contained in the header of an existing U-Boot image; this includes
5335checksum verification:
5336
5337	tools/mkimage -l image
5338	  -l ==> list image header information
5339
5340The second form (with "-d" option) is used to build a U-Boot image
5341from a "data file" which is used as image payload:
5342
5343	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5344		      -n name -d data_file image
5345	  -A ==> set architecture to 'arch'
5346	  -O ==> set operating system to 'os'
5347	  -T ==> set image type to 'type'
5348	  -C ==> set compression type 'comp'
5349	  -a ==> set load address to 'addr' (hex)
5350	  -e ==> set entry point to 'ep' (hex)
5351	  -n ==> set image name to 'name'
5352	  -d ==> use image data from 'datafile'
5353
5354Right now, all Linux kernels for PowerPC systems use the same load
5355address (0x00000000), but the entry point address depends on the
5356kernel version:
5357
5358- 2.2.x kernels have the entry point at 0x0000000C,
5359- 2.3.x and later kernels have the entry point at 0x00000000.
5360
5361So a typical call to build a U-Boot image would read:
5362
5363	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5364	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5365	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5366	> examples/uImage.TQM850L
5367	Image Name:   2.4.4 kernel for TQM850L
5368	Created:      Wed Jul 19 02:34:59 2000
5369	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5370	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5371	Load Address: 0x00000000
5372	Entry Point:  0x00000000
5373
5374To verify the contents of the image (or check for corruption):
5375
5376	-> tools/mkimage -l examples/uImage.TQM850L
5377	Image Name:   2.4.4 kernel for TQM850L
5378	Created:      Wed Jul 19 02:34:59 2000
5379	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5380	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5381	Load Address: 0x00000000
5382	Entry Point:  0x00000000
5383
5384NOTE: for embedded systems where boot time is critical you can trade
5385speed for memory and install an UNCOMPRESSED image instead: this
5386needs more space in Flash, but boots much faster since it does not
5387need to be uncompressed:
5388
5389	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5390	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5391	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5392	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5393	> examples/uImage.TQM850L-uncompressed
5394	Image Name:   2.4.4 kernel for TQM850L
5395	Created:      Wed Jul 19 02:34:59 2000
5396	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5397	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5398	Load Address: 0x00000000
5399	Entry Point:  0x00000000
5400
5401
5402Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5403when your kernel is intended to use an initial ramdisk:
5404
5405	-> tools/mkimage -n 'Simple Ramdisk Image' \
5406	> -A ppc -O linux -T ramdisk -C gzip \
5407	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5408	Image Name:   Simple Ramdisk Image
5409	Created:      Wed Jan 12 14:01:50 2000
5410	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5411	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5412	Load Address: 0x00000000
5413	Entry Point:  0x00000000
5414
5415The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5416option performs the converse operation of the mkimage's second form (the "-d"
5417option). Given an image built by mkimage, the dumpimage extracts a "data file"
5418from the image:
5419
5420	tools/dumpimage -i image -p position data_file
5421	  -i ==> extract from the 'image' a specific 'data_file', \
5422	   indexed by 'position'
5423
5424
5425Installing a Linux Image:
5426-------------------------
5427
5428To downloading a U-Boot image over the serial (console) interface,
5429you must convert the image to S-Record format:
5430
5431	objcopy -I binary -O srec examples/image examples/image.srec
5432
5433The 'objcopy' does not understand the information in the U-Boot
5434image header, so the resulting S-Record file will be relative to
5435address 0x00000000. To load it to a given address, you need to
5436specify the target address as 'offset' parameter with the 'loads'
5437command.
5438
5439Example: install the image to address 0x40100000 (which on the
5440TQM8xxL is in the first Flash bank):
5441
5442	=> erase 40100000 401FFFFF
5443
5444	.......... done
5445	Erased 8 sectors
5446
5447	=> loads 40100000
5448	## Ready for S-Record download ...
5449	~>examples/image.srec
5450	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5451	...
5452	15989 15990 15991 15992
5453	[file transfer complete]
5454	[connected]
5455	## Start Addr = 0x00000000
5456
5457
5458You can check the success of the download using the 'iminfo' command;
5459this includes a checksum verification so you can be sure no data
5460corruption happened:
5461
5462	=> imi 40100000
5463
5464	## Checking Image at 40100000 ...
5465	   Image Name:	 2.2.13 for initrd on TQM850L
5466	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5467	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5468	   Load Address: 00000000
5469	   Entry Point:	 0000000c
5470	   Verifying Checksum ... OK
5471
5472
5473Boot Linux:
5474-----------
5475
5476The "bootm" command is used to boot an application that is stored in
5477memory (RAM or Flash). In case of a Linux kernel image, the contents
5478of the "bootargs" environment variable is passed to the kernel as
5479parameters. You can check and modify this variable using the
5480"printenv" and "setenv" commands:
5481
5482
5483	=> printenv bootargs
5484	bootargs=root=/dev/ram
5485
5486	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5487
5488	=> printenv bootargs
5489	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5490
5491	=> bootm 40020000
5492	## Booting Linux kernel at 40020000 ...
5493	   Image Name:	 2.2.13 for NFS on TQM850L
5494	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5495	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5496	   Load Address: 00000000
5497	   Entry Point:	 0000000c
5498	   Verifying Checksum ... OK
5499	   Uncompressing Kernel Image ... OK
5500	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
5501	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5502	time_init: decrementer frequency = 187500000/60
5503	Calibrating delay loop... 49.77 BogoMIPS
5504	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5505	...
5506
5507If you want to boot a Linux kernel with initial RAM disk, you pass
5508the memory addresses of both the kernel and the initrd image (PPBCOOT
5509format!) to the "bootm" command:
5510
5511	=> imi 40100000 40200000
5512
5513	## Checking Image at 40100000 ...
5514	   Image Name:	 2.2.13 for initrd on TQM850L
5515	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5516	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5517	   Load Address: 00000000
5518	   Entry Point:	 0000000c
5519	   Verifying Checksum ... OK
5520
5521	## Checking Image at 40200000 ...
5522	   Image Name:	 Simple Ramdisk Image
5523	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5524	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5525	   Load Address: 00000000
5526	   Entry Point:	 00000000
5527	   Verifying Checksum ... OK
5528
5529	=> bootm 40100000 40200000
5530	## Booting Linux kernel at 40100000 ...
5531	   Image Name:	 2.2.13 for initrd on TQM850L
5532	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5533	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5534	   Load Address: 00000000
5535	   Entry Point:	 0000000c
5536	   Verifying Checksum ... OK
5537	   Uncompressing Kernel Image ... OK
5538	## Loading RAMDisk Image at 40200000 ...
5539	   Image Name:	 Simple Ramdisk Image
5540	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5541	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5542	   Load Address: 00000000
5543	   Entry Point:	 00000000
5544	   Verifying Checksum ... OK
5545	   Loading Ramdisk ... OK
5546	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
5547	Boot arguments: root=/dev/ram
5548	time_init: decrementer frequency = 187500000/60
5549	Calibrating delay loop... 49.77 BogoMIPS
5550	...
5551	RAMDISK: Compressed image found at block 0
5552	VFS: Mounted root (ext2 filesystem).
5553
5554	bash#
5555
5556Boot Linux and pass a flat device tree:
5557-----------
5558
5559First, U-Boot must be compiled with the appropriate defines. See the section
5560titled "Linux Kernel Interface" above for a more in depth explanation. The
5561following is an example of how to start a kernel and pass an updated
5562flat device tree:
5563
5564=> print oftaddr
5565oftaddr=0x300000
5566=> print oft
5567oft=oftrees/mpc8540ads.dtb
5568=> tftp $oftaddr $oft
5569Speed: 1000, full duplex
5570Using TSEC0 device
5571TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5572Filename 'oftrees/mpc8540ads.dtb'.
5573Load address: 0x300000
5574Loading: #
5575done
5576Bytes transferred = 4106 (100a hex)
5577=> tftp $loadaddr $bootfile
5578Speed: 1000, full duplex
5579Using TSEC0 device
5580TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5581Filename 'uImage'.
5582Load address: 0x200000
5583Loading:############
5584done
5585Bytes transferred = 1029407 (fb51f hex)
5586=> print loadaddr
5587loadaddr=200000
5588=> print oftaddr
5589oftaddr=0x300000
5590=> bootm $loadaddr - $oftaddr
5591## Booting image at 00200000 ...
5592   Image Name:	 Linux-2.6.17-dirty
5593   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5594   Data Size:	 1029343 Bytes = 1005.2 kB
5595   Load Address: 00000000
5596   Entry Point:	 00000000
5597   Verifying Checksum ... OK
5598   Uncompressing Kernel Image ... OK
5599Booting using flat device tree at 0x300000
5600Using MPC85xx ADS machine description
5601Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5602[snip]
5603
5604
5605More About U-Boot Image Types:
5606------------------------------
5607
5608U-Boot supports the following image types:
5609
5610   "Standalone Programs" are directly runnable in the environment
5611	provided by U-Boot; it is expected that (if they behave
5612	well) you can continue to work in U-Boot after return from
5613	the Standalone Program.
5614   "OS Kernel Images" are usually images of some Embedded OS which
5615	will take over control completely. Usually these programs
5616	will install their own set of exception handlers, device
5617	drivers, set up the MMU, etc. - this means, that you cannot
5618	expect to re-enter U-Boot except by resetting the CPU.
5619   "RAMDisk Images" are more or less just data blocks, and their
5620	parameters (address, size) are passed to an OS kernel that is
5621	being started.
5622   "Multi-File Images" contain several images, typically an OS
5623	(Linux) kernel image and one or more data images like
5624	RAMDisks. This construct is useful for instance when you want
5625	to boot over the network using BOOTP etc., where the boot
5626	server provides just a single image file, but you want to get
5627	for instance an OS kernel and a RAMDisk image.
5628
5629	"Multi-File Images" start with a list of image sizes, each
5630	image size (in bytes) specified by an "uint32_t" in network
5631	byte order. This list is terminated by an "(uint32_t)0".
5632	Immediately after the terminating 0 follow the images, one by
5633	one, all aligned on "uint32_t" boundaries (size rounded up to
5634	a multiple of 4 bytes).
5635
5636   "Firmware Images" are binary images containing firmware (like
5637	U-Boot or FPGA images) which usually will be programmed to
5638	flash memory.
5639
5640   "Script files" are command sequences that will be executed by
5641	U-Boot's command interpreter; this feature is especially
5642	useful when you configure U-Boot to use a real shell (hush)
5643	as command interpreter.
5644
5645Booting the Linux zImage:
5646-------------------------
5647
5648On some platforms, it's possible to boot Linux zImage. This is done
5649using the "bootz" command. The syntax of "bootz" command is the same
5650as the syntax of "bootm" command.
5651
5652Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5653kernel with raw initrd images. The syntax is slightly different, the
5654address of the initrd must be augmented by it's size, in the following
5655format: "<initrd addres>:<initrd size>".
5656
5657
5658Standalone HOWTO:
5659=================
5660
5661One of the features of U-Boot is that you can dynamically load and
5662run "standalone" applications, which can use some resources of
5663U-Boot like console I/O functions or interrupt services.
5664
5665Two simple examples are included with the sources:
5666
5667"Hello World" Demo:
5668-------------------
5669
5670'examples/hello_world.c' contains a small "Hello World" Demo
5671application; it is automatically compiled when you build U-Boot.
5672It's configured to run at address 0x00040004, so you can play with it
5673like that:
5674
5675	=> loads
5676	## Ready for S-Record download ...
5677	~>examples/hello_world.srec
5678	1 2 3 4 5 6 7 8 9 10 11 ...
5679	[file transfer complete]
5680	[connected]
5681	## Start Addr = 0x00040004
5682
5683	=> go 40004 Hello World! This is a test.
5684	## Starting application at 0x00040004 ...
5685	Hello World
5686	argc = 7
5687	argv[0] = "40004"
5688	argv[1] = "Hello"
5689	argv[2] = "World!"
5690	argv[3] = "This"
5691	argv[4] = "is"
5692	argv[5] = "a"
5693	argv[6] = "test."
5694	argv[7] = "<NULL>"
5695	Hit any key to exit ...
5696
5697	## Application terminated, rc = 0x0
5698
5699Another example, which demonstrates how to register a CPM interrupt
5700handler with the U-Boot code, can be found in 'examples/timer.c'.
5701Here, a CPM timer is set up to generate an interrupt every second.
5702The interrupt service routine is trivial, just printing a '.'
5703character, but this is just a demo program. The application can be
5704controlled by the following keys:
5705
5706	? - print current values og the CPM Timer registers
5707	b - enable interrupts and start timer
5708	e - stop timer and disable interrupts
5709	q - quit application
5710
5711	=> loads
5712	## Ready for S-Record download ...
5713	~>examples/timer.srec
5714	1 2 3 4 5 6 7 8 9 10 11 ...
5715	[file transfer complete]
5716	[connected]
5717	## Start Addr = 0x00040004
5718
5719	=> go 40004
5720	## Starting application at 0x00040004 ...
5721	TIMERS=0xfff00980
5722	Using timer 1
5723	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5724
5725Hit 'b':
5726	[q, b, e, ?] Set interval 1000000 us
5727	Enabling timer
5728Hit '?':
5729	[q, b, e, ?] ........
5730	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5731Hit '?':
5732	[q, b, e, ?] .
5733	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5734Hit '?':
5735	[q, b, e, ?] .
5736	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5737Hit '?':
5738	[q, b, e, ?] .
5739	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5740Hit 'e':
5741	[q, b, e, ?] ...Stopping timer
5742Hit 'q':
5743	[q, b, e, ?] ## Application terminated, rc = 0x0
5744
5745
5746Minicom warning:
5747================
5748
5749Over time, many people have reported problems when trying to use the
5750"minicom" terminal emulation program for serial download. I (wd)
5751consider minicom to be broken, and recommend not to use it. Under
5752Unix, I recommend to use C-Kermit for general purpose use (and
5753especially for kermit binary protocol download ("loadb" command), and
5754use "cu" for S-Record download ("loads" command).  See
5755http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5756for help with kermit.
5757
5758
5759Nevertheless, if you absolutely want to use it try adding this
5760configuration to your "File transfer protocols" section:
5761
5762	   Name	   Program			Name U/D FullScr IO-Red. Multi
5763	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5764	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5765
5766
5767NetBSD Notes:
5768=============
5769
5770Starting at version 0.9.2, U-Boot supports NetBSD both as host
5771(build U-Boot) and target system (boots NetBSD/mpc8xx).
5772
5773Building requires a cross environment; it is known to work on
5774NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5775need gmake since the Makefiles are not compatible with BSD make).
5776Note that the cross-powerpc package does not install include files;
5777attempting to build U-Boot will fail because <machine/ansi.h> is
5778missing.  This file has to be installed and patched manually:
5779
5780	# cd /usr/pkg/cross/powerpc-netbsd/include
5781	# mkdir powerpc
5782	# ln -s powerpc machine
5783	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5784	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5785
5786Native builds *don't* work due to incompatibilities between native
5787and U-Boot include files.
5788
5789Booting assumes that (the first part of) the image booted is a
5790stage-2 loader which in turn loads and then invokes the kernel
5791proper. Loader sources will eventually appear in the NetBSD source
5792tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5793meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5794
5795
5796Implementation Internals:
5797=========================
5798
5799The following is not intended to be a complete description of every
5800implementation detail. However, it should help to understand the
5801inner workings of U-Boot and make it easier to port it to custom
5802hardware.
5803
5804
5805Initial Stack, Global Data:
5806---------------------------
5807
5808The implementation of U-Boot is complicated by the fact that U-Boot
5809starts running out of ROM (flash memory), usually without access to
5810system RAM (because the memory controller is not initialized yet).
5811This means that we don't have writable Data or BSS segments, and BSS
5812is not initialized as zero. To be able to get a C environment working
5813at all, we have to allocate at least a minimal stack. Implementation
5814options for this are defined and restricted by the CPU used: Some CPU
5815models provide on-chip memory (like the IMMR area on MPC8xx and
5816MPC826x processors), on others (parts of) the data cache can be
5817locked as (mis-) used as memory, etc.
5818
5819	Chris Hallinan posted a good summary of these issues to the
5820	U-Boot mailing list:
5821
5822	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5823	From: "Chris Hallinan" <clh@net1plus.com>
5824	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5825	...
5826
5827	Correct me if I'm wrong, folks, but the way I understand it
5828	is this: Using DCACHE as initial RAM for Stack, etc, does not
5829	require any physical RAM backing up the cache. The cleverness
5830	is that the cache is being used as a temporary supply of
5831	necessary storage before the SDRAM controller is setup. It's
5832	beyond the scope of this list to explain the details, but you
5833	can see how this works by studying the cache architecture and
5834	operation in the architecture and processor-specific manuals.
5835
5836	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5837	is another option for the system designer to use as an
5838	initial stack/RAM area prior to SDRAM being available. Either
5839	option should work for you. Using CS 4 should be fine if your
5840	board designers haven't used it for something that would
5841	cause you grief during the initial boot! It is frequently not
5842	used.
5843
5844	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5845	with your processor/board/system design. The default value
5846	you will find in any recent u-boot distribution in
5847	walnut.h should work for you. I'd set it to a value larger
5848	than your SDRAM module. If you have a 64MB SDRAM module, set
5849	it above 400_0000. Just make sure your board has no resources
5850	that are supposed to respond to that address! That code in
5851	start.S has been around a while and should work as is when
5852	you get the config right.
5853
5854	-Chris Hallinan
5855	DS4.COM, Inc.
5856
5857It is essential to remember this, since it has some impact on the C
5858code for the initialization procedures:
5859
5860* Initialized global data (data segment) is read-only. Do not attempt
5861  to write it.
5862
5863* Do not use any uninitialized global data (or implicitely initialized
5864  as zero data - BSS segment) at all - this is undefined, initiali-
5865  zation is performed later (when relocating to RAM).
5866
5867* Stack space is very limited. Avoid big data buffers or things like
5868  that.
5869
5870Having only the stack as writable memory limits means we cannot use
5871normal global data to share information beween the code. But it
5872turned out that the implementation of U-Boot can be greatly
5873simplified by making a global data structure (gd_t) available to all
5874functions. We could pass a pointer to this data as argument to _all_
5875functions, but this would bloat the code. Instead we use a feature of
5876the GCC compiler (Global Register Variables) to share the data: we
5877place a pointer (gd) to the global data into a register which we
5878reserve for this purpose.
5879
5880When choosing a register for such a purpose we are restricted by the
5881relevant  (E)ABI  specifications for the current architecture, and by
5882GCC's implementation.
5883
5884For PowerPC, the following registers have specific use:
5885	R1:	stack pointer
5886	R2:	reserved for system use
5887	R3-R4:	parameter passing and return values
5888	R5-R10: parameter passing
5889	R13:	small data area pointer
5890	R30:	GOT pointer
5891	R31:	frame pointer
5892
5893	(U-Boot also uses R12 as internal GOT pointer. r12
5894	is a volatile register so r12 needs to be reset when
5895	going back and forth between asm and C)
5896
5897    ==> U-Boot will use R2 to hold a pointer to the global data
5898
5899    Note: on PPC, we could use a static initializer (since the
5900    address of the global data structure is known at compile time),
5901    but it turned out that reserving a register results in somewhat
5902    smaller code - although the code savings are not that big (on
5903    average for all boards 752 bytes for the whole U-Boot image,
5904    624 text + 127 data).
5905
5906On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5907	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5908
5909    ==> U-Boot will use P3 to hold a pointer to the global data
5910
5911On ARM, the following registers are used:
5912
5913	R0:	function argument word/integer result
5914	R1-R3:	function argument word
5915	R9:	platform specific
5916	R10:	stack limit (used only if stack checking is enabled)
5917	R11:	argument (frame) pointer
5918	R12:	temporary workspace
5919	R13:	stack pointer
5920	R14:	link register
5921	R15:	program counter
5922
5923    ==> U-Boot will use R9 to hold a pointer to the global data
5924
5925    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5926
5927On Nios II, the ABI is documented here:
5928	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5929
5930    ==> U-Boot will use gp to hold a pointer to the global data
5931
5932    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5933    to access small data sections, so gp is free.
5934
5935On NDS32, the following registers are used:
5936
5937	R0-R1:	argument/return
5938	R2-R5:	argument
5939	R15:	temporary register for assembler
5940	R16:	trampoline register
5941	R28:	frame pointer (FP)
5942	R29:	global pointer (GP)
5943	R30:	link register (LP)
5944	R31:	stack pointer (SP)
5945	PC:	program counter (PC)
5946
5947    ==> U-Boot will use R10 to hold a pointer to the global data
5948
5949NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5950or current versions of GCC may "optimize" the code too much.
5951
5952Memory Management:
5953------------------
5954
5955U-Boot runs in system state and uses physical addresses, i.e. the
5956MMU is not used either for address mapping nor for memory protection.
5957
5958The available memory is mapped to fixed addresses using the memory
5959controller. In this process, a contiguous block is formed for each
5960memory type (Flash, SDRAM, SRAM), even when it consists of several
5961physical memory banks.
5962
5963U-Boot is installed in the first 128 kB of the first Flash bank (on
5964TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5965booting and sizing and initializing DRAM, the code relocates itself
5966to the upper end of DRAM. Immediately below the U-Boot code some
5967memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5968configuration setting]. Below that, a structure with global Board
5969Info data is placed, followed by the stack (growing downward).
5970
5971Additionally, some exception handler code is copied to the low 8 kB
5972of DRAM (0x00000000 ... 0x00001FFF).
5973
5974So a typical memory configuration with 16 MB of DRAM could look like
5975this:
5976
5977	0x0000 0000	Exception Vector code
5978	      :
5979	0x0000 1FFF
5980	0x0000 2000	Free for Application Use
5981	      :
5982	      :
5983
5984	      :
5985	      :
5986	0x00FB FF20	Monitor Stack (Growing downward)
5987	0x00FB FFAC	Board Info Data and permanent copy of global data
5988	0x00FC 0000	Malloc Arena
5989	      :
5990	0x00FD FFFF
5991	0x00FE 0000	RAM Copy of Monitor Code
5992	...		eventually: LCD or video framebuffer
5993	...		eventually: pRAM (Protected RAM - unchanged by reset)
5994	0x00FF FFFF	[End of RAM]
5995
5996
5997System Initialization:
5998----------------------
5999
6000In the reset configuration, U-Boot starts at the reset entry point
6001(on most PowerPC systems at address 0x00000100). Because of the reset
6002configuration for CS0# this is a mirror of the onboard Flash memory.
6003To be able to re-map memory U-Boot then jumps to its link address.
6004To be able to implement the initialization code in C, a (small!)
6005initial stack is set up in the internal Dual Ported RAM (in case CPUs
6006which provide such a feature like MPC8xx or MPC8260), or in a locked
6007part of the data cache. After that, U-Boot initializes the CPU core,
6008the caches and the SIU.
6009
6010Next, all (potentially) available memory banks are mapped using a
6011preliminary mapping. For example, we put them on 512 MB boundaries
6012(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6013on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6014programmed for SDRAM access. Using the temporary configuration, a
6015simple memory test is run that determines the size of the SDRAM
6016banks.
6017
6018When there is more than one SDRAM bank, and the banks are of
6019different size, the largest is mapped first. For equal size, the first
6020bank (CS2#) is mapped first. The first mapping is always for address
60210x00000000, with any additional banks following immediately to create
6022contiguous memory starting from 0.
6023
6024Then, the monitor installs itself at the upper end of the SDRAM area
6025and allocates memory for use by malloc() and for the global Board
6026Info data; also, the exception vector code is copied to the low RAM
6027pages, and the final stack is set up.
6028
6029Only after this relocation will you have a "normal" C environment;
6030until that you are restricted in several ways, mostly because you are
6031running from ROM, and because the code will have to be relocated to a
6032new address in RAM.
6033
6034
6035U-Boot Porting Guide:
6036----------------------
6037
6038[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6039list, October 2002]
6040
6041
6042int main(int argc, char *argv[])
6043{
6044	sighandler_t no_more_time;
6045
6046	signal(SIGALRM, no_more_time);
6047	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6048
6049	if (available_money > available_manpower) {
6050		Pay consultant to port U-Boot;
6051		return 0;
6052	}
6053
6054	Download latest U-Boot source;
6055
6056	Subscribe to u-boot mailing list;
6057
6058	if (clueless)
6059		email("Hi, I am new to U-Boot, how do I get started?");
6060
6061	while (learning) {
6062		Read the README file in the top level directory;
6063		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6064		Read applicable doc/*.README;
6065		Read the source, Luke;
6066		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6067	}
6068
6069	if (available_money > toLocalCurrency ($2500))
6070		Buy a BDI3000;
6071	else
6072		Add a lot of aggravation and time;
6073
6074	if (a similar board exists) {	/* hopefully... */
6075		cp -a board/<similar> board/<myboard>
6076		cp include/configs/<similar>.h include/configs/<myboard>.h
6077	} else {
6078		Create your own board support subdirectory;
6079		Create your own board include/configs/<myboard>.h file;
6080	}
6081	Edit new board/<myboard> files
6082	Edit new include/configs/<myboard>.h
6083
6084	while (!accepted) {
6085		while (!running) {
6086			do {
6087				Add / modify source code;
6088			} until (compiles);
6089			Debug;
6090			if (clueless)
6091				email("Hi, I am having problems...");
6092		}
6093		Send patch file to the U-Boot email list;
6094		if (reasonable critiques)
6095			Incorporate improvements from email list code review;
6096		else
6097			Defend code as written;
6098	}
6099
6100	return 0;
6101}
6102
6103void no_more_time (int sig)
6104{
6105      hire_a_guru();
6106}
6107
6108
6109Coding Standards:
6110-----------------
6111
6112All contributions to U-Boot should conform to the Linux kernel
6113coding style; see the file "Documentation/CodingStyle" and the script
6114"scripts/Lindent" in your Linux kernel source directory.
6115
6116Source files originating from a different project (for example the
6117MTD subsystem) are generally exempt from these guidelines and are not
6118reformated to ease subsequent migration to newer versions of those
6119sources.
6120
6121Please note that U-Boot is implemented in C (and to some small parts in
6122Assembler); no C++ is used, so please do not use C++ style comments (//)
6123in your code.
6124
6125Please also stick to the following formatting rules:
6126- remove any trailing white space
6127- use TAB characters for indentation and vertical alignment, not spaces
6128- make sure NOT to use DOS '\r\n' line feeds
6129- do not add more than 2 consecutive empty lines to source files
6130- do not add trailing empty lines to source files
6131
6132Submissions which do not conform to the standards may be returned
6133with a request to reformat the changes.
6134
6135
6136Submitting Patches:
6137-------------------
6138
6139Since the number of patches for U-Boot is growing, we need to
6140establish some rules. Submissions which do not conform to these rules
6141may be rejected, even when they contain important and valuable stuff.
6142
6143Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6144
6145Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6146see http://lists.denx.de/mailman/listinfo/u-boot
6147
6148When you send a patch, please include the following information with
6149it:
6150
6151* For bug fixes: a description of the bug and how your patch fixes
6152  this bug. Please try to include a way of demonstrating that the
6153  patch actually fixes something.
6154
6155* For new features: a description of the feature and your
6156  implementation.
6157
6158* A CHANGELOG entry as plaintext (separate from the patch)
6159
6160* For major contributions, your entry to the CREDITS file
6161
6162* When you add support for a new board, don't forget to add a
6163  maintainer e-mail address to the boards.cfg file, too.
6164
6165* If your patch adds new configuration options, don't forget to
6166  document these in the README file.
6167
6168* The patch itself. If you are using git (which is *strongly*
6169  recommended) you can easily generate the patch using the
6170  "git format-patch". If you then use "git send-email" to send it to
6171  the U-Boot mailing list, you will avoid most of the common problems
6172  with some other mail clients.
6173
6174  If you cannot use git, use "diff -purN OLD NEW". If your version of
6175  diff does not support these options, then get the latest version of
6176  GNU diff.
6177
6178  The current directory when running this command shall be the parent
6179  directory of the U-Boot source tree (i. e. please make sure that
6180  your patch includes sufficient directory information for the
6181  affected files).
6182
6183  We prefer patches as plain text. MIME attachments are discouraged,
6184  and compressed attachments must not be used.
6185
6186* If one logical set of modifications affects or creates several
6187  files, all these changes shall be submitted in a SINGLE patch file.
6188
6189* Changesets that contain different, unrelated modifications shall be
6190  submitted as SEPARATE patches, one patch per changeset.
6191
6192
6193Notes:
6194
6195* Before sending the patch, run the MAKEALL script on your patched
6196  source tree and make sure that no errors or warnings are reported
6197  for any of the boards.
6198
6199* Keep your modifications to the necessary minimum: A patch
6200  containing several unrelated changes or arbitrary reformats will be
6201  returned with a request to re-formatting / split it.
6202
6203* If you modify existing code, make sure that your new code does not
6204  add to the memory footprint of the code ;-) Small is beautiful!
6205  When adding new features, these should compile conditionally only
6206  (using #ifdef), and the resulting code with the new feature
6207  disabled must not need more memory than the old code without your
6208  modification.
6209
6210* Remember that there is a size limit of 100 kB per message on the
6211  u-boot mailing list. Bigger patches will be moderated. If they are
6212  reasonable and not too big, they will be acknowledged. But patches
6213  bigger than the size limit should be avoided.
6214