xref: /rk3399_rockchip-uboot/README (revision 4d16f67e7ba1a69929b55852f1a274c457a0db27)
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_CMD_FPGA_LOADMK
2576
2577		Enable support for fpga loadmk command
2578
2579		CONFIG_CMD_FPGA_LOADP
2580
2581		Enable support for fpga loadp command - load partial bitstream
2582
2583		CONFIG_CMD_FPGA_LOADBP
2584
2585		Enable support for fpga loadbp command - load partial bitstream
2586		(Xilinx only)
2587
2588		CONFIG_SYS_FPGA_PROG_FEEDBACK
2589
2590		Enable printing of hash marks during FPGA configuration.
2591
2592		CONFIG_SYS_FPGA_CHECK_BUSY
2593
2594		Enable checks on FPGA configuration interface busy
2595		status by the configuration function. This option
2596		will require a board or device specific function to
2597		be written.
2598
2599		CONFIG_FPGA_DELAY
2600
2601		If defined, a function that provides delays in the FPGA
2602		configuration driver.
2603
2604		CONFIG_SYS_FPGA_CHECK_CTRLC
2605		Allow Control-C to interrupt FPGA configuration
2606
2607		CONFIG_SYS_FPGA_CHECK_ERROR
2608
2609		Check for configuration errors during FPGA bitfile
2610		loading. For example, abort during Virtex II
2611		configuration if the INIT_B line goes low (which
2612		indicated a CRC error).
2613
2614		CONFIG_SYS_FPGA_WAIT_INIT
2615
2616		Maximum time to wait for the INIT_B line to deassert
2617		after PROB_B has been deasserted during a Virtex II
2618		FPGA configuration sequence. The default time is 500
2619		ms.
2620
2621		CONFIG_SYS_FPGA_WAIT_BUSY
2622
2623		Maximum time to wait for BUSY to deassert during
2624		Virtex II FPGA configuration. The default is 5 ms.
2625
2626		CONFIG_SYS_FPGA_WAIT_CONFIG
2627
2628		Time to wait after FPGA configuration. The default is
2629		200 ms.
2630
2631- Configuration Management:
2632		CONFIG_IDENT_STRING
2633
2634		If defined, this string will be added to the U-Boot
2635		version information (U_BOOT_VERSION)
2636
2637- Vendor Parameter Protection:
2638
2639		U-Boot considers the values of the environment
2640		variables "serial#" (Board Serial Number) and
2641		"ethaddr" (Ethernet Address) to be parameters that
2642		are set once by the board vendor / manufacturer, and
2643		protects these variables from casual modification by
2644		the user. Once set, these variables are read-only,
2645		and write or delete attempts are rejected. You can
2646		change this behaviour:
2647
2648		If CONFIG_ENV_OVERWRITE is #defined in your config
2649		file, the write protection for vendor parameters is
2650		completely disabled. Anybody can change or delete
2651		these parameters.
2652
2653		Alternatively, if you #define _both_ CONFIG_ETHADDR
2654		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2655		Ethernet address is installed in the environment,
2656		which can be changed exactly ONCE by the user. [The
2657		serial# is unaffected by this, i. e. it remains
2658		read-only.]
2659
2660		The same can be accomplished in a more flexible way
2661		for any variable by configuring the type of access
2662		to allow for those variables in the ".flags" variable
2663		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2664
2665- Protected RAM:
2666		CONFIG_PRAM
2667
2668		Define this variable to enable the reservation of
2669		"protected RAM", i. e. RAM which is not overwritten
2670		by U-Boot. Define CONFIG_PRAM to hold the number of
2671		kB you want to reserve for pRAM. You can overwrite
2672		this default value by defining an environment
2673		variable "pram" to the number of kB you want to
2674		reserve. Note that the board info structure will
2675		still show the full amount of RAM. If pRAM is
2676		reserved, a new environment variable "mem" will
2677		automatically be defined to hold the amount of
2678		remaining RAM in a form that can be passed as boot
2679		argument to Linux, for instance like that:
2680
2681			setenv bootargs ... mem=\${mem}
2682			saveenv
2683
2684		This way you can tell Linux not to use this memory,
2685		either, which results in a memory region that will
2686		not be affected by reboots.
2687
2688		*WARNING* If your board configuration uses automatic
2689		detection of the RAM size, you must make sure that
2690		this memory test is non-destructive. So far, the
2691		following board configurations are known to be
2692		"pRAM-clean":
2693
2694			IVMS8, IVML24, SPD8xx, TQM8xxL,
2695			HERMES, IP860, RPXlite, LWMON,
2696			FLAGADM, TQM8260
2697
2698- Access to physical memory region (> 4GB)
2699		Some basic support is provided for operations on memory not
2700		normally accessible to U-Boot - e.g. some architectures
2701		support access to more than 4GB of memory on 32-bit
2702		machines using physical address extension or similar.
2703		Define CONFIG_PHYSMEM to access this basic support, which
2704		currently only supports clearing the memory.
2705
2706- Error Recovery:
2707		CONFIG_PANIC_HANG
2708
2709		Define this variable to stop the system in case of a
2710		fatal error, so that you have to reset it manually.
2711		This is probably NOT a good idea for an embedded
2712		system where you want the system to reboot
2713		automatically as fast as possible, but it may be
2714		useful during development since you can try to debug
2715		the conditions that lead to the situation.
2716
2717		CONFIG_NET_RETRY_COUNT
2718
2719		This variable defines the number of retries for
2720		network operations like ARP, RARP, TFTP, or BOOTP
2721		before giving up the operation. If not defined, a
2722		default value of 5 is used.
2723
2724		CONFIG_ARP_TIMEOUT
2725
2726		Timeout waiting for an ARP reply in milliseconds.
2727
2728		CONFIG_NFS_TIMEOUT
2729
2730		Timeout in milliseconds used in NFS protocol.
2731		If you encounter "ERROR: Cannot umount" in nfs command,
2732		try longer timeout such as
2733		#define CONFIG_NFS_TIMEOUT 10000UL
2734
2735- Command Interpreter:
2736		CONFIG_AUTO_COMPLETE
2737
2738		Enable auto completion of commands using TAB.
2739
2740		Note that this feature has NOT been implemented yet
2741		for the "hush" shell.
2742
2743
2744		CONFIG_SYS_HUSH_PARSER
2745
2746		Define this variable to enable the "hush" shell (from
2747		Busybox) as command line interpreter, thus enabling
2748		powerful command line syntax like
2749		if...then...else...fi conditionals or `&&' and '||'
2750		constructs ("shell scripts").
2751
2752		If undefined, you get the old, much simpler behaviour
2753		with a somewhat smaller memory footprint.
2754
2755
2756		CONFIG_SYS_PROMPT_HUSH_PS2
2757
2758		This defines the secondary prompt string, which is
2759		printed when the command interpreter needs more input
2760		to complete a command. Usually "> ".
2761
2762	Note:
2763
2764		In the current implementation, the local variables
2765		space and global environment variables space are
2766		separated. Local variables are those you define by
2767		simply typing `name=value'. To access a local
2768		variable later on, you have write `$name' or
2769		`${name}'; to execute the contents of a variable
2770		directly type `$name' at the command prompt.
2771
2772		Global environment variables are those you use
2773		setenv/printenv to work with. To run a command stored
2774		in such a variable, you need to use the run command,
2775		and you must not use the '$' sign to access them.
2776
2777		To store commands and special characters in a
2778		variable, please use double quotation marks
2779		surrounding the whole text of the variable, instead
2780		of the backslashes before semicolons and special
2781		symbols.
2782
2783- Commandline Editing and History:
2784		CONFIG_CMDLINE_EDITING
2785
2786		Enable editing and History functions for interactive
2787		commandline input operations
2788
2789- Default Environment:
2790		CONFIG_EXTRA_ENV_SETTINGS
2791
2792		Define this to contain any number of null terminated
2793		strings (variable = value pairs) that will be part of
2794		the default environment compiled into the boot image.
2795
2796		For example, place something like this in your
2797		board's config file:
2798
2799		#define CONFIG_EXTRA_ENV_SETTINGS \
2800			"myvar1=value1\0" \
2801			"myvar2=value2\0"
2802
2803		Warning: This method is based on knowledge about the
2804		internal format how the environment is stored by the
2805		U-Boot code. This is NOT an official, exported
2806		interface! Although it is unlikely that this format
2807		will change soon, there is no guarantee either.
2808		You better know what you are doing here.
2809
2810		Note: overly (ab)use of the default environment is
2811		discouraged. Make sure to check other ways to preset
2812		the environment like the "source" command or the
2813		boot command first.
2814
2815		CONFIG_ENV_VARS_UBOOT_CONFIG
2816
2817		Define this in order to add variables describing the
2818		U-Boot build configuration to the default environment.
2819		These will be named arch, cpu, board, vendor, and soc.
2820
2821		Enabling this option will cause the following to be defined:
2822
2823		- CONFIG_SYS_ARCH
2824		- CONFIG_SYS_CPU
2825		- CONFIG_SYS_BOARD
2826		- CONFIG_SYS_VENDOR
2827		- CONFIG_SYS_SOC
2828
2829		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2830
2831		Define this in order to add variables describing certain
2832		run-time determined information about the hardware to the
2833		environment.  These will be named board_name, board_rev.
2834
2835		CONFIG_DELAY_ENVIRONMENT
2836
2837		Normally the environment is loaded when the board is
2838		intialised so that it is available to U-Boot. This inhibits
2839		that so that the environment is not available until
2840		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2841		this is instead controlled by the value of
2842		/config/load-environment.
2843
2844- DataFlash Support:
2845		CONFIG_HAS_DATAFLASH
2846
2847		Defining this option enables DataFlash features and
2848		allows to read/write in Dataflash via the standard
2849		commands cp, md...
2850
2851- Serial Flash support
2852		CONFIG_CMD_SF
2853
2854		Defining this option enables SPI flash commands
2855		'sf probe/read/write/erase/update'.
2856
2857		Usage requires an initial 'probe' to define the serial
2858		flash parameters, followed by read/write/erase/update
2859		commands.
2860
2861		The following defaults may be provided by the platform
2862		to handle the common case when only a single serial
2863		flash is present on the system.
2864
2865		CONFIG_SF_DEFAULT_BUS		Bus identifier
2866		CONFIG_SF_DEFAULT_CS		Chip-select
2867		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2868		CONFIG_SF_DEFAULT_SPEED		in Hz
2869
2870		CONFIG_CMD_SF_TEST
2871
2872		Define this option to include a destructive SPI flash
2873		test ('sf test').
2874
2875		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2876
2877		Define this option to use the Bank addr/Extended addr
2878		support on SPI flashes which has size > 16Mbytes.
2879
2880		CONFIG_SF_DUAL_FLASH		Dual flash memories
2881
2882		Define this option to use dual flash support where two flash
2883		memories can be connected with a given cs line.
2884		currently Xilinx Zynq qspi support these type of connections.
2885
2886- SystemACE Support:
2887		CONFIG_SYSTEMACE
2888
2889		Adding this option adds support for Xilinx SystemACE
2890		chips attached via some sort of local bus. The address
2891		of the chip must also be defined in the
2892		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2893
2894		#define CONFIG_SYSTEMACE
2895		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2896
2897		When SystemACE support is added, the "ace" device type
2898		becomes available to the fat commands, i.e. fatls.
2899
2900- TFTP Fixed UDP Port:
2901		CONFIG_TFTP_PORT
2902
2903		If this is defined, the environment variable tftpsrcp
2904		is used to supply the TFTP UDP source port value.
2905		If tftpsrcp isn't defined, the normal pseudo-random port
2906		number generator is used.
2907
2908		Also, the environment variable tftpdstp is used to supply
2909		the TFTP UDP destination port value.  If tftpdstp isn't
2910		defined, the normal port 69 is used.
2911
2912		The purpose for tftpsrcp is to allow a TFTP server to
2913		blindly start the TFTP transfer using the pre-configured
2914		target IP address and UDP port. This has the effect of
2915		"punching through" the (Windows XP) firewall, allowing
2916		the remainder of the TFTP transfer to proceed normally.
2917		A better solution is to properly configure the firewall,
2918		but sometimes that is not allowed.
2919
2920- Hashing support:
2921		CONFIG_CMD_HASH
2922
2923		This enables a generic 'hash' command which can produce
2924		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2925
2926		CONFIG_HASH_VERIFY
2927
2928		Enable the hash verify command (hash -v). This adds to code
2929		size a little.
2930
2931		CONFIG_SHA1 - support SHA1 hashing
2932		CONFIG_SHA256 - support SHA256 hashing
2933
2934		Note: There is also a sha1sum command, which should perhaps
2935		be deprecated in favour of 'hash sha1'.
2936
2937- Freescale i.MX specific commands:
2938		CONFIG_CMD_HDMIDETECT
2939		This enables 'hdmidet' command which returns true if an
2940		HDMI monitor is detected.  This command is i.MX 6 specific.
2941
2942		CONFIG_CMD_BMODE
2943		This enables the 'bmode' (bootmode) command for forcing
2944		a boot from specific media.
2945
2946		This is useful for forcing the ROM's usb downloader to
2947		activate upon a watchdog reset which is nice when iterating
2948		on U-Boot.  Using the reset button or running bmode normal
2949		will set it back to normal.  This command currently
2950		supports i.MX53 and i.MX6.
2951
2952- Signing support:
2953		CONFIG_RSA
2954
2955		This enables the RSA algorithm used for FIT image verification
2956		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2957
2958		The signing part is build into mkimage regardless of this
2959		option.
2960
2961- bootcount support:
2962		CONFIG_BOOTCOUNT_LIMIT
2963
2964		This enables the bootcounter support, see:
2965		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2966
2967		CONFIG_AT91SAM9XE
2968		enable special bootcounter support on at91sam9xe based boards.
2969		CONFIG_BLACKFIN
2970		enable special bootcounter support on blackfin based boards.
2971		CONFIG_SOC_DA8XX
2972		enable special bootcounter support on da850 based boards.
2973		CONFIG_BOOTCOUNT_RAM
2974		enable support for the bootcounter in RAM
2975		CONFIG_BOOTCOUNT_I2C
2976		enable support for the bootcounter on an i2c (like RTC) device.
2977			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2978			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2979						    the bootcounter.
2980			CONFIG_BOOTCOUNT_ALEN = address len
2981
2982- Show boot progress:
2983		CONFIG_SHOW_BOOT_PROGRESS
2984
2985		Defining this option allows to add some board-
2986		specific code (calling a user-provided function
2987		"show_boot_progress(int)") that enables you to show
2988		the system's boot progress on some display (for
2989		example, some LED's) on your board. At the moment,
2990		the following checkpoints are implemented:
2991
2992- Detailed boot stage timing
2993		CONFIG_BOOTSTAGE
2994		Define this option to get detailed timing of each stage
2995		of the boot process.
2996
2997		CONFIG_BOOTSTAGE_USER_COUNT
2998		This is the number of available user bootstage records.
2999		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
3000		a new ID will be allocated from this stash. If you exceed
3001		the limit, recording will stop.
3002
3003		CONFIG_BOOTSTAGE_REPORT
3004		Define this to print a report before boot, similar to this:
3005
3006		Timer summary in microseconds:
3007		       Mark    Elapsed  Stage
3008			  0          0  reset
3009		  3,575,678  3,575,678  board_init_f start
3010		  3,575,695         17  arch_cpu_init A9
3011		  3,575,777         82  arch_cpu_init done
3012		  3,659,598     83,821  board_init_r start
3013		  3,910,375    250,777  main_loop
3014		 29,916,167 26,005,792  bootm_start
3015		 30,361,327    445,160  start_kernel
3016
3017		CONFIG_CMD_BOOTSTAGE
3018		Add a 'bootstage' command which supports printing a report
3019		and un/stashing of bootstage data.
3020
3021		CONFIG_BOOTSTAGE_FDT
3022		Stash the bootstage information in the FDT. A root 'bootstage'
3023		node is created with each bootstage id as a child. Each child
3024		has a 'name' property and either 'mark' containing the
3025		mark time in microsecond, or 'accum' containing the
3026		accumulated time for that bootstage id in microseconds.
3027		For example:
3028
3029		bootstage {
3030			154 {
3031				name = "board_init_f";
3032				mark = <3575678>;
3033			};
3034			170 {
3035				name = "lcd";
3036				accum = <33482>;
3037			};
3038		};
3039
3040		Code in the Linux kernel can find this in /proc/devicetree.
3041
3042Legacy uImage format:
3043
3044  Arg	Where			When
3045    1	common/cmd_bootm.c	before attempting to boot an image
3046   -1	common/cmd_bootm.c	Image header has bad	 magic number
3047    2	common/cmd_bootm.c	Image header has correct magic number
3048   -2	common/cmd_bootm.c	Image header has bad	 checksum
3049    3	common/cmd_bootm.c	Image header has correct checksum
3050   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3051    4	common/cmd_bootm.c	Image data   has correct checksum
3052   -4	common/cmd_bootm.c	Image is for unsupported architecture
3053    5	common/cmd_bootm.c	Architecture check OK
3054   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3055    6	common/cmd_bootm.c	Image Type check OK
3056   -6	common/cmd_bootm.c	gunzip uncompression error
3057   -7	common/cmd_bootm.c	Unimplemented compression type
3058    7	common/cmd_bootm.c	Uncompression OK
3059    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3060   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3061
3062    9	common/image.c		Start initial ramdisk verification
3063  -10	common/image.c		Ramdisk header has bad	   magic number
3064  -11	common/image.c		Ramdisk header has bad	   checksum
3065   10	common/image.c		Ramdisk header is OK
3066  -12	common/image.c		Ramdisk data   has bad	   checksum
3067   11	common/image.c		Ramdisk data   has correct checksum
3068   12	common/image.c		Ramdisk verification complete, start loading
3069  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3070   13	common/image.c		Start multifile image verification
3071   14	common/image.c		No initial ramdisk, no multifile, continue.
3072
3073   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3074
3075  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3076  -31	post/post.c		POST test failed, detected by post_output_backlog()
3077  -32	post/post.c		POST test failed, detected by post_run_single()
3078
3079   34	common/cmd_doc.c	before loading a Image from a DOC device
3080  -35	common/cmd_doc.c	Bad usage of "doc" command
3081   35	common/cmd_doc.c	correct usage of "doc" command
3082  -36	common/cmd_doc.c	No boot device
3083   36	common/cmd_doc.c	correct boot device
3084  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3085   37	common/cmd_doc.c	correct chip ID found, device available
3086  -38	common/cmd_doc.c	Read Error on boot device
3087   38	common/cmd_doc.c	reading Image header from DOC device OK
3088  -39	common/cmd_doc.c	Image header has bad magic number
3089   39	common/cmd_doc.c	Image header has correct magic number
3090  -40	common/cmd_doc.c	Error reading Image from DOC device
3091   40	common/cmd_doc.c	Image header has correct magic number
3092   41	common/cmd_ide.c	before loading a Image from a IDE device
3093  -42	common/cmd_ide.c	Bad usage of "ide" command
3094   42	common/cmd_ide.c	correct usage of "ide" command
3095  -43	common/cmd_ide.c	No boot device
3096   43	common/cmd_ide.c	boot device found
3097  -44	common/cmd_ide.c	Device not available
3098   44	common/cmd_ide.c	Device available
3099  -45	common/cmd_ide.c	wrong partition selected
3100   45	common/cmd_ide.c	partition selected
3101  -46	common/cmd_ide.c	Unknown partition table
3102   46	common/cmd_ide.c	valid partition table found
3103  -47	common/cmd_ide.c	Invalid partition type
3104   47	common/cmd_ide.c	correct partition type
3105  -48	common/cmd_ide.c	Error reading Image Header on boot device
3106   48	common/cmd_ide.c	reading Image Header from IDE device OK
3107  -49	common/cmd_ide.c	Image header has bad magic number
3108   49	common/cmd_ide.c	Image header has correct magic number
3109  -50	common/cmd_ide.c	Image header has bad	 checksum
3110   50	common/cmd_ide.c	Image header has correct checksum
3111  -51	common/cmd_ide.c	Error reading Image from IDE device
3112   51	common/cmd_ide.c	reading Image from IDE device OK
3113   52	common/cmd_nand.c	before loading a Image from a NAND device
3114  -53	common/cmd_nand.c	Bad usage of "nand" command
3115   53	common/cmd_nand.c	correct usage of "nand" command
3116  -54	common/cmd_nand.c	No boot device
3117   54	common/cmd_nand.c	boot device found
3118  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3119   55	common/cmd_nand.c	correct chip ID found, device available
3120  -56	common/cmd_nand.c	Error reading Image Header on boot device
3121   56	common/cmd_nand.c	reading Image Header from NAND device OK
3122  -57	common/cmd_nand.c	Image header has bad magic number
3123   57	common/cmd_nand.c	Image header has correct magic number
3124  -58	common/cmd_nand.c	Error reading Image from NAND device
3125   58	common/cmd_nand.c	reading Image from NAND device OK
3126
3127  -60	common/env_common.c	Environment has a bad CRC, using default
3128
3129   64	net/eth.c		starting with Ethernet configuration.
3130  -64	net/eth.c		no Ethernet found.
3131   65	net/eth.c		Ethernet found.
3132
3133  -80	common/cmd_net.c	usage wrong
3134   80	common/cmd_net.c	before calling NetLoop()
3135  -81	common/cmd_net.c	some error in NetLoop() occurred
3136   81	common/cmd_net.c	NetLoop() back without error
3137  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3138   82	common/cmd_net.c	trying automatic boot
3139   83	common/cmd_net.c	running "source" command
3140  -83	common/cmd_net.c	some error in automatic boot or "source" command
3141   84	common/cmd_net.c	end without errors
3142
3143FIT uImage format:
3144
3145  Arg	Where			When
3146  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3147 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3148  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3149 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3150  102	common/cmd_bootm.c	Kernel unit name specified
3151 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3152  103	common/cmd_bootm.c	Found configuration node
3153  104	common/cmd_bootm.c	Got kernel subimage node offset
3154 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3155  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3156 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3157  106	common/cmd_bootm.c	Architecture check OK
3158 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3159  107	common/cmd_bootm.c	Kernel subimage type OK
3160 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3161  108	common/cmd_bootm.c	Got kernel subimage data/size
3162 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3163 -109	common/cmd_bootm.c	Can't get kernel subimage type
3164 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3165 -111	common/cmd_bootm.c	Can't get kernel subimage os
3166 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3167 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3168
3169  120	common/image.c		Start initial ramdisk verification
3170 -120	common/image.c		Ramdisk FIT image has incorrect format
3171  121	common/image.c		Ramdisk FIT image has correct format
3172  122	common/image.c		No ramdisk subimage unit name, using configuration
3173 -122	common/image.c		Can't get configuration for ramdisk subimage
3174  123	common/image.c		Ramdisk unit name specified
3175 -124	common/image.c		Can't get ramdisk subimage node offset
3176  125	common/image.c		Got ramdisk subimage node offset
3177 -125	common/image.c		Ramdisk subimage hash verification failed
3178  126	common/image.c		Ramdisk subimage hash verification OK
3179 -126	common/image.c		Ramdisk subimage for unsupported architecture
3180  127	common/image.c		Architecture check OK
3181 -127	common/image.c		Can't get ramdisk subimage data/size
3182  128	common/image.c		Got ramdisk subimage data/size
3183  129	common/image.c		Can't get ramdisk load address
3184 -129	common/image.c		Got ramdisk load address
3185
3186 -130	common/cmd_doc.c	Incorrect FIT image format
3187  131	common/cmd_doc.c	FIT image format OK
3188
3189 -140	common/cmd_ide.c	Incorrect FIT image format
3190  141	common/cmd_ide.c	FIT image format OK
3191
3192 -150	common/cmd_nand.c	Incorrect FIT image format
3193  151	common/cmd_nand.c	FIT image format OK
3194
3195- FIT image support:
3196		CONFIG_FIT
3197		Enable support for the FIT uImage format.
3198
3199		CONFIG_FIT_BEST_MATCH
3200		When no configuration is explicitly selected, default to the
3201		one whose fdt's compatibility field best matches that of
3202		U-Boot itself. A match is considered "best" if it matches the
3203		most specific compatibility entry of U-Boot's fdt's root node.
3204		The order of entries in the configuration's fdt is ignored.
3205
3206		CONFIG_FIT_SIGNATURE
3207		This option enables signature verification of FIT uImages,
3208		using a hash signed and verified using RSA. See
3209		doc/uImage.FIT/signature.txt for more details.
3210
3211- Standalone program support:
3212		CONFIG_STANDALONE_LOAD_ADDR
3213
3214		This option defines a board specific value for the
3215		address where standalone program gets loaded, thus
3216		overwriting the architecture dependent default
3217		settings.
3218
3219- Frame Buffer Address:
3220		CONFIG_FB_ADDR
3221
3222		Define CONFIG_FB_ADDR if you want to use specific
3223		address for frame buffer.  This is typically the case
3224		when using a graphics controller has separate video
3225		memory.  U-Boot will then place the frame buffer at
3226		the given address instead of dynamically reserving it
3227		in system RAM by calling lcd_setmem(), which grabs
3228		the memory for the frame buffer depending on the
3229		configured panel size.
3230
3231		Please see board_init_f function.
3232
3233- Automatic software updates via TFTP server
3234		CONFIG_UPDATE_TFTP
3235		CONFIG_UPDATE_TFTP_CNT_MAX
3236		CONFIG_UPDATE_TFTP_MSEC_MAX
3237
3238		These options enable and control the auto-update feature;
3239		for a more detailed description refer to doc/README.update.
3240
3241- MTD Support (mtdparts command, UBI support)
3242		CONFIG_MTD_DEVICE
3243
3244		Adds the MTD device infrastructure from the Linux kernel.
3245		Needed for mtdparts command support.
3246
3247		CONFIG_MTD_PARTITIONS
3248
3249		Adds the MTD partitioning infrastructure from the Linux
3250		kernel. Needed for UBI support.
3251
3252- UBI support
3253		CONFIG_CMD_UBI
3254
3255		Adds commands for interacting with MTD partitions formatted
3256		with the UBI flash translation layer
3257
3258		Requires also defining CONFIG_RBTREE
3259
3260		CONFIG_UBI_SILENCE_MSG
3261
3262		Make the verbose messages from UBI stop printing.  This leaves
3263		warnings and errors enabled.
3264
3265- UBIFS support
3266		CONFIG_CMD_UBIFS
3267
3268		Adds commands for interacting with UBI volumes formatted as
3269		UBIFS.  UBIFS is read-only in u-boot.
3270
3271		Requires UBI support as well as CONFIG_LZO
3272
3273		CONFIG_UBIFS_SILENCE_MSG
3274
3275		Make the verbose messages from UBIFS stop printing.  This leaves
3276		warnings and errors enabled.
3277
3278- SPL framework
3279		CONFIG_SPL
3280		Enable building of SPL globally.
3281
3282		CONFIG_SPL_LDSCRIPT
3283		LDSCRIPT for linking the SPL binary.
3284
3285		CONFIG_SPL_MAX_FOOTPRINT
3286		Maximum size in memory allocated to the SPL, BSS included.
3287		When defined, the linker checks that the actual memory
3288		used by SPL from _start to __bss_end does not exceed it.
3289		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3290		must not be both defined at the same time.
3291
3292		CONFIG_SPL_MAX_SIZE
3293		Maximum size of the SPL image (text, data, rodata, and
3294		linker lists sections), BSS excluded.
3295		When defined, the linker checks that the actual size does
3296		not exceed it.
3297
3298		CONFIG_SPL_TEXT_BASE
3299		TEXT_BASE for linking the SPL binary.
3300
3301		CONFIG_SPL_RELOC_TEXT_BASE
3302		Address to relocate to.  If unspecified, this is equal to
3303		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3304
3305		CONFIG_SPL_BSS_START_ADDR
3306		Link address for the BSS within the SPL binary.
3307
3308		CONFIG_SPL_BSS_MAX_SIZE
3309		Maximum size in memory allocated to the SPL BSS.
3310		When defined, the linker checks that the actual memory used
3311		by SPL from __bss_start to __bss_end does not exceed it.
3312		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3313		must not be both defined at the same time.
3314
3315		CONFIG_SPL_STACK
3316		Adress of the start of the stack SPL will use
3317
3318		CONFIG_SPL_RELOC_STACK
3319		Adress of the start of the stack SPL will use after
3320		relocation.  If unspecified, this is equal to
3321		CONFIG_SPL_STACK.
3322
3323		CONFIG_SYS_SPL_MALLOC_START
3324		Starting address of the malloc pool used in SPL.
3325
3326		CONFIG_SYS_SPL_MALLOC_SIZE
3327		The size of the malloc pool used in SPL.
3328
3329		CONFIG_SPL_FRAMEWORK
3330		Enable the SPL framework under common/.  This framework
3331		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3332		NAND loading of the Linux Kernel.
3333
3334		CONFIG_SPL_OS_BOOT
3335		Enable booting directly to an OS from SPL.
3336		See also: doc/README.falcon
3337
3338		CONFIG_SPL_DISPLAY_PRINT
3339		For ARM, enable an optional function to print more information
3340		about the running system.
3341
3342		CONFIG_SPL_INIT_MINIMAL
3343		Arch init code should be built for a very small image
3344
3345		CONFIG_SPL_LIBCOMMON_SUPPORT
3346		Support for common/libcommon.o in SPL binary
3347
3348		CONFIG_SPL_LIBDISK_SUPPORT
3349		Support for disk/libdisk.o in SPL binary
3350
3351		CONFIG_SPL_I2C_SUPPORT
3352		Support for drivers/i2c/libi2c.o in SPL binary
3353
3354		CONFIG_SPL_GPIO_SUPPORT
3355		Support for drivers/gpio/libgpio.o in SPL binary
3356
3357		CONFIG_SPL_MMC_SUPPORT
3358		Support for drivers/mmc/libmmc.o in SPL binary
3359
3360		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3361		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3362		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3363		Address, size and partition on the MMC to load U-Boot from
3364		when the MMC is being used in raw mode.
3365
3366		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3367		Sector to load kernel uImage from when MMC is being
3368		used in raw mode (for Falcon mode)
3369
3370		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3371		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3372		Sector and number of sectors to load kernel argument
3373		parameters from when MMC is being used in raw mode
3374		(for falcon mode)
3375
3376		CONFIG_SPL_FAT_SUPPORT
3377		Support for fs/fat/libfat.o in SPL binary
3378
3379		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3380		Filename to read to load U-Boot when reading from FAT
3381
3382		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3383		Filename to read to load kernel uImage when reading
3384		from FAT (for Falcon mode)
3385
3386		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3387		Filename to read to load kernel argument parameters
3388		when reading from FAT (for Falcon mode)
3389
3390		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3391		Set this for NAND SPL on PPC mpc83xx targets, so that
3392		start.S waits for the rest of the SPL to load before
3393		continuing (the hardware starts execution after just
3394		loading the first page rather than the full 4K).
3395
3396		CONFIG_SPL_SKIP_RELOCATE
3397		Avoid SPL relocation
3398
3399		CONFIG_SPL_NAND_BASE
3400		Include nand_base.c in the SPL.  Requires
3401		CONFIG_SPL_NAND_DRIVERS.
3402
3403		CONFIG_SPL_NAND_DRIVERS
3404		SPL uses normal NAND drivers, not minimal drivers.
3405
3406		CONFIG_SPL_NAND_ECC
3407		Include standard software ECC in the SPL
3408
3409		CONFIG_SPL_NAND_SIMPLE
3410		Support for NAND boot using simple NAND drivers that
3411		expose the cmd_ctrl() interface.
3412
3413		CONFIG_SPL_MTD_SUPPORT
3414		Support for the MTD subsystem within SPL.  Useful for
3415		environment on NAND support within SPL.
3416
3417		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3418		Set for the SPL on PPC mpc8xxx targets, support for
3419		drivers/ddr/fsl/libddr.o in SPL binary.
3420
3421		CONFIG_SPL_COMMON_INIT_DDR
3422		Set for common ddr init with serial presence detect in
3423		SPL binary.
3424
3425		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3426		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3427		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3428		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3429		CONFIG_SYS_NAND_ECCBYTES
3430		Defines the size and behavior of the NAND that SPL uses
3431		to read U-Boot
3432
3433		CONFIG_SPL_NAND_BOOT
3434		Add support NAND boot
3435
3436		CONFIG_SYS_NAND_U_BOOT_OFFS
3437		Location in NAND to read U-Boot from
3438
3439		CONFIG_SYS_NAND_U_BOOT_DST
3440		Location in memory to load U-Boot to
3441
3442		CONFIG_SYS_NAND_U_BOOT_SIZE
3443		Size of image to load
3444
3445		CONFIG_SYS_NAND_U_BOOT_START
3446		Entry point in loaded image to jump to
3447
3448		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3449		Define this if you need to first read the OOB and then the
3450		data. This is used for example on davinci plattforms.
3451
3452		CONFIG_SPL_OMAP3_ID_NAND
3453		Support for an OMAP3-specific set of functions to return the
3454		ID and MFR of the first attached NAND chip, if present.
3455
3456		CONFIG_SPL_SERIAL_SUPPORT
3457		Support for drivers/serial/libserial.o in SPL binary
3458
3459		CONFIG_SPL_SPI_FLASH_SUPPORT
3460		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3461
3462		CONFIG_SPL_SPI_SUPPORT
3463		Support for drivers/spi/libspi.o in SPL binary
3464
3465		CONFIG_SPL_RAM_DEVICE
3466		Support for running image already present in ram, in SPL binary
3467
3468		CONFIG_SPL_LIBGENERIC_SUPPORT
3469		Support for lib/libgeneric.o in SPL binary
3470
3471		CONFIG_SPL_ENV_SUPPORT
3472		Support for the environment operating in SPL binary
3473
3474		CONFIG_SPL_NET_SUPPORT
3475		Support for the net/libnet.o in SPL binary.
3476		It conflicts with SPL env from storage medium specified by
3477		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3478
3479		CONFIG_SPL_PAD_TO
3480		Image offset to which the SPL should be padded before appending
3481		the SPL payload. By default, this is defined as
3482		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3483		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3484		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3485
3486		CONFIG_SPL_TARGET
3487		Final target image containing SPL and payload.  Some SPLs
3488		use an arch-specific makefile fragment instead, for
3489		example if more than one image needs to be produced.
3490
3491		CONFIG_FIT_SPL_PRINT
3492		Printing information about a FIT image adds quite a bit of
3493		code to SPL. So this is normally disabled in SPL. Use this
3494		option to re-enable it. This will affect the output of the
3495		bootm command when booting a FIT image.
3496
3497- TPL framework
3498		CONFIG_TPL
3499		Enable building of TPL globally.
3500
3501		CONFIG_TPL_PAD_TO
3502		Image offset to which the TPL should be padded before appending
3503		the TPL payload. By default, this is defined as
3504		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3505		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3506		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3507
3508Modem Support:
3509--------------
3510
3511[so far only for SMDK2400 boards]
3512
3513- Modem support enable:
3514		CONFIG_MODEM_SUPPORT
3515
3516- RTS/CTS Flow control enable:
3517		CONFIG_HWFLOW
3518
3519- Modem debug support:
3520		CONFIG_MODEM_SUPPORT_DEBUG
3521
3522		Enables debugging stuff (char screen[1024], dbg())
3523		for modem support. Useful only with BDI2000.
3524
3525- Interrupt support (PPC):
3526
3527		There are common interrupt_init() and timer_interrupt()
3528		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3529		for CPU specific initialization. interrupt_init_cpu()
3530		should set decrementer_count to appropriate value. If
3531		CPU resets decrementer automatically after interrupt
3532		(ppc4xx) it should set decrementer_count to zero.
3533		timer_interrupt() calls timer_interrupt_cpu() for CPU
3534		specific handling. If board has watchdog / status_led
3535		/ other_activity_monitor it works automatically from
3536		general timer_interrupt().
3537
3538- General:
3539
3540		In the target system modem support is enabled when a
3541		specific key (key combination) is pressed during
3542		power-on. Otherwise U-Boot will boot normally
3543		(autoboot). The key_pressed() function is called from
3544		board_init(). Currently key_pressed() is a dummy
3545		function, returning 1 and thus enabling modem
3546		initialization.
3547
3548		If there are no modem init strings in the
3549		environment, U-Boot proceed to autoboot; the
3550		previous output (banner, info printfs) will be
3551		suppressed, though.
3552
3553		See also: doc/README.Modem
3554
3555Board initialization settings:
3556------------------------------
3557
3558During Initialization u-boot calls a number of board specific functions
3559to allow the preparation of board specific prerequisites, e.g. pin setup
3560before drivers are initialized. To enable these callbacks the
3561following configuration macros have to be defined. Currently this is
3562architecture specific, so please check arch/your_architecture/lib/board.c
3563typically in board_init_f() and board_init_r().
3564
3565- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3566- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3567- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3568- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3569
3570Configuration Settings:
3571-----------------------
3572
3573- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3574		Optionally it can be defined to support 64-bit memory commands.
3575
3576- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3577		undefine this when you're short of memory.
3578
3579- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3580		width of the commands listed in the 'help' command output.
3581
3582- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3583		prompt for user input.
3584
3585- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3586
3587- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3588
3589- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3590
3591- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3592		the application (usually a Linux kernel) when it is
3593		booted
3594
3595- CONFIG_SYS_BAUDRATE_TABLE:
3596		List of legal baudrate settings for this board.
3597
3598- CONFIG_SYS_CONSOLE_INFO_QUIET
3599		Suppress display of console information at boot.
3600
3601- CONFIG_SYS_CONSOLE_IS_IN_ENV
3602		If the board specific function
3603			extern int overwrite_console (void);
3604		returns 1, the stdin, stderr and stdout are switched to the
3605		serial port, else the settings in the environment are used.
3606
3607- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3608		Enable the call to overwrite_console().
3609
3610- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3611		Enable overwrite of previous console environment settings.
3612
3613- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3614		Begin and End addresses of the area used by the
3615		simple memory test.
3616
3617- CONFIG_SYS_ALT_MEMTEST:
3618		Enable an alternate, more extensive memory test.
3619
3620- CONFIG_SYS_MEMTEST_SCRATCH:
3621		Scratch address used by the alternate memory test
3622		You only need to set this if address zero isn't writeable
3623
3624- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3625		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3626		this specified memory area will get subtracted from the top
3627		(end) of RAM and won't get "touched" at all by U-Boot. By
3628		fixing up gd->ram_size the Linux kernel should gets passed
3629		the now "corrected" memory size and won't touch it either.
3630		This should work for arch/ppc and arch/powerpc. Only Linux
3631		board ports in arch/powerpc with bootwrapper support that
3632		recalculate the memory size from the SDRAM controller setup
3633		will have to get fixed in Linux additionally.
3634
3635		This option can be used as a workaround for the 440EPx/GRx
3636		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3637		be touched.
3638
3639		WARNING: Please make sure that this value is a multiple of
3640		the Linux page size (normally 4k). If this is not the case,
3641		then the end address of the Linux memory will be located at a
3642		non page size aligned address and this could cause major
3643		problems.
3644
3645- CONFIG_SYS_LOADS_BAUD_CHANGE:
3646		Enable temporary baudrate change while serial download
3647
3648- CONFIG_SYS_SDRAM_BASE:
3649		Physical start address of SDRAM. _Must_ be 0 here.
3650
3651- CONFIG_SYS_MBIO_BASE:
3652		Physical start address of Motherboard I/O (if using a
3653		Cogent motherboard)
3654
3655- CONFIG_SYS_FLASH_BASE:
3656		Physical start address of Flash memory.
3657
3658- CONFIG_SYS_MONITOR_BASE:
3659		Physical start address of boot monitor code (set by
3660		make config files to be same as the text base address
3661		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3662		CONFIG_SYS_FLASH_BASE when booting from flash.
3663
3664- CONFIG_SYS_MONITOR_LEN:
3665		Size of memory reserved for monitor code, used to
3666		determine _at_compile_time_ (!) if the environment is
3667		embedded within the U-Boot image, or in a separate
3668		flash sector.
3669
3670- CONFIG_SYS_MALLOC_LEN:
3671		Size of DRAM reserved for malloc() use.
3672
3673- CONFIG_SYS_BOOTM_LEN:
3674		Normally compressed uImages are limited to an
3675		uncompressed size of 8 MBytes. If this is not enough,
3676		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3677		to adjust this setting to your needs.
3678
3679- CONFIG_SYS_BOOTMAPSZ:
3680		Maximum size of memory mapped by the startup code of
3681		the Linux kernel; all data that must be processed by
3682		the Linux kernel (bd_info, boot arguments, FDT blob if
3683		used) must be put below this limit, unless "bootm_low"
3684		environment variable is defined and non-zero. In such case
3685		all data for the Linux kernel must be between "bootm_low"
3686		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3687		variable "bootm_mapsize" will override the value of
3688		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3689		then the value in "bootm_size" will be used instead.
3690
3691- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3692		Enable initrd_high functionality.  If defined then the
3693		initrd_high feature is enabled and the bootm ramdisk subcommand
3694		is enabled.
3695
3696- CONFIG_SYS_BOOT_GET_CMDLINE:
3697		Enables allocating and saving kernel cmdline in space between
3698		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3699
3700- CONFIG_SYS_BOOT_GET_KBD:
3701		Enables allocating and saving a kernel copy of the bd_info in
3702		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3703
3704- CONFIG_SYS_MAX_FLASH_BANKS:
3705		Max number of Flash memory banks
3706
3707- CONFIG_SYS_MAX_FLASH_SECT:
3708		Max number of sectors on a Flash chip
3709
3710- CONFIG_SYS_FLASH_ERASE_TOUT:
3711		Timeout for Flash erase operations (in ms)
3712
3713- CONFIG_SYS_FLASH_WRITE_TOUT:
3714		Timeout for Flash write operations (in ms)
3715
3716- CONFIG_SYS_FLASH_LOCK_TOUT
3717		Timeout for Flash set sector lock bit operation (in ms)
3718
3719- CONFIG_SYS_FLASH_UNLOCK_TOUT
3720		Timeout for Flash clear lock bits operation (in ms)
3721
3722- CONFIG_SYS_FLASH_PROTECTION
3723		If defined, hardware flash sectors protection is used
3724		instead of U-Boot software protection.
3725
3726- CONFIG_SYS_DIRECT_FLASH_TFTP:
3727
3728		Enable TFTP transfers directly to flash memory;
3729		without this option such a download has to be
3730		performed in two steps: (1) download to RAM, and (2)
3731		copy from RAM to flash.
3732
3733		The two-step approach is usually more reliable, since
3734		you can check if the download worked before you erase
3735		the flash, but in some situations (when system RAM is
3736		too limited to allow for a temporary copy of the
3737		downloaded image) this option may be very useful.
3738
3739- CONFIG_SYS_FLASH_CFI:
3740		Define if the flash driver uses extra elements in the
3741		common flash structure for storing flash geometry.
3742
3743- CONFIG_FLASH_CFI_DRIVER
3744		This option also enables the building of the cfi_flash driver
3745		in the drivers directory
3746
3747- CONFIG_FLASH_CFI_MTD
3748		This option enables the building of the cfi_mtd driver
3749		in the drivers directory. The driver exports CFI flash
3750		to the MTD layer.
3751
3752- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3753		Use buffered writes to flash.
3754
3755- CONFIG_FLASH_SPANSION_S29WS_N
3756		s29ws-n MirrorBit flash has non-standard addresses for buffered
3757		write commands.
3758
3759- CONFIG_SYS_FLASH_QUIET_TEST
3760		If this option is defined, the common CFI flash doesn't
3761		print it's warning upon not recognized FLASH banks. This
3762		is useful, if some of the configured banks are only
3763		optionally available.
3764
3765- CONFIG_FLASH_SHOW_PROGRESS
3766		If defined (must be an integer), print out countdown
3767		digits and dots.  Recommended value: 45 (9..1) for 80
3768		column displays, 15 (3..1) for 40 column displays.
3769
3770- CONFIG_FLASH_VERIFY
3771		If defined, the content of the flash (destination) is compared
3772		against the source after the write operation. An error message
3773		will be printed when the contents are not identical.
3774		Please note that this option is useless in nearly all cases,
3775		since such flash programming errors usually are detected earlier
3776		while unprotecting/erasing/programming. Please only enable
3777		this option if you really know what you are doing.
3778
3779- CONFIG_SYS_RX_ETH_BUFFER:
3780		Defines the number of Ethernet receive buffers. On some
3781		Ethernet controllers it is recommended to set this value
3782		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3783		buffers can be full shortly after enabling the interface
3784		on high Ethernet traffic.
3785		Defaults to 4 if not defined.
3786
3787- CONFIG_ENV_MAX_ENTRIES
3788
3789	Maximum number of entries in the hash table that is used
3790	internally to store the environment settings. The default
3791	setting is supposed to be generous and should work in most
3792	cases. This setting can be used to tune behaviour; see
3793	lib/hashtable.c for details.
3794
3795- CONFIG_ENV_FLAGS_LIST_DEFAULT
3796- CONFIG_ENV_FLAGS_LIST_STATIC
3797	Enable validation of the values given to environment variables when
3798	calling env set.  Variables can be restricted to only decimal,
3799	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3800	the variables can also be restricted to IP address or MAC address.
3801
3802	The format of the list is:
3803		type_attribute = [s|d|x|b|i|m]
3804		access_atribute = [a|r|o|c]
3805		attributes = type_attribute[access_atribute]
3806		entry = variable_name[:attributes]
3807		list = entry[,list]
3808
3809	The type attributes are:
3810		s - String (default)
3811		d - Decimal
3812		x - Hexadecimal
3813		b - Boolean ([1yYtT|0nNfF])
3814		i - IP address
3815		m - MAC address
3816
3817	The access attributes are:
3818		a - Any (default)
3819		r - Read-only
3820		o - Write-once
3821		c - Change-default
3822
3823	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3824		Define this to a list (string) to define the ".flags"
3825		envirnoment variable in the default or embedded environment.
3826
3827	- CONFIG_ENV_FLAGS_LIST_STATIC
3828		Define this to a list (string) to define validation that
3829		should be done if an entry is not found in the ".flags"
3830		environment variable.  To override a setting in the static
3831		list, simply add an entry for the same variable name to the
3832		".flags" variable.
3833
3834- CONFIG_ENV_ACCESS_IGNORE_FORCE
3835	If defined, don't allow the -f switch to env set override variable
3836	access flags.
3837
3838- CONFIG_SYS_GENERIC_BOARD
3839	This selects the architecture-generic board system instead of the
3840	architecture-specific board files. It is intended to move boards
3841	to this new framework over time. Defining this will disable the
3842	arch/foo/lib/board.c file and use common/board_f.c and
3843	common/board_r.c instead. To use this option your architecture
3844	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3845	its config.mk file). If you find problems enabling this option on
3846	your board please report the problem and send patches!
3847
3848- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3849	This is set by OMAP boards for the max time that reset should
3850	be asserted. See doc/README.omap-reset-time for details on how
3851	the value can be calulated on a given board.
3852
3853The following definitions that deal with the placement and management
3854of environment data (variable area); in general, we support the
3855following configurations:
3856
3857- CONFIG_BUILD_ENVCRC:
3858
3859	Builds up envcrc with the target environment so that external utils
3860	may easily extract it and embed it in final U-Boot images.
3861
3862- CONFIG_ENV_IS_IN_FLASH:
3863
3864	Define this if the environment is in flash memory.
3865
3866	a) The environment occupies one whole flash sector, which is
3867	   "embedded" in the text segment with the U-Boot code. This
3868	   happens usually with "bottom boot sector" or "top boot
3869	   sector" type flash chips, which have several smaller
3870	   sectors at the start or the end. For instance, such a
3871	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3872	   such a case you would place the environment in one of the
3873	   4 kB sectors - with U-Boot code before and after it. With
3874	   "top boot sector" type flash chips, you would put the
3875	   environment in one of the last sectors, leaving a gap
3876	   between U-Boot and the environment.
3877
3878	- CONFIG_ENV_OFFSET:
3879
3880	   Offset of environment data (variable area) to the
3881	   beginning of flash memory; for instance, with bottom boot
3882	   type flash chips the second sector can be used: the offset
3883	   for this sector is given here.
3884
3885	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3886
3887	- CONFIG_ENV_ADDR:
3888
3889	   This is just another way to specify the start address of
3890	   the flash sector containing the environment (instead of
3891	   CONFIG_ENV_OFFSET).
3892
3893	- CONFIG_ENV_SECT_SIZE:
3894
3895	   Size of the sector containing the environment.
3896
3897
3898	b) Sometimes flash chips have few, equal sized, BIG sectors.
3899	   In such a case you don't want to spend a whole sector for
3900	   the environment.
3901
3902	- CONFIG_ENV_SIZE:
3903
3904	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3905	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3906	   of this flash sector for the environment. This saves
3907	   memory for the RAM copy of the environment.
3908
3909	   It may also save flash memory if you decide to use this
3910	   when your environment is "embedded" within U-Boot code,
3911	   since then the remainder of the flash sector could be used
3912	   for U-Boot code. It should be pointed out that this is
3913	   STRONGLY DISCOURAGED from a robustness point of view:
3914	   updating the environment in flash makes it always
3915	   necessary to erase the WHOLE sector. If something goes
3916	   wrong before the contents has been restored from a copy in
3917	   RAM, your target system will be dead.
3918
3919	- CONFIG_ENV_ADDR_REDUND
3920	  CONFIG_ENV_SIZE_REDUND
3921
3922	   These settings describe a second storage area used to hold
3923	   a redundant copy of the environment data, so that there is
3924	   a valid backup copy in case there is a power failure during
3925	   a "saveenv" operation.
3926
3927BE CAREFUL! Any changes to the flash layout, and some changes to the
3928source code will make it necessary to adapt <board>/u-boot.lds*
3929accordingly!
3930
3931
3932- CONFIG_ENV_IS_IN_NVRAM:
3933
3934	Define this if you have some non-volatile memory device
3935	(NVRAM, battery buffered SRAM) which you want to use for the
3936	environment.
3937
3938	- CONFIG_ENV_ADDR:
3939	- CONFIG_ENV_SIZE:
3940
3941	  These two #defines are used to determine the memory area you
3942	  want to use for environment. It is assumed that this memory
3943	  can just be read and written to, without any special
3944	  provision.
3945
3946BE CAREFUL! The first access to the environment happens quite early
3947in U-Boot initalization (when we try to get the setting of for the
3948console baudrate). You *MUST* have mapped your NVRAM area then, or
3949U-Boot will hang.
3950
3951Please note that even with NVRAM we still use a copy of the
3952environment in RAM: we could work on NVRAM directly, but we want to
3953keep settings there always unmodified except somebody uses "saveenv"
3954to save the current settings.
3955
3956
3957- CONFIG_ENV_IS_IN_EEPROM:
3958
3959	Use this if you have an EEPROM or similar serial access
3960	device and a driver for it.
3961
3962	- CONFIG_ENV_OFFSET:
3963	- CONFIG_ENV_SIZE:
3964
3965	  These two #defines specify the offset and size of the
3966	  environment area within the total memory of your EEPROM.
3967
3968	- CONFIG_SYS_I2C_EEPROM_ADDR:
3969	  If defined, specified the chip address of the EEPROM device.
3970	  The default address is zero.
3971
3972	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3973	  If defined, the number of bits used to address bytes in a
3974	  single page in the EEPROM device.  A 64 byte page, for example
3975	  would require six bits.
3976
3977	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3978	  If defined, the number of milliseconds to delay between
3979	  page writes.	The default is zero milliseconds.
3980
3981	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3982	  The length in bytes of the EEPROM memory array address.  Note
3983	  that this is NOT the chip address length!
3984
3985	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3986	  EEPROM chips that implement "address overflow" are ones
3987	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3988	  address and the extra bits end up in the "chip address" bit
3989	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3990	  byte chips.
3991
3992	  Note that we consider the length of the address field to
3993	  still be one byte because the extra address bits are hidden
3994	  in the chip address.
3995
3996	- CONFIG_SYS_EEPROM_SIZE:
3997	  The size in bytes of the EEPROM device.
3998
3999	- CONFIG_ENV_EEPROM_IS_ON_I2C
4000	  define this, if you have I2C and SPI activated, and your
4001	  EEPROM, which holds the environment, is on the I2C bus.
4002
4003	- CONFIG_I2C_ENV_EEPROM_BUS
4004	  if you have an Environment on an EEPROM reached over
4005	  I2C muxes, you can define here, how to reach this
4006	  EEPROM. For example:
4007
4008	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4009
4010	  EEPROM which holds the environment, is reached over
4011	  a pca9547 i2c mux with address 0x70, channel 3.
4012
4013- CONFIG_ENV_IS_IN_DATAFLASH:
4014
4015	Define this if you have a DataFlash memory device which you
4016	want to use for the environment.
4017
4018	- CONFIG_ENV_OFFSET:
4019	- CONFIG_ENV_ADDR:
4020	- CONFIG_ENV_SIZE:
4021
4022	  These three #defines specify the offset and size of the
4023	  environment area within the total memory of your DataFlash placed
4024	  at the specified address.
4025
4026- CONFIG_ENV_IS_IN_REMOTE:
4027
4028	Define this if you have a remote memory space which you
4029	want to use for the local device's environment.
4030
4031	- CONFIG_ENV_ADDR:
4032	- CONFIG_ENV_SIZE:
4033
4034	  These two #defines specify the address and size of the
4035	  environment area within the remote memory space. The
4036	  local device can get the environment from remote memory
4037	  space by SRIO or PCIE links.
4038
4039BE CAREFUL! For some special cases, the local device can not use
4040"saveenv" command. For example, the local device will get the
4041environment stored in a remote NOR flash by SRIO or PCIE link,
4042but it can not erase, write this NOR flash by SRIO or PCIE interface.
4043
4044- CONFIG_ENV_IS_IN_NAND:
4045
4046	Define this if you have a NAND device which you want to use
4047	for the environment.
4048
4049	- CONFIG_ENV_OFFSET:
4050	- CONFIG_ENV_SIZE:
4051
4052	  These two #defines specify the offset and size of the environment
4053	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4054	  aligned to an erase block boundary.
4055
4056	- CONFIG_ENV_OFFSET_REDUND (optional):
4057
4058	  This setting describes a second storage area of CONFIG_ENV_SIZE
4059	  size used to hold a redundant copy of the environment data, so
4060	  that there is a valid backup copy in case there is a power failure
4061	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4062	  aligned to an erase block boundary.
4063
4064	- CONFIG_ENV_RANGE (optional):
4065
4066	  Specifies the length of the region in which the environment
4067	  can be written.  This should be a multiple of the NAND device's
4068	  block size.  Specifying a range with more erase blocks than
4069	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4070	  the range to be avoided.
4071
4072	- CONFIG_ENV_OFFSET_OOB (optional):
4073
4074	  Enables support for dynamically retrieving the offset of the
4075	  environment from block zero's out-of-band data.  The
4076	  "nand env.oob" command can be used to record this offset.
4077	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4078	  using CONFIG_ENV_OFFSET_OOB.
4079
4080- CONFIG_NAND_ENV_DST
4081
4082	Defines address in RAM to which the nand_spl code should copy the
4083	environment. If redundant environment is used, it will be copied to
4084	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4085
4086- CONFIG_ENV_IS_IN_UBI:
4087
4088	Define this if you have an UBI volume that you want to use for the
4089	environment.  This has the benefit of wear-leveling the environment
4090	accesses, which is important on NAND.
4091
4092	- CONFIG_ENV_UBI_PART:
4093
4094	  Define this to a string that is the mtd partition containing the UBI.
4095
4096	- CONFIG_ENV_UBI_VOLUME:
4097
4098	  Define this to the name of the volume that you want to store the
4099	  environment in.
4100
4101	- CONFIG_ENV_UBI_VOLUME_REDUND:
4102
4103	  Define this to the name of another volume to store a second copy of
4104	  the environment in.  This will enable redundant environments in UBI.
4105	  It is assumed that both volumes are in the same MTD partition.
4106
4107	- CONFIG_UBI_SILENCE_MSG
4108	- CONFIG_UBIFS_SILENCE_MSG
4109
4110	  You will probably want to define these to avoid a really noisy system
4111	  when storing the env in UBI.
4112
4113- CONFIG_ENV_IS_IN_MMC:
4114
4115	Define this if you have an MMC device which you want to use for the
4116	environment.
4117
4118	- CONFIG_SYS_MMC_ENV_DEV:
4119
4120	  Specifies which MMC device the environment is stored in.
4121
4122	- CONFIG_SYS_MMC_ENV_PART (optional):
4123
4124	  Specifies which MMC partition the environment is stored in. If not
4125	  set, defaults to partition 0, the user area. Common values might be
4126	  1 (first MMC boot partition), 2 (second MMC boot partition).
4127
4128	- CONFIG_ENV_OFFSET:
4129	- CONFIG_ENV_SIZE:
4130
4131	  These two #defines specify the offset and size of the environment
4132	  area within the specified MMC device.
4133
4134	  If offset is positive (the usual case), it is treated as relative to
4135	  the start of the MMC partition. If offset is negative, it is treated
4136	  as relative to the end of the MMC partition. This can be useful if
4137	  your board may be fitted with different MMC devices, which have
4138	  different sizes for the MMC partitions, and you always want the
4139	  environment placed at the very end of the partition, to leave the
4140	  maximum possible space before it, to store other data.
4141
4142	  These two values are in units of bytes, but must be aligned to an
4143	  MMC sector boundary.
4144
4145	- CONFIG_ENV_OFFSET_REDUND (optional):
4146
4147	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4148	  hold a redundant copy of the environment data. This provides a
4149	  valid backup copy in case the other copy is corrupted, e.g. due
4150	  to a power failure during a "saveenv" operation.
4151
4152	  This value may also be positive or negative; this is handled in the
4153	  same way as CONFIG_ENV_OFFSET.
4154
4155	  This value is also in units of bytes, but must also be aligned to
4156	  an MMC sector boundary.
4157
4158	- CONFIG_ENV_SIZE_REDUND (optional):
4159
4160	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4161	  set. If this value is set, it must be set to the same value as
4162	  CONFIG_ENV_SIZE.
4163
4164- CONFIG_SYS_SPI_INIT_OFFSET
4165
4166	Defines offset to the initial SPI buffer area in DPRAM. The
4167	area is used at an early stage (ROM part) if the environment
4168	is configured to reside in the SPI EEPROM: We need a 520 byte
4169	scratch DPRAM area. It is used between the two initialization
4170	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4171	to be a good choice since it makes it far enough from the
4172	start of the data area as well as from the stack pointer.
4173
4174Please note that the environment is read-only until the monitor
4175has been relocated to RAM and a RAM copy of the environment has been
4176created; also, when using EEPROM you will have to use getenv_f()
4177until then to read environment variables.
4178
4179The environment is protected by a CRC32 checksum. Before the monitor
4180is relocated into RAM, as a result of a bad CRC you will be working
4181with the compiled-in default environment - *silently*!!! [This is
4182necessary, because the first environment variable we need is the
4183"baudrate" setting for the console - if we have a bad CRC, we don't
4184have any device yet where we could complain.]
4185
4186Note: once the monitor has been relocated, then it will complain if
4187the default environment is used; a new CRC is computed as soon as you
4188use the "saveenv" command to store a valid environment.
4189
4190- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4191		Echo the inverted Ethernet link state to the fault LED.
4192
4193		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4194		      also needs to be defined.
4195
4196- CONFIG_SYS_FAULT_MII_ADDR:
4197		MII address of the PHY to check for the Ethernet link state.
4198
4199- CONFIG_NS16550_MIN_FUNCTIONS:
4200		Define this if you desire to only have use of the NS16550_init
4201		and NS16550_putc functions for the serial driver located at
4202		drivers/serial/ns16550.c.  This option is useful for saving
4203		space for already greatly restricted images, including but not
4204		limited to NAND_SPL configurations.
4205
4206- CONFIG_DISPLAY_BOARDINFO
4207		Display information about the board that U-Boot is running on
4208		when U-Boot starts up. The board function checkboard() is called
4209		to do this.
4210
4211- CONFIG_DISPLAY_BOARDINFO_LATE
4212		Similar to the previous option, but display this information
4213		later, once stdio is running and output goes to the LCD, if
4214		present.
4215
4216Low Level (hardware related) configuration options:
4217---------------------------------------------------
4218
4219- CONFIG_SYS_CACHELINE_SIZE:
4220		Cache Line Size of the CPU.
4221
4222- CONFIG_SYS_DEFAULT_IMMR:
4223		Default address of the IMMR after system reset.
4224
4225		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4226		and RPXsuper) to be able to adjust the position of
4227		the IMMR register after a reset.
4228
4229- CONFIG_SYS_CCSRBAR_DEFAULT:
4230		Default (power-on reset) physical address of CCSR on Freescale
4231		PowerPC SOCs.
4232
4233- CONFIG_SYS_CCSRBAR:
4234		Virtual address of CCSR.  On a 32-bit build, this is typically
4235		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4236
4237		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4238		for cross-platform code that uses that macro instead.
4239
4240- CONFIG_SYS_CCSRBAR_PHYS:
4241		Physical address of CCSR.  CCSR can be relocated to a new
4242		physical address, if desired.  In this case, this macro should
4243		be set to that address.	 Otherwise, it should be set to the
4244		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4245		is typically relocated on 36-bit builds.  It is recommended
4246		that this macro be defined via the _HIGH and _LOW macros:
4247
4248		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4249			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4250
4251- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4252		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4253		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4254		used in assembly code, so it must not contain typecasts or
4255		integer size suffixes (e.g. "ULL").
4256
4257- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4258		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4259		used in assembly code, so it must not contain typecasts or
4260		integer size suffixes (e.g. "ULL").
4261
4262- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4263		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4264		forced to a value that ensures that CCSR is not relocated.
4265
4266- Floppy Disk Support:
4267		CONFIG_SYS_FDC_DRIVE_NUMBER
4268
4269		the default drive number (default value 0)
4270
4271		CONFIG_SYS_ISA_IO_STRIDE
4272
4273		defines the spacing between FDC chipset registers
4274		(default value 1)
4275
4276		CONFIG_SYS_ISA_IO_OFFSET
4277
4278		defines the offset of register from address. It
4279		depends on which part of the data bus is connected to
4280		the FDC chipset. (default value 0)
4281
4282		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4283		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4284		default value.
4285
4286		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4287		fdc_hw_init() is called at the beginning of the FDC
4288		setup. fdc_hw_init() must be provided by the board
4289		source code. It is used to make hardware dependant
4290		initializations.
4291
4292- CONFIG_IDE_AHB:
4293		Most IDE controllers were designed to be connected with PCI
4294		interface. Only few of them were designed for AHB interface.
4295		When software is doing ATA command and data transfer to
4296		IDE devices through IDE-AHB controller, some additional
4297		registers accessing to these kind of IDE-AHB controller
4298		is requierd.
4299
4300- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4301		DO NOT CHANGE unless you know exactly what you're
4302		doing! (11-4) [MPC8xx/82xx systems only]
4303
4304- CONFIG_SYS_INIT_RAM_ADDR:
4305
4306		Start address of memory area that can be used for
4307		initial data and stack; please note that this must be
4308		writable memory that is working WITHOUT special
4309		initialization, i. e. you CANNOT use normal RAM which
4310		will become available only after programming the
4311		memory controller and running certain initialization
4312		sequences.
4313
4314		U-Boot uses the following memory types:
4315		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4316		- MPC824X: data cache
4317		- PPC4xx:  data cache
4318
4319- CONFIG_SYS_GBL_DATA_OFFSET:
4320
4321		Offset of the initial data structure in the memory
4322		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4323		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4324		data is located at the end of the available space
4325		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4326		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4327		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4328		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4329
4330	Note:
4331		On the MPC824X (or other systems that use the data
4332		cache for initial memory) the address chosen for
4333		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4334		point to an otherwise UNUSED address space between
4335		the top of RAM and the start of the PCI space.
4336
4337- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4338
4339- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4340
4341- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4342
4343- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4344
4345- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4346
4347- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4348
4349- CONFIG_SYS_OR_TIMING_SDRAM:
4350		SDRAM timing
4351
4352- CONFIG_SYS_MAMR_PTA:
4353		periodic timer for refresh
4354
4355- CONFIG_SYS_DER:	Debug Event Register (37-47)
4356
4357- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4358  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4359  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4360  CONFIG_SYS_BR1_PRELIM:
4361		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4362
4363- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4364  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4365  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4366		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4367
4368- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4369  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4370		Machine Mode Register and Memory Periodic Timer
4371		Prescaler definitions (SDRAM timing)
4372
4373- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4374		enable I2C microcode relocation patch (MPC8xx);
4375		define relocation offset in DPRAM [DSP2]
4376
4377- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4378		enable SMC microcode relocation patch (MPC8xx);
4379		define relocation offset in DPRAM [SMC1]
4380
4381- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4382		enable SPI microcode relocation patch (MPC8xx);
4383		define relocation offset in DPRAM [SCC4]
4384
4385- CONFIG_SYS_USE_OSCCLK:
4386		Use OSCM clock mode on MBX8xx board. Be careful,
4387		wrong setting might damage your board. Read
4388		doc/README.MBX before setting this variable!
4389
4390- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4391		Offset of the bootmode word in DPRAM used by post
4392		(Power On Self Tests). This definition overrides
4393		#define'd default value in commproc.h resp.
4394		cpm_8260.h.
4395
4396- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4397  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4398  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4399  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4400  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4401  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4402  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4403  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4404		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4405
4406- CONFIG_PCI_DISABLE_PCIE:
4407		Disable PCI-Express on systems where it is supported but not
4408		required.
4409
4410- CONFIG_PCI_ENUM_ONLY
4411		Only scan through and get the devices on the busses.
4412		Don't do any setup work, presumably because someone or
4413		something has already done it, and we don't need to do it
4414		a second time.	Useful for platforms that are pre-booted
4415		by coreboot or similar.
4416
4417- CONFIG_PCI_INDIRECT_BRIDGE:
4418		Enable support for indirect PCI bridges.
4419
4420- CONFIG_SYS_SRIO:
4421		Chip has SRIO or not
4422
4423- CONFIG_SRIO1:
4424		Board has SRIO 1 port available
4425
4426- CONFIG_SRIO2:
4427		Board has SRIO 2 port available
4428
4429- CONFIG_SRIO_PCIE_BOOT_MASTER
4430		Board can support master function for Boot from SRIO and PCIE
4431
4432- CONFIG_SYS_SRIOn_MEM_VIRT:
4433		Virtual Address of SRIO port 'n' memory region
4434
4435- CONFIG_SYS_SRIOn_MEM_PHYS:
4436		Physical Address of SRIO port 'n' memory region
4437
4438- CONFIG_SYS_SRIOn_MEM_SIZE:
4439		Size of SRIO port 'n' memory region
4440
4441- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4442		Defined to tell the NAND controller that the NAND chip is using
4443		a 16 bit bus.
4444		Not all NAND drivers use this symbol.
4445		Example of drivers that use it:
4446		- drivers/mtd/nand/ndfc.c
4447		- drivers/mtd/nand/mxc_nand.c
4448
4449- CONFIG_SYS_NDFC_EBC0_CFG
4450		Sets the EBC0_CFG register for the NDFC. If not defined
4451		a default value will be used.
4452
4453- CONFIG_SPD_EEPROM
4454		Get DDR timing information from an I2C EEPROM. Common
4455		with pluggable memory modules such as SODIMMs
4456
4457  SPD_EEPROM_ADDRESS
4458		I2C address of the SPD EEPROM
4459
4460- CONFIG_SYS_SPD_BUS_NUM
4461		If SPD EEPROM is on an I2C bus other than the first
4462		one, specify here. Note that the value must resolve
4463		to something your driver can deal with.
4464
4465- CONFIG_SYS_DDR_RAW_TIMING
4466		Get DDR timing information from other than SPD. Common with
4467		soldered DDR chips onboard without SPD. DDR raw timing
4468		parameters are extracted from datasheet and hard-coded into
4469		header files or board specific files.
4470
4471- CONFIG_FSL_DDR_INTERACTIVE
4472		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4473
4474- CONFIG_SYS_83XX_DDR_USES_CS0
4475		Only for 83xx systems. If specified, then DDR should
4476		be configured using CS0 and CS1 instead of CS2 and CS3.
4477
4478- CONFIG_ETHER_ON_FEC[12]
4479		Define to enable FEC[12] on a 8xx series processor.
4480
4481- CONFIG_FEC[12]_PHY
4482		Define to the hardcoded PHY address which corresponds
4483		to the given FEC; i. e.
4484			#define CONFIG_FEC1_PHY 4
4485		means that the PHY with address 4 is connected to FEC1
4486
4487		When set to -1, means to probe for first available.
4488
4489- CONFIG_FEC[12]_PHY_NORXERR
4490		The PHY does not have a RXERR line (RMII only).
4491		(so program the FEC to ignore it).
4492
4493- CONFIG_RMII
4494		Enable RMII mode for all FECs.
4495		Note that this is a global option, we can't
4496		have one FEC in standard MII mode and another in RMII mode.
4497
4498- CONFIG_CRC32_VERIFY
4499		Add a verify option to the crc32 command.
4500		The syntax is:
4501
4502		=> crc32 -v <address> <count> <crc32>
4503
4504		Where address/count indicate a memory area
4505		and crc32 is the correct crc32 which the
4506		area should have.
4507
4508- CONFIG_LOOPW
4509		Add the "loopw" memory command. This only takes effect if
4510		the memory commands are activated globally (CONFIG_CMD_MEM).
4511
4512- CONFIG_MX_CYCLIC
4513		Add the "mdc" and "mwc" memory commands. These are cyclic
4514		"md/mw" commands.
4515		Examples:
4516
4517		=> mdc.b 10 4 500
4518		This command will print 4 bytes (10,11,12,13) each 500 ms.
4519
4520		=> mwc.l 100 12345678 10
4521		This command will write 12345678 to address 100 all 10 ms.
4522
4523		This only takes effect if the memory commands are activated
4524		globally (CONFIG_CMD_MEM).
4525
4526- CONFIG_SKIP_LOWLEVEL_INIT
4527		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4528		low level initializations (like setting up the memory
4529		controller) are omitted and/or U-Boot does not
4530		relocate itself into RAM.
4531
4532		Normally this variable MUST NOT be defined. The only
4533		exception is when U-Boot is loaded (to RAM) by some
4534		other boot loader or by a debugger which performs
4535		these initializations itself.
4536
4537- CONFIG_SPL_BUILD
4538		Modifies the behaviour of start.S when compiling a loader
4539		that is executed before the actual U-Boot. E.g. when
4540		compiling a NAND SPL.
4541
4542- CONFIG_TPL_BUILD
4543		Modifies the behaviour of start.S  when compiling a loader
4544		that is executed after the SPL and before the actual U-Boot.
4545		It is loaded by the SPL.
4546
4547- CONFIG_SYS_MPC85XX_NO_RESETVEC
4548		Only for 85xx systems. If this variable is specified, the section
4549		.resetvec is not kept and the section .bootpg is placed in the
4550		previous 4k of the .text section.
4551
4552- CONFIG_ARCH_MAP_SYSMEM
4553		Generally U-Boot (and in particular the md command) uses
4554		effective address. It is therefore not necessary to regard
4555		U-Boot address as virtual addresses that need to be translated
4556		to physical addresses. However, sandbox requires this, since
4557		it maintains its own little RAM buffer which contains all
4558		addressable memory. This option causes some memory accesses
4559		to be mapped through map_sysmem() / unmap_sysmem().
4560
4561- CONFIG_USE_ARCH_MEMCPY
4562  CONFIG_USE_ARCH_MEMSET
4563		If these options are used a optimized version of memcpy/memset will
4564		be used if available. These functions may be faster under some
4565		conditions but may increase the binary size.
4566
4567- CONFIG_X86_RESET_VECTOR
4568		If defined, the x86 reset vector code is included. This is not
4569		needed when U-Boot is running from Coreboot.
4570
4571- CONFIG_SYS_MPUCLK
4572		Defines the MPU clock speed (in MHz).
4573
4574		NOTE : currently only supported on AM335x platforms.
4575
4576- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4577		Enables the RTC32K OSC on AM33xx based plattforms
4578
4579- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4580		Option to disable subpage write in NAND driver
4581		driver that uses this:
4582		drivers/mtd/nand/davinci_nand.c
4583
4584Freescale QE/FMAN Firmware Support:
4585-----------------------------------
4586
4587The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4588loading of "firmware", which is encoded in the QE firmware binary format.
4589This firmware often needs to be loaded during U-Boot booting, so macros
4590are used to identify the storage device (NOR flash, SPI, etc) and the address
4591within that device.
4592
4593- CONFIG_SYS_FMAN_FW_ADDR
4594	The address in the storage device where the FMAN microcode is located.  The
4595	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4596	is also specified.
4597
4598- CONFIG_SYS_QE_FW_ADDR
4599	The address in the storage device where the QE microcode is located.  The
4600	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4601	is also specified.
4602
4603- CONFIG_SYS_QE_FMAN_FW_LENGTH
4604	The maximum possible size of the firmware.  The firmware binary format
4605	has a field that specifies the actual size of the firmware, but it
4606	might not be possible to read any part of the firmware unless some
4607	local storage is allocated to hold the entire firmware first.
4608
4609- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4610	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4611	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4612	virtual address in NOR flash.
4613
4614- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4615	Specifies that QE/FMAN firmware is located in NAND flash.
4616	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4617
4618- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4619	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4620	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4621
4622- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4623	Specifies that QE/FMAN firmware is located on the primary SPI
4624	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4625
4626- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4627	Specifies that QE/FMAN firmware is located in the remote (master)
4628	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4629	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4630	window->master inbound window->master LAW->the ucode address in
4631	master's memory space.
4632
4633Building the Software:
4634======================
4635
4636Building U-Boot has been tested in several native build environments
4637and in many different cross environments. Of course we cannot support
4638all possibly existing versions of cross development tools in all
4639(potentially obsolete) versions. In case of tool chain problems we
4640recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4641which is extensively used to build and test U-Boot.
4642
4643If you are not using a native environment, it is assumed that you
4644have GNU cross compiling tools available in your path. In this case,
4645you must set the environment variable CROSS_COMPILE in your shell.
4646Note that no changes to the Makefile or any other source files are
4647necessary. For example using the ELDK on a 4xx CPU, please enter:
4648
4649	$ CROSS_COMPILE=ppc_4xx-
4650	$ export CROSS_COMPILE
4651
4652Note: If you wish to generate Windows versions of the utilities in
4653      the tools directory you can use the MinGW toolchain
4654      (http://www.mingw.org).  Set your HOST tools to the MinGW
4655      toolchain and execute 'make tools'.  For example:
4656
4657       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4658
4659      Binaries such as tools/mkimage.exe will be created which can
4660      be executed on computers running Windows.
4661
4662U-Boot is intended to be simple to build. After installing the
4663sources you must configure U-Boot for one specific board type. This
4664is done by typing:
4665
4666	make NAME_config
4667
4668where "NAME_config" is the name of one of the existing configu-
4669rations; see boards.cfg for supported names.
4670
4671Note: for some board special configuration names may exist; check if
4672      additional information is available from the board vendor; for
4673      instance, the TQM823L systems are available without (standard)
4674      or with LCD support. You can select such additional "features"
4675      when choosing the configuration, i. e.
4676
4677      make TQM823L_config
4678	- will configure for a plain TQM823L, i. e. no LCD support
4679
4680      make TQM823L_LCD_config
4681	- will configure for a TQM823L with U-Boot console on LCD
4682
4683      etc.
4684
4685
4686Finally, type "make all", and you should get some working U-Boot
4687images ready for download to / installation on your system:
4688
4689- "u-boot.bin" is a raw binary image
4690- "u-boot" is an image in ELF binary format
4691- "u-boot.srec" is in Motorola S-Record format
4692
4693By default the build is performed locally and the objects are saved
4694in the source directory. One of the two methods can be used to change
4695this behavior and build U-Boot to some external directory:
4696
46971. Add O= to the make command line invocations:
4698
4699	make O=/tmp/build distclean
4700	make O=/tmp/build NAME_config
4701	make O=/tmp/build all
4702
47032. Set environment variable BUILD_DIR to point to the desired location:
4704
4705	export BUILD_DIR=/tmp/build
4706	make distclean
4707	make NAME_config
4708	make all
4709
4710Note that the command line "O=" setting overrides the BUILD_DIR environment
4711variable.
4712
4713
4714Please be aware that the Makefiles assume you are using GNU make, so
4715for instance on NetBSD you might need to use "gmake" instead of
4716native "make".
4717
4718
4719If the system board that you have is not listed, then you will need
4720to port U-Boot to your hardware platform. To do this, follow these
4721steps:
4722
47231.  Add a new configuration option for your board to the toplevel
4724    "boards.cfg" file, using the existing entries as examples.
4725    Follow the instructions there to keep the boards in order.
47262.  Create a new directory to hold your board specific code. Add any
4727    files you need. In your board directory, you will need at least
4728    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
47293.  Create a new configuration file "include/configs/<board>.h" for
4730    your board
47313.  If you're porting U-Boot to a new CPU, then also create a new
4732    directory to hold your CPU specific code. Add any files you need.
47334.  Run "make <board>_config" with your new name.
47345.  Type "make", and you should get a working "u-boot.srec" file
4735    to be installed on your target system.
47366.  Debug and solve any problems that might arise.
4737    [Of course, this last step is much harder than it sounds.]
4738
4739
4740Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4741==============================================================
4742
4743If you have modified U-Boot sources (for instance added a new board
4744or support for new devices, a new CPU, etc.) you are expected to
4745provide feedback to the other developers. The feedback normally takes
4746the form of a "patch", i. e. a context diff against a certain (latest
4747official or latest in the git repository) version of U-Boot sources.
4748
4749But before you submit such a patch, please verify that your modifi-
4750cation did not break existing code. At least make sure that *ALL* of
4751the supported boards compile WITHOUT ANY compiler warnings. To do so,
4752just run the "MAKEALL" script, which will configure and build U-Boot
4753for ALL supported system. Be warned, this will take a while. You can
4754select which (cross) compiler to use by passing a `CROSS_COMPILE'
4755environment variable to the script, i. e. to use the ELDK cross tools
4756you can type
4757
4758	CROSS_COMPILE=ppc_8xx- MAKEALL
4759
4760or to build on a native PowerPC system you can type
4761
4762	CROSS_COMPILE=' ' MAKEALL
4763
4764When using the MAKEALL script, the default behaviour is to build
4765U-Boot in the source directory. This location can be changed by
4766setting the BUILD_DIR environment variable. Also, for each target
4767built, the MAKEALL script saves two log files (<target>.ERR and
4768<target>.MAKEALL) in the <source dir>/LOG directory. This default
4769location can be changed by setting the MAKEALL_LOGDIR environment
4770variable. For example:
4771
4772	export BUILD_DIR=/tmp/build
4773	export MAKEALL_LOGDIR=/tmp/log
4774	CROSS_COMPILE=ppc_8xx- MAKEALL
4775
4776With the above settings build objects are saved in the /tmp/build,
4777log files are saved in the /tmp/log and the source tree remains clean
4778during the whole build process.
4779
4780
4781See also "U-Boot Porting Guide" below.
4782
4783
4784Monitor Commands - Overview:
4785============================
4786
4787go	- start application at address 'addr'
4788run	- run commands in an environment variable
4789bootm	- boot application image from memory
4790bootp	- boot image via network using BootP/TFTP protocol
4791bootz   - boot zImage from memory
4792tftpboot- boot image via network using TFTP protocol
4793	       and env variables "ipaddr" and "serverip"
4794	       (and eventually "gatewayip")
4795tftpput - upload a file via network using TFTP protocol
4796rarpboot- boot image via network using RARP/TFTP protocol
4797diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4798loads	- load S-Record file over serial line
4799loadb	- load binary file over serial line (kermit mode)
4800md	- memory display
4801mm	- memory modify (auto-incrementing)
4802nm	- memory modify (constant address)
4803mw	- memory write (fill)
4804cp	- memory copy
4805cmp	- memory compare
4806crc32	- checksum calculation
4807i2c	- I2C sub-system
4808sspi	- SPI utility commands
4809base	- print or set address offset
4810printenv- print environment variables
4811setenv	- set environment variables
4812saveenv - save environment variables to persistent storage
4813protect - enable or disable FLASH write protection
4814erase	- erase FLASH memory
4815flinfo	- print FLASH memory information
4816nand	- NAND memory operations (see doc/README.nand)
4817bdinfo	- print Board Info structure
4818iminfo	- print header information for application image
4819coninfo - print console devices and informations
4820ide	- IDE sub-system
4821loop	- infinite loop on address range
4822loopw	- infinite write loop on address range
4823mtest	- simple RAM test
4824icache	- enable or disable instruction cache
4825dcache	- enable or disable data cache
4826reset	- Perform RESET of the CPU
4827echo	- echo args to console
4828version - print monitor version
4829help	- print online help
4830?	- alias for 'help'
4831
4832
4833Monitor Commands - Detailed Description:
4834========================================
4835
4836TODO.
4837
4838For now: just type "help <command>".
4839
4840
4841Environment Variables:
4842======================
4843
4844U-Boot supports user configuration using Environment Variables which
4845can be made persistent by saving to Flash memory.
4846
4847Environment Variables are set using "setenv", printed using
4848"printenv", and saved to Flash using "saveenv". Using "setenv"
4849without a value can be used to delete a variable from the
4850environment. As long as you don't save the environment you are
4851working with an in-memory copy. In case the Flash area containing the
4852environment is erased by accident, a default environment is provided.
4853
4854Some configuration options can be set using Environment Variables.
4855
4856List of environment variables (most likely not complete):
4857
4858  baudrate	- see CONFIG_BAUDRATE
4859
4860  bootdelay	- see CONFIG_BOOTDELAY
4861
4862  bootcmd	- see CONFIG_BOOTCOMMAND
4863
4864  bootargs	- Boot arguments when booting an RTOS image
4865
4866  bootfile	- Name of the image to load with TFTP
4867
4868  bootm_low	- Memory range available for image processing in the bootm
4869		  command can be restricted. This variable is given as
4870		  a hexadecimal number and defines lowest address allowed
4871		  for use by the bootm command. See also "bootm_size"
4872		  environment variable. Address defined by "bootm_low" is
4873		  also the base of the initial memory mapping for the Linux
4874		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4875		  bootm_mapsize.
4876
4877  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4878		  This variable is given as a hexadecimal number and it
4879		  defines the size of the memory region starting at base
4880		  address bootm_low that is accessible by the Linux kernel
4881		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4882		  as the default value if it is defined, and bootm_size is
4883		  used otherwise.
4884
4885  bootm_size	- Memory range available for image processing in the bootm
4886		  command can be restricted. This variable is given as
4887		  a hexadecimal number and defines the size of the region
4888		  allowed for use by the bootm command. See also "bootm_low"
4889		  environment variable.
4890
4891  updatefile	- Location of the software update file on a TFTP server, used
4892		  by the automatic software update feature. Please refer to
4893		  documentation in doc/README.update for more details.
4894
4895  autoload	- if set to "no" (any string beginning with 'n'),
4896		  "bootp" will just load perform a lookup of the
4897		  configuration from the BOOTP server, but not try to
4898		  load any image using TFTP
4899
4900  autostart	- if set to "yes", an image loaded using the "bootp",
4901		  "rarpboot", "tftpboot" or "diskboot" commands will
4902		  be automatically started (by internally calling
4903		  "bootm")
4904
4905		  If set to "no", a standalone image passed to the
4906		  "bootm" command will be copied to the load address
4907		  (and eventually uncompressed), but NOT be started.
4908		  This can be used to load and uncompress arbitrary
4909		  data.
4910
4911  fdt_high	- if set this restricts the maximum address that the
4912		  flattened device tree will be copied into upon boot.
4913		  For example, if you have a system with 1 GB memory
4914		  at physical address 0x10000000, while Linux kernel
4915		  only recognizes the first 704 MB as low memory, you
4916		  may need to set fdt_high as 0x3C000000 to have the
4917		  device tree blob be copied to the maximum address
4918		  of the 704 MB low memory, so that Linux kernel can
4919		  access it during the boot procedure.
4920
4921		  If this is set to the special value 0xFFFFFFFF then
4922		  the fdt will not be copied at all on boot.  For this
4923		  to work it must reside in writable memory, have
4924		  sufficient padding on the end of it for u-boot to
4925		  add the information it needs into it, and the memory
4926		  must be accessible by the kernel.
4927
4928  fdtcontroladdr- if set this is the address of the control flattened
4929		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4930		  defined.
4931
4932  i2cfast	- (PPC405GP|PPC405EP only)
4933		  if set to 'y' configures Linux I2C driver for fast
4934		  mode (400kHZ). This environment variable is used in
4935		  initialization code. So, for changes to be effective
4936		  it must be saved and board must be reset.
4937
4938  initrd_high	- restrict positioning of initrd images:
4939		  If this variable is not set, initrd images will be
4940		  copied to the highest possible address in RAM; this
4941		  is usually what you want since it allows for
4942		  maximum initrd size. If for some reason you want to
4943		  make sure that the initrd image is loaded below the
4944		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4945		  variable to a value of "no" or "off" or "0".
4946		  Alternatively, you can set it to a maximum upper
4947		  address to use (U-Boot will still check that it
4948		  does not overwrite the U-Boot stack and data).
4949
4950		  For instance, when you have a system with 16 MB
4951		  RAM, and want to reserve 4 MB from use by Linux,
4952		  you can do this by adding "mem=12M" to the value of
4953		  the "bootargs" variable. However, now you must make
4954		  sure that the initrd image is placed in the first
4955		  12 MB as well - this can be done with
4956
4957		  setenv initrd_high 00c00000
4958
4959		  If you set initrd_high to 0xFFFFFFFF, this is an
4960		  indication to U-Boot that all addresses are legal
4961		  for the Linux kernel, including addresses in flash
4962		  memory. In this case U-Boot will NOT COPY the
4963		  ramdisk at all. This may be useful to reduce the
4964		  boot time on your system, but requires that this
4965		  feature is supported by your Linux kernel.
4966
4967  ipaddr	- IP address; needed for tftpboot command
4968
4969  loadaddr	- Default load address for commands like "bootp",
4970		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4971
4972  loads_echo	- see CONFIG_LOADS_ECHO
4973
4974  serverip	- TFTP server IP address; needed for tftpboot command
4975
4976  bootretry	- see CONFIG_BOOT_RETRY_TIME
4977
4978  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4979
4980  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4981
4982  ethprime	- controls which interface is used first.
4983
4984  ethact	- controls which interface is currently active.
4985		  For example you can do the following
4986
4987		  => setenv ethact FEC
4988		  => ping 192.168.0.1 # traffic sent on FEC
4989		  => setenv ethact SCC
4990		  => ping 10.0.0.1 # traffic sent on SCC
4991
4992  ethrotate	- When set to "no" U-Boot does not go through all
4993		  available network interfaces.
4994		  It just stays at the currently selected interface.
4995
4996  netretry	- When set to "no" each network operation will
4997		  either succeed or fail without retrying.
4998		  When set to "once" the network operation will
4999		  fail when all the available network interfaces
5000		  are tried once without success.
5001		  Useful on scripts which control the retry operation
5002		  themselves.
5003
5004  npe_ucode	- set load address for the NPE microcode
5005
5006  silent_linux  - If set then linux will be told to boot silently, by
5007		  changing the console to be empty. If "yes" it will be
5008		  made silent. If "no" it will not be made silent. If
5009		  unset, then it will be made silent if the U-Boot console
5010		  is silent.
5011
5012  tftpsrcport	- If this is set, the value is used for TFTP's
5013		  UDP source port.
5014
5015  tftpdstport	- If this is set, the value is used for TFTP's UDP
5016		  destination port instead of the Well Know Port 69.
5017
5018  tftpblocksize - Block size to use for TFTP transfers; if not set,
5019		  we use the TFTP server's default block size
5020
5021  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5022		  seconds, minimum value is 1000 = 1 second). Defines
5023		  when a packet is considered to be lost so it has to
5024		  be retransmitted. The default is 5000 = 5 seconds.
5025		  Lowering this value may make downloads succeed
5026		  faster in networks with high packet loss rates or
5027		  with unreliable TFTP servers.
5028
5029  vlan		- When set to a value < 4095 the traffic over
5030		  Ethernet is encapsulated/received over 802.1q
5031		  VLAN tagged frames.
5032
5033The following image location variables contain the location of images
5034used in booting. The "Image" column gives the role of the image and is
5035not an environment variable name. The other columns are environment
5036variable names. "File Name" gives the name of the file on a TFTP
5037server, "RAM Address" gives the location in RAM the image will be
5038loaded to, and "Flash Location" gives the image's address in NOR
5039flash or offset in NAND flash.
5040
5041*Note* - these variables don't have to be defined for all boards, some
5042boards currenlty use other variables for these purposes, and some
5043boards use these variables for other purposes.
5044
5045Image		    File Name	     RAM Address       Flash Location
5046-----		    ---------	     -----------       --------------
5047u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5048Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5049device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5050ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5051
5052The following environment variables may be used and automatically
5053updated by the network boot commands ("bootp" and "rarpboot"),
5054depending the information provided by your boot server:
5055
5056  bootfile	- see above
5057  dnsip		- IP address of your Domain Name Server
5058  dnsip2	- IP address of your secondary Domain Name Server
5059  gatewayip	- IP address of the Gateway (Router) to use
5060  hostname	- Target hostname
5061  ipaddr	- see above
5062  netmask	- Subnet Mask
5063  rootpath	- Pathname of the root filesystem on the NFS server
5064  serverip	- see above
5065
5066
5067There are two special Environment Variables:
5068
5069  serial#	- contains hardware identification information such
5070		  as type string and/or serial number
5071  ethaddr	- Ethernet address
5072
5073These variables can be set only once (usually during manufacturing of
5074the board). U-Boot refuses to delete or overwrite these variables
5075once they have been set once.
5076
5077
5078Further special Environment Variables:
5079
5080  ver		- Contains the U-Boot version string as printed
5081		  with the "version" command. This variable is
5082		  readonly (see CONFIG_VERSION_VARIABLE).
5083
5084
5085Please note that changes to some configuration parameters may take
5086only effect after the next boot (yes, that's just like Windoze :-).
5087
5088
5089Callback functions for environment variables:
5090---------------------------------------------
5091
5092For some environment variables, the behavior of u-boot needs to change
5093when their values are changed.  This functionailty allows functions to
5094be associated with arbitrary variables.  On creation, overwrite, or
5095deletion, the callback will provide the opportunity for some side
5096effect to happen or for the change to be rejected.
5097
5098The callbacks are named and associated with a function using the
5099U_BOOT_ENV_CALLBACK macro in your board or driver code.
5100
5101These callbacks are associated with variables in one of two ways.  The
5102static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5103in the board configuration to a string that defines a list of
5104associations.  The list must be in the following format:
5105
5106	entry = variable_name[:callback_name]
5107	list = entry[,list]
5108
5109If the callback name is not specified, then the callback is deleted.
5110Spaces are also allowed anywhere in the list.
5111
5112Callbacks can also be associated by defining the ".callbacks" variable
5113with the same list format above.  Any association in ".callbacks" will
5114override any association in the static list. You can define
5115CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5116".callbacks" envirnoment variable in the default or embedded environment.
5117
5118
5119Command Line Parsing:
5120=====================
5121
5122There are two different command line parsers available with U-Boot:
5123the old "simple" one, and the much more powerful "hush" shell:
5124
5125Old, simple command line parser:
5126--------------------------------
5127
5128- supports environment variables (through setenv / saveenv commands)
5129- several commands on one line, separated by ';'
5130- variable substitution using "... ${name} ..." syntax
5131- special characters ('$', ';') can be escaped by prefixing with '\',
5132  for example:
5133	setenv bootcmd bootm \${address}
5134- You can also escape text by enclosing in single apostrophes, for example:
5135	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5136
5137Hush shell:
5138-----------
5139
5140- similar to Bourne shell, with control structures like
5141  if...then...else...fi, for...do...done; while...do...done,
5142  until...do...done, ...
5143- supports environment ("global") variables (through setenv / saveenv
5144  commands) and local shell variables (through standard shell syntax
5145  "name=value"); only environment variables can be used with "run"
5146  command
5147
5148General rules:
5149--------------
5150
5151(1) If a command line (or an environment variable executed by a "run"
5152    command) contains several commands separated by semicolon, and
5153    one of these commands fails, then the remaining commands will be
5154    executed anyway.
5155
5156(2) If you execute several variables with one call to run (i. e.
5157    calling run with a list of variables as arguments), any failing
5158    command will cause "run" to terminate, i. e. the remaining
5159    variables are not executed.
5160
5161Note for Redundant Ethernet Interfaces:
5162=======================================
5163
5164Some boards come with redundant Ethernet interfaces; U-Boot supports
5165such configurations and is capable of automatic selection of a
5166"working" interface when needed. MAC assignment works as follows:
5167
5168Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5169MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5170"eth1addr" (=>eth1), "eth2addr", ...
5171
5172If the network interface stores some valid MAC address (for instance
5173in SROM), this is used as default address if there is NO correspon-
5174ding setting in the environment; if the corresponding environment
5175variable is set, this overrides the settings in the card; that means:
5176
5177o If the SROM has a valid MAC address, and there is no address in the
5178  environment, the SROM's address is used.
5179
5180o If there is no valid address in the SROM, and a definition in the
5181  environment exists, then the value from the environment variable is
5182  used.
5183
5184o If both the SROM and the environment contain a MAC address, and
5185  both addresses are the same, this MAC address is used.
5186
5187o If both the SROM and the environment contain a MAC address, and the
5188  addresses differ, the value from the environment is used and a
5189  warning is printed.
5190
5191o If neither SROM nor the environment contain a MAC address, an error
5192  is raised.
5193
5194If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5195will be programmed into hardware as part of the initialization process.	 This
5196may be skipped by setting the appropriate 'ethmacskip' environment variable.
5197The naming convention is as follows:
5198"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5199
5200Image Formats:
5201==============
5202
5203U-Boot is capable of booting (and performing other auxiliary operations on)
5204images in two formats:
5205
5206New uImage format (FIT)
5207-----------------------
5208
5209Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5210to Flattened Device Tree). It allows the use of images with multiple
5211components (several kernels, ramdisks, etc.), with contents protected by
5212SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5213
5214
5215Old uImage format
5216-----------------
5217
5218Old image format is based on binary files which can be basically anything,
5219preceded by a special header; see the definitions in include/image.h for
5220details; basically, the header defines the following image properties:
5221
5222* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5223  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5224  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5225  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5226  INTEGRITY).
5227* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5228  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5229  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5230* Compression Type (uncompressed, gzip, bzip2)
5231* Load Address
5232* Entry Point
5233* Image Name
5234* Image Timestamp
5235
5236The header is marked by a special Magic Number, and both the header
5237and the data portions of the image are secured against corruption by
5238CRC32 checksums.
5239
5240
5241Linux Support:
5242==============
5243
5244Although U-Boot should support any OS or standalone application
5245easily, the main focus has always been on Linux during the design of
5246U-Boot.
5247
5248U-Boot includes many features that so far have been part of some
5249special "boot loader" code within the Linux kernel. Also, any
5250"initrd" images to be used are no longer part of one big Linux image;
5251instead, kernel and "initrd" are separate images. This implementation
5252serves several purposes:
5253
5254- the same features can be used for other OS or standalone
5255  applications (for instance: using compressed images to reduce the
5256  Flash memory footprint)
5257
5258- it becomes much easier to port new Linux kernel versions because
5259  lots of low-level, hardware dependent stuff are done by U-Boot
5260
5261- the same Linux kernel image can now be used with different "initrd"
5262  images; of course this also means that different kernel images can
5263  be run with the same "initrd". This makes testing easier (you don't
5264  have to build a new "zImage.initrd" Linux image when you just
5265  change a file in your "initrd"). Also, a field-upgrade of the
5266  software is easier now.
5267
5268
5269Linux HOWTO:
5270============
5271
5272Porting Linux to U-Boot based systems:
5273---------------------------------------
5274
5275U-Boot cannot save you from doing all the necessary modifications to
5276configure the Linux device drivers for use with your target hardware
5277(no, we don't intend to provide a full virtual machine interface to
5278Linux :-).
5279
5280But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5281
5282Just make sure your machine specific header file (for instance
5283include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5284Information structure as we define in include/asm-<arch>/u-boot.h,
5285and make sure that your definition of IMAP_ADDR uses the same value
5286as your U-Boot configuration in CONFIG_SYS_IMMR.
5287
5288
5289Configuring the Linux kernel:
5290-----------------------------
5291
5292No specific requirements for U-Boot. Make sure you have some root
5293device (initial ramdisk, NFS) for your target system.
5294
5295
5296Building a Linux Image:
5297-----------------------
5298
5299With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5300not used. If you use recent kernel source, a new build target
5301"uImage" will exist which automatically builds an image usable by
5302U-Boot. Most older kernels also have support for a "pImage" target,
5303which was introduced for our predecessor project PPCBoot and uses a
5304100% compatible format.
5305
5306Example:
5307
5308	make TQM850L_config
5309	make oldconfig
5310	make dep
5311	make uImage
5312
5313The "uImage" build target uses a special tool (in 'tools/mkimage') to
5314encapsulate a compressed Linux kernel image with header	 information,
5315CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5316
5317* build a standard "vmlinux" kernel image (in ELF binary format):
5318
5319* convert the kernel into a raw binary image:
5320
5321	${CROSS_COMPILE}-objcopy -O binary \
5322				 -R .note -R .comment \
5323				 -S vmlinux linux.bin
5324
5325* compress the binary image:
5326
5327	gzip -9 linux.bin
5328
5329* package compressed binary image for U-Boot:
5330
5331	mkimage -A ppc -O linux -T kernel -C gzip \
5332		-a 0 -e 0 -n "Linux Kernel Image" \
5333		-d linux.bin.gz uImage
5334
5335
5336The "mkimage" tool can also be used to create ramdisk images for use
5337with U-Boot, either separated from the Linux kernel image, or
5338combined into one file. "mkimage" encapsulates the images with a 64
5339byte header containing information about target architecture,
5340operating system, image type, compression method, entry points, time
5341stamp, CRC32 checksums, etc.
5342
5343"mkimage" can be called in two ways: to verify existing images and
5344print the header information, or to build new images.
5345
5346In the first form (with "-l" option) mkimage lists the information
5347contained in the header of an existing U-Boot image; this includes
5348checksum verification:
5349
5350	tools/mkimage -l image
5351	  -l ==> list image header information
5352
5353The second form (with "-d" option) is used to build a U-Boot image
5354from a "data file" which is used as image payload:
5355
5356	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5357		      -n name -d data_file image
5358	  -A ==> set architecture to 'arch'
5359	  -O ==> set operating system to 'os'
5360	  -T ==> set image type to 'type'
5361	  -C ==> set compression type 'comp'
5362	  -a ==> set load address to 'addr' (hex)
5363	  -e ==> set entry point to 'ep' (hex)
5364	  -n ==> set image name to 'name'
5365	  -d ==> use image data from 'datafile'
5366
5367Right now, all Linux kernels for PowerPC systems use the same load
5368address (0x00000000), but the entry point address depends on the
5369kernel version:
5370
5371- 2.2.x kernels have the entry point at 0x0000000C,
5372- 2.3.x and later kernels have the entry point at 0x00000000.
5373
5374So a typical call to build a U-Boot image would read:
5375
5376	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5377	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5378	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5379	> examples/uImage.TQM850L
5380	Image Name:   2.4.4 kernel for TQM850L
5381	Created:      Wed Jul 19 02:34:59 2000
5382	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5383	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5384	Load Address: 0x00000000
5385	Entry Point:  0x00000000
5386
5387To verify the contents of the image (or check for corruption):
5388
5389	-> tools/mkimage -l examples/uImage.TQM850L
5390	Image Name:   2.4.4 kernel for TQM850L
5391	Created:      Wed Jul 19 02:34:59 2000
5392	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5393	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5394	Load Address: 0x00000000
5395	Entry Point:  0x00000000
5396
5397NOTE: for embedded systems where boot time is critical you can trade
5398speed for memory and install an UNCOMPRESSED image instead: this
5399needs more space in Flash, but boots much faster since it does not
5400need to be uncompressed:
5401
5402	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5403	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5404	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5405	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5406	> examples/uImage.TQM850L-uncompressed
5407	Image Name:   2.4.4 kernel for TQM850L
5408	Created:      Wed Jul 19 02:34:59 2000
5409	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5410	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5411	Load Address: 0x00000000
5412	Entry Point:  0x00000000
5413
5414
5415Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5416when your kernel is intended to use an initial ramdisk:
5417
5418	-> tools/mkimage -n 'Simple Ramdisk Image' \
5419	> -A ppc -O linux -T ramdisk -C gzip \
5420	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5421	Image Name:   Simple Ramdisk Image
5422	Created:      Wed Jan 12 14:01:50 2000
5423	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5424	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5425	Load Address: 0x00000000
5426	Entry Point:  0x00000000
5427
5428The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5429option performs the converse operation of the mkimage's second form (the "-d"
5430option). Given an image built by mkimage, the dumpimage extracts a "data file"
5431from the image:
5432
5433	tools/dumpimage -i image -p position data_file
5434	  -i ==> extract from the 'image' a specific 'data_file', \
5435	   indexed by 'position'
5436
5437
5438Installing a Linux Image:
5439-------------------------
5440
5441To downloading a U-Boot image over the serial (console) interface,
5442you must convert the image to S-Record format:
5443
5444	objcopy -I binary -O srec examples/image examples/image.srec
5445
5446The 'objcopy' does not understand the information in the U-Boot
5447image header, so the resulting S-Record file will be relative to
5448address 0x00000000. To load it to a given address, you need to
5449specify the target address as 'offset' parameter with the 'loads'
5450command.
5451
5452Example: install the image to address 0x40100000 (which on the
5453TQM8xxL is in the first Flash bank):
5454
5455	=> erase 40100000 401FFFFF
5456
5457	.......... done
5458	Erased 8 sectors
5459
5460	=> loads 40100000
5461	## Ready for S-Record download ...
5462	~>examples/image.srec
5463	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5464	...
5465	15989 15990 15991 15992
5466	[file transfer complete]
5467	[connected]
5468	## Start Addr = 0x00000000
5469
5470
5471You can check the success of the download using the 'iminfo' command;
5472this includes a checksum verification so you can be sure no data
5473corruption happened:
5474
5475	=> imi 40100000
5476
5477	## Checking Image at 40100000 ...
5478	   Image Name:	 2.2.13 for initrd on TQM850L
5479	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5480	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5481	   Load Address: 00000000
5482	   Entry Point:	 0000000c
5483	   Verifying Checksum ... OK
5484
5485
5486Boot Linux:
5487-----------
5488
5489The "bootm" command is used to boot an application that is stored in
5490memory (RAM or Flash). In case of a Linux kernel image, the contents
5491of the "bootargs" environment variable is passed to the kernel as
5492parameters. You can check and modify this variable using the
5493"printenv" and "setenv" commands:
5494
5495
5496	=> printenv bootargs
5497	bootargs=root=/dev/ram
5498
5499	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5500
5501	=> printenv bootargs
5502	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5503
5504	=> bootm 40020000
5505	## Booting Linux kernel at 40020000 ...
5506	   Image Name:	 2.2.13 for NFS on TQM850L
5507	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5508	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5509	   Load Address: 00000000
5510	   Entry Point:	 0000000c
5511	   Verifying Checksum ... OK
5512	   Uncompressing Kernel Image ... OK
5513	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
5514	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5515	time_init: decrementer frequency = 187500000/60
5516	Calibrating delay loop... 49.77 BogoMIPS
5517	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5518	...
5519
5520If you want to boot a Linux kernel with initial RAM disk, you pass
5521the memory addresses of both the kernel and the initrd image (PPBCOOT
5522format!) to the "bootm" command:
5523
5524	=> imi 40100000 40200000
5525
5526	## Checking Image at 40100000 ...
5527	   Image Name:	 2.2.13 for initrd on TQM850L
5528	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5529	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5530	   Load Address: 00000000
5531	   Entry Point:	 0000000c
5532	   Verifying Checksum ... OK
5533
5534	## Checking Image at 40200000 ...
5535	   Image Name:	 Simple Ramdisk Image
5536	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5537	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5538	   Load Address: 00000000
5539	   Entry Point:	 00000000
5540	   Verifying Checksum ... OK
5541
5542	=> bootm 40100000 40200000
5543	## Booting Linux kernel at 40100000 ...
5544	   Image Name:	 2.2.13 for initrd on TQM850L
5545	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5546	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5547	   Load Address: 00000000
5548	   Entry Point:	 0000000c
5549	   Verifying Checksum ... OK
5550	   Uncompressing Kernel Image ... OK
5551	## Loading RAMDisk Image at 40200000 ...
5552	   Image Name:	 Simple Ramdisk Image
5553	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5554	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5555	   Load Address: 00000000
5556	   Entry Point:	 00000000
5557	   Verifying Checksum ... OK
5558	   Loading Ramdisk ... OK
5559	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
5560	Boot arguments: root=/dev/ram
5561	time_init: decrementer frequency = 187500000/60
5562	Calibrating delay loop... 49.77 BogoMIPS
5563	...
5564	RAMDISK: Compressed image found at block 0
5565	VFS: Mounted root (ext2 filesystem).
5566
5567	bash#
5568
5569Boot Linux and pass a flat device tree:
5570-----------
5571
5572First, U-Boot must be compiled with the appropriate defines. See the section
5573titled "Linux Kernel Interface" above for a more in depth explanation. The
5574following is an example of how to start a kernel and pass an updated
5575flat device tree:
5576
5577=> print oftaddr
5578oftaddr=0x300000
5579=> print oft
5580oft=oftrees/mpc8540ads.dtb
5581=> tftp $oftaddr $oft
5582Speed: 1000, full duplex
5583Using TSEC0 device
5584TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5585Filename 'oftrees/mpc8540ads.dtb'.
5586Load address: 0x300000
5587Loading: #
5588done
5589Bytes transferred = 4106 (100a hex)
5590=> tftp $loadaddr $bootfile
5591Speed: 1000, full duplex
5592Using TSEC0 device
5593TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5594Filename 'uImage'.
5595Load address: 0x200000
5596Loading:############
5597done
5598Bytes transferred = 1029407 (fb51f hex)
5599=> print loadaddr
5600loadaddr=200000
5601=> print oftaddr
5602oftaddr=0x300000
5603=> bootm $loadaddr - $oftaddr
5604## Booting image at 00200000 ...
5605   Image Name:	 Linux-2.6.17-dirty
5606   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5607   Data Size:	 1029343 Bytes = 1005.2 kB
5608   Load Address: 00000000
5609   Entry Point:	 00000000
5610   Verifying Checksum ... OK
5611   Uncompressing Kernel Image ... OK
5612Booting using flat device tree at 0x300000
5613Using MPC85xx ADS machine description
5614Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5615[snip]
5616
5617
5618More About U-Boot Image Types:
5619------------------------------
5620
5621U-Boot supports the following image types:
5622
5623   "Standalone Programs" are directly runnable in the environment
5624	provided by U-Boot; it is expected that (if they behave
5625	well) you can continue to work in U-Boot after return from
5626	the Standalone Program.
5627   "OS Kernel Images" are usually images of some Embedded OS which
5628	will take over control completely. Usually these programs
5629	will install their own set of exception handlers, device
5630	drivers, set up the MMU, etc. - this means, that you cannot
5631	expect to re-enter U-Boot except by resetting the CPU.
5632   "RAMDisk Images" are more or less just data blocks, and their
5633	parameters (address, size) are passed to an OS kernel that is
5634	being started.
5635   "Multi-File Images" contain several images, typically an OS
5636	(Linux) kernel image and one or more data images like
5637	RAMDisks. This construct is useful for instance when you want
5638	to boot over the network using BOOTP etc., where the boot
5639	server provides just a single image file, but you want to get
5640	for instance an OS kernel and a RAMDisk image.
5641
5642	"Multi-File Images" start with a list of image sizes, each
5643	image size (in bytes) specified by an "uint32_t" in network
5644	byte order. This list is terminated by an "(uint32_t)0".
5645	Immediately after the terminating 0 follow the images, one by
5646	one, all aligned on "uint32_t" boundaries (size rounded up to
5647	a multiple of 4 bytes).
5648
5649   "Firmware Images" are binary images containing firmware (like
5650	U-Boot or FPGA images) which usually will be programmed to
5651	flash memory.
5652
5653   "Script files" are command sequences that will be executed by
5654	U-Boot's command interpreter; this feature is especially
5655	useful when you configure U-Boot to use a real shell (hush)
5656	as command interpreter.
5657
5658Booting the Linux zImage:
5659-------------------------
5660
5661On some platforms, it's possible to boot Linux zImage. This is done
5662using the "bootz" command. The syntax of "bootz" command is the same
5663as the syntax of "bootm" command.
5664
5665Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5666kernel with raw initrd images. The syntax is slightly different, the
5667address of the initrd must be augmented by it's size, in the following
5668format: "<initrd addres>:<initrd size>".
5669
5670
5671Standalone HOWTO:
5672=================
5673
5674One of the features of U-Boot is that you can dynamically load and
5675run "standalone" applications, which can use some resources of
5676U-Boot like console I/O functions or interrupt services.
5677
5678Two simple examples are included with the sources:
5679
5680"Hello World" Demo:
5681-------------------
5682
5683'examples/hello_world.c' contains a small "Hello World" Demo
5684application; it is automatically compiled when you build U-Boot.
5685It's configured to run at address 0x00040004, so you can play with it
5686like that:
5687
5688	=> loads
5689	## Ready for S-Record download ...
5690	~>examples/hello_world.srec
5691	1 2 3 4 5 6 7 8 9 10 11 ...
5692	[file transfer complete]
5693	[connected]
5694	## Start Addr = 0x00040004
5695
5696	=> go 40004 Hello World! This is a test.
5697	## Starting application at 0x00040004 ...
5698	Hello World
5699	argc = 7
5700	argv[0] = "40004"
5701	argv[1] = "Hello"
5702	argv[2] = "World!"
5703	argv[3] = "This"
5704	argv[4] = "is"
5705	argv[5] = "a"
5706	argv[6] = "test."
5707	argv[7] = "<NULL>"
5708	Hit any key to exit ...
5709
5710	## Application terminated, rc = 0x0
5711
5712Another example, which demonstrates how to register a CPM interrupt
5713handler with the U-Boot code, can be found in 'examples/timer.c'.
5714Here, a CPM timer is set up to generate an interrupt every second.
5715The interrupt service routine is trivial, just printing a '.'
5716character, but this is just a demo program. The application can be
5717controlled by the following keys:
5718
5719	? - print current values og the CPM Timer registers
5720	b - enable interrupts and start timer
5721	e - stop timer and disable interrupts
5722	q - quit application
5723
5724	=> loads
5725	## Ready for S-Record download ...
5726	~>examples/timer.srec
5727	1 2 3 4 5 6 7 8 9 10 11 ...
5728	[file transfer complete]
5729	[connected]
5730	## Start Addr = 0x00040004
5731
5732	=> go 40004
5733	## Starting application at 0x00040004 ...
5734	TIMERS=0xfff00980
5735	Using timer 1
5736	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5737
5738Hit 'b':
5739	[q, b, e, ?] Set interval 1000000 us
5740	Enabling timer
5741Hit '?':
5742	[q, b, e, ?] ........
5743	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5744Hit '?':
5745	[q, b, e, ?] .
5746	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5747Hit '?':
5748	[q, b, e, ?] .
5749	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5750Hit '?':
5751	[q, b, e, ?] .
5752	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5753Hit 'e':
5754	[q, b, e, ?] ...Stopping timer
5755Hit 'q':
5756	[q, b, e, ?] ## Application terminated, rc = 0x0
5757
5758
5759Minicom warning:
5760================
5761
5762Over time, many people have reported problems when trying to use the
5763"minicom" terminal emulation program for serial download. I (wd)
5764consider minicom to be broken, and recommend not to use it. Under
5765Unix, I recommend to use C-Kermit for general purpose use (and
5766especially for kermit binary protocol download ("loadb" command), and
5767use "cu" for S-Record download ("loads" command).  See
5768http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5769for help with kermit.
5770
5771
5772Nevertheless, if you absolutely want to use it try adding this
5773configuration to your "File transfer protocols" section:
5774
5775	   Name	   Program			Name U/D FullScr IO-Red. Multi
5776	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5777	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5778
5779
5780NetBSD Notes:
5781=============
5782
5783Starting at version 0.9.2, U-Boot supports NetBSD both as host
5784(build U-Boot) and target system (boots NetBSD/mpc8xx).
5785
5786Building requires a cross environment; it is known to work on
5787NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5788need gmake since the Makefiles are not compatible with BSD make).
5789Note that the cross-powerpc package does not install include files;
5790attempting to build U-Boot will fail because <machine/ansi.h> is
5791missing.  This file has to be installed and patched manually:
5792
5793	# cd /usr/pkg/cross/powerpc-netbsd/include
5794	# mkdir powerpc
5795	# ln -s powerpc machine
5796	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5797	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5798
5799Native builds *don't* work due to incompatibilities between native
5800and U-Boot include files.
5801
5802Booting assumes that (the first part of) the image booted is a
5803stage-2 loader which in turn loads and then invokes the kernel
5804proper. Loader sources will eventually appear in the NetBSD source
5805tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5806meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5807
5808
5809Implementation Internals:
5810=========================
5811
5812The following is not intended to be a complete description of every
5813implementation detail. However, it should help to understand the
5814inner workings of U-Boot and make it easier to port it to custom
5815hardware.
5816
5817
5818Initial Stack, Global Data:
5819---------------------------
5820
5821The implementation of U-Boot is complicated by the fact that U-Boot
5822starts running out of ROM (flash memory), usually without access to
5823system RAM (because the memory controller is not initialized yet).
5824This means that we don't have writable Data or BSS segments, and BSS
5825is not initialized as zero. To be able to get a C environment working
5826at all, we have to allocate at least a minimal stack. Implementation
5827options for this are defined and restricted by the CPU used: Some CPU
5828models provide on-chip memory (like the IMMR area on MPC8xx and
5829MPC826x processors), on others (parts of) the data cache can be
5830locked as (mis-) used as memory, etc.
5831
5832	Chris Hallinan posted a good summary of these issues to the
5833	U-Boot mailing list:
5834
5835	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5836	From: "Chris Hallinan" <clh@net1plus.com>
5837	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5838	...
5839
5840	Correct me if I'm wrong, folks, but the way I understand it
5841	is this: Using DCACHE as initial RAM for Stack, etc, does not
5842	require any physical RAM backing up the cache. The cleverness
5843	is that the cache is being used as a temporary supply of
5844	necessary storage before the SDRAM controller is setup. It's
5845	beyond the scope of this list to explain the details, but you
5846	can see how this works by studying the cache architecture and
5847	operation in the architecture and processor-specific manuals.
5848
5849	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5850	is another option for the system designer to use as an
5851	initial stack/RAM area prior to SDRAM being available. Either
5852	option should work for you. Using CS 4 should be fine if your
5853	board designers haven't used it for something that would
5854	cause you grief during the initial boot! It is frequently not
5855	used.
5856
5857	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5858	with your processor/board/system design. The default value
5859	you will find in any recent u-boot distribution in
5860	walnut.h should work for you. I'd set it to a value larger
5861	than your SDRAM module. If you have a 64MB SDRAM module, set
5862	it above 400_0000. Just make sure your board has no resources
5863	that are supposed to respond to that address! That code in
5864	start.S has been around a while and should work as is when
5865	you get the config right.
5866
5867	-Chris Hallinan
5868	DS4.COM, Inc.
5869
5870It is essential to remember this, since it has some impact on the C
5871code for the initialization procedures:
5872
5873* Initialized global data (data segment) is read-only. Do not attempt
5874  to write it.
5875
5876* Do not use any uninitialized global data (or implicitely initialized
5877  as zero data - BSS segment) at all - this is undefined, initiali-
5878  zation is performed later (when relocating to RAM).
5879
5880* Stack space is very limited. Avoid big data buffers or things like
5881  that.
5882
5883Having only the stack as writable memory limits means we cannot use
5884normal global data to share information beween the code. But it
5885turned out that the implementation of U-Boot can be greatly
5886simplified by making a global data structure (gd_t) available to all
5887functions. We could pass a pointer to this data as argument to _all_
5888functions, but this would bloat the code. Instead we use a feature of
5889the GCC compiler (Global Register Variables) to share the data: we
5890place a pointer (gd) to the global data into a register which we
5891reserve for this purpose.
5892
5893When choosing a register for such a purpose we are restricted by the
5894relevant  (E)ABI  specifications for the current architecture, and by
5895GCC's implementation.
5896
5897For PowerPC, the following registers have specific use:
5898	R1:	stack pointer
5899	R2:	reserved for system use
5900	R3-R4:	parameter passing and return values
5901	R5-R10: parameter passing
5902	R13:	small data area pointer
5903	R30:	GOT pointer
5904	R31:	frame pointer
5905
5906	(U-Boot also uses R12 as internal GOT pointer. r12
5907	is a volatile register so r12 needs to be reset when
5908	going back and forth between asm and C)
5909
5910    ==> U-Boot will use R2 to hold a pointer to the global data
5911
5912    Note: on PPC, we could use a static initializer (since the
5913    address of the global data structure is known at compile time),
5914    but it turned out that reserving a register results in somewhat
5915    smaller code - although the code savings are not that big (on
5916    average for all boards 752 bytes for the whole U-Boot image,
5917    624 text + 127 data).
5918
5919On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5920	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5921
5922    ==> U-Boot will use P3 to hold a pointer to the global data
5923
5924On ARM, the following registers are used:
5925
5926	R0:	function argument word/integer result
5927	R1-R3:	function argument word
5928	R9:	platform specific
5929	R10:	stack limit (used only if stack checking is enabled)
5930	R11:	argument (frame) pointer
5931	R12:	temporary workspace
5932	R13:	stack pointer
5933	R14:	link register
5934	R15:	program counter
5935
5936    ==> U-Boot will use R9 to hold a pointer to the global data
5937
5938    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5939
5940On Nios II, the ABI is documented here:
5941	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5942
5943    ==> U-Boot will use gp to hold a pointer to the global data
5944
5945    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5946    to access small data sections, so gp is free.
5947
5948On NDS32, the following registers are used:
5949
5950	R0-R1:	argument/return
5951	R2-R5:	argument
5952	R15:	temporary register for assembler
5953	R16:	trampoline register
5954	R28:	frame pointer (FP)
5955	R29:	global pointer (GP)
5956	R30:	link register (LP)
5957	R31:	stack pointer (SP)
5958	PC:	program counter (PC)
5959
5960    ==> U-Boot will use R10 to hold a pointer to the global data
5961
5962NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5963or current versions of GCC may "optimize" the code too much.
5964
5965Memory Management:
5966------------------
5967
5968U-Boot runs in system state and uses physical addresses, i.e. the
5969MMU is not used either for address mapping nor for memory protection.
5970
5971The available memory is mapped to fixed addresses using the memory
5972controller. In this process, a contiguous block is formed for each
5973memory type (Flash, SDRAM, SRAM), even when it consists of several
5974physical memory banks.
5975
5976U-Boot is installed in the first 128 kB of the first Flash bank (on
5977TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5978booting and sizing and initializing DRAM, the code relocates itself
5979to the upper end of DRAM. Immediately below the U-Boot code some
5980memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5981configuration setting]. Below that, a structure with global Board
5982Info data is placed, followed by the stack (growing downward).
5983
5984Additionally, some exception handler code is copied to the low 8 kB
5985of DRAM (0x00000000 ... 0x00001FFF).
5986
5987So a typical memory configuration with 16 MB of DRAM could look like
5988this:
5989
5990	0x0000 0000	Exception Vector code
5991	      :
5992	0x0000 1FFF
5993	0x0000 2000	Free for Application Use
5994	      :
5995	      :
5996
5997	      :
5998	      :
5999	0x00FB FF20	Monitor Stack (Growing downward)
6000	0x00FB FFAC	Board Info Data and permanent copy of global data
6001	0x00FC 0000	Malloc Arena
6002	      :
6003	0x00FD FFFF
6004	0x00FE 0000	RAM Copy of Monitor Code
6005	...		eventually: LCD or video framebuffer
6006	...		eventually: pRAM (Protected RAM - unchanged by reset)
6007	0x00FF FFFF	[End of RAM]
6008
6009
6010System Initialization:
6011----------------------
6012
6013In the reset configuration, U-Boot starts at the reset entry point
6014(on most PowerPC systems at address 0x00000100). Because of the reset
6015configuration for CS0# this is a mirror of the onboard Flash memory.
6016To be able to re-map memory U-Boot then jumps to its link address.
6017To be able to implement the initialization code in C, a (small!)
6018initial stack is set up in the internal Dual Ported RAM (in case CPUs
6019which provide such a feature like MPC8xx or MPC8260), or in a locked
6020part of the data cache. After that, U-Boot initializes the CPU core,
6021the caches and the SIU.
6022
6023Next, all (potentially) available memory banks are mapped using a
6024preliminary mapping. For example, we put them on 512 MB boundaries
6025(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6026on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6027programmed for SDRAM access. Using the temporary configuration, a
6028simple memory test is run that determines the size of the SDRAM
6029banks.
6030
6031When there is more than one SDRAM bank, and the banks are of
6032different size, the largest is mapped first. For equal size, the first
6033bank (CS2#) is mapped first. The first mapping is always for address
60340x00000000, with any additional banks following immediately to create
6035contiguous memory starting from 0.
6036
6037Then, the monitor installs itself at the upper end of the SDRAM area
6038and allocates memory for use by malloc() and for the global Board
6039Info data; also, the exception vector code is copied to the low RAM
6040pages, and the final stack is set up.
6041
6042Only after this relocation will you have a "normal" C environment;
6043until that you are restricted in several ways, mostly because you are
6044running from ROM, and because the code will have to be relocated to a
6045new address in RAM.
6046
6047
6048U-Boot Porting Guide:
6049----------------------
6050
6051[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6052list, October 2002]
6053
6054
6055int main(int argc, char *argv[])
6056{
6057	sighandler_t no_more_time;
6058
6059	signal(SIGALRM, no_more_time);
6060	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6061
6062	if (available_money > available_manpower) {
6063		Pay consultant to port U-Boot;
6064		return 0;
6065	}
6066
6067	Download latest U-Boot source;
6068
6069	Subscribe to u-boot mailing list;
6070
6071	if (clueless)
6072		email("Hi, I am new to U-Boot, how do I get started?");
6073
6074	while (learning) {
6075		Read the README file in the top level directory;
6076		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6077		Read applicable doc/*.README;
6078		Read the source, Luke;
6079		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6080	}
6081
6082	if (available_money > toLocalCurrency ($2500))
6083		Buy a BDI3000;
6084	else
6085		Add a lot of aggravation and time;
6086
6087	if (a similar board exists) {	/* hopefully... */
6088		cp -a board/<similar> board/<myboard>
6089		cp include/configs/<similar>.h include/configs/<myboard>.h
6090	} else {
6091		Create your own board support subdirectory;
6092		Create your own board include/configs/<myboard>.h file;
6093	}
6094	Edit new board/<myboard> files
6095	Edit new include/configs/<myboard>.h
6096
6097	while (!accepted) {
6098		while (!running) {
6099			do {
6100				Add / modify source code;
6101			} until (compiles);
6102			Debug;
6103			if (clueless)
6104				email("Hi, I am having problems...");
6105		}
6106		Send patch file to the U-Boot email list;
6107		if (reasonable critiques)
6108			Incorporate improvements from email list code review;
6109		else
6110			Defend code as written;
6111	}
6112
6113	return 0;
6114}
6115
6116void no_more_time (int sig)
6117{
6118      hire_a_guru();
6119}
6120
6121
6122Coding Standards:
6123-----------------
6124
6125All contributions to U-Boot should conform to the Linux kernel
6126coding style; see the file "Documentation/CodingStyle" and the script
6127"scripts/Lindent" in your Linux kernel source directory.
6128
6129Source files originating from a different project (for example the
6130MTD subsystem) are generally exempt from these guidelines and are not
6131reformated to ease subsequent migration to newer versions of those
6132sources.
6133
6134Please note that U-Boot is implemented in C (and to some small parts in
6135Assembler); no C++ is used, so please do not use C++ style comments (//)
6136in your code.
6137
6138Please also stick to the following formatting rules:
6139- remove any trailing white space
6140- use TAB characters for indentation and vertical alignment, not spaces
6141- make sure NOT to use DOS '\r\n' line feeds
6142- do not add more than 2 consecutive empty lines to source files
6143- do not add trailing empty lines to source files
6144
6145Submissions which do not conform to the standards may be returned
6146with a request to reformat the changes.
6147
6148
6149Submitting Patches:
6150-------------------
6151
6152Since the number of patches for U-Boot is growing, we need to
6153establish some rules. Submissions which do not conform to these rules
6154may be rejected, even when they contain important and valuable stuff.
6155
6156Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6157
6158Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6159see http://lists.denx.de/mailman/listinfo/u-boot
6160
6161When you send a patch, please include the following information with
6162it:
6163
6164* For bug fixes: a description of the bug and how your patch fixes
6165  this bug. Please try to include a way of demonstrating that the
6166  patch actually fixes something.
6167
6168* For new features: a description of the feature and your
6169  implementation.
6170
6171* A CHANGELOG entry as plaintext (separate from the patch)
6172
6173* For major contributions, your entry to the CREDITS file
6174
6175* When you add support for a new board, don't forget to add a
6176  maintainer e-mail address to the boards.cfg file, too.
6177
6178* If your patch adds new configuration options, don't forget to
6179  document these in the README file.
6180
6181* The patch itself. If you are using git (which is *strongly*
6182  recommended) you can easily generate the patch using the
6183  "git format-patch". If you then use "git send-email" to send it to
6184  the U-Boot mailing list, you will avoid most of the common problems
6185  with some other mail clients.
6186
6187  If you cannot use git, use "diff -purN OLD NEW". If your version of
6188  diff does not support these options, then get the latest version of
6189  GNU diff.
6190
6191  The current directory when running this command shall be the parent
6192  directory of the U-Boot source tree (i. e. please make sure that
6193  your patch includes sufficient directory information for the
6194  affected files).
6195
6196  We prefer patches as plain text. MIME attachments are discouraged,
6197  and compressed attachments must not be used.
6198
6199* If one logical set of modifications affects or creates several
6200  files, all these changes shall be submitted in a SINGLE patch file.
6201
6202* Changesets that contain different, unrelated modifications shall be
6203  submitted as SEPARATE patches, one patch per changeset.
6204
6205
6206Notes:
6207
6208* Before sending the patch, run the MAKEALL script on your patched
6209  source tree and make sure that no errors or warnings are reported
6210  for any of the boards.
6211
6212* Keep your modifications to the necessary minimum: A patch
6213  containing several unrelated changes or arbitrary reformats will be
6214  returned with a request to re-formatting / split it.
6215
6216* If you modify existing code, make sure that your new code does not
6217  add to the memory footprint of the code ;-) Small is beautiful!
6218  When adding new features, these should compile conditionally only
6219  (using #ifdef), and the resulting code with the new feature
6220  disabled must not need more memory than the old code without your
6221  modification.
6222
6223* Remember that there is a size limit of 100 kB per message on the
6224  u-boot mailing list. Bigger patches will be moderated. If they are
6225  reasonable and not too big, they will be acknowledged. But patches
6226  bigger than the size limit should be avoided.
6227