xref: /rk3399_rockchip-uboot/README (revision dedf37bb61b2a4893f51f7aea2f37fe70d77ab0c)
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- Marvell Family Member
325		CONFIG_SYS_MVFS		- define it if you want to enable
326					  multiple fs option at one time
327					  for marvell soc family
328
329- MPC824X Family Member (if CONFIG_MPC824X is defined)
330		Define exactly one of
331		CONFIG_MPC8240, CONFIG_MPC8245
332
333- 8xx CPU Options: (if using an MPC8xx CPU)
334		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
335					  get_gclk_freq() cannot work
336					  e.g. if there is no 32KHz
337					  reference PIT/RTC clock
338		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
339					  or XTAL/EXTAL)
340
341- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
342		CONFIG_SYS_8xx_CPUCLK_MIN
343		CONFIG_SYS_8xx_CPUCLK_MAX
344		CONFIG_8xx_CPUCLK_DEFAULT
345			See doc/README.MPC866
346
347		CONFIG_SYS_MEASURE_CPUCLK
348
349		Define this to measure the actual CPU clock instead
350		of relying on the correctness of the configured
351		values. Mostly useful for board bringup to make sure
352		the PLL is locked at the intended frequency. Note
353		that this requires a (stable) reference clock (32 kHz
354		RTC clock or CONFIG_SYS_8XX_XIN)
355
356		CONFIG_SYS_DELAYED_ICACHE
357
358		Define this option if you want to enable the
359		ICache only when Code runs from RAM.
360
361- 85xx CPU Options:
362		CONFIG_SYS_PPC64
363
364		Specifies that the core is a 64-bit PowerPC implementation (implements
365		the "64" category of the Power ISA). This is necessary for ePAPR
366		compliance, among other possible reasons.
367
368		CONFIG_SYS_FSL_TBCLK_DIV
369
370		Defines the core time base clock divider ratio compared to the
371		system clock.  On most PQ3 devices this is 8, on newer QorIQ
372		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
373
374		CONFIG_SYS_FSL_PCIE_COMPAT
375
376		Defines the string to utilize when trying to match PCIe device
377		tree nodes for the given platform.
378
379		CONFIG_SYS_PPC_E500_DEBUG_TLB
380
381		Enables a temporary TLB entry to be used during boot to work
382		around limitations in e500v1 and e500v2 external debugger
383		support. This reduces the portions of the boot code where
384		breakpoints and single stepping do not work.  The value of this
385		symbol should be set to the TLB1 entry to be used for this
386		purpose.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510
389
390		Enables a workaround for erratum A004510.  If set,
391		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
392		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
393
394		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
395		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
396
397		Defines one or two SoC revisions (low 8 bits of SVR)
398		for which the A004510 workaround should be applied.
399
400		The rest of SVR is either not relevant to the decision
401		of whether the erratum is present (e.g. p2040 versus
402		p2041) or is implied by the build target, which controls
403		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
404
405		See Freescale App Note 4493 for more information about
406		this erratum.
407
408		CONFIG_A003399_NOR_WORKAROUND
409		Enables a workaround for IFC erratum A003399. It is only
410		requred during NOR boot.
411
412		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
413
414		This is the value to write into CCSR offset 0x18600
415		according to the A004510 workaround.
416
417		CONFIG_SYS_FSL_DSP_DDR_ADDR
418		This value denotes start offset of DDR memory which is
419		connected exclusively to the DSP cores.
420
421		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
422		This value denotes start offset of M2 memory
423		which is directly connected to the DSP core.
424
425		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
426		This value denotes start offset of M3 memory which is directly
427		connected to the DSP core.
428
429		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
430		This value denotes start offset of DSP CCSR space.
431
432		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
433		Single Source Clock is clocking mode present in some of FSL SoC's.
434		In this mode, a single differential clock is used to supply
435		clocks to the sysclock, ddrclock and usbclock.
436
437		CONFIG_SYS_CPC_REINIT_F
438		This CONFIG is defined when the CPC is configured as SRAM at the
439		time of U-boot entry and is required to be re-initialized.
440
441		CONFIG_DEEP_SLEEP
442		Inidcates this SoC supports deep sleep feature. If deep sleep is
443		supported, core will start to execute uboot when wakes up.
444
445- Generic CPU options:
446		CONFIG_SYS_GENERIC_GLOBAL_DATA
447		Defines global data is initialized in generic board board_init_f().
448		If this macro is defined, global data is created and cleared in
449		generic board board_init_f(). Without this macro, architecture/board
450		should initialize global data before calling board_init_f().
451
452		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
453
454		Defines the endianess of the CPU. Implementation of those
455		values is arch specific.
456
457		CONFIG_SYS_FSL_DDR
458		Freescale DDR driver in use. This type of DDR controller is
459		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
460		SoCs.
461
462		CONFIG_SYS_FSL_DDR_ADDR
463		Freescale DDR memory-mapped register base.
464
465		CONFIG_SYS_FSL_DDR_EMU
466		Specify emulator support for DDR. Some DDR features such as
467		deskew training are not available.
468
469		CONFIG_SYS_FSL_DDRC_GEN1
470		Freescale DDR1 controller.
471
472		CONFIG_SYS_FSL_DDRC_GEN2
473		Freescale DDR2 controller.
474
475		CONFIG_SYS_FSL_DDRC_GEN3
476		Freescale DDR3 controller.
477
478		CONFIG_SYS_FSL_DDRC_GEN4
479		Freescale DDR4 controller.
480
481		CONFIG_SYS_FSL_DDRC_ARM_GEN3
482		Freescale DDR3 controller for ARM-based SoCs.
483
484		CONFIG_SYS_FSL_DDR1
485		Board config to use DDR1. It can be enabled for SoCs with
486		Freescale DDR1 or DDR2 controllers, depending on the board
487		implemetation.
488
489		CONFIG_SYS_FSL_DDR2
490		Board config to use DDR2. It can be eanbeld for SoCs with
491		Freescale DDR2 or DDR3 controllers, depending on the board
492		implementation.
493
494		CONFIG_SYS_FSL_DDR3
495		Board config to use DDR3. It can be enabled for SoCs with
496		Freescale DDR3 or DDR3L controllers.
497
498		CONFIG_SYS_FSL_DDR3L
499		Board config to use DDR3L. It can be enabled for SoCs with
500		DDR3L controllers.
501
502		CONFIG_SYS_FSL_DDR4
503		Board config to use DDR4. It can be enabled for SoCs with
504		DDR4 controllers.
505
506		CONFIG_SYS_FSL_IFC_BE
507		Defines the IFC controller register space as Big Endian
508
509		CONFIG_SYS_FSL_IFC_LE
510		Defines the IFC controller register space as Little Endian
511
512		CONFIG_SYS_FSL_PBL_PBI
513		It enables addition of RCW (Power on reset configuration) in built image.
514		Please refer doc/README.pblimage for more details
515
516		CONFIG_SYS_FSL_PBL_RCW
517		It adds PBI(pre-boot instructions) commands in u-boot build image.
518		PBI commands can be used to configure SoC before it starts the execution.
519		Please refer doc/README.pblimage for more details
520
521		CONFIG_SPL_FSL_PBL
522		It adds a target to create boot binary having SPL binary in PBI format
523		concatenated with u-boot binary.
524
525		CONFIG_SYS_FSL_DDR_BE
526		Defines the DDR controller register space as Big Endian
527
528		CONFIG_SYS_FSL_DDR_LE
529		Defines the DDR controller register space as Little Endian
530
531		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
532		Physical address from the view of DDR controllers. It is the
533		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
534		it could be different for ARM SoCs.
535
536		CONFIG_SYS_FSL_DDR_INTLV_256B
537		DDR controller interleaving on 256-byte. This is a special
538		interleaving mode, handled by Dickens for Freescale layerscape
539		SoCs with ARM core.
540
541- Intel Monahans options:
542		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
543
544		Defines the Monahans run mode to oscillator
545		ratio. Valid values are 8, 16, 24, 31. The core
546		frequency is this value multiplied by 13 MHz.
547
548		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
549
550		Defines the Monahans turbo mode to oscillator
551		ratio. Valid values are 1 (default if undefined) and
552		2. The core frequency as calculated above is multiplied
553		by this value.
554
555- MIPS CPU options:
556		CONFIG_SYS_INIT_SP_OFFSET
557
558		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
559		pointer. This is needed for the temporary stack before
560		relocation.
561
562		CONFIG_SYS_MIPS_CACHE_MODE
563
564		Cache operation mode for the MIPS CPU.
565		See also arch/mips/include/asm/mipsregs.h.
566		Possible values are:
567			CONF_CM_CACHABLE_NO_WA
568			CONF_CM_CACHABLE_WA
569			CONF_CM_UNCACHED
570			CONF_CM_CACHABLE_NONCOHERENT
571			CONF_CM_CACHABLE_CE
572			CONF_CM_CACHABLE_COW
573			CONF_CM_CACHABLE_CUW
574			CONF_CM_CACHABLE_ACCELERATED
575
576		CONFIG_SYS_XWAY_EBU_BOOTCFG
577
578		Special option for Lantiq XWAY SoCs for booting from NOR flash.
579		See also arch/mips/cpu/mips32/start.S.
580
581		CONFIG_XWAY_SWAP_BYTES
582
583		Enable compilation of tools/xway-swap-bytes needed for Lantiq
584		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
585		be swapped if a flash programmer is used.
586
587- ARM options:
588		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
589
590		Select high exception vectors of the ARM core, e.g., do not
591		clear the V bit of the c1 register of CP15.
592
593		CONFIG_SYS_THUMB_BUILD
594
595		Use this flag to build U-Boot using the Thumb instruction
596		set for ARM architectures. Thumb instruction set provides
597		better code density. For ARM architectures that support
598		Thumb2 this flag will result in Thumb2 code generated by
599		GCC.
600
601		CONFIG_ARM_ERRATA_716044
602		CONFIG_ARM_ERRATA_742230
603		CONFIG_ARM_ERRATA_743622
604		CONFIG_ARM_ERRATA_751472
605		CONFIG_ARM_ERRATA_794072
606		CONFIG_ARM_ERRATA_761320
607
608		If set, the workarounds for these ARM errata are applied early
609		during U-Boot startup. Note that these options force the
610		workarounds to be applied; no CPU-type/version detection
611		exists, unlike the similar options in the Linux kernel. Do not
612		set these options unless they apply!
613
614- CPU timer options:
615		CONFIG_SYS_HZ
616
617		The frequency of the timer returned by get_timer().
618		get_timer() must operate in milliseconds and this CONFIG
619		option must be set to 1000.
620
621- Linux Kernel Interface:
622		CONFIG_CLOCKS_IN_MHZ
623
624		U-Boot stores all clock information in Hz
625		internally. For binary compatibility with older Linux
626		kernels (which expect the clocks passed in the
627		bd_info data to be in MHz) the environment variable
628		"clocks_in_mhz" can be defined so that U-Boot
629		converts clock data to MHZ before passing it to the
630		Linux kernel.
631		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
632		"clocks_in_mhz=1" is automatically included in the
633		default environment.
634
635		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
636
637		When transferring memsize parameter to linux, some versions
638		expect it to be in bytes, others in MB.
639		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
640
641		CONFIG_OF_LIBFDT
642
643		New kernel versions are expecting firmware settings to be
644		passed using flattened device trees (based on open firmware
645		concepts).
646
647		CONFIG_OF_LIBFDT
648		 * New libfdt-based support
649		 * Adds the "fdt" command
650		 * The bootm command automatically updates the fdt
651
652		OF_CPU - The proper name of the cpus node (only required for
653			MPC512X and MPC5xxx based boards).
654		OF_SOC - The proper name of the soc node (only required for
655			MPC512X and MPC5xxx based boards).
656		OF_TBCLK - The timebase frequency.
657		OF_STDOUT_PATH - The path to the console device
658
659		boards with QUICC Engines require OF_QE to set UCC MAC
660		addresses
661
662		CONFIG_OF_BOARD_SETUP
663
664		Board code has addition modification that it wants to make
665		to the flat device tree before handing it off to the kernel
666
667		CONFIG_OF_BOOT_CPU
668
669		This define fills in the correct boot CPU in the boot
670		param header, the default value is zero if undefined.
671
672		CONFIG_OF_IDE_FIXUP
673
674		U-Boot can detect if an IDE device is present or not.
675		If not, and this new config option is activated, U-Boot
676		removes the ATA node from the DTS before booting Linux,
677		so the Linux IDE driver does not probe the device and
678		crash. This is needed for buggy hardware (uc101) where
679		no pull down resistor is connected to the signal IDE5V_DD7.
680
681		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
682
683		This setting is mandatory for all boards that have only one
684		machine type and must be used to specify the machine type
685		number as it appears in the ARM machine registry
686		(see http://www.arm.linux.org.uk/developer/machines/).
687		Only boards that have multiple machine types supported
688		in a single configuration file and the machine type is
689		runtime discoverable, do not have to use this setting.
690
691- vxWorks boot parameters:
692
693		bootvx constructs a valid bootline using the following
694		environments variables: bootfile, ipaddr, serverip, hostname.
695		It loads the vxWorks image pointed bootfile.
696
697		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
698		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
699		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
700		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
701
702		CONFIG_SYS_VXWORKS_ADD_PARAMS
703
704		Add it at the end of the bootline. E.g "u=username pw=secret"
705
706		Note: If a "bootargs" environment is defined, it will overwride
707		the defaults discussed just above.
708
709- Cache Configuration:
710		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
711		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
712		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
713
714- Cache Configuration for ARM:
715		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
716				      controller
717		CONFIG_SYS_PL310_BASE - Physical base address of PL310
718					controller register space
719
720- Serial Ports:
721		CONFIG_PL010_SERIAL
722
723		Define this if you want support for Amba PrimeCell PL010 UARTs.
724
725		CONFIG_PL011_SERIAL
726
727		Define this if you want support for Amba PrimeCell PL011 UARTs.
728
729		CONFIG_PL011_CLOCK
730
731		If you have Amba PrimeCell PL011 UARTs, set this variable to
732		the clock speed of the UARTs.
733
734		CONFIG_PL01x_PORTS
735
736		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
737		define this to a list of base addresses for each (supported)
738		port. See e.g. include/configs/versatile.h
739
740		CONFIG_PL011_SERIAL_RLCR
741
742		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
743		have separate receive and transmit line control registers.  Set
744		this variable to initialize the extra register.
745
746		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
747
748		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
749		boot loader that has already initialized the UART.  Define this
750		variable to flush the UART at init time.
751
752		CONFIG_SERIAL_HW_FLOW_CONTROL
753
754		Define this variable to enable hw flow control in serial driver.
755		Current user of this option is drivers/serial/nsl16550.c driver
756
757- Console Interface:
758		Depending on board, define exactly one serial port
759		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
760		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
761		console by defining CONFIG_8xx_CONS_NONE
762
763		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
764		port routines must be defined elsewhere
765		(i.e. serial_init(), serial_getc(), ...)
766
767		CONFIG_CFB_CONSOLE
768		Enables console device for a color framebuffer. Needs following
769		defines (cf. smiLynxEM, i8042)
770			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
771						(default big endian)
772			VIDEO_HW_RECTFILL	graphic chip supports
773						rectangle fill
774						(cf. smiLynxEM)
775			VIDEO_HW_BITBLT		graphic chip supports
776						bit-blit (cf. smiLynxEM)
777			VIDEO_VISIBLE_COLS	visible pixel columns
778						(cols=pitch)
779			VIDEO_VISIBLE_ROWS	visible pixel rows
780			VIDEO_PIXEL_SIZE	bytes per pixel
781			VIDEO_DATA_FORMAT	graphic data format
782						(0-5, cf. cfb_console.c)
783			VIDEO_FB_ADRS		framebuffer address
784			VIDEO_KBD_INIT_FCT	keyboard int fct
785						(i.e. i8042_kbd_init())
786			VIDEO_TSTC_FCT		test char fct
787						(i.e. i8042_tstc)
788			VIDEO_GETC_FCT		get char fct
789						(i.e. i8042_getc)
790			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
791						(requires blink timer
792						cf. i8042.c)
793			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
794			CONFIG_CONSOLE_TIME	display time/date info in
795						upper right corner
796						(requires CONFIG_CMD_DATE)
797			CONFIG_VIDEO_LOGO	display Linux logo in
798						upper left corner
799			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
800						linux_logo.h for logo.
801						Requires CONFIG_VIDEO_LOGO
802			CONFIG_CONSOLE_EXTRA_INFO
803						additional board info beside
804						the logo
805
806		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
807		a limited number of ANSI escape sequences (cursor control,
808		erase functions and limited graphics rendition control).
809
810		When CONFIG_CFB_CONSOLE is defined, video console is
811		default i/o. Serial console can be forced with
812		environment 'console=serial'.
813
814		When CONFIG_SILENT_CONSOLE is defined, all console
815		messages (by U-Boot and Linux!) can be silenced with
816		the "silent" environment variable. See
817		doc/README.silent for more information.
818
819		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
820			is 0x00.
821		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
822			is 0xa0.
823
824- Console Baudrate:
825		CONFIG_BAUDRATE - in bps
826		Select one of the baudrates listed in
827		CONFIG_SYS_BAUDRATE_TABLE, see below.
828		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
829
830- Console Rx buffer length
831		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
832		the maximum receive buffer length for the SMC.
833		This option is actual only for 82xx and 8xx possible.
834		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
835		must be defined, to setup the maximum idle timeout for
836		the SMC.
837
838- Pre-Console Buffer:
839		Prior to the console being initialised (i.e. serial UART
840		initialised etc) all console output is silently discarded.
841		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
842		buffer any console messages prior to the console being
843		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
844		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
845		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
846		bytes are output before the console is initialised, the
847		earlier bytes are discarded.
848
849		'Sane' compilers will generate smaller code if
850		CONFIG_PRE_CON_BUF_SZ is a power of 2
851
852- Safe printf() functions
853		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
854		the printf() functions. These are defined in
855		include/vsprintf.h and include snprintf(), vsnprintf() and
856		so on. Code size increase is approximately 300-500 bytes.
857		If this option is not given then these functions will
858		silently discard their buffer size argument - this means
859		you are not getting any overflow checking in this case.
860
861- Boot Delay:	CONFIG_BOOTDELAY - in seconds
862		Delay before automatically booting the default image;
863		set to -1 to disable autoboot.
864		set to -2 to autoboot with no delay and not check for abort
865		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
866
867		See doc/README.autoboot for these options that
868		work with CONFIG_BOOTDELAY. None are required.
869		CONFIG_BOOT_RETRY_TIME
870		CONFIG_BOOT_RETRY_MIN
871		CONFIG_AUTOBOOT_KEYED
872		CONFIG_AUTOBOOT_PROMPT
873		CONFIG_AUTOBOOT_DELAY_STR
874		CONFIG_AUTOBOOT_STOP_STR
875		CONFIG_AUTOBOOT_DELAY_STR2
876		CONFIG_AUTOBOOT_STOP_STR2
877		CONFIG_ZERO_BOOTDELAY_CHECK
878		CONFIG_RESET_TO_RETRY
879
880- Autoboot Command:
881		CONFIG_BOOTCOMMAND
882		Only needed when CONFIG_BOOTDELAY is enabled;
883		define a command string that is automatically executed
884		when no character is read on the console interface
885		within "Boot Delay" after reset.
886
887		CONFIG_BOOTARGS
888		This can be used to pass arguments to the bootm
889		command. The value of CONFIG_BOOTARGS goes into the
890		environment value "bootargs".
891
892		CONFIG_RAMBOOT and CONFIG_NFSBOOT
893		The value of these goes into the environment as
894		"ramboot" and "nfsboot" respectively, and can be used
895		as a convenience, when switching between booting from
896		RAM and NFS.
897
898- Bootcount:
899		CONFIG_BOOTCOUNT_LIMIT
900		Implements a mechanism for detecting a repeating reboot
901		cycle, see:
902		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
903
904		CONFIG_BOOTCOUNT_ENV
905		If no softreset save registers are found on the hardware
906		"bootcount" is stored in the environment. To prevent a
907		saveenv on all reboots, the environment variable
908		"upgrade_available" is used. If "upgrade_available" is
909		0, "bootcount" is always 0, if "upgrade_available" is
910		1 "bootcount" is incremented in the environment.
911		So the Userspace Applikation must set the "upgrade_available"
912		and "bootcount" variable to 0, if a boot was successfully.
913
914- Pre-Boot Commands:
915		CONFIG_PREBOOT
916
917		When this option is #defined, the existence of the
918		environment variable "preboot" will be checked
919		immediately before starting the CONFIG_BOOTDELAY
920		countdown and/or running the auto-boot command resp.
921		entering interactive mode.
922
923		This feature is especially useful when "preboot" is
924		automatically generated or modified. For an example
925		see the LWMON board specific code: here "preboot" is
926		modified when the user holds down a certain
927		combination of keys on the (special) keyboard when
928		booting the systems
929
930- Serial Download Echo Mode:
931		CONFIG_LOADS_ECHO
932		If defined to 1, all characters received during a
933		serial download (using the "loads" command) are
934		echoed back. This might be needed by some terminal
935		emulations (like "cu"), but may as well just take
936		time on others. This setting #define's the initial
937		value of the "loads_echo" environment variable.
938
939- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
940		CONFIG_KGDB_BAUDRATE
941		Select one of the baudrates listed in
942		CONFIG_SYS_BAUDRATE_TABLE, see below.
943
944- Monitor Functions:
945		Monitor commands can be included or excluded
946		from the build by using the #include files
947		<config_cmd_all.h> and #undef'ing unwanted
948		commands, or using <config_cmd_default.h>
949		and augmenting with additional #define's
950		for wanted commands.
951
952		The default command configuration includes all commands
953		except those marked below with a "*".
954
955		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
956		CONFIG_CMD_ASKENV	* ask for env variable
957		CONFIG_CMD_BDI		  bdinfo
958		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
959		CONFIG_CMD_BMP		* BMP support
960		CONFIG_CMD_BSP		* Board specific commands
961		CONFIG_CMD_BOOTD	  bootd
962		CONFIG_CMD_CACHE	* icache, dcache
963		CONFIG_CMD_CLK   	* clock command support
964		CONFIG_CMD_CONSOLE	  coninfo
965		CONFIG_CMD_CRC32	* crc32
966		CONFIG_CMD_DATE		* support for RTC, date/time...
967		CONFIG_CMD_DHCP		* DHCP support
968		CONFIG_CMD_DIAG		* Diagnostics
969		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
970		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
971		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
972		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
973		CONFIG_CMD_DTT		* Digital Therm and Thermostat
974		CONFIG_CMD_ECHO		  echo arguments
975		CONFIG_CMD_EDITENV	  edit env variable
976		CONFIG_CMD_EEPROM	* EEPROM read/write support
977		CONFIG_CMD_ELF		* bootelf, bootvx
978		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
979		CONFIG_CMD_ENV_FLAGS	* display details about env flags
980		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
981		CONFIG_CMD_EXPORTENV	* export the environment
982		CONFIG_CMD_EXT2		* ext2 command support
983		CONFIG_CMD_EXT4		* ext4 command support
984		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
985					  that work for multiple fs types
986		CONFIG_CMD_SAVEENV	  saveenv
987		CONFIG_CMD_FDC		* Floppy Disk Support
988		CONFIG_CMD_FAT		* FAT command support
989		CONFIG_CMD_FLASH	  flinfo, erase, protect
990		CONFIG_CMD_FPGA		  FPGA device initialization support
991		CONFIG_CMD_FUSE		* Device fuse support
992		CONFIG_CMD_GETTIME	* Get time since boot
993		CONFIG_CMD_GO		* the 'go' command (exec code)
994		CONFIG_CMD_GREPENV	* search environment
995		CONFIG_CMD_HASH		* calculate hash / digest
996		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
997		CONFIG_CMD_I2C		* I2C serial bus support
998		CONFIG_CMD_IDE		* IDE harddisk support
999		CONFIG_CMD_IMI		  iminfo
1000		CONFIG_CMD_IMLS		  List all images found in NOR flash
1001		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
1002		CONFIG_CMD_IMMAP	* IMMR dump support
1003		CONFIG_CMD_IMPORTENV	* import an environment
1004		CONFIG_CMD_INI		* import data from an ini file into the env
1005		CONFIG_CMD_IRQ		* irqinfo
1006		CONFIG_CMD_ITEST	  Integer/string test of 2 values
1007		CONFIG_CMD_JFFS2	* JFFS2 Support
1008		CONFIG_CMD_KGDB		* kgdb
1009		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
1010		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
1011					  (169.254.*.*)
1012		CONFIG_CMD_LOADB	  loadb
1013		CONFIG_CMD_LOADS	  loads
1014		CONFIG_CMD_MD5SUM	* print md5 message digest
1015					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
1016		CONFIG_CMD_MEMINFO	* Display detailed memory information
1017		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
1018					  loop, loopw
1019		CONFIG_CMD_MEMTEST	* mtest
1020		CONFIG_CMD_MISC		  Misc functions like sleep etc
1021		CONFIG_CMD_MMC		* MMC memory mapped support
1022		CONFIG_CMD_MII		* MII utility commands
1023		CONFIG_CMD_MTDPARTS	* MTD partition support
1024		CONFIG_CMD_NAND		* NAND support
1025		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
1026		CONFIG_CMD_NFS		  NFS support
1027		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1028		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1029		CONFIG_CMD_PCI		* pciinfo
1030		CONFIG_CMD_PCMCIA		* PCMCIA support
1031		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1032					  host
1033		CONFIG_CMD_PORTIO	* Port I/O
1034		CONFIG_CMD_READ		* Read raw data from partition
1035		CONFIG_CMD_REGINFO	* Register dump
1036		CONFIG_CMD_RUN		  run command in env variable
1037		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1038		CONFIG_CMD_SAVES	* save S record dump
1039		CONFIG_CMD_SCSI		* SCSI Support
1040		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1041					  (requires CONFIG_CMD_I2C)
1042		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1043					  (4xx only)
1044		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1045		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1046					  (requires CONFIG_CMD_MEMORY)
1047		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1048		CONFIG_CMD_SOURCE	  "source" command Support
1049		CONFIG_CMD_SPI		* SPI serial bus support
1050		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1051		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1052		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1053		CONFIG_CMD_TIMER	* access to the system tick timer
1054		CONFIG_CMD_USB		* USB support
1055		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1056		CONFIG_CMD_MFSL		* Microblaze FSL support
1057		CONFIG_CMD_XIMG		  Load part of Multi Image
1058		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1059
1060		EXAMPLE: If you want all functions except of network
1061		support you can write:
1062
1063		#include "config_cmd_all.h"
1064		#undef CONFIG_CMD_NET
1065
1066	Other Commands:
1067		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1068
1069	Note:	Don't enable the "icache" and "dcache" commands
1070		(configuration option CONFIG_CMD_CACHE) unless you know
1071		what you (and your U-Boot users) are doing. Data
1072		cache cannot be enabled on systems like the 8xx or
1073		8260 (where accesses to the IMMR region must be
1074		uncached), and it cannot be disabled on all other
1075		systems where we (mis-) use the data cache to hold an
1076		initial stack and some data.
1077
1078
1079		XXX - this list needs to get updated!
1080
1081- Regular expression support:
1082		CONFIG_REGEX
1083		If this variable is defined, U-Boot is linked against
1084		the SLRE (Super Light Regular Expression) library,
1085		which adds regex support to some commands, as for
1086		example "env grep" and "setexpr".
1087
1088- Device tree:
1089		CONFIG_OF_CONTROL
1090		If this variable is defined, U-Boot will use a device tree
1091		to configure its devices, instead of relying on statically
1092		compiled #defines in the board file. This option is
1093		experimental and only available on a few boards. The device
1094		tree is available in the global data as gd->fdt_blob.
1095
1096		U-Boot needs to get its device tree from somewhere. This can
1097		be done using one of the two options below:
1098
1099		CONFIG_OF_EMBED
1100		If this variable is defined, U-Boot will embed a device tree
1101		binary in its image. This device tree file should be in the
1102		board directory and called <soc>-<board>.dts. The binary file
1103		is then picked up in board_init_f() and made available through
1104		the global data structure as gd->blob.
1105
1106		CONFIG_OF_SEPARATE
1107		If this variable is defined, U-Boot will build a device tree
1108		binary. It will be called u-boot.dtb. Architecture-specific
1109		code will locate it at run-time. Generally this works by:
1110
1111			cat u-boot.bin u-boot.dtb >image.bin
1112
1113		and in fact, U-Boot does this for you, creating a file called
1114		u-boot-dtb.bin which is useful in the common case. You can
1115		still use the individual files if you need something more
1116		exotic.
1117
1118- Watchdog:
1119		CONFIG_WATCHDOG
1120		If this variable is defined, it enables watchdog
1121		support for the SoC. There must be support in the SoC
1122		specific code for a watchdog. For the 8xx and 8260
1123		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1124		register.  When supported for a specific SoC is
1125		available, then no further board specific code should
1126		be needed to use it.
1127
1128		CONFIG_HW_WATCHDOG
1129		When using a watchdog circuitry external to the used
1130		SoC, then define this variable and provide board
1131		specific code for the "hw_watchdog_reset" function.
1132
1133- U-Boot Version:
1134		CONFIG_VERSION_VARIABLE
1135		If this variable is defined, an environment variable
1136		named "ver" is created by U-Boot showing the U-Boot
1137		version as printed by the "version" command.
1138		Any change to this variable will be reverted at the
1139		next reset.
1140
1141- Real-Time Clock:
1142
1143		When CONFIG_CMD_DATE is selected, the type of the RTC
1144		has to be selected, too. Define exactly one of the
1145		following options:
1146
1147		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1148		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1149		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1150		CONFIG_RTC_MC146818	- use MC146818 RTC
1151		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1152		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1153		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1154		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1155		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1156		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1157		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1158		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1159					  RV3029 RTC.
1160
1161		Note that if the RTC uses I2C, then the I2C interface
1162		must also be configured. See I2C Support, below.
1163
1164- GPIO Support:
1165		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1166
1167		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1168		chip-ngpio pairs that tell the PCA953X driver the number of
1169		pins supported by a particular chip.
1170
1171		Note that if the GPIO device uses I2C, then the I2C interface
1172		must also be configured. See I2C Support, below.
1173
1174- Timestamp Support:
1175
1176		When CONFIG_TIMESTAMP is selected, the timestamp
1177		(date and time) of an image is printed by image
1178		commands like bootm or iminfo. This option is
1179		automatically enabled when you select CONFIG_CMD_DATE .
1180
1181- Partition Labels (disklabels) Supported:
1182		Zero or more of the following:
1183		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1184		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1185				       Intel architecture, USB sticks, etc.
1186		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1187		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1188				       bootloader.  Note 2TB partition limit; see
1189				       disk/part_efi.c
1190		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1191
1192		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1193		CONFIG_CMD_SCSI) you must configure support for at
1194		least one non-MTD partition type as well.
1195
1196- IDE Reset method:
1197		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1198		board configurations files but used nowhere!
1199
1200		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1201		be performed by calling the function
1202			ide_set_reset(int reset)
1203		which has to be defined in a board specific file
1204
1205- ATAPI Support:
1206		CONFIG_ATAPI
1207
1208		Set this to enable ATAPI support.
1209
1210- LBA48 Support
1211		CONFIG_LBA48
1212
1213		Set this to enable support for disks larger than 137GB
1214		Also look at CONFIG_SYS_64BIT_LBA.
1215		Whithout these , LBA48 support uses 32bit variables and will 'only'
1216		support disks up to 2.1TB.
1217
1218		CONFIG_SYS_64BIT_LBA:
1219			When enabled, makes the IDE subsystem use 64bit sector addresses.
1220			Default is 32bit.
1221
1222- SCSI Support:
1223		At the moment only there is only support for the
1224		SYM53C8XX SCSI controller; define
1225		CONFIG_SCSI_SYM53C8XX to enable it.
1226
1227		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1228		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1229		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1230		maximum numbers of LUNs, SCSI ID's and target
1231		devices.
1232		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1233
1234		The environment variable 'scsidevs' is set to the number of
1235		SCSI devices found during the last scan.
1236
1237- NETWORK Support (PCI):
1238		CONFIG_E1000
1239		Support for Intel 8254x/8257x gigabit chips.
1240
1241		CONFIG_E1000_SPI
1242		Utility code for direct access to the SPI bus on Intel 8257x.
1243		This does not do anything useful unless you set at least one
1244		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1245
1246		CONFIG_E1000_SPI_GENERIC
1247		Allow generic access to the SPI bus on the Intel 8257x, for
1248		example with the "sspi" command.
1249
1250		CONFIG_CMD_E1000
1251		Management command for E1000 devices.  When used on devices
1252		with SPI support you can reprogram the EEPROM from U-Boot.
1253
1254		CONFIG_E1000_FALLBACK_MAC
1255		default MAC for empty EEPROM after production.
1256
1257		CONFIG_EEPRO100
1258		Support for Intel 82557/82559/82559ER chips.
1259		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1260		write routine for first time initialisation.
1261
1262		CONFIG_TULIP
1263		Support for Digital 2114x chips.
1264		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1265		modem chip initialisation (KS8761/QS6611).
1266
1267		CONFIG_NATSEMI
1268		Support for National dp83815 chips.
1269
1270		CONFIG_NS8382X
1271		Support for National dp8382[01] gigabit chips.
1272
1273- NETWORK Support (other):
1274
1275		CONFIG_DRIVER_AT91EMAC
1276		Support for AT91RM9200 EMAC.
1277
1278			CONFIG_RMII
1279			Define this to use reduced MII inteface
1280
1281			CONFIG_DRIVER_AT91EMAC_QUIET
1282			If this defined, the driver is quiet.
1283			The driver doen't show link status messages.
1284
1285		CONFIG_CALXEDA_XGMAC
1286		Support for the Calxeda XGMAC device
1287
1288		CONFIG_LAN91C96
1289		Support for SMSC's LAN91C96 chips.
1290
1291			CONFIG_LAN91C96_BASE
1292			Define this to hold the physical address
1293			of the LAN91C96's I/O space
1294
1295			CONFIG_LAN91C96_USE_32_BIT
1296			Define this to enable 32 bit addressing
1297
1298		CONFIG_SMC91111
1299		Support for SMSC's LAN91C111 chip
1300
1301			CONFIG_SMC91111_BASE
1302			Define this to hold the physical address
1303			of the device (I/O space)
1304
1305			CONFIG_SMC_USE_32_BIT
1306			Define this if data bus is 32 bits
1307
1308			CONFIG_SMC_USE_IOFUNCS
1309			Define this to use i/o functions instead of macros
1310			(some hardware wont work with macros)
1311
1312		CONFIG_DRIVER_TI_EMAC
1313		Support for davinci emac
1314
1315			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1316			Define this if you have more then 3 PHYs.
1317
1318		CONFIG_FTGMAC100
1319		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1320
1321			CONFIG_FTGMAC100_EGIGA
1322			Define this to use GE link update with gigabit PHY.
1323			Define this if FTGMAC100 is connected to gigabit PHY.
1324			If your system has 10/100 PHY only, it might not occur
1325			wrong behavior. Because PHY usually return timeout or
1326			useless data when polling gigabit status and gigabit
1327			control registers. This behavior won't affect the
1328			correctnessof 10/100 link speed update.
1329
1330		CONFIG_SMC911X
1331		Support for SMSC's LAN911x and LAN921x chips
1332
1333			CONFIG_SMC911X_BASE
1334			Define this to hold the physical address
1335			of the device (I/O space)
1336
1337			CONFIG_SMC911X_32_BIT
1338			Define this if data bus is 32 bits
1339
1340			CONFIG_SMC911X_16_BIT
1341			Define this if data bus is 16 bits. If your processor
1342			automatically converts one 32 bit word to two 16 bit
1343			words you may also try CONFIG_SMC911X_32_BIT.
1344
1345		CONFIG_SH_ETHER
1346		Support for Renesas on-chip Ethernet controller
1347
1348			CONFIG_SH_ETHER_USE_PORT
1349			Define the number of ports to be used
1350
1351			CONFIG_SH_ETHER_PHY_ADDR
1352			Define the ETH PHY's address
1353
1354			CONFIG_SH_ETHER_CACHE_WRITEBACK
1355			If this option is set, the driver enables cache flush.
1356
1357- TPM Support:
1358		CONFIG_TPM
1359		Support TPM devices.
1360
1361		CONFIG_TPM_TIS_I2C
1362		Support for i2c bus TPM devices. Only one device
1363		per system is supported at this time.
1364
1365			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1366			Define the the i2c bus number for the TPM device
1367
1368			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1369			Define the TPM's address on the i2c bus
1370
1371			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1372			Define the burst count bytes upper limit
1373
1374		CONFIG_TPM_ATMEL_TWI
1375		Support for Atmel TWI TPM device. Requires I2C support.
1376
1377		CONFIG_TPM_TIS_LPC
1378		Support for generic parallel port TPM devices. Only one device
1379		per system is supported at this time.
1380
1381			CONFIG_TPM_TIS_BASE_ADDRESS
1382			Base address where the generic TPM device is mapped
1383			to. Contemporary x86 systems usually map it at
1384			0xfed40000.
1385
1386		CONFIG_CMD_TPM
1387		Add tpm monitor functions.
1388		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1389		provides monitor access to authorized functions.
1390
1391		CONFIG_TPM
1392		Define this to enable the TPM support library which provides
1393		functional interfaces to some TPM commands.
1394		Requires support for a TPM device.
1395
1396		CONFIG_TPM_AUTH_SESSIONS
1397		Define this to enable authorized functions in the TPM library.
1398		Requires CONFIG_TPM and CONFIG_SHA1.
1399
1400- USB Support:
1401		At the moment only the UHCI host controller is
1402		supported (PIP405, MIP405, MPC5200); define
1403		CONFIG_USB_UHCI to enable it.
1404		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1405		and define CONFIG_USB_STORAGE to enable the USB
1406		storage devices.
1407		Note:
1408		Supported are USB Keyboards and USB Floppy drives
1409		(TEAC FD-05PUB).
1410		MPC5200 USB requires additional defines:
1411			CONFIG_USB_CLOCK
1412				for 528 MHz Clock: 0x0001bbbb
1413			CONFIG_PSC3_USB
1414				for USB on PSC3
1415			CONFIG_USB_CONFIG
1416				for differential drivers: 0x00001000
1417				for single ended drivers: 0x00005000
1418				for differential drivers on PSC3: 0x00000100
1419				for single ended drivers on PSC3: 0x00004100
1420			CONFIG_SYS_USB_EVENT_POLL
1421				May be defined to allow interrupt polling
1422				instead of using asynchronous interrupts
1423
1424		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1425		txfilltuning field in the EHCI controller on reset.
1426
1427		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1428		interval for usb hub power-on delay.(minimum 100msec)
1429
1430- USB Device:
1431		Define the below if you wish to use the USB console.
1432		Once firmware is rebuilt from a serial console issue the
1433		command "setenv stdin usbtty; setenv stdout usbtty" and
1434		attach your USB cable. The Unix command "dmesg" should print
1435		it has found a new device. The environment variable usbtty
1436		can be set to gserial or cdc_acm to enable your device to
1437		appear to a USB host as a Linux gserial device or a
1438		Common Device Class Abstract Control Model serial device.
1439		If you select usbtty = gserial you should be able to enumerate
1440		a Linux host by
1441		# modprobe usbserial vendor=0xVendorID product=0xProductID
1442		else if using cdc_acm, simply setting the environment
1443		variable usbtty to be cdc_acm should suffice. The following
1444		might be defined in YourBoardName.h
1445
1446			CONFIG_USB_DEVICE
1447			Define this to build a UDC device
1448
1449			CONFIG_USB_TTY
1450			Define this to have a tty type of device available to
1451			talk to the UDC device
1452
1453			CONFIG_USBD_HS
1454			Define this to enable the high speed support for usb
1455			device and usbtty. If this feature is enabled, a routine
1456			int is_usbd_high_speed(void)
1457			also needs to be defined by the driver to dynamically poll
1458			whether the enumeration has succeded at high speed or full
1459			speed.
1460
1461			CONFIG_SYS_CONSOLE_IS_IN_ENV
1462			Define this if you want stdin, stdout &/or stderr to
1463			be set to usbtty.
1464
1465			mpc8xx:
1466				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1467				Derive USB clock from external clock "blah"
1468				- CONFIG_SYS_USB_EXTC_CLK 0x02
1469
1470				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1471				Derive USB clock from brgclk
1472				- CONFIG_SYS_USB_BRG_CLK 0x04
1473
1474		If you have a USB-IF assigned VendorID then you may wish to
1475		define your own vendor specific values either in BoardName.h
1476		or directly in usbd_vendor_info.h. If you don't define
1477		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1478		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1479		should pretend to be a Linux device to it's target host.
1480
1481			CONFIG_USBD_MANUFACTURER
1482			Define this string as the name of your company for
1483			- CONFIG_USBD_MANUFACTURER "my company"
1484
1485			CONFIG_USBD_PRODUCT_NAME
1486			Define this string as the name of your product
1487			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1488
1489			CONFIG_USBD_VENDORID
1490			Define this as your assigned Vendor ID from the USB
1491			Implementors Forum. This *must* be a genuine Vendor ID
1492			to avoid polluting the USB namespace.
1493			- CONFIG_USBD_VENDORID 0xFFFF
1494
1495			CONFIG_USBD_PRODUCTID
1496			Define this as the unique Product ID
1497			for your device
1498			- CONFIG_USBD_PRODUCTID 0xFFFF
1499
1500- ULPI Layer Support:
1501		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1502		the generic ULPI layer. The generic layer accesses the ULPI PHY
1503		via the platform viewport, so you need both the genric layer and
1504		the viewport enabled. Currently only Chipidea/ARC based
1505		viewport is supported.
1506		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1507		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1508		If your ULPI phy needs a different reference clock than the
1509		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1510		the appropriate value in Hz.
1511
1512- MMC Support:
1513		The MMC controller on the Intel PXA is supported. To
1514		enable this define CONFIG_MMC. The MMC can be
1515		accessed from the boot prompt by mapping the device
1516		to physical memory similar to flash. Command line is
1517		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1518		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1519
1520		CONFIG_SH_MMCIF
1521		Support for Renesas on-chip MMCIF controller
1522
1523			CONFIG_SH_MMCIF_ADDR
1524			Define the base address of MMCIF registers
1525
1526			CONFIG_SH_MMCIF_CLK
1527			Define the clock frequency for MMCIF
1528
1529		CONFIG_GENERIC_MMC
1530		Enable the generic MMC driver
1531
1532		CONFIG_SUPPORT_EMMC_BOOT
1533		Enable some additional features of the eMMC boot partitions.
1534
1535		CONFIG_SUPPORT_EMMC_RPMB
1536		Enable the commands for reading, writing and programming the
1537		key for the Replay Protection Memory Block partition in eMMC.
1538
1539- USB Device Firmware Update (DFU) class support:
1540		CONFIG_DFU_FUNCTION
1541		This enables the USB portion of the DFU USB class
1542
1543		CONFIG_CMD_DFU
1544		This enables the command "dfu" which is used to have
1545		U-Boot create a DFU class device via USB.  This command
1546		requires that the "dfu_alt_info" environment variable be
1547		set and define the alt settings to expose to the host.
1548
1549		CONFIG_DFU_MMC
1550		This enables support for exposing (e)MMC devices via DFU.
1551
1552		CONFIG_DFU_NAND
1553		This enables support for exposing NAND devices via DFU.
1554
1555		CONFIG_DFU_RAM
1556		This enables support for exposing RAM via DFU.
1557		Note: DFU spec refer to non-volatile memory usage, but
1558		allow usages beyond the scope of spec - here RAM usage,
1559		one that would help mostly the developer.
1560
1561		CONFIG_SYS_DFU_DATA_BUF_SIZE
1562		Dfu transfer uses a buffer before writing data to the
1563		raw storage device. Make the size (in bytes) of this buffer
1564		configurable. The size of this buffer is also configurable
1565		through the "dfu_bufsiz" environment variable.
1566
1567		CONFIG_SYS_DFU_MAX_FILE_SIZE
1568		When updating files rather than the raw storage device,
1569		we use a static buffer to copy the file into and then write
1570		the buffer once we've been given the whole file.  Define
1571		this to the maximum filesize (in bytes) for the buffer.
1572		Default is 4 MiB if undefined.
1573
1574		DFU_DEFAULT_POLL_TIMEOUT
1575		Poll timeout [ms], is the timeout a device can send to the
1576		host. The host must wait for this timeout before sending
1577		a subsequent DFU_GET_STATUS request to the device.
1578
1579		DFU_MANIFEST_POLL_TIMEOUT
1580		Poll timeout [ms], which the device sends to the host when
1581		entering dfuMANIFEST state. Host waits this timeout, before
1582		sending again an USB request to the device.
1583
1584- USB Device Android Fastboot support:
1585		CONFIG_CMD_FASTBOOT
1586		This enables the command "fastboot" which enables the Android
1587		fastboot mode for the platform's USB device. Fastboot is a USB
1588		protocol for downloading images, flashing and device control
1589		used on Android devices.
1590		See doc/README.android-fastboot for more information.
1591
1592		CONFIG_ANDROID_BOOT_IMAGE
1593		This enables support for booting images which use the Android
1594		image format header.
1595
1596		CONFIG_USB_FASTBOOT_BUF_ADDR
1597		The fastboot protocol requires a large memory buffer for
1598		downloads. Define this to the starting RAM address to use for
1599		downloaded images.
1600
1601		CONFIG_USB_FASTBOOT_BUF_SIZE
1602		The fastboot protocol requires a large memory buffer for
1603		downloads. This buffer should be as large as possible for a
1604		platform. Define this to the size available RAM for fastboot.
1605
1606- Journaling Flash filesystem support:
1607		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1608		CONFIG_JFFS2_NAND_DEV
1609		Define these for a default partition on a NAND device
1610
1611		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1612		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1613		Define these for a default partition on a NOR device
1614
1615		CONFIG_SYS_JFFS_CUSTOM_PART
1616		Define this to create an own partition. You have to provide a
1617		function struct part_info* jffs2_part_info(int part_num)
1618
1619		If you define only one JFFS2 partition you may also want to
1620		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1621		to disable the command chpart. This is the default when you
1622		have not defined a custom partition
1623
1624- FAT(File Allocation Table) filesystem write function support:
1625		CONFIG_FAT_WRITE
1626
1627		Define this to enable support for saving memory data as a
1628		file in FAT formatted partition.
1629
1630		This will also enable the command "fatwrite" enabling the
1631		user to write files to FAT.
1632
1633CBFS (Coreboot Filesystem) support
1634		CONFIG_CMD_CBFS
1635
1636		Define this to enable support for reading from a Coreboot
1637		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1638		and cbfsload.
1639
1640- FAT(File Allocation Table) filesystem cluster size:
1641		CONFIG_FS_FAT_MAX_CLUSTSIZE
1642
1643		Define the max cluster size for fat operations else
1644		a default value of 65536 will be defined.
1645
1646- Keyboard Support:
1647		CONFIG_ISA_KEYBOARD
1648
1649		Define this to enable standard (PC-Style) keyboard
1650		support
1651
1652		CONFIG_I8042_KBD
1653		Standard PC keyboard driver with US (is default) and
1654		GERMAN key layout (switch via environment 'keymap=de') support.
1655		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1656		for cfb_console. Supports cursor blinking.
1657
1658		CONFIG_CROS_EC_KEYB
1659		Enables a Chrome OS keyboard using the CROS_EC interface.
1660		This uses CROS_EC to communicate with a second microcontroller
1661		which provides key scans on request.
1662
1663- Video support:
1664		CONFIG_VIDEO
1665
1666		Define this to enable video support (for output to
1667		video).
1668
1669		CONFIG_VIDEO_CT69000
1670
1671		Enable Chips & Technologies 69000 Video chip
1672
1673		CONFIG_VIDEO_SMI_LYNXEM
1674		Enable Silicon Motion SMI 712/710/810 Video chip. The
1675		video output is selected via environment 'videoout'
1676		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1677		assumed.
1678
1679		For the CT69000 and SMI_LYNXEM drivers, videomode is
1680		selected via environment 'videomode'. Two different ways
1681		are possible:
1682		- "videomode=num"   'num' is a standard LiLo mode numbers.
1683		Following standard modes are supported	(* is default):
1684
1685		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1686		-------------+---------------------------------------------
1687		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1688		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1689		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1690		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1691		-------------+---------------------------------------------
1692		(i.e. setenv videomode 317; saveenv; reset;)
1693
1694		- "videomode=bootargs" all the video parameters are parsed
1695		from the bootargs. (See drivers/video/videomodes.c)
1696
1697
1698		CONFIG_VIDEO_SED13806
1699		Enable Epson SED13806 driver. This driver supports 8bpp
1700		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1701		or CONFIG_VIDEO_SED13806_16BPP
1702
1703		CONFIG_FSL_DIU_FB
1704		Enable the Freescale DIU video driver.	Reference boards for
1705		SOCs that have a DIU should define this macro to enable DIU
1706		support, and should also define these other macros:
1707
1708			CONFIG_SYS_DIU_ADDR
1709			CONFIG_VIDEO
1710			CONFIG_CMD_BMP
1711			CONFIG_CFB_CONSOLE
1712			CONFIG_VIDEO_SW_CURSOR
1713			CONFIG_VGA_AS_SINGLE_DEVICE
1714			CONFIG_VIDEO_LOGO
1715			CONFIG_VIDEO_BMP_LOGO
1716
1717		The DIU driver will look for the 'video-mode' environment
1718		variable, and if defined, enable the DIU as a console during
1719		boot.  See the documentation file README.video for a
1720		description of this variable.
1721
1722		CONFIG_VIDEO_VGA
1723
1724		Enable the VGA video / BIOS for x86. The alternative if you
1725		are using coreboot is to use the coreboot frame buffer
1726		driver.
1727
1728
1729- Keyboard Support:
1730		CONFIG_KEYBOARD
1731
1732		Define this to enable a custom keyboard support.
1733		This simply calls drv_keyboard_init() which must be
1734		defined in your board-specific files.
1735		The only board using this so far is RBC823.
1736
1737- LCD Support:	CONFIG_LCD
1738
1739		Define this to enable LCD support (for output to LCD
1740		display); also select one of the supported displays
1741		by defining one of these:
1742
1743		CONFIG_ATMEL_LCD:
1744
1745			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1746
1747		CONFIG_NEC_NL6448AC33:
1748
1749			NEC NL6448AC33-18. Active, color, single scan.
1750
1751		CONFIG_NEC_NL6448BC20
1752
1753			NEC NL6448BC20-08. 6.5", 640x480.
1754			Active, color, single scan.
1755
1756		CONFIG_NEC_NL6448BC33_54
1757
1758			NEC NL6448BC33-54. 10.4", 640x480.
1759			Active, color, single scan.
1760
1761		CONFIG_SHARP_16x9
1762
1763			Sharp 320x240. Active, color, single scan.
1764			It isn't 16x9, and I am not sure what it is.
1765
1766		CONFIG_SHARP_LQ64D341
1767
1768			Sharp LQ64D341 display, 640x480.
1769			Active, color, single scan.
1770
1771		CONFIG_HLD1045
1772
1773			HLD1045 display, 640x480.
1774			Active, color, single scan.
1775
1776		CONFIG_OPTREX_BW
1777
1778			Optrex	 CBL50840-2 NF-FW 99 22 M5
1779			or
1780			Hitachi	 LMG6912RPFC-00T
1781			or
1782			Hitachi	 SP14Q002
1783
1784			320x240. Black & white.
1785
1786		Normally display is black on white background; define
1787		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1788
1789		CONFIG_LCD_ALIGNMENT
1790
1791		Normally the LCD is page-aligned (tyically 4KB). If this is
1792		defined then the LCD will be aligned to this value instead.
1793		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1794		here, since it is cheaper to change data cache settings on
1795		a per-section basis.
1796
1797		CONFIG_CONSOLE_SCROLL_LINES
1798
1799		When the console need to be scrolled, this is the number of
1800		lines to scroll by. It defaults to 1. Increasing this makes
1801		the console jump but can help speed up operation when scrolling
1802		is slow.
1803
1804		CONFIG_LCD_BMP_RLE8
1805
1806		Support drawing of RLE8-compressed bitmaps on the LCD.
1807
1808		CONFIG_I2C_EDID
1809
1810		Enables an 'i2c edid' command which can read EDID
1811		information over I2C from an attached LCD display.
1812
1813- Splash Screen Support: CONFIG_SPLASH_SCREEN
1814
1815		If this option is set, the environment is checked for
1816		a variable "splashimage". If found, the usual display
1817		of logo, copyright and system information on the LCD
1818		is suppressed and the BMP image at the address
1819		specified in "splashimage" is loaded instead. The
1820		console is redirected to the "nulldev", too. This
1821		allows for a "silent" boot where a splash screen is
1822		loaded very quickly after power-on.
1823
1824		CONFIG_SPLASHIMAGE_GUARD
1825
1826		If this option is set, then U-Boot will prevent the environment
1827		variable "splashimage" from being set to a problematic address
1828		(see README.displaying-bmps).
1829		This option is useful for targets where, due to alignment
1830		restrictions, an improperly aligned BMP image will cause a data
1831		abort. If you think you will not have problems with unaligned
1832		accesses (for example because your toolchain prevents them)
1833		there is no need to set this option.
1834
1835		CONFIG_SPLASH_SCREEN_ALIGN
1836
1837		If this option is set the splash image can be freely positioned
1838		on the screen. Environment variable "splashpos" specifies the
1839		position as "x,y". If a positive number is given it is used as
1840		number of pixel from left/top. If a negative number is given it
1841		is used as number of pixel from right/bottom. You can also
1842		specify 'm' for centering the image.
1843
1844		Example:
1845		setenv splashpos m,m
1846			=> image at center of screen
1847
1848		setenv splashpos 30,20
1849			=> image at x = 30 and y = 20
1850
1851		setenv splashpos -10,m
1852			=> vertically centered image
1853			   at x = dspWidth - bmpWidth - 9
1854
1855- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1856
1857		If this option is set, additionally to standard BMP
1858		images, gzipped BMP images can be displayed via the
1859		splashscreen support or the bmp command.
1860
1861- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1862
1863		If this option is set, 8-bit RLE compressed BMP images
1864		can be displayed via the splashscreen support or the
1865		bmp command.
1866
1867- Do compresssing for memory range:
1868		CONFIG_CMD_ZIP
1869
1870		If this option is set, it would use zlib deflate method
1871		to compress the specified memory at its best effort.
1872
1873- Compression support:
1874		CONFIG_GZIP
1875
1876		Enabled by default to support gzip compressed images.
1877
1878		CONFIG_BZIP2
1879
1880		If this option is set, support for bzip2 compressed
1881		images is included. If not, only uncompressed and gzip
1882		compressed images are supported.
1883
1884		NOTE: the bzip2 algorithm requires a lot of RAM, so
1885		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1886		be at least 4MB.
1887
1888		CONFIG_LZMA
1889
1890		If this option is set, support for lzma compressed
1891		images is included.
1892
1893		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1894		requires an amount of dynamic memory that is given by the
1895		formula:
1896
1897			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1898
1899		Where lc and lp stand for, respectively, Literal context bits
1900		and Literal pos bits.
1901
1902		This value is upper-bounded by 14MB in the worst case. Anyway,
1903		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1904		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1905		a very small buffer.
1906
1907		Use the lzmainfo tool to determinate the lc and lp values and
1908		then calculate the amount of needed dynamic memory (ensuring
1909		the appropriate CONFIG_SYS_MALLOC_LEN value).
1910
1911		CONFIG_LZO
1912
1913		If this option is set, support for LZO compressed images
1914		is included.
1915
1916- MII/PHY support:
1917		CONFIG_PHY_ADDR
1918
1919		The address of PHY on MII bus.
1920
1921		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1922
1923		The clock frequency of the MII bus
1924
1925		CONFIG_PHY_GIGE
1926
1927		If this option is set, support for speed/duplex
1928		detection of gigabit PHY is included.
1929
1930		CONFIG_PHY_RESET_DELAY
1931
1932		Some PHY like Intel LXT971A need extra delay after
1933		reset before any MII register access is possible.
1934		For such PHY, set this option to the usec delay
1935		required. (minimum 300usec for LXT971A)
1936
1937		CONFIG_PHY_CMD_DELAY (ppc4xx)
1938
1939		Some PHY like Intel LXT971A need extra delay after
1940		command issued before MII status register can be read
1941
1942- Ethernet address:
1943		CONFIG_ETHADDR
1944		CONFIG_ETH1ADDR
1945		CONFIG_ETH2ADDR
1946		CONFIG_ETH3ADDR
1947		CONFIG_ETH4ADDR
1948		CONFIG_ETH5ADDR
1949
1950		Define a default value for Ethernet address to use
1951		for the respective Ethernet interface, in case this
1952		is not determined automatically.
1953
1954- IP address:
1955		CONFIG_IPADDR
1956
1957		Define a default value for the IP address to use for
1958		the default Ethernet interface, in case this is not
1959		determined through e.g. bootp.
1960		(Environment variable "ipaddr")
1961
1962- Server IP address:
1963		CONFIG_SERVERIP
1964
1965		Defines a default value for the IP address of a TFTP
1966		server to contact when using the "tftboot" command.
1967		(Environment variable "serverip")
1968
1969		CONFIG_KEEP_SERVERADDR
1970
1971		Keeps the server's MAC address, in the env 'serveraddr'
1972		for passing to bootargs (like Linux's netconsole option)
1973
1974- Gateway IP address:
1975		CONFIG_GATEWAYIP
1976
1977		Defines a default value for the IP address of the
1978		default router where packets to other networks are
1979		sent to.
1980		(Environment variable "gatewayip")
1981
1982- Subnet mask:
1983		CONFIG_NETMASK
1984
1985		Defines a default value for the subnet mask (or
1986		routing prefix) which is used to determine if an IP
1987		address belongs to the local subnet or needs to be
1988		forwarded through a router.
1989		(Environment variable "netmask")
1990
1991- Multicast TFTP Mode:
1992		CONFIG_MCAST_TFTP
1993
1994		Defines whether you want to support multicast TFTP as per
1995		rfc-2090; for example to work with atftp.  Lets lots of targets
1996		tftp down the same boot image concurrently.  Note: the Ethernet
1997		driver in use must provide a function: mcast() to join/leave a
1998		multicast group.
1999
2000- BOOTP Recovery Mode:
2001		CONFIG_BOOTP_RANDOM_DELAY
2002
2003		If you have many targets in a network that try to
2004		boot using BOOTP, you may want to avoid that all
2005		systems send out BOOTP requests at precisely the same
2006		moment (which would happen for instance at recovery
2007		from a power failure, when all systems will try to
2008		boot, thus flooding the BOOTP server. Defining
2009		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2010		inserted before sending out BOOTP requests. The
2011		following delays are inserted then:
2012
2013		1st BOOTP request:	delay 0 ... 1 sec
2014		2nd BOOTP request:	delay 0 ... 2 sec
2015		3rd BOOTP request:	delay 0 ... 4 sec
2016		4th and following
2017		BOOTP requests:		delay 0 ... 8 sec
2018
2019- DHCP Advanced Options:
2020		You can fine tune the DHCP functionality by defining
2021		CONFIG_BOOTP_* symbols:
2022
2023		CONFIG_BOOTP_SUBNETMASK
2024		CONFIG_BOOTP_GATEWAY
2025		CONFIG_BOOTP_HOSTNAME
2026		CONFIG_BOOTP_NISDOMAIN
2027		CONFIG_BOOTP_BOOTPATH
2028		CONFIG_BOOTP_BOOTFILESIZE
2029		CONFIG_BOOTP_DNS
2030		CONFIG_BOOTP_DNS2
2031		CONFIG_BOOTP_SEND_HOSTNAME
2032		CONFIG_BOOTP_NTPSERVER
2033		CONFIG_BOOTP_TIMEOFFSET
2034		CONFIG_BOOTP_VENDOREX
2035		CONFIG_BOOTP_MAY_FAIL
2036
2037		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2038		environment variable, not the BOOTP server.
2039
2040		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2041		after the configured retry count, the call will fail
2042		instead of starting over.  This can be used to fail over
2043		to Link-local IP address configuration if the DHCP server
2044		is not available.
2045
2046		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2047		serverip from a DHCP server, it is possible that more
2048		than one DNS serverip is offered to the client.
2049		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2050		serverip will be stored in the additional environment
2051		variable "dnsip2". The first DNS serverip is always
2052		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2053		is defined.
2054
2055		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2056		to do a dynamic update of a DNS server. To do this, they
2057		need the hostname of the DHCP requester.
2058		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2059		of the "hostname" environment variable is passed as
2060		option 12 to the DHCP server.
2061
2062		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2063
2064		A 32bit value in microseconds for a delay between
2065		receiving a "DHCP Offer" and sending the "DHCP Request".
2066		This fixes a problem with certain DHCP servers that don't
2067		respond 100% of the time to a "DHCP request". E.g. On an
2068		AT91RM9200 processor running at 180MHz, this delay needed
2069		to be *at least* 15,000 usec before a Windows Server 2003
2070		DHCP server would reply 100% of the time. I recommend at
2071		least 50,000 usec to be safe. The alternative is to hope
2072		that one of the retries will be successful but note that
2073		the DHCP timeout and retry process takes a longer than
2074		this delay.
2075
2076 - Link-local IP address negotiation:
2077		Negotiate with other link-local clients on the local network
2078		for an address that doesn't require explicit configuration.
2079		This is especially useful if a DHCP server cannot be guaranteed
2080		to exist in all environments that the device must operate.
2081
2082		See doc/README.link-local for more information.
2083
2084 - CDP Options:
2085		CONFIG_CDP_DEVICE_ID
2086
2087		The device id used in CDP trigger frames.
2088
2089		CONFIG_CDP_DEVICE_ID_PREFIX
2090
2091		A two character string which is prefixed to the MAC address
2092		of the device.
2093
2094		CONFIG_CDP_PORT_ID
2095
2096		A printf format string which contains the ascii name of
2097		the port. Normally is set to "eth%d" which sets
2098		eth0 for the first Ethernet, eth1 for the second etc.
2099
2100		CONFIG_CDP_CAPABILITIES
2101
2102		A 32bit integer which indicates the device capabilities;
2103		0x00000010 for a normal host which does not forwards.
2104
2105		CONFIG_CDP_VERSION
2106
2107		An ascii string containing the version of the software.
2108
2109		CONFIG_CDP_PLATFORM
2110
2111		An ascii string containing the name of the platform.
2112
2113		CONFIG_CDP_TRIGGER
2114
2115		A 32bit integer sent on the trigger.
2116
2117		CONFIG_CDP_POWER_CONSUMPTION
2118
2119		A 16bit integer containing the power consumption of the
2120		device in .1 of milliwatts.
2121
2122		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2123
2124		A byte containing the id of the VLAN.
2125
2126- Status LED:	CONFIG_STATUS_LED
2127
2128		Several configurations allow to display the current
2129		status using a LED. For instance, the LED will blink
2130		fast while running U-Boot code, stop blinking as
2131		soon as a reply to a BOOTP request was received, and
2132		start blinking slow once the Linux kernel is running
2133		(supported by a status LED driver in the Linux
2134		kernel). Defining CONFIG_STATUS_LED enables this
2135		feature in U-Boot.
2136
2137		Additional options:
2138
2139		CONFIG_GPIO_LED
2140		The status LED can be connected to a GPIO pin.
2141		In such cases, the gpio_led driver can be used as a
2142		status LED backend implementation. Define CONFIG_GPIO_LED
2143		to include the gpio_led driver in the U-Boot binary.
2144
2145		CONFIG_GPIO_LED_INVERTED_TABLE
2146		Some GPIO connected LEDs may have inverted polarity in which
2147		case the GPIO high value corresponds to LED off state and
2148		GPIO low value corresponds to LED on state.
2149		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2150		with a list of GPIO LEDs that have inverted polarity.
2151
2152- CAN Support:	CONFIG_CAN_DRIVER
2153
2154		Defining CONFIG_CAN_DRIVER enables CAN driver support
2155		on those systems that support this (optional)
2156		feature, like the TQM8xxL modules.
2157
2158- I2C Support:	CONFIG_SYS_I2C
2159
2160		This enable the NEW i2c subsystem, and will allow you to use
2161		i2c commands at the u-boot command line (as long as you set
2162		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2163		based realtime clock chips or other i2c devices. See
2164		common/cmd_i2c.c for a description of the command line
2165		interface.
2166
2167		ported i2c driver to the new framework:
2168		- drivers/i2c/soft_i2c.c:
2169		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2170		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2171		    for defining speed and slave address
2172		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2173		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2174		    for defining speed and slave address
2175		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2176		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2177		    for defining speed and slave address
2178		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2179		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2180		    for defining speed and slave address
2181
2182		- drivers/i2c/fsl_i2c.c:
2183		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2184		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2185		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2186		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2187		    bus.
2188		  - If your board supports a second fsl i2c bus, define
2189		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2190		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2191		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2192		    second bus.
2193
2194		- drivers/i2c/tegra_i2c.c:
2195		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2196		  - This driver adds 4 i2c buses with a fix speed from
2197		    100000 and the slave addr 0!
2198
2199		- drivers/i2c/ppc4xx_i2c.c
2200		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2201		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2202		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2203
2204		- drivers/i2c/i2c_mxc.c
2205		  - activate this driver with CONFIG_SYS_I2C_MXC
2206		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2207		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2208		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2209		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2210		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2211		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2212		If thoses defines are not set, default value is 100000
2213		for speed, and 0 for slave.
2214
2215		- drivers/i2c/rcar_i2c.c:
2216		  - activate this driver with CONFIG_SYS_I2C_RCAR
2217		  - This driver adds 4 i2c buses
2218
2219		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2220		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2221		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2222		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2223		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2224		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2225		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2226		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2227		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2228
2229		- drivers/i2c/sh_i2c.c:
2230		  - activate this driver with CONFIG_SYS_I2C_SH
2231		  - This driver adds from 2 to 5 i2c buses
2232
2233		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2234		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2235		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2236		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2237		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2238		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2239		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2240		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2241		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2242		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2243		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2244		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2245		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2246
2247		- drivers/i2c/omap24xx_i2c.c
2248		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2249		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2250		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2251		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2252		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2253		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2254		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2255		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2256		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2257		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2258		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2259
2260		- drivers/i2c/zynq_i2c.c
2261		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2262		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2263		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2264
2265		- drivers/i2c/s3c24x0_i2c.c:
2266		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2267		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2268		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2269		    with a fix speed from 100000 and the slave addr 0!
2270
2271		additional defines:
2272
2273		CONFIG_SYS_NUM_I2C_BUSES
2274		Hold the number of i2c busses you want to use. If you
2275		don't use/have i2c muxes on your i2c bus, this
2276		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2277		omit this define.
2278
2279		CONFIG_SYS_I2C_DIRECT_BUS
2280		define this, if you don't use i2c muxes on your hardware.
2281		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2282		omit this define.
2283
2284		CONFIG_SYS_I2C_MAX_HOPS
2285		define how many muxes are maximal consecutively connected
2286		on one i2c bus. If you not use i2c muxes, omit this
2287		define.
2288
2289		CONFIG_SYS_I2C_BUSES
2290		hold a list of busses you want to use, only used if
2291		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2292		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2293		CONFIG_SYS_NUM_I2C_BUSES = 9:
2294
2295		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2296					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2297					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2298					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2299					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2300					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2301					{1, {I2C_NULL_HOP}}, \
2302					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2303					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2304					}
2305
2306		which defines
2307			bus 0 on adapter 0 without a mux
2308			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2309			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2310			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2311			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2312			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2313			bus 6 on adapter 1 without a mux
2314			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2315			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2316
2317		If you do not have i2c muxes on your board, omit this define.
2318
2319- Legacy I2C Support:	CONFIG_HARD_I2C
2320
2321		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2322		provides the following compelling advantages:
2323
2324		- more than one i2c adapter is usable
2325		- approved multibus support
2326		- better i2c mux support
2327
2328		** Please consider updating your I2C driver now. **
2329
2330		These enable legacy I2C serial bus commands. Defining
2331		CONFIG_HARD_I2C will include the appropriate I2C driver
2332		for the selected CPU.
2333
2334		This will allow you to use i2c commands at the u-boot
2335		command line (as long as you set CONFIG_CMD_I2C in
2336		CONFIG_COMMANDS) and communicate with i2c based realtime
2337		clock chips. See common/cmd_i2c.c for a description of the
2338		command line interface.
2339
2340		CONFIG_HARD_I2C selects a hardware I2C controller.
2341
2342		There are several other quantities that must also be
2343		defined when you define CONFIG_HARD_I2C.
2344
2345		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2346		to be the frequency (in Hz) at which you wish your i2c bus
2347		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2348		the CPU's i2c node address).
2349
2350		Now, the u-boot i2c code for the mpc8xx
2351		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2352		and so its address should therefore be cleared to 0 (See,
2353		eg, MPC823e User's Manual p.16-473). So, set
2354		CONFIG_SYS_I2C_SLAVE to 0.
2355
2356		CONFIG_SYS_I2C_INIT_MPC5XXX
2357
2358		When a board is reset during an i2c bus transfer
2359		chips might think that the current transfer is still
2360		in progress.  Reset the slave devices by sending start
2361		commands until the slave device responds.
2362
2363		That's all that's required for CONFIG_HARD_I2C.
2364
2365		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2366		then the following macros need to be defined (examples are
2367		from include/configs/lwmon.h):
2368
2369		I2C_INIT
2370
2371		(Optional). Any commands necessary to enable the I2C
2372		controller or configure ports.
2373
2374		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2375
2376		I2C_PORT
2377
2378		(Only for MPC8260 CPU). The I/O port to use (the code
2379		assumes both bits are on the same port). Valid values
2380		are 0..3 for ports A..D.
2381
2382		I2C_ACTIVE
2383
2384		The code necessary to make the I2C data line active
2385		(driven).  If the data line is open collector, this
2386		define can be null.
2387
2388		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2389
2390		I2C_TRISTATE
2391
2392		The code necessary to make the I2C data line tri-stated
2393		(inactive).  If the data line is open collector, this
2394		define can be null.
2395
2396		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2397
2398		I2C_READ
2399
2400		Code that returns true if the I2C data line is high,
2401		false if it is low.
2402
2403		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2404
2405		I2C_SDA(bit)
2406
2407		If <bit> is true, sets the I2C data line high. If it
2408		is false, it clears it (low).
2409
2410		eg: #define I2C_SDA(bit) \
2411			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2412			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2413
2414		I2C_SCL(bit)
2415
2416		If <bit> is true, sets the I2C clock line high. If it
2417		is false, it clears it (low).
2418
2419		eg: #define I2C_SCL(bit) \
2420			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2421			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2422
2423		I2C_DELAY
2424
2425		This delay is invoked four times per clock cycle so this
2426		controls the rate of data transfer.  The data rate thus
2427		is 1 / (I2C_DELAY * 4). Often defined to be something
2428		like:
2429
2430		#define I2C_DELAY  udelay(2)
2431
2432		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2433
2434		If your arch supports the generic GPIO framework (asm/gpio.h),
2435		then you may alternatively define the two GPIOs that are to be
2436		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2437		have GPIO-based defaults assigned to them as appropriate.
2438
2439		You should define these to the GPIO value as given directly to
2440		the generic GPIO functions.
2441
2442		CONFIG_SYS_I2C_INIT_BOARD
2443
2444		When a board is reset during an i2c bus transfer
2445		chips might think that the current transfer is still
2446		in progress. On some boards it is possible to access
2447		the i2c SCLK line directly, either by using the
2448		processor pin as a GPIO or by having a second pin
2449		connected to the bus. If this option is defined a
2450		custom i2c_init_board() routine in boards/xxx/board.c
2451		is run early in the boot sequence.
2452
2453		CONFIG_SYS_I2C_BOARD_LATE_INIT
2454
2455		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2456		defined a custom i2c_board_late_init() routine in
2457		boards/xxx/board.c is run AFTER the operations in i2c_init()
2458		is completed. This callpoint can be used to unreset i2c bus
2459		using CPU i2c controller register accesses for CPUs whose i2c
2460		controller provide such a method. It is called at the end of
2461		i2c_init() to allow i2c_init operations to setup the i2c bus
2462		controller on the CPU (e.g. setting bus speed & slave address).
2463
2464		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2465
2466		This option enables configuration of bi_iic_fast[] flags
2467		in u-boot bd_info structure based on u-boot environment
2468		variable "i2cfast". (see also i2cfast)
2469
2470		CONFIG_I2C_MULTI_BUS
2471
2472		This option allows the use of multiple I2C buses, each of which
2473		must have a controller.	 At any point in time, only one bus is
2474		active.	 To switch to a different bus, use the 'i2c dev' command.
2475		Note that bus numbering is zero-based.
2476
2477		CONFIG_SYS_I2C_NOPROBES
2478
2479		This option specifies a list of I2C devices that will be skipped
2480		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2481		is set, specify a list of bus-device pairs.  Otherwise, specify
2482		a 1D array of device addresses
2483
2484		e.g.
2485			#undef	CONFIG_I2C_MULTI_BUS
2486			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2487
2488		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2489
2490			#define CONFIG_I2C_MULTI_BUS
2491			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2492
2493		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2494
2495		CONFIG_SYS_SPD_BUS_NUM
2496
2497		If defined, then this indicates the I2C bus number for DDR SPD.
2498		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2499
2500		CONFIG_SYS_RTC_BUS_NUM
2501
2502		If defined, then this indicates the I2C bus number for the RTC.
2503		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2504
2505		CONFIG_SYS_DTT_BUS_NUM
2506
2507		If defined, then this indicates the I2C bus number for the DTT.
2508		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2509
2510		CONFIG_SYS_I2C_DTT_ADDR:
2511
2512		If defined, specifies the I2C address of the DTT device.
2513		If not defined, then U-Boot uses predefined value for
2514		specified DTT device.
2515
2516		CONFIG_SOFT_I2C_READ_REPEATED_START
2517
2518		defining this will force the i2c_read() function in
2519		the soft_i2c driver to perform an I2C repeated start
2520		between writing the address pointer and reading the
2521		data.  If this define is omitted the default behaviour
2522		of doing a stop-start sequence will be used.  Most I2C
2523		devices can use either method, but some require one or
2524		the other.
2525
2526- SPI Support:	CONFIG_SPI
2527
2528		Enables SPI driver (so far only tested with
2529		SPI EEPROM, also an instance works with Crystal A/D and
2530		D/As on the SACSng board)
2531
2532		CONFIG_SH_SPI
2533
2534		Enables the driver for SPI controller on SuperH. Currently
2535		only SH7757 is supported.
2536
2537		CONFIG_SPI_X
2538
2539		Enables extended (16-bit) SPI EEPROM addressing.
2540		(symmetrical to CONFIG_I2C_X)
2541
2542		CONFIG_SOFT_SPI
2543
2544		Enables a software (bit-bang) SPI driver rather than
2545		using hardware support. This is a general purpose
2546		driver that only requires three general I/O port pins
2547		(two outputs, one input) to function. If this is
2548		defined, the board configuration must define several
2549		SPI configuration items (port pins to use, etc). For
2550		an example, see include/configs/sacsng.h.
2551
2552		CONFIG_HARD_SPI
2553
2554		Enables a hardware SPI driver for general-purpose reads
2555		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2556		must define a list of chip-select function pointers.
2557		Currently supported on some MPC8xxx processors.	 For an
2558		example, see include/configs/mpc8349emds.h.
2559
2560		CONFIG_MXC_SPI
2561
2562		Enables the driver for the SPI controllers on i.MX and MXC
2563		SoCs. Currently i.MX31/35/51 are supported.
2564
2565- FPGA Support: CONFIG_FPGA
2566
2567		Enables FPGA subsystem.
2568
2569		CONFIG_FPGA_<vendor>
2570
2571		Enables support for specific chip vendors.
2572		(ALTERA, XILINX)
2573
2574		CONFIG_FPGA_<family>
2575
2576		Enables support for FPGA family.
2577		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2578
2579		CONFIG_FPGA_COUNT
2580
2581		Specify the number of FPGA devices to support.
2582
2583		CONFIG_CMD_FPGA_LOADMK
2584
2585		Enable support for fpga loadmk command
2586
2587		CONFIG_CMD_FPGA_LOADP
2588
2589		Enable support for fpga loadp command - load partial bitstream
2590
2591		CONFIG_CMD_FPGA_LOADBP
2592
2593		Enable support for fpga loadbp command - load partial bitstream
2594		(Xilinx only)
2595
2596		CONFIG_SYS_FPGA_PROG_FEEDBACK
2597
2598		Enable printing of hash marks during FPGA configuration.
2599
2600		CONFIG_SYS_FPGA_CHECK_BUSY
2601
2602		Enable checks on FPGA configuration interface busy
2603		status by the configuration function. This option
2604		will require a board or device specific function to
2605		be written.
2606
2607		CONFIG_FPGA_DELAY
2608
2609		If defined, a function that provides delays in the FPGA
2610		configuration driver.
2611
2612		CONFIG_SYS_FPGA_CHECK_CTRLC
2613		Allow Control-C to interrupt FPGA configuration
2614
2615		CONFIG_SYS_FPGA_CHECK_ERROR
2616
2617		Check for configuration errors during FPGA bitfile
2618		loading. For example, abort during Virtex II
2619		configuration if the INIT_B line goes low (which
2620		indicated a CRC error).
2621
2622		CONFIG_SYS_FPGA_WAIT_INIT
2623
2624		Maximum time to wait for the INIT_B line to deassert
2625		after PROB_B has been deasserted during a Virtex II
2626		FPGA configuration sequence. The default time is 500
2627		ms.
2628
2629		CONFIG_SYS_FPGA_WAIT_BUSY
2630
2631		Maximum time to wait for BUSY to deassert during
2632		Virtex II FPGA configuration. The default is 5 ms.
2633
2634		CONFIG_SYS_FPGA_WAIT_CONFIG
2635
2636		Time to wait after FPGA configuration. The default is
2637		200 ms.
2638
2639- Configuration Management:
2640		CONFIG_IDENT_STRING
2641
2642		If defined, this string will be added to the U-Boot
2643		version information (U_BOOT_VERSION)
2644
2645- Vendor Parameter Protection:
2646
2647		U-Boot considers the values of the environment
2648		variables "serial#" (Board Serial Number) and
2649		"ethaddr" (Ethernet Address) to be parameters that
2650		are set once by the board vendor / manufacturer, and
2651		protects these variables from casual modification by
2652		the user. Once set, these variables are read-only,
2653		and write or delete attempts are rejected. You can
2654		change this behaviour:
2655
2656		If CONFIG_ENV_OVERWRITE is #defined in your config
2657		file, the write protection for vendor parameters is
2658		completely disabled. Anybody can change or delete
2659		these parameters.
2660
2661		Alternatively, if you #define _both_ CONFIG_ETHADDR
2662		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2663		Ethernet address is installed in the environment,
2664		which can be changed exactly ONCE by the user. [The
2665		serial# is unaffected by this, i. e. it remains
2666		read-only.]
2667
2668		The same can be accomplished in a more flexible way
2669		for any variable by configuring the type of access
2670		to allow for those variables in the ".flags" variable
2671		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2672
2673- Protected RAM:
2674		CONFIG_PRAM
2675
2676		Define this variable to enable the reservation of
2677		"protected RAM", i. e. RAM which is not overwritten
2678		by U-Boot. Define CONFIG_PRAM to hold the number of
2679		kB you want to reserve for pRAM. You can overwrite
2680		this default value by defining an environment
2681		variable "pram" to the number of kB you want to
2682		reserve. Note that the board info structure will
2683		still show the full amount of RAM. If pRAM is
2684		reserved, a new environment variable "mem" will
2685		automatically be defined to hold the amount of
2686		remaining RAM in a form that can be passed as boot
2687		argument to Linux, for instance like that:
2688
2689			setenv bootargs ... mem=\${mem}
2690			saveenv
2691
2692		This way you can tell Linux not to use this memory,
2693		either, which results in a memory region that will
2694		not be affected by reboots.
2695
2696		*WARNING* If your board configuration uses automatic
2697		detection of the RAM size, you must make sure that
2698		this memory test is non-destructive. So far, the
2699		following board configurations are known to be
2700		"pRAM-clean":
2701
2702			IVMS8, IVML24, SPD8xx, TQM8xxL,
2703			HERMES, IP860, RPXlite, LWMON,
2704			FLAGADM, TQM8260
2705
2706- Access to physical memory region (> 4GB)
2707		Some basic support is provided for operations on memory not
2708		normally accessible to U-Boot - e.g. some architectures
2709		support access to more than 4GB of memory on 32-bit
2710		machines using physical address extension or similar.
2711		Define CONFIG_PHYSMEM to access this basic support, which
2712		currently only supports clearing the memory.
2713
2714- Error Recovery:
2715		CONFIG_PANIC_HANG
2716
2717		Define this variable to stop the system in case of a
2718		fatal error, so that you have to reset it manually.
2719		This is probably NOT a good idea for an embedded
2720		system where you want the system to reboot
2721		automatically as fast as possible, but it may be
2722		useful during development since you can try to debug
2723		the conditions that lead to the situation.
2724
2725		CONFIG_NET_RETRY_COUNT
2726
2727		This variable defines the number of retries for
2728		network operations like ARP, RARP, TFTP, or BOOTP
2729		before giving up the operation. If not defined, a
2730		default value of 5 is used.
2731
2732		CONFIG_ARP_TIMEOUT
2733
2734		Timeout waiting for an ARP reply in milliseconds.
2735
2736		CONFIG_NFS_TIMEOUT
2737
2738		Timeout in milliseconds used in NFS protocol.
2739		If you encounter "ERROR: Cannot umount" in nfs command,
2740		try longer timeout such as
2741		#define CONFIG_NFS_TIMEOUT 10000UL
2742
2743- Command Interpreter:
2744		CONFIG_AUTO_COMPLETE
2745
2746		Enable auto completion of commands using TAB.
2747
2748		Note that this feature has NOT been implemented yet
2749		for the "hush" shell.
2750
2751
2752		CONFIG_SYS_HUSH_PARSER
2753
2754		Define this variable to enable the "hush" shell (from
2755		Busybox) as command line interpreter, thus enabling
2756		powerful command line syntax like
2757		if...then...else...fi conditionals or `&&' and '||'
2758		constructs ("shell scripts").
2759
2760		If undefined, you get the old, much simpler behaviour
2761		with a somewhat smaller memory footprint.
2762
2763
2764		CONFIG_SYS_PROMPT_HUSH_PS2
2765
2766		This defines the secondary prompt string, which is
2767		printed when the command interpreter needs more input
2768		to complete a command. Usually "> ".
2769
2770	Note:
2771
2772		In the current implementation, the local variables
2773		space and global environment variables space are
2774		separated. Local variables are those you define by
2775		simply typing `name=value'. To access a local
2776		variable later on, you have write `$name' or
2777		`${name}'; to execute the contents of a variable
2778		directly type `$name' at the command prompt.
2779
2780		Global environment variables are those you use
2781		setenv/printenv to work with. To run a command stored
2782		in such a variable, you need to use the run command,
2783		and you must not use the '$' sign to access them.
2784
2785		To store commands and special characters in a
2786		variable, please use double quotation marks
2787		surrounding the whole text of the variable, instead
2788		of the backslashes before semicolons and special
2789		symbols.
2790
2791- Commandline Editing and History:
2792		CONFIG_CMDLINE_EDITING
2793
2794		Enable editing and History functions for interactive
2795		commandline input operations
2796
2797- Default Environment:
2798		CONFIG_EXTRA_ENV_SETTINGS
2799
2800		Define this to contain any number of null terminated
2801		strings (variable = value pairs) that will be part of
2802		the default environment compiled into the boot image.
2803
2804		For example, place something like this in your
2805		board's config file:
2806
2807		#define CONFIG_EXTRA_ENV_SETTINGS \
2808			"myvar1=value1\0" \
2809			"myvar2=value2\0"
2810
2811		Warning: This method is based on knowledge about the
2812		internal format how the environment is stored by the
2813		U-Boot code. This is NOT an official, exported
2814		interface! Although it is unlikely that this format
2815		will change soon, there is no guarantee either.
2816		You better know what you are doing here.
2817
2818		Note: overly (ab)use of the default environment is
2819		discouraged. Make sure to check other ways to preset
2820		the environment like the "source" command or the
2821		boot command first.
2822
2823		CONFIG_ENV_VARS_UBOOT_CONFIG
2824
2825		Define this in order to add variables describing the
2826		U-Boot build configuration to the default environment.
2827		These will be named arch, cpu, board, vendor, and soc.
2828
2829		Enabling this option will cause the following to be defined:
2830
2831		- CONFIG_SYS_ARCH
2832		- CONFIG_SYS_CPU
2833		- CONFIG_SYS_BOARD
2834		- CONFIG_SYS_VENDOR
2835		- CONFIG_SYS_SOC
2836
2837		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2838
2839		Define this in order to add variables describing certain
2840		run-time determined information about the hardware to the
2841		environment.  These will be named board_name, board_rev.
2842
2843		CONFIG_DELAY_ENVIRONMENT
2844
2845		Normally the environment is loaded when the board is
2846		intialised so that it is available to U-Boot. This inhibits
2847		that so that the environment is not available until
2848		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2849		this is instead controlled by the value of
2850		/config/load-environment.
2851
2852- DataFlash Support:
2853		CONFIG_HAS_DATAFLASH
2854
2855		Defining this option enables DataFlash features and
2856		allows to read/write in Dataflash via the standard
2857		commands cp, md...
2858
2859- Serial Flash support
2860		CONFIG_CMD_SF
2861
2862		Defining this option enables SPI flash commands
2863		'sf probe/read/write/erase/update'.
2864
2865		Usage requires an initial 'probe' to define the serial
2866		flash parameters, followed by read/write/erase/update
2867		commands.
2868
2869		The following defaults may be provided by the platform
2870		to handle the common case when only a single serial
2871		flash is present on the system.
2872
2873		CONFIG_SF_DEFAULT_BUS		Bus identifier
2874		CONFIG_SF_DEFAULT_CS		Chip-select
2875		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2876		CONFIG_SF_DEFAULT_SPEED		in Hz
2877
2878		CONFIG_CMD_SF_TEST
2879
2880		Define this option to include a destructive SPI flash
2881		test ('sf test').
2882
2883		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2884
2885		Define this option to use the Bank addr/Extended addr
2886		support on SPI flashes which has size > 16Mbytes.
2887
2888		CONFIG_SF_DUAL_FLASH		Dual flash memories
2889
2890		Define this option to use dual flash support where two flash
2891		memories can be connected with a given cs line.
2892		currently Xilinx Zynq qspi support these type of connections.
2893
2894- SystemACE Support:
2895		CONFIG_SYSTEMACE
2896
2897		Adding this option adds support for Xilinx SystemACE
2898		chips attached via some sort of local bus. The address
2899		of the chip must also be defined in the
2900		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2901
2902		#define CONFIG_SYSTEMACE
2903		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2904
2905		When SystemACE support is added, the "ace" device type
2906		becomes available to the fat commands, i.e. fatls.
2907
2908- TFTP Fixed UDP Port:
2909		CONFIG_TFTP_PORT
2910
2911		If this is defined, the environment variable tftpsrcp
2912		is used to supply the TFTP UDP source port value.
2913		If tftpsrcp isn't defined, the normal pseudo-random port
2914		number generator is used.
2915
2916		Also, the environment variable tftpdstp is used to supply
2917		the TFTP UDP destination port value.  If tftpdstp isn't
2918		defined, the normal port 69 is used.
2919
2920		The purpose for tftpsrcp is to allow a TFTP server to
2921		blindly start the TFTP transfer using the pre-configured
2922		target IP address and UDP port. This has the effect of
2923		"punching through" the (Windows XP) firewall, allowing
2924		the remainder of the TFTP transfer to proceed normally.
2925		A better solution is to properly configure the firewall,
2926		but sometimes that is not allowed.
2927
2928- Hashing support:
2929		CONFIG_CMD_HASH
2930
2931		This enables a generic 'hash' command which can produce
2932		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2933
2934		CONFIG_HASH_VERIFY
2935
2936		Enable the hash verify command (hash -v). This adds to code
2937		size a little.
2938
2939		CONFIG_SHA1 - support SHA1 hashing
2940		CONFIG_SHA256 - support SHA256 hashing
2941
2942		Note: There is also a sha1sum command, which should perhaps
2943		be deprecated in favour of 'hash sha1'.
2944
2945- Freescale i.MX specific commands:
2946		CONFIG_CMD_HDMIDETECT
2947		This enables 'hdmidet' command which returns true if an
2948		HDMI monitor is detected.  This command is i.MX 6 specific.
2949
2950		CONFIG_CMD_BMODE
2951		This enables the 'bmode' (bootmode) command for forcing
2952		a boot from specific media.
2953
2954		This is useful for forcing the ROM's usb downloader to
2955		activate upon a watchdog reset which is nice when iterating
2956		on U-Boot.  Using the reset button or running bmode normal
2957		will set it back to normal.  This command currently
2958		supports i.MX53 and i.MX6.
2959
2960- Signing support:
2961		CONFIG_RSA
2962
2963		This enables the RSA algorithm used for FIT image verification
2964		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2965
2966		The signing part is build into mkimage regardless of this
2967		option.
2968
2969- bootcount support:
2970		CONFIG_BOOTCOUNT_LIMIT
2971
2972		This enables the bootcounter support, see:
2973		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2974
2975		CONFIG_AT91SAM9XE
2976		enable special bootcounter support on at91sam9xe based boards.
2977		CONFIG_BLACKFIN
2978		enable special bootcounter support on blackfin based boards.
2979		CONFIG_SOC_DA8XX
2980		enable special bootcounter support on da850 based boards.
2981		CONFIG_BOOTCOUNT_RAM
2982		enable support for the bootcounter in RAM
2983		CONFIG_BOOTCOUNT_I2C
2984		enable support for the bootcounter on an i2c (like RTC) device.
2985			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2986			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2987						    the bootcounter.
2988			CONFIG_BOOTCOUNT_ALEN = address len
2989
2990- Show boot progress:
2991		CONFIG_SHOW_BOOT_PROGRESS
2992
2993		Defining this option allows to add some board-
2994		specific code (calling a user-provided function
2995		"show_boot_progress(int)") that enables you to show
2996		the system's boot progress on some display (for
2997		example, some LED's) on your board. At the moment,
2998		the following checkpoints are implemented:
2999
3000- Detailed boot stage timing
3001		CONFIG_BOOTSTAGE
3002		Define this option to get detailed timing of each stage
3003		of the boot process.
3004
3005		CONFIG_BOOTSTAGE_USER_COUNT
3006		This is the number of available user bootstage records.
3007		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
3008		a new ID will be allocated from this stash. If you exceed
3009		the limit, recording will stop.
3010
3011		CONFIG_BOOTSTAGE_REPORT
3012		Define this to print a report before boot, similar to this:
3013
3014		Timer summary in microseconds:
3015		       Mark    Elapsed  Stage
3016			  0          0  reset
3017		  3,575,678  3,575,678  board_init_f start
3018		  3,575,695         17  arch_cpu_init A9
3019		  3,575,777         82  arch_cpu_init done
3020		  3,659,598     83,821  board_init_r start
3021		  3,910,375    250,777  main_loop
3022		 29,916,167 26,005,792  bootm_start
3023		 30,361,327    445,160  start_kernel
3024
3025		CONFIG_CMD_BOOTSTAGE
3026		Add a 'bootstage' command which supports printing a report
3027		and un/stashing of bootstage data.
3028
3029		CONFIG_BOOTSTAGE_FDT
3030		Stash the bootstage information in the FDT. A root 'bootstage'
3031		node is created with each bootstage id as a child. Each child
3032		has a 'name' property and either 'mark' containing the
3033		mark time in microsecond, or 'accum' containing the
3034		accumulated time for that bootstage id in microseconds.
3035		For example:
3036
3037		bootstage {
3038			154 {
3039				name = "board_init_f";
3040				mark = <3575678>;
3041			};
3042			170 {
3043				name = "lcd";
3044				accum = <33482>;
3045			};
3046		};
3047
3048		Code in the Linux kernel can find this in /proc/devicetree.
3049
3050Legacy uImage format:
3051
3052  Arg	Where			When
3053    1	common/cmd_bootm.c	before attempting to boot an image
3054   -1	common/cmd_bootm.c	Image header has bad	 magic number
3055    2	common/cmd_bootm.c	Image header has correct magic number
3056   -2	common/cmd_bootm.c	Image header has bad	 checksum
3057    3	common/cmd_bootm.c	Image header has correct checksum
3058   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3059    4	common/cmd_bootm.c	Image data   has correct checksum
3060   -4	common/cmd_bootm.c	Image is for unsupported architecture
3061    5	common/cmd_bootm.c	Architecture check OK
3062   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3063    6	common/cmd_bootm.c	Image Type check OK
3064   -6	common/cmd_bootm.c	gunzip uncompression error
3065   -7	common/cmd_bootm.c	Unimplemented compression type
3066    7	common/cmd_bootm.c	Uncompression OK
3067    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3068   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3069
3070    9	common/image.c		Start initial ramdisk verification
3071  -10	common/image.c		Ramdisk header has bad	   magic number
3072  -11	common/image.c		Ramdisk header has bad	   checksum
3073   10	common/image.c		Ramdisk header is OK
3074  -12	common/image.c		Ramdisk data   has bad	   checksum
3075   11	common/image.c		Ramdisk data   has correct checksum
3076   12	common/image.c		Ramdisk verification complete, start loading
3077  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3078   13	common/image.c		Start multifile image verification
3079   14	common/image.c		No initial ramdisk, no multifile, continue.
3080
3081   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3082
3083  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3084  -31	post/post.c		POST test failed, detected by post_output_backlog()
3085  -32	post/post.c		POST test failed, detected by post_run_single()
3086
3087   34	common/cmd_doc.c	before loading a Image from a DOC device
3088  -35	common/cmd_doc.c	Bad usage of "doc" command
3089   35	common/cmd_doc.c	correct usage of "doc" command
3090  -36	common/cmd_doc.c	No boot device
3091   36	common/cmd_doc.c	correct boot device
3092  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3093   37	common/cmd_doc.c	correct chip ID found, device available
3094  -38	common/cmd_doc.c	Read Error on boot device
3095   38	common/cmd_doc.c	reading Image header from DOC device OK
3096  -39	common/cmd_doc.c	Image header has bad magic number
3097   39	common/cmd_doc.c	Image header has correct magic number
3098  -40	common/cmd_doc.c	Error reading Image from DOC device
3099   40	common/cmd_doc.c	Image header has correct magic number
3100   41	common/cmd_ide.c	before loading a Image from a IDE device
3101  -42	common/cmd_ide.c	Bad usage of "ide" command
3102   42	common/cmd_ide.c	correct usage of "ide" command
3103  -43	common/cmd_ide.c	No boot device
3104   43	common/cmd_ide.c	boot device found
3105  -44	common/cmd_ide.c	Device not available
3106   44	common/cmd_ide.c	Device available
3107  -45	common/cmd_ide.c	wrong partition selected
3108   45	common/cmd_ide.c	partition selected
3109  -46	common/cmd_ide.c	Unknown partition table
3110   46	common/cmd_ide.c	valid partition table found
3111  -47	common/cmd_ide.c	Invalid partition type
3112   47	common/cmd_ide.c	correct partition type
3113  -48	common/cmd_ide.c	Error reading Image Header on boot device
3114   48	common/cmd_ide.c	reading Image Header from IDE device OK
3115  -49	common/cmd_ide.c	Image header has bad magic number
3116   49	common/cmd_ide.c	Image header has correct magic number
3117  -50	common/cmd_ide.c	Image header has bad	 checksum
3118   50	common/cmd_ide.c	Image header has correct checksum
3119  -51	common/cmd_ide.c	Error reading Image from IDE device
3120   51	common/cmd_ide.c	reading Image from IDE device OK
3121   52	common/cmd_nand.c	before loading a Image from a NAND device
3122  -53	common/cmd_nand.c	Bad usage of "nand" command
3123   53	common/cmd_nand.c	correct usage of "nand" command
3124  -54	common/cmd_nand.c	No boot device
3125   54	common/cmd_nand.c	boot device found
3126  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3127   55	common/cmd_nand.c	correct chip ID found, device available
3128  -56	common/cmd_nand.c	Error reading Image Header on boot device
3129   56	common/cmd_nand.c	reading Image Header from NAND device OK
3130  -57	common/cmd_nand.c	Image header has bad magic number
3131   57	common/cmd_nand.c	Image header has correct magic number
3132  -58	common/cmd_nand.c	Error reading Image from NAND device
3133   58	common/cmd_nand.c	reading Image from NAND device OK
3134
3135  -60	common/env_common.c	Environment has a bad CRC, using default
3136
3137   64	net/eth.c		starting with Ethernet configuration.
3138  -64	net/eth.c		no Ethernet found.
3139   65	net/eth.c		Ethernet found.
3140
3141  -80	common/cmd_net.c	usage wrong
3142   80	common/cmd_net.c	before calling NetLoop()
3143  -81	common/cmd_net.c	some error in NetLoop() occurred
3144   81	common/cmd_net.c	NetLoop() back without error
3145  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3146   82	common/cmd_net.c	trying automatic boot
3147   83	common/cmd_net.c	running "source" command
3148  -83	common/cmd_net.c	some error in automatic boot or "source" command
3149   84	common/cmd_net.c	end without errors
3150
3151FIT uImage format:
3152
3153  Arg	Where			When
3154  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3155 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3156  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3157 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3158  102	common/cmd_bootm.c	Kernel unit name specified
3159 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3160  103	common/cmd_bootm.c	Found configuration node
3161  104	common/cmd_bootm.c	Got kernel subimage node offset
3162 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3163  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3164 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3165  106	common/cmd_bootm.c	Architecture check OK
3166 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3167  107	common/cmd_bootm.c	Kernel subimage type OK
3168 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3169  108	common/cmd_bootm.c	Got kernel subimage data/size
3170 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3171 -109	common/cmd_bootm.c	Can't get kernel subimage type
3172 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3173 -111	common/cmd_bootm.c	Can't get kernel subimage os
3174 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3175 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3176
3177  120	common/image.c		Start initial ramdisk verification
3178 -120	common/image.c		Ramdisk FIT image has incorrect format
3179  121	common/image.c		Ramdisk FIT image has correct format
3180  122	common/image.c		No ramdisk subimage unit name, using configuration
3181 -122	common/image.c		Can't get configuration for ramdisk subimage
3182  123	common/image.c		Ramdisk unit name specified
3183 -124	common/image.c		Can't get ramdisk subimage node offset
3184  125	common/image.c		Got ramdisk subimage node offset
3185 -125	common/image.c		Ramdisk subimage hash verification failed
3186  126	common/image.c		Ramdisk subimage hash verification OK
3187 -126	common/image.c		Ramdisk subimage for unsupported architecture
3188  127	common/image.c		Architecture check OK
3189 -127	common/image.c		Can't get ramdisk subimage data/size
3190  128	common/image.c		Got ramdisk subimage data/size
3191  129	common/image.c		Can't get ramdisk load address
3192 -129	common/image.c		Got ramdisk load address
3193
3194 -130	common/cmd_doc.c	Incorrect FIT image format
3195  131	common/cmd_doc.c	FIT image format OK
3196
3197 -140	common/cmd_ide.c	Incorrect FIT image format
3198  141	common/cmd_ide.c	FIT image format OK
3199
3200 -150	common/cmd_nand.c	Incorrect FIT image format
3201  151	common/cmd_nand.c	FIT image format OK
3202
3203- FIT image support:
3204		CONFIG_FIT
3205		Enable support for the FIT uImage format.
3206
3207		CONFIG_FIT_BEST_MATCH
3208		When no configuration is explicitly selected, default to the
3209		one whose fdt's compatibility field best matches that of
3210		U-Boot itself. A match is considered "best" if it matches the
3211		most specific compatibility entry of U-Boot's fdt's root node.
3212		The order of entries in the configuration's fdt is ignored.
3213
3214		CONFIG_FIT_SIGNATURE
3215		This option enables signature verification of FIT uImages,
3216		using a hash signed and verified using RSA. See
3217		doc/uImage.FIT/signature.txt for more details.
3218
3219- Standalone program support:
3220		CONFIG_STANDALONE_LOAD_ADDR
3221
3222		This option defines a board specific value for the
3223		address where standalone program gets loaded, thus
3224		overwriting the architecture dependent default
3225		settings.
3226
3227- Frame Buffer Address:
3228		CONFIG_FB_ADDR
3229
3230		Define CONFIG_FB_ADDR if you want to use specific
3231		address for frame buffer.  This is typically the case
3232		when using a graphics controller has separate video
3233		memory.  U-Boot will then place the frame buffer at
3234		the given address instead of dynamically reserving it
3235		in system RAM by calling lcd_setmem(), which grabs
3236		the memory for the frame buffer depending on the
3237		configured panel size.
3238
3239		Please see board_init_f function.
3240
3241- Automatic software updates via TFTP server
3242		CONFIG_UPDATE_TFTP
3243		CONFIG_UPDATE_TFTP_CNT_MAX
3244		CONFIG_UPDATE_TFTP_MSEC_MAX
3245
3246		These options enable and control the auto-update feature;
3247		for a more detailed description refer to doc/README.update.
3248
3249- MTD Support (mtdparts command, UBI support)
3250		CONFIG_MTD_DEVICE
3251
3252		Adds the MTD device infrastructure from the Linux kernel.
3253		Needed for mtdparts command support.
3254
3255		CONFIG_MTD_PARTITIONS
3256
3257		Adds the MTD partitioning infrastructure from the Linux
3258		kernel. Needed for UBI support.
3259
3260- UBI support
3261		CONFIG_CMD_UBI
3262
3263		Adds commands for interacting with MTD partitions formatted
3264		with the UBI flash translation layer
3265
3266		Requires also defining CONFIG_RBTREE
3267
3268		CONFIG_UBI_SILENCE_MSG
3269
3270		Make the verbose messages from UBI stop printing.  This leaves
3271		warnings and errors enabled.
3272
3273- UBIFS support
3274		CONFIG_CMD_UBIFS
3275
3276		Adds commands for interacting with UBI volumes formatted as
3277		UBIFS.  UBIFS is read-only in u-boot.
3278
3279		Requires UBI support as well as CONFIG_LZO
3280
3281		CONFIG_UBIFS_SILENCE_MSG
3282
3283		Make the verbose messages from UBIFS stop printing.  This leaves
3284		warnings and errors enabled.
3285
3286- SPL framework
3287		CONFIG_SPL
3288		Enable building of SPL globally.
3289
3290		CONFIG_SPL_LDSCRIPT
3291		LDSCRIPT for linking the SPL binary.
3292
3293		CONFIG_SPL_MAX_FOOTPRINT
3294		Maximum size in memory allocated to the SPL, BSS included.
3295		When defined, the linker checks that the actual memory
3296		used by SPL from _start to __bss_end does not exceed it.
3297		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3298		must not be both defined at the same time.
3299
3300		CONFIG_SPL_MAX_SIZE
3301		Maximum size of the SPL image (text, data, rodata, and
3302		linker lists sections), BSS excluded.
3303		When defined, the linker checks that the actual size does
3304		not exceed it.
3305
3306		CONFIG_SPL_TEXT_BASE
3307		TEXT_BASE for linking the SPL binary.
3308
3309		CONFIG_SPL_RELOC_TEXT_BASE
3310		Address to relocate to.  If unspecified, this is equal to
3311		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3312
3313		CONFIG_SPL_BSS_START_ADDR
3314		Link address for the BSS within the SPL binary.
3315
3316		CONFIG_SPL_BSS_MAX_SIZE
3317		Maximum size in memory allocated to the SPL BSS.
3318		When defined, the linker checks that the actual memory used
3319		by SPL from __bss_start to __bss_end does not exceed it.
3320		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3321		must not be both defined at the same time.
3322
3323		CONFIG_SPL_STACK
3324		Adress of the start of the stack SPL will use
3325
3326		CONFIG_SPL_RELOC_STACK
3327		Adress of the start of the stack SPL will use after
3328		relocation.  If unspecified, this is equal to
3329		CONFIG_SPL_STACK.
3330
3331		CONFIG_SYS_SPL_MALLOC_START
3332		Starting address of the malloc pool used in SPL.
3333
3334		CONFIG_SYS_SPL_MALLOC_SIZE
3335		The size of the malloc pool used in SPL.
3336
3337		CONFIG_SPL_FRAMEWORK
3338		Enable the SPL framework under common/.  This framework
3339		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3340		NAND loading of the Linux Kernel.
3341
3342		CONFIG_SPL_OS_BOOT
3343		Enable booting directly to an OS from SPL.
3344		See also: doc/README.falcon
3345
3346		CONFIG_SPL_DISPLAY_PRINT
3347		For ARM, enable an optional function to print more information
3348		about the running system.
3349
3350		CONFIG_SPL_INIT_MINIMAL
3351		Arch init code should be built for a very small image
3352
3353		CONFIG_SPL_LIBCOMMON_SUPPORT
3354		Support for common/libcommon.o in SPL binary
3355
3356		CONFIG_SPL_LIBDISK_SUPPORT
3357		Support for disk/libdisk.o in SPL binary
3358
3359		CONFIG_SPL_I2C_SUPPORT
3360		Support for drivers/i2c/libi2c.o in SPL binary
3361
3362		CONFIG_SPL_GPIO_SUPPORT
3363		Support for drivers/gpio/libgpio.o in SPL binary
3364
3365		CONFIG_SPL_MMC_SUPPORT
3366		Support for drivers/mmc/libmmc.o in SPL binary
3367
3368		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3369		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3370		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3371		Address, size and partition on the MMC to load U-Boot from
3372		when the MMC is being used in raw mode.
3373
3374		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3375		Sector to load kernel uImage from when MMC is being
3376		used in raw mode (for Falcon mode)
3377
3378		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3379		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3380		Sector and number of sectors to load kernel argument
3381		parameters from when MMC is being used in raw mode
3382		(for falcon mode)
3383
3384		CONFIG_SPL_FAT_SUPPORT
3385		Support for fs/fat/libfat.o in SPL binary
3386
3387		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3388		Filename to read to load U-Boot when reading from FAT
3389
3390		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3391		Filename to read to load kernel uImage when reading
3392		from FAT (for Falcon mode)
3393
3394		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3395		Filename to read to load kernel argument parameters
3396		when reading from FAT (for Falcon mode)
3397
3398		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3399		Set this for NAND SPL on PPC mpc83xx targets, so that
3400		start.S waits for the rest of the SPL to load before
3401		continuing (the hardware starts execution after just
3402		loading the first page rather than the full 4K).
3403
3404		CONFIG_SPL_SKIP_RELOCATE
3405		Avoid SPL relocation
3406
3407		CONFIG_SPL_NAND_BASE
3408		Include nand_base.c in the SPL.  Requires
3409		CONFIG_SPL_NAND_DRIVERS.
3410
3411		CONFIG_SPL_NAND_DRIVERS
3412		SPL uses normal NAND drivers, not minimal drivers.
3413
3414		CONFIG_SPL_NAND_ECC
3415		Include standard software ECC in the SPL
3416
3417		CONFIG_SPL_NAND_SIMPLE
3418		Support for NAND boot using simple NAND drivers that
3419		expose the cmd_ctrl() interface.
3420
3421		CONFIG_SPL_MTD_SUPPORT
3422		Support for the MTD subsystem within SPL.  Useful for
3423		environment on NAND support within SPL.
3424
3425		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3426		Set for the SPL on PPC mpc8xxx targets, support for
3427		drivers/ddr/fsl/libddr.o in SPL binary.
3428
3429		CONFIG_SPL_COMMON_INIT_DDR
3430		Set for common ddr init with serial presence detect in
3431		SPL binary.
3432
3433		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3434		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3435		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3436		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3437		CONFIG_SYS_NAND_ECCBYTES
3438		Defines the size and behavior of the NAND that SPL uses
3439		to read U-Boot
3440
3441		CONFIG_SPL_NAND_BOOT
3442		Add support NAND boot
3443
3444		CONFIG_SYS_NAND_U_BOOT_OFFS
3445		Location in NAND to read U-Boot from
3446
3447		CONFIG_SYS_NAND_U_BOOT_DST
3448		Location in memory to load U-Boot to
3449
3450		CONFIG_SYS_NAND_U_BOOT_SIZE
3451		Size of image to load
3452
3453		CONFIG_SYS_NAND_U_BOOT_START
3454		Entry point in loaded image to jump to
3455
3456		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3457		Define this if you need to first read the OOB and then the
3458		data. This is used for example on davinci plattforms.
3459
3460		CONFIG_SPL_OMAP3_ID_NAND
3461		Support for an OMAP3-specific set of functions to return the
3462		ID and MFR of the first attached NAND chip, if present.
3463
3464		CONFIG_SPL_SERIAL_SUPPORT
3465		Support for drivers/serial/libserial.o in SPL binary
3466
3467		CONFIG_SPL_SPI_FLASH_SUPPORT
3468		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3469
3470		CONFIG_SPL_SPI_SUPPORT
3471		Support for drivers/spi/libspi.o in SPL binary
3472
3473		CONFIG_SPL_RAM_DEVICE
3474		Support for running image already present in ram, in SPL binary
3475
3476		CONFIG_SPL_LIBGENERIC_SUPPORT
3477		Support for lib/libgeneric.o in SPL binary
3478
3479		CONFIG_SPL_ENV_SUPPORT
3480		Support for the environment operating in SPL binary
3481
3482		CONFIG_SPL_NET_SUPPORT
3483		Support for the net/libnet.o in SPL binary.
3484		It conflicts with SPL env from storage medium specified by
3485		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3486
3487		CONFIG_SPL_PAD_TO
3488		Image offset to which the SPL should be padded before appending
3489		the SPL payload. By default, this is defined as
3490		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3491		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3492		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3493
3494		CONFIG_SPL_TARGET
3495		Final target image containing SPL and payload.  Some SPLs
3496		use an arch-specific makefile fragment instead, for
3497		example if more than one image needs to be produced.
3498
3499		CONFIG_FIT_SPL_PRINT
3500		Printing information about a FIT image adds quite a bit of
3501		code to SPL. So this is normally disabled in SPL. Use this
3502		option to re-enable it. This will affect the output of the
3503		bootm command when booting a FIT image.
3504
3505- TPL framework
3506		CONFIG_TPL
3507		Enable building of TPL globally.
3508
3509		CONFIG_TPL_PAD_TO
3510		Image offset to which the TPL should be padded before appending
3511		the TPL payload. By default, this is defined as
3512		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3513		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3514		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3515
3516Modem Support:
3517--------------
3518
3519[so far only for SMDK2400 boards]
3520
3521- Modem support enable:
3522		CONFIG_MODEM_SUPPORT
3523
3524- RTS/CTS Flow control enable:
3525		CONFIG_HWFLOW
3526
3527- Modem debug support:
3528		CONFIG_MODEM_SUPPORT_DEBUG
3529
3530		Enables debugging stuff (char screen[1024], dbg())
3531		for modem support. Useful only with BDI2000.
3532
3533- Interrupt support (PPC):
3534
3535		There are common interrupt_init() and timer_interrupt()
3536		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3537		for CPU specific initialization. interrupt_init_cpu()
3538		should set decrementer_count to appropriate value. If
3539		CPU resets decrementer automatically after interrupt
3540		(ppc4xx) it should set decrementer_count to zero.
3541		timer_interrupt() calls timer_interrupt_cpu() for CPU
3542		specific handling. If board has watchdog / status_led
3543		/ other_activity_monitor it works automatically from
3544		general timer_interrupt().
3545
3546- General:
3547
3548		In the target system modem support is enabled when a
3549		specific key (key combination) is pressed during
3550		power-on. Otherwise U-Boot will boot normally
3551		(autoboot). The key_pressed() function is called from
3552		board_init(). Currently key_pressed() is a dummy
3553		function, returning 1 and thus enabling modem
3554		initialization.
3555
3556		If there are no modem init strings in the
3557		environment, U-Boot proceed to autoboot; the
3558		previous output (banner, info printfs) will be
3559		suppressed, though.
3560
3561		See also: doc/README.Modem
3562
3563Board initialization settings:
3564------------------------------
3565
3566During Initialization u-boot calls a number of board specific functions
3567to allow the preparation of board specific prerequisites, e.g. pin setup
3568before drivers are initialized. To enable these callbacks the
3569following configuration macros have to be defined. Currently this is
3570architecture specific, so please check arch/your_architecture/lib/board.c
3571typically in board_init_f() and board_init_r().
3572
3573- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3574- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3575- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3576- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3577
3578Configuration Settings:
3579-----------------------
3580
3581- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3582		Optionally it can be defined to support 64-bit memory commands.
3583
3584- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3585		undefine this when you're short of memory.
3586
3587- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3588		width of the commands listed in the 'help' command output.
3589
3590- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3591		prompt for user input.
3592
3593- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3594
3595- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3596
3597- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3598
3599- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3600		the application (usually a Linux kernel) when it is
3601		booted
3602
3603- CONFIG_SYS_BAUDRATE_TABLE:
3604		List of legal baudrate settings for this board.
3605
3606- CONFIG_SYS_CONSOLE_INFO_QUIET
3607		Suppress display of console information at boot.
3608
3609- CONFIG_SYS_CONSOLE_IS_IN_ENV
3610		If the board specific function
3611			extern int overwrite_console (void);
3612		returns 1, the stdin, stderr and stdout are switched to the
3613		serial port, else the settings in the environment are used.
3614
3615- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3616		Enable the call to overwrite_console().
3617
3618- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3619		Enable overwrite of previous console environment settings.
3620
3621- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3622		Begin and End addresses of the area used by the
3623		simple memory test.
3624
3625- CONFIG_SYS_ALT_MEMTEST:
3626		Enable an alternate, more extensive memory test.
3627
3628- CONFIG_SYS_MEMTEST_SCRATCH:
3629		Scratch address used by the alternate memory test
3630		You only need to set this if address zero isn't writeable
3631
3632- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3633		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3634		this specified memory area will get subtracted from the top
3635		(end) of RAM and won't get "touched" at all by U-Boot. By
3636		fixing up gd->ram_size the Linux kernel should gets passed
3637		the now "corrected" memory size and won't touch it either.
3638		This should work for arch/ppc and arch/powerpc. Only Linux
3639		board ports in arch/powerpc with bootwrapper support that
3640		recalculate the memory size from the SDRAM controller setup
3641		will have to get fixed in Linux additionally.
3642
3643		This option can be used as a workaround for the 440EPx/GRx
3644		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3645		be touched.
3646
3647		WARNING: Please make sure that this value is a multiple of
3648		the Linux page size (normally 4k). If this is not the case,
3649		then the end address of the Linux memory will be located at a
3650		non page size aligned address and this could cause major
3651		problems.
3652
3653- CONFIG_SYS_LOADS_BAUD_CHANGE:
3654		Enable temporary baudrate change while serial download
3655
3656- CONFIG_SYS_SDRAM_BASE:
3657		Physical start address of SDRAM. _Must_ be 0 here.
3658
3659- CONFIG_SYS_MBIO_BASE:
3660		Physical start address of Motherboard I/O (if using a
3661		Cogent motherboard)
3662
3663- CONFIG_SYS_FLASH_BASE:
3664		Physical start address of Flash memory.
3665
3666- CONFIG_SYS_MONITOR_BASE:
3667		Physical start address of boot monitor code (set by
3668		make config files to be same as the text base address
3669		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3670		CONFIG_SYS_FLASH_BASE when booting from flash.
3671
3672- CONFIG_SYS_MONITOR_LEN:
3673		Size of memory reserved for monitor code, used to
3674		determine _at_compile_time_ (!) if the environment is
3675		embedded within the U-Boot image, or in a separate
3676		flash sector.
3677
3678- CONFIG_SYS_MALLOC_LEN:
3679		Size of DRAM reserved for malloc() use.
3680
3681- CONFIG_SYS_BOOTM_LEN:
3682		Normally compressed uImages are limited to an
3683		uncompressed size of 8 MBytes. If this is not enough,
3684		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3685		to adjust this setting to your needs.
3686
3687- CONFIG_SYS_BOOTMAPSZ:
3688		Maximum size of memory mapped by the startup code of
3689		the Linux kernel; all data that must be processed by
3690		the Linux kernel (bd_info, boot arguments, FDT blob if
3691		used) must be put below this limit, unless "bootm_low"
3692		environment variable is defined and non-zero. In such case
3693		all data for the Linux kernel must be between "bootm_low"
3694		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3695		variable "bootm_mapsize" will override the value of
3696		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3697		then the value in "bootm_size" will be used instead.
3698
3699- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3700		Enable initrd_high functionality.  If defined then the
3701		initrd_high feature is enabled and the bootm ramdisk subcommand
3702		is enabled.
3703
3704- CONFIG_SYS_BOOT_GET_CMDLINE:
3705		Enables allocating and saving kernel cmdline in space between
3706		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3707
3708- CONFIG_SYS_BOOT_GET_KBD:
3709		Enables allocating and saving a kernel copy of the bd_info in
3710		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3711
3712- CONFIG_SYS_MAX_FLASH_BANKS:
3713		Max number of Flash memory banks
3714
3715- CONFIG_SYS_MAX_FLASH_SECT:
3716		Max number of sectors on a Flash chip
3717
3718- CONFIG_SYS_FLASH_ERASE_TOUT:
3719		Timeout for Flash erase operations (in ms)
3720
3721- CONFIG_SYS_FLASH_WRITE_TOUT:
3722		Timeout for Flash write operations (in ms)
3723
3724- CONFIG_SYS_FLASH_LOCK_TOUT
3725		Timeout for Flash set sector lock bit operation (in ms)
3726
3727- CONFIG_SYS_FLASH_UNLOCK_TOUT
3728		Timeout for Flash clear lock bits operation (in ms)
3729
3730- CONFIG_SYS_FLASH_PROTECTION
3731		If defined, hardware flash sectors protection is used
3732		instead of U-Boot software protection.
3733
3734- CONFIG_SYS_DIRECT_FLASH_TFTP:
3735
3736		Enable TFTP transfers directly to flash memory;
3737		without this option such a download has to be
3738		performed in two steps: (1) download to RAM, and (2)
3739		copy from RAM to flash.
3740
3741		The two-step approach is usually more reliable, since
3742		you can check if the download worked before you erase
3743		the flash, but in some situations (when system RAM is
3744		too limited to allow for a temporary copy of the
3745		downloaded image) this option may be very useful.
3746
3747- CONFIG_SYS_FLASH_CFI:
3748		Define if the flash driver uses extra elements in the
3749		common flash structure for storing flash geometry.
3750
3751- CONFIG_FLASH_CFI_DRIVER
3752		This option also enables the building of the cfi_flash driver
3753		in the drivers directory
3754
3755- CONFIG_FLASH_CFI_MTD
3756		This option enables the building of the cfi_mtd driver
3757		in the drivers directory. The driver exports CFI flash
3758		to the MTD layer.
3759
3760- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3761		Use buffered writes to flash.
3762
3763- CONFIG_FLASH_SPANSION_S29WS_N
3764		s29ws-n MirrorBit flash has non-standard addresses for buffered
3765		write commands.
3766
3767- CONFIG_SYS_FLASH_QUIET_TEST
3768		If this option is defined, the common CFI flash doesn't
3769		print it's warning upon not recognized FLASH banks. This
3770		is useful, if some of the configured banks are only
3771		optionally available.
3772
3773- CONFIG_FLASH_SHOW_PROGRESS
3774		If defined (must be an integer), print out countdown
3775		digits and dots.  Recommended value: 45 (9..1) for 80
3776		column displays, 15 (3..1) for 40 column displays.
3777
3778- CONFIG_FLASH_VERIFY
3779		If defined, the content of the flash (destination) is compared
3780		against the source after the write operation. An error message
3781		will be printed when the contents are not identical.
3782		Please note that this option is useless in nearly all cases,
3783		since such flash programming errors usually are detected earlier
3784		while unprotecting/erasing/programming. Please only enable
3785		this option if you really know what you are doing.
3786
3787- CONFIG_SYS_RX_ETH_BUFFER:
3788		Defines the number of Ethernet receive buffers. On some
3789		Ethernet controllers it is recommended to set this value
3790		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3791		buffers can be full shortly after enabling the interface
3792		on high Ethernet traffic.
3793		Defaults to 4 if not defined.
3794
3795- CONFIG_ENV_MAX_ENTRIES
3796
3797	Maximum number of entries in the hash table that is used
3798	internally to store the environment settings. The default
3799	setting is supposed to be generous and should work in most
3800	cases. This setting can be used to tune behaviour; see
3801	lib/hashtable.c for details.
3802
3803- CONFIG_ENV_FLAGS_LIST_DEFAULT
3804- CONFIG_ENV_FLAGS_LIST_STATIC
3805	Enable validation of the values given to environment variables when
3806	calling env set.  Variables can be restricted to only decimal,
3807	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3808	the variables can also be restricted to IP address or MAC address.
3809
3810	The format of the list is:
3811		type_attribute = [s|d|x|b|i|m]
3812		access_atribute = [a|r|o|c]
3813		attributes = type_attribute[access_atribute]
3814		entry = variable_name[:attributes]
3815		list = entry[,list]
3816
3817	The type attributes are:
3818		s - String (default)
3819		d - Decimal
3820		x - Hexadecimal
3821		b - Boolean ([1yYtT|0nNfF])
3822		i - IP address
3823		m - MAC address
3824
3825	The access attributes are:
3826		a - Any (default)
3827		r - Read-only
3828		o - Write-once
3829		c - Change-default
3830
3831	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3832		Define this to a list (string) to define the ".flags"
3833		envirnoment variable in the default or embedded environment.
3834
3835	- CONFIG_ENV_FLAGS_LIST_STATIC
3836		Define this to a list (string) to define validation that
3837		should be done if an entry is not found in the ".flags"
3838		environment variable.  To override a setting in the static
3839		list, simply add an entry for the same variable name to the
3840		".flags" variable.
3841
3842- CONFIG_ENV_ACCESS_IGNORE_FORCE
3843	If defined, don't allow the -f switch to env set override variable
3844	access flags.
3845
3846- CONFIG_SYS_GENERIC_BOARD
3847	This selects the architecture-generic board system instead of the
3848	architecture-specific board files. It is intended to move boards
3849	to this new framework over time. Defining this will disable the
3850	arch/foo/lib/board.c file and use common/board_f.c and
3851	common/board_r.c instead. To use this option your architecture
3852	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3853	its config.mk file). If you find problems enabling this option on
3854	your board please report the problem and send patches!
3855
3856- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3857	This is set by OMAP boards for the max time that reset should
3858	be asserted. See doc/README.omap-reset-time for details on how
3859	the value can be calulated on a given board.
3860
3861The following definitions that deal with the placement and management
3862of environment data (variable area); in general, we support the
3863following configurations:
3864
3865- CONFIG_BUILD_ENVCRC:
3866
3867	Builds up envcrc with the target environment so that external utils
3868	may easily extract it and embed it in final U-Boot images.
3869
3870- CONFIG_ENV_IS_IN_FLASH:
3871
3872	Define this if the environment is in flash memory.
3873
3874	a) The environment occupies one whole flash sector, which is
3875	   "embedded" in the text segment with the U-Boot code. This
3876	   happens usually with "bottom boot sector" or "top boot
3877	   sector" type flash chips, which have several smaller
3878	   sectors at the start or the end. For instance, such a
3879	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3880	   such a case you would place the environment in one of the
3881	   4 kB sectors - with U-Boot code before and after it. With
3882	   "top boot sector" type flash chips, you would put the
3883	   environment in one of the last sectors, leaving a gap
3884	   between U-Boot and the environment.
3885
3886	- CONFIG_ENV_OFFSET:
3887
3888	   Offset of environment data (variable area) to the
3889	   beginning of flash memory; for instance, with bottom boot
3890	   type flash chips the second sector can be used: the offset
3891	   for this sector is given here.
3892
3893	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3894
3895	- CONFIG_ENV_ADDR:
3896
3897	   This is just another way to specify the start address of
3898	   the flash sector containing the environment (instead of
3899	   CONFIG_ENV_OFFSET).
3900
3901	- CONFIG_ENV_SECT_SIZE:
3902
3903	   Size of the sector containing the environment.
3904
3905
3906	b) Sometimes flash chips have few, equal sized, BIG sectors.
3907	   In such a case you don't want to spend a whole sector for
3908	   the environment.
3909
3910	- CONFIG_ENV_SIZE:
3911
3912	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3913	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3914	   of this flash sector for the environment. This saves
3915	   memory for the RAM copy of the environment.
3916
3917	   It may also save flash memory if you decide to use this
3918	   when your environment is "embedded" within U-Boot code,
3919	   since then the remainder of the flash sector could be used
3920	   for U-Boot code. It should be pointed out that this is
3921	   STRONGLY DISCOURAGED from a robustness point of view:
3922	   updating the environment in flash makes it always
3923	   necessary to erase the WHOLE sector. If something goes
3924	   wrong before the contents has been restored from a copy in
3925	   RAM, your target system will be dead.
3926
3927	- CONFIG_ENV_ADDR_REDUND
3928	  CONFIG_ENV_SIZE_REDUND
3929
3930	   These settings describe a second storage area used to hold
3931	   a redundant copy of the environment data, so that there is
3932	   a valid backup copy in case there is a power failure during
3933	   a "saveenv" operation.
3934
3935BE CAREFUL! Any changes to the flash layout, and some changes to the
3936source code will make it necessary to adapt <board>/u-boot.lds*
3937accordingly!
3938
3939
3940- CONFIG_ENV_IS_IN_NVRAM:
3941
3942	Define this if you have some non-volatile memory device
3943	(NVRAM, battery buffered SRAM) which you want to use for the
3944	environment.
3945
3946	- CONFIG_ENV_ADDR:
3947	- CONFIG_ENV_SIZE:
3948
3949	  These two #defines are used to determine the memory area you
3950	  want to use for environment. It is assumed that this memory
3951	  can just be read and written to, without any special
3952	  provision.
3953
3954BE CAREFUL! The first access to the environment happens quite early
3955in U-Boot initalization (when we try to get the setting of for the
3956console baudrate). You *MUST* have mapped your NVRAM area then, or
3957U-Boot will hang.
3958
3959Please note that even with NVRAM we still use a copy of the
3960environment in RAM: we could work on NVRAM directly, but we want to
3961keep settings there always unmodified except somebody uses "saveenv"
3962to save the current settings.
3963
3964
3965- CONFIG_ENV_IS_IN_EEPROM:
3966
3967	Use this if you have an EEPROM or similar serial access
3968	device and a driver for it.
3969
3970	- CONFIG_ENV_OFFSET:
3971	- CONFIG_ENV_SIZE:
3972
3973	  These two #defines specify the offset and size of the
3974	  environment area within the total memory of your EEPROM.
3975
3976	- CONFIG_SYS_I2C_EEPROM_ADDR:
3977	  If defined, specified the chip address of the EEPROM device.
3978	  The default address is zero.
3979
3980	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3981	  If defined, the number of bits used to address bytes in a
3982	  single page in the EEPROM device.  A 64 byte page, for example
3983	  would require six bits.
3984
3985	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3986	  If defined, the number of milliseconds to delay between
3987	  page writes.	The default is zero milliseconds.
3988
3989	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3990	  The length in bytes of the EEPROM memory array address.  Note
3991	  that this is NOT the chip address length!
3992
3993	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3994	  EEPROM chips that implement "address overflow" are ones
3995	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3996	  address and the extra bits end up in the "chip address" bit
3997	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3998	  byte chips.
3999
4000	  Note that we consider the length of the address field to
4001	  still be one byte because the extra address bits are hidden
4002	  in the chip address.
4003
4004	- CONFIG_SYS_EEPROM_SIZE:
4005	  The size in bytes of the EEPROM device.
4006
4007	- CONFIG_ENV_EEPROM_IS_ON_I2C
4008	  define this, if you have I2C and SPI activated, and your
4009	  EEPROM, which holds the environment, is on the I2C bus.
4010
4011	- CONFIG_I2C_ENV_EEPROM_BUS
4012	  if you have an Environment on an EEPROM reached over
4013	  I2C muxes, you can define here, how to reach this
4014	  EEPROM. For example:
4015
4016	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4017
4018	  EEPROM which holds the environment, is reached over
4019	  a pca9547 i2c mux with address 0x70, channel 3.
4020
4021- CONFIG_ENV_IS_IN_DATAFLASH:
4022
4023	Define this if you have a DataFlash memory device which you
4024	want to use for the environment.
4025
4026	- CONFIG_ENV_OFFSET:
4027	- CONFIG_ENV_ADDR:
4028	- CONFIG_ENV_SIZE:
4029
4030	  These three #defines specify the offset and size of the
4031	  environment area within the total memory of your DataFlash placed
4032	  at the specified address.
4033
4034- CONFIG_ENV_IS_IN_REMOTE:
4035
4036	Define this if you have a remote memory space which you
4037	want to use for the local device's environment.
4038
4039	- CONFIG_ENV_ADDR:
4040	- CONFIG_ENV_SIZE:
4041
4042	  These two #defines specify the address and size of the
4043	  environment area within the remote memory space. The
4044	  local device can get the environment from remote memory
4045	  space by SRIO or PCIE links.
4046
4047BE CAREFUL! For some special cases, the local device can not use
4048"saveenv" command. For example, the local device will get the
4049environment stored in a remote NOR flash by SRIO or PCIE link,
4050but it can not erase, write this NOR flash by SRIO or PCIE interface.
4051
4052- CONFIG_ENV_IS_IN_NAND:
4053
4054	Define this if you have a NAND device which you want to use
4055	for the environment.
4056
4057	- CONFIG_ENV_OFFSET:
4058	- CONFIG_ENV_SIZE:
4059
4060	  These two #defines specify the offset and size of the environment
4061	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4062	  aligned to an erase block boundary.
4063
4064	- CONFIG_ENV_OFFSET_REDUND (optional):
4065
4066	  This setting describes a second storage area of CONFIG_ENV_SIZE
4067	  size used to hold a redundant copy of the environment data, so
4068	  that there is a valid backup copy in case there is a power failure
4069	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4070	  aligned to an erase block boundary.
4071
4072	- CONFIG_ENV_RANGE (optional):
4073
4074	  Specifies the length of the region in which the environment
4075	  can be written.  This should be a multiple of the NAND device's
4076	  block size.  Specifying a range with more erase blocks than
4077	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4078	  the range to be avoided.
4079
4080	- CONFIG_ENV_OFFSET_OOB (optional):
4081
4082	  Enables support for dynamically retrieving the offset of the
4083	  environment from block zero's out-of-band data.  The
4084	  "nand env.oob" command can be used to record this offset.
4085	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4086	  using CONFIG_ENV_OFFSET_OOB.
4087
4088- CONFIG_NAND_ENV_DST
4089
4090	Defines address in RAM to which the nand_spl code should copy the
4091	environment. If redundant environment is used, it will be copied to
4092	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4093
4094- CONFIG_ENV_IS_IN_UBI:
4095
4096	Define this if you have an UBI volume that you want to use for the
4097	environment.  This has the benefit of wear-leveling the environment
4098	accesses, which is important on NAND.
4099
4100	- CONFIG_ENV_UBI_PART:
4101
4102	  Define this to a string that is the mtd partition containing the UBI.
4103
4104	- CONFIG_ENV_UBI_VOLUME:
4105
4106	  Define this to the name of the volume that you want to store the
4107	  environment in.
4108
4109	- CONFIG_ENV_UBI_VOLUME_REDUND:
4110
4111	  Define this to the name of another volume to store a second copy of
4112	  the environment in.  This will enable redundant environments in UBI.
4113	  It is assumed that both volumes are in the same MTD partition.
4114
4115	- CONFIG_UBI_SILENCE_MSG
4116	- CONFIG_UBIFS_SILENCE_MSG
4117
4118	  You will probably want to define these to avoid a really noisy system
4119	  when storing the env in UBI.
4120
4121- CONFIG_ENV_IS_IN_MMC:
4122
4123	Define this if you have an MMC device which you want to use for the
4124	environment.
4125
4126	- CONFIG_SYS_MMC_ENV_DEV:
4127
4128	  Specifies which MMC device the environment is stored in.
4129
4130	- CONFIG_SYS_MMC_ENV_PART (optional):
4131
4132	  Specifies which MMC partition the environment is stored in. If not
4133	  set, defaults to partition 0, the user area. Common values might be
4134	  1 (first MMC boot partition), 2 (second MMC boot partition).
4135
4136	- CONFIG_ENV_OFFSET:
4137	- CONFIG_ENV_SIZE:
4138
4139	  These two #defines specify the offset and size of the environment
4140	  area within the specified MMC device.
4141
4142	  If offset is positive (the usual case), it is treated as relative to
4143	  the start of the MMC partition. If offset is negative, it is treated
4144	  as relative to the end of the MMC partition. This can be useful if
4145	  your board may be fitted with different MMC devices, which have
4146	  different sizes for the MMC partitions, and you always want the
4147	  environment placed at the very end of the partition, to leave the
4148	  maximum possible space before it, to store other data.
4149
4150	  These two values are in units of bytes, but must be aligned to an
4151	  MMC sector boundary.
4152
4153	- CONFIG_ENV_OFFSET_REDUND (optional):
4154
4155	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4156	  hold a redundant copy of the environment data. This provides a
4157	  valid backup copy in case the other copy is corrupted, e.g. due
4158	  to a power failure during a "saveenv" operation.
4159
4160	  This value may also be positive or negative; this is handled in the
4161	  same way as CONFIG_ENV_OFFSET.
4162
4163	  This value is also in units of bytes, but must also be aligned to
4164	  an MMC sector boundary.
4165
4166	- CONFIG_ENV_SIZE_REDUND (optional):
4167
4168	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4169	  set. If this value is set, it must be set to the same value as
4170	  CONFIG_ENV_SIZE.
4171
4172- CONFIG_SYS_SPI_INIT_OFFSET
4173
4174	Defines offset to the initial SPI buffer area in DPRAM. The
4175	area is used at an early stage (ROM part) if the environment
4176	is configured to reside in the SPI EEPROM: We need a 520 byte
4177	scratch DPRAM area. It is used between the two initialization
4178	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4179	to be a good choice since it makes it far enough from the
4180	start of the data area as well as from the stack pointer.
4181
4182Please note that the environment is read-only until the monitor
4183has been relocated to RAM and a RAM copy of the environment has been
4184created; also, when using EEPROM you will have to use getenv_f()
4185until then to read environment variables.
4186
4187The environment is protected by a CRC32 checksum. Before the monitor
4188is relocated into RAM, as a result of a bad CRC you will be working
4189with the compiled-in default environment - *silently*!!! [This is
4190necessary, because the first environment variable we need is the
4191"baudrate" setting for the console - if we have a bad CRC, we don't
4192have any device yet where we could complain.]
4193
4194Note: once the monitor has been relocated, then it will complain if
4195the default environment is used; a new CRC is computed as soon as you
4196use the "saveenv" command to store a valid environment.
4197
4198- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4199		Echo the inverted Ethernet link state to the fault LED.
4200
4201		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4202		      also needs to be defined.
4203
4204- CONFIG_SYS_FAULT_MII_ADDR:
4205		MII address of the PHY to check for the Ethernet link state.
4206
4207- CONFIG_NS16550_MIN_FUNCTIONS:
4208		Define this if you desire to only have use of the NS16550_init
4209		and NS16550_putc functions for the serial driver located at
4210		drivers/serial/ns16550.c.  This option is useful for saving
4211		space for already greatly restricted images, including but not
4212		limited to NAND_SPL configurations.
4213
4214- CONFIG_DISPLAY_BOARDINFO
4215		Display information about the board that U-Boot is running on
4216		when U-Boot starts up. The board function checkboard() is called
4217		to do this.
4218
4219- CONFIG_DISPLAY_BOARDINFO_LATE
4220		Similar to the previous option, but display this information
4221		later, once stdio is running and output goes to the LCD, if
4222		present.
4223
4224Low Level (hardware related) configuration options:
4225---------------------------------------------------
4226
4227- CONFIG_SYS_CACHELINE_SIZE:
4228		Cache Line Size of the CPU.
4229
4230- CONFIG_SYS_DEFAULT_IMMR:
4231		Default address of the IMMR after system reset.
4232
4233		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4234		and RPXsuper) to be able to adjust the position of
4235		the IMMR register after a reset.
4236
4237- CONFIG_SYS_CCSRBAR_DEFAULT:
4238		Default (power-on reset) physical address of CCSR on Freescale
4239		PowerPC SOCs.
4240
4241- CONFIG_SYS_CCSRBAR:
4242		Virtual address of CCSR.  On a 32-bit build, this is typically
4243		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4244
4245		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4246		for cross-platform code that uses that macro instead.
4247
4248- CONFIG_SYS_CCSRBAR_PHYS:
4249		Physical address of CCSR.  CCSR can be relocated to a new
4250		physical address, if desired.  In this case, this macro should
4251		be set to that address.	 Otherwise, it should be set to the
4252		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4253		is typically relocated on 36-bit builds.  It is recommended
4254		that this macro be defined via the _HIGH and _LOW macros:
4255
4256		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4257			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4258
4259- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4260		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4261		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4262		used in assembly code, so it must not contain typecasts or
4263		integer size suffixes (e.g. "ULL").
4264
4265- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4266		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4267		used in assembly code, so it must not contain typecasts or
4268		integer size suffixes (e.g. "ULL").
4269
4270- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4271		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4272		forced to a value that ensures that CCSR is not relocated.
4273
4274- Floppy Disk Support:
4275		CONFIG_SYS_FDC_DRIVE_NUMBER
4276
4277		the default drive number (default value 0)
4278
4279		CONFIG_SYS_ISA_IO_STRIDE
4280
4281		defines the spacing between FDC chipset registers
4282		(default value 1)
4283
4284		CONFIG_SYS_ISA_IO_OFFSET
4285
4286		defines the offset of register from address. It
4287		depends on which part of the data bus is connected to
4288		the FDC chipset. (default value 0)
4289
4290		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4291		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4292		default value.
4293
4294		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4295		fdc_hw_init() is called at the beginning of the FDC
4296		setup. fdc_hw_init() must be provided by the board
4297		source code. It is used to make hardware dependant
4298		initializations.
4299
4300- CONFIG_IDE_AHB:
4301		Most IDE controllers were designed to be connected with PCI
4302		interface. Only few of them were designed for AHB interface.
4303		When software is doing ATA command and data transfer to
4304		IDE devices through IDE-AHB controller, some additional
4305		registers accessing to these kind of IDE-AHB controller
4306		is requierd.
4307
4308- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4309		DO NOT CHANGE unless you know exactly what you're
4310		doing! (11-4) [MPC8xx/82xx systems only]
4311
4312- CONFIG_SYS_INIT_RAM_ADDR:
4313
4314		Start address of memory area that can be used for
4315		initial data and stack; please note that this must be
4316		writable memory that is working WITHOUT special
4317		initialization, i. e. you CANNOT use normal RAM which
4318		will become available only after programming the
4319		memory controller and running certain initialization
4320		sequences.
4321
4322		U-Boot uses the following memory types:
4323		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4324		- MPC824X: data cache
4325		- PPC4xx:  data cache
4326
4327- CONFIG_SYS_GBL_DATA_OFFSET:
4328
4329		Offset of the initial data structure in the memory
4330		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4331		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4332		data is located at the end of the available space
4333		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4334		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4335		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4336		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4337
4338	Note:
4339		On the MPC824X (or other systems that use the data
4340		cache for initial memory) the address chosen for
4341		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4342		point to an otherwise UNUSED address space between
4343		the top of RAM and the start of the PCI space.
4344
4345- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4346
4347- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4348
4349- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4350
4351- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4352
4353- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4354
4355- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4356
4357- CONFIG_SYS_OR_TIMING_SDRAM:
4358		SDRAM timing
4359
4360- CONFIG_SYS_MAMR_PTA:
4361		periodic timer for refresh
4362
4363- CONFIG_SYS_DER:	Debug Event Register (37-47)
4364
4365- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4366  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4367  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4368  CONFIG_SYS_BR1_PRELIM:
4369		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4370
4371- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4372  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4373  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4374		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4375
4376- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4377  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4378		Machine Mode Register and Memory Periodic Timer
4379		Prescaler definitions (SDRAM timing)
4380
4381- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4382		enable I2C microcode relocation patch (MPC8xx);
4383		define relocation offset in DPRAM [DSP2]
4384
4385- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4386		enable SMC microcode relocation patch (MPC8xx);
4387		define relocation offset in DPRAM [SMC1]
4388
4389- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4390		enable SPI microcode relocation patch (MPC8xx);
4391		define relocation offset in DPRAM [SCC4]
4392
4393- CONFIG_SYS_USE_OSCCLK:
4394		Use OSCM clock mode on MBX8xx board. Be careful,
4395		wrong setting might damage your board. Read
4396		doc/README.MBX before setting this variable!
4397
4398- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4399		Offset of the bootmode word in DPRAM used by post
4400		(Power On Self Tests). This definition overrides
4401		#define'd default value in commproc.h resp.
4402		cpm_8260.h.
4403
4404- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4405  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4406  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4407  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4408  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4409  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4410  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4411  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4412		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4413
4414- CONFIG_PCI_DISABLE_PCIE:
4415		Disable PCI-Express on systems where it is supported but not
4416		required.
4417
4418- CONFIG_PCI_ENUM_ONLY
4419		Only scan through and get the devices on the busses.
4420		Don't do any setup work, presumably because someone or
4421		something has already done it, and we don't need to do it
4422		a second time.	Useful for platforms that are pre-booted
4423		by coreboot or similar.
4424
4425- CONFIG_PCI_INDIRECT_BRIDGE:
4426		Enable support for indirect PCI bridges.
4427
4428- CONFIG_SYS_SRIO:
4429		Chip has SRIO or not
4430
4431- CONFIG_SRIO1:
4432		Board has SRIO 1 port available
4433
4434- CONFIG_SRIO2:
4435		Board has SRIO 2 port available
4436
4437- CONFIG_SRIO_PCIE_BOOT_MASTER
4438		Board can support master function for Boot from SRIO and PCIE
4439
4440- CONFIG_SYS_SRIOn_MEM_VIRT:
4441		Virtual Address of SRIO port 'n' memory region
4442
4443- CONFIG_SYS_SRIOn_MEM_PHYS:
4444		Physical Address of SRIO port 'n' memory region
4445
4446- CONFIG_SYS_SRIOn_MEM_SIZE:
4447		Size of SRIO port 'n' memory region
4448
4449- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4450		Defined to tell the NAND controller that the NAND chip is using
4451		a 16 bit bus.
4452		Not all NAND drivers use this symbol.
4453		Example of drivers that use it:
4454		- drivers/mtd/nand/ndfc.c
4455		- drivers/mtd/nand/mxc_nand.c
4456
4457- CONFIG_SYS_NDFC_EBC0_CFG
4458		Sets the EBC0_CFG register for the NDFC. If not defined
4459		a default value will be used.
4460
4461- CONFIG_SPD_EEPROM
4462		Get DDR timing information from an I2C EEPROM. Common
4463		with pluggable memory modules such as SODIMMs
4464
4465  SPD_EEPROM_ADDRESS
4466		I2C address of the SPD EEPROM
4467
4468- CONFIG_SYS_SPD_BUS_NUM
4469		If SPD EEPROM is on an I2C bus other than the first
4470		one, specify here. Note that the value must resolve
4471		to something your driver can deal with.
4472
4473- CONFIG_SYS_DDR_RAW_TIMING
4474		Get DDR timing information from other than SPD. Common with
4475		soldered DDR chips onboard without SPD. DDR raw timing
4476		parameters are extracted from datasheet and hard-coded into
4477		header files or board specific files.
4478
4479- CONFIG_FSL_DDR_INTERACTIVE
4480		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4481
4482- CONFIG_SYS_83XX_DDR_USES_CS0
4483		Only for 83xx systems. If specified, then DDR should
4484		be configured using CS0 and CS1 instead of CS2 and CS3.
4485
4486- CONFIG_ETHER_ON_FEC[12]
4487		Define to enable FEC[12] on a 8xx series processor.
4488
4489- CONFIG_FEC[12]_PHY
4490		Define to the hardcoded PHY address which corresponds
4491		to the given FEC; i. e.
4492			#define CONFIG_FEC1_PHY 4
4493		means that the PHY with address 4 is connected to FEC1
4494
4495		When set to -1, means to probe for first available.
4496
4497- CONFIG_FEC[12]_PHY_NORXERR
4498		The PHY does not have a RXERR line (RMII only).
4499		(so program the FEC to ignore it).
4500
4501- CONFIG_RMII
4502		Enable RMII mode for all FECs.
4503		Note that this is a global option, we can't
4504		have one FEC in standard MII mode and another in RMII mode.
4505
4506- CONFIG_CRC32_VERIFY
4507		Add a verify option to the crc32 command.
4508		The syntax is:
4509
4510		=> crc32 -v <address> <count> <crc32>
4511
4512		Where address/count indicate a memory area
4513		and crc32 is the correct crc32 which the
4514		area should have.
4515
4516- CONFIG_LOOPW
4517		Add the "loopw" memory command. This only takes effect if
4518		the memory commands are activated globally (CONFIG_CMD_MEM).
4519
4520- CONFIG_MX_CYCLIC
4521		Add the "mdc" and "mwc" memory commands. These are cyclic
4522		"md/mw" commands.
4523		Examples:
4524
4525		=> mdc.b 10 4 500
4526		This command will print 4 bytes (10,11,12,13) each 500 ms.
4527
4528		=> mwc.l 100 12345678 10
4529		This command will write 12345678 to address 100 all 10 ms.
4530
4531		This only takes effect if the memory commands are activated
4532		globally (CONFIG_CMD_MEM).
4533
4534- CONFIG_SKIP_LOWLEVEL_INIT
4535		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4536		low level initializations (like setting up the memory
4537		controller) are omitted and/or U-Boot does not
4538		relocate itself into RAM.
4539
4540		Normally this variable MUST NOT be defined. The only
4541		exception is when U-Boot is loaded (to RAM) by some
4542		other boot loader or by a debugger which performs
4543		these initializations itself.
4544
4545- CONFIG_SPL_BUILD
4546		Modifies the behaviour of start.S when compiling a loader
4547		that is executed before the actual U-Boot. E.g. when
4548		compiling a NAND SPL.
4549
4550- CONFIG_TPL_BUILD
4551		Modifies the behaviour of start.S  when compiling a loader
4552		that is executed after the SPL and before the actual U-Boot.
4553		It is loaded by the SPL.
4554
4555- CONFIG_SYS_MPC85XX_NO_RESETVEC
4556		Only for 85xx systems. If this variable is specified, the section
4557		.resetvec is not kept and the section .bootpg is placed in the
4558		previous 4k of the .text section.
4559
4560- CONFIG_ARCH_MAP_SYSMEM
4561		Generally U-Boot (and in particular the md command) uses
4562		effective address. It is therefore not necessary to regard
4563		U-Boot address as virtual addresses that need to be translated
4564		to physical addresses. However, sandbox requires this, since
4565		it maintains its own little RAM buffer which contains all
4566		addressable memory. This option causes some memory accesses
4567		to be mapped through map_sysmem() / unmap_sysmem().
4568
4569- CONFIG_USE_ARCH_MEMCPY
4570  CONFIG_USE_ARCH_MEMSET
4571		If these options are used a optimized version of memcpy/memset will
4572		be used if available. These functions may be faster under some
4573		conditions but may increase the binary size.
4574
4575- CONFIG_X86_RESET_VECTOR
4576		If defined, the x86 reset vector code is included. This is not
4577		needed when U-Boot is running from Coreboot.
4578
4579- CONFIG_SYS_MPUCLK
4580		Defines the MPU clock speed (in MHz).
4581
4582		NOTE : currently only supported on AM335x platforms.
4583
4584- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4585		Enables the RTC32K OSC on AM33xx based plattforms
4586
4587- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4588		Option to disable subpage write in NAND driver
4589		driver that uses this:
4590		drivers/mtd/nand/davinci_nand.c
4591
4592Freescale QE/FMAN Firmware Support:
4593-----------------------------------
4594
4595The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4596loading of "firmware", which is encoded in the QE firmware binary format.
4597This firmware often needs to be loaded during U-Boot booting, so macros
4598are used to identify the storage device (NOR flash, SPI, etc) and the address
4599within that device.
4600
4601- CONFIG_SYS_FMAN_FW_ADDR
4602	The address in the storage device where the FMAN microcode is located.  The
4603	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4604	is also specified.
4605
4606- CONFIG_SYS_QE_FW_ADDR
4607	The address in the storage device where the QE microcode is located.  The
4608	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4609	is also specified.
4610
4611- CONFIG_SYS_QE_FMAN_FW_LENGTH
4612	The maximum possible size of the firmware.  The firmware binary format
4613	has a field that specifies the actual size of the firmware, but it
4614	might not be possible to read any part of the firmware unless some
4615	local storage is allocated to hold the entire firmware first.
4616
4617- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4618	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4619	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4620	virtual address in NOR flash.
4621
4622- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4623	Specifies that QE/FMAN firmware is located in NAND flash.
4624	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4625
4626- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4627	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4628	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4629
4630- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4631	Specifies that QE/FMAN firmware is located on the primary SPI
4632	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4633
4634- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4635	Specifies that QE/FMAN firmware is located in the remote (master)
4636	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4637	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4638	window->master inbound window->master LAW->the ucode address in
4639	master's memory space.
4640
4641Building the Software:
4642======================
4643
4644Building U-Boot has been tested in several native build environments
4645and in many different cross environments. Of course we cannot support
4646all possibly existing versions of cross development tools in all
4647(potentially obsolete) versions. In case of tool chain problems we
4648recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4649which is extensively used to build and test U-Boot.
4650
4651If you are not using a native environment, it is assumed that you
4652have GNU cross compiling tools available in your path. In this case,
4653you must set the environment variable CROSS_COMPILE in your shell.
4654Note that no changes to the Makefile or any other source files are
4655necessary. For example using the ELDK on a 4xx CPU, please enter:
4656
4657	$ CROSS_COMPILE=ppc_4xx-
4658	$ export CROSS_COMPILE
4659
4660Note: If you wish to generate Windows versions of the utilities in
4661      the tools directory you can use the MinGW toolchain
4662      (http://www.mingw.org).  Set your HOST tools to the MinGW
4663      toolchain and execute 'make tools'.  For example:
4664
4665       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4666
4667      Binaries such as tools/mkimage.exe will be created which can
4668      be executed on computers running Windows.
4669
4670U-Boot is intended to be simple to build. After installing the
4671sources you must configure U-Boot for one specific board type. This
4672is done by typing:
4673
4674	make NAME_config
4675
4676where "NAME_config" is the name of one of the existing configu-
4677rations; see boards.cfg for supported names.
4678
4679Note: for some board special configuration names may exist; check if
4680      additional information is available from the board vendor; for
4681      instance, the TQM823L systems are available without (standard)
4682      or with LCD support. You can select such additional "features"
4683      when choosing the configuration, i. e.
4684
4685      make TQM823L_config
4686	- will configure for a plain TQM823L, i. e. no LCD support
4687
4688      make TQM823L_LCD_config
4689	- will configure for a TQM823L with U-Boot console on LCD
4690
4691      etc.
4692
4693
4694Finally, type "make all", and you should get some working U-Boot
4695images ready for download to / installation on your system:
4696
4697- "u-boot.bin" is a raw binary image
4698- "u-boot" is an image in ELF binary format
4699- "u-boot.srec" is in Motorola S-Record format
4700
4701By default the build is performed locally and the objects are saved
4702in the source directory. One of the two methods can be used to change
4703this behavior and build U-Boot to some external directory:
4704
47051. Add O= to the make command line invocations:
4706
4707	make O=/tmp/build distclean
4708	make O=/tmp/build NAME_config
4709	make O=/tmp/build all
4710
47112. Set environment variable BUILD_DIR to point to the desired location:
4712
4713	export BUILD_DIR=/tmp/build
4714	make distclean
4715	make NAME_config
4716	make all
4717
4718Note that the command line "O=" setting overrides the BUILD_DIR environment
4719variable.
4720
4721
4722Please be aware that the Makefiles assume you are using GNU make, so
4723for instance on NetBSD you might need to use "gmake" instead of
4724native "make".
4725
4726
4727If the system board that you have is not listed, then you will need
4728to port U-Boot to your hardware platform. To do this, follow these
4729steps:
4730
47311.  Add a new configuration option for your board to the toplevel
4732    "boards.cfg" file, using the existing entries as examples.
4733    Follow the instructions there to keep the boards in order.
47342.  Create a new directory to hold your board specific code. Add any
4735    files you need. In your board directory, you will need at least
4736    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
47373.  Create a new configuration file "include/configs/<board>.h" for
4738    your board
47393.  If you're porting U-Boot to a new CPU, then also create a new
4740    directory to hold your CPU specific code. Add any files you need.
47414.  Run "make <board>_config" with your new name.
47425.  Type "make", and you should get a working "u-boot.srec" file
4743    to be installed on your target system.
47446.  Debug and solve any problems that might arise.
4745    [Of course, this last step is much harder than it sounds.]
4746
4747
4748Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4749==============================================================
4750
4751If you have modified U-Boot sources (for instance added a new board
4752or support for new devices, a new CPU, etc.) you are expected to
4753provide feedback to the other developers. The feedback normally takes
4754the form of a "patch", i. e. a context diff against a certain (latest
4755official or latest in the git repository) version of U-Boot sources.
4756
4757But before you submit such a patch, please verify that your modifi-
4758cation did not break existing code. At least make sure that *ALL* of
4759the supported boards compile WITHOUT ANY compiler warnings. To do so,
4760just run the "MAKEALL" script, which will configure and build U-Boot
4761for ALL supported system. Be warned, this will take a while. You can
4762select which (cross) compiler to use by passing a `CROSS_COMPILE'
4763environment variable to the script, i. e. to use the ELDK cross tools
4764you can type
4765
4766	CROSS_COMPILE=ppc_8xx- MAKEALL
4767
4768or to build on a native PowerPC system you can type
4769
4770	CROSS_COMPILE=' ' MAKEALL
4771
4772When using the MAKEALL script, the default behaviour is to build
4773U-Boot in the source directory. This location can be changed by
4774setting the BUILD_DIR environment variable. Also, for each target
4775built, the MAKEALL script saves two log files (<target>.ERR and
4776<target>.MAKEALL) in the <source dir>/LOG directory. This default
4777location can be changed by setting the MAKEALL_LOGDIR environment
4778variable. For example:
4779
4780	export BUILD_DIR=/tmp/build
4781	export MAKEALL_LOGDIR=/tmp/log
4782	CROSS_COMPILE=ppc_8xx- MAKEALL
4783
4784With the above settings build objects are saved in the /tmp/build,
4785log files are saved in the /tmp/log and the source tree remains clean
4786during the whole build process.
4787
4788
4789See also "U-Boot Porting Guide" below.
4790
4791
4792Monitor Commands - Overview:
4793============================
4794
4795go	- start application at address 'addr'
4796run	- run commands in an environment variable
4797bootm	- boot application image from memory
4798bootp	- boot image via network using BootP/TFTP protocol
4799bootz   - boot zImage from memory
4800tftpboot- boot image via network using TFTP protocol
4801	       and env variables "ipaddr" and "serverip"
4802	       (and eventually "gatewayip")
4803tftpput - upload a file via network using TFTP protocol
4804rarpboot- boot image via network using RARP/TFTP protocol
4805diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4806loads	- load S-Record file over serial line
4807loadb	- load binary file over serial line (kermit mode)
4808md	- memory display
4809mm	- memory modify (auto-incrementing)
4810nm	- memory modify (constant address)
4811mw	- memory write (fill)
4812cp	- memory copy
4813cmp	- memory compare
4814crc32	- checksum calculation
4815i2c	- I2C sub-system
4816sspi	- SPI utility commands
4817base	- print or set address offset
4818printenv- print environment variables
4819setenv	- set environment variables
4820saveenv - save environment variables to persistent storage
4821protect - enable or disable FLASH write protection
4822erase	- erase FLASH memory
4823flinfo	- print FLASH memory information
4824nand	- NAND memory operations (see doc/README.nand)
4825bdinfo	- print Board Info structure
4826iminfo	- print header information for application image
4827coninfo - print console devices and informations
4828ide	- IDE sub-system
4829loop	- infinite loop on address range
4830loopw	- infinite write loop on address range
4831mtest	- simple RAM test
4832icache	- enable or disable instruction cache
4833dcache	- enable or disable data cache
4834reset	- Perform RESET of the CPU
4835echo	- echo args to console
4836version - print monitor version
4837help	- print online help
4838?	- alias for 'help'
4839
4840
4841Monitor Commands - Detailed Description:
4842========================================
4843
4844TODO.
4845
4846For now: just type "help <command>".
4847
4848
4849Environment Variables:
4850======================
4851
4852U-Boot supports user configuration using Environment Variables which
4853can be made persistent by saving to Flash memory.
4854
4855Environment Variables are set using "setenv", printed using
4856"printenv", and saved to Flash using "saveenv". Using "setenv"
4857without a value can be used to delete a variable from the
4858environment. As long as you don't save the environment you are
4859working with an in-memory copy. In case the Flash area containing the
4860environment is erased by accident, a default environment is provided.
4861
4862Some configuration options can be set using Environment Variables.
4863
4864List of environment variables (most likely not complete):
4865
4866  baudrate	- see CONFIG_BAUDRATE
4867
4868  bootdelay	- see CONFIG_BOOTDELAY
4869
4870  bootcmd	- see CONFIG_BOOTCOMMAND
4871
4872  bootargs	- Boot arguments when booting an RTOS image
4873
4874  bootfile	- Name of the image to load with TFTP
4875
4876  bootm_low	- Memory range available for image processing in the bootm
4877		  command can be restricted. This variable is given as
4878		  a hexadecimal number and defines lowest address allowed
4879		  for use by the bootm command. See also "bootm_size"
4880		  environment variable. Address defined by "bootm_low" is
4881		  also the base of the initial memory mapping for the Linux
4882		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4883		  bootm_mapsize.
4884
4885  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4886		  This variable is given as a hexadecimal number and it
4887		  defines the size of the memory region starting at base
4888		  address bootm_low that is accessible by the Linux kernel
4889		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4890		  as the default value if it is defined, and bootm_size is
4891		  used otherwise.
4892
4893  bootm_size	- Memory range available for image processing in the bootm
4894		  command can be restricted. This variable is given as
4895		  a hexadecimal number and defines the size of the region
4896		  allowed for use by the bootm command. See also "bootm_low"
4897		  environment variable.
4898
4899  updatefile	- Location of the software update file on a TFTP server, used
4900		  by the automatic software update feature. Please refer to
4901		  documentation in doc/README.update for more details.
4902
4903  autoload	- if set to "no" (any string beginning with 'n'),
4904		  "bootp" will just load perform a lookup of the
4905		  configuration from the BOOTP server, but not try to
4906		  load any image using TFTP
4907
4908  autostart	- if set to "yes", an image loaded using the "bootp",
4909		  "rarpboot", "tftpboot" or "diskboot" commands will
4910		  be automatically started (by internally calling
4911		  "bootm")
4912
4913		  If set to "no", a standalone image passed to the
4914		  "bootm" command will be copied to the load address
4915		  (and eventually uncompressed), but NOT be started.
4916		  This can be used to load and uncompress arbitrary
4917		  data.
4918
4919  fdt_high	- if set this restricts the maximum address that the
4920		  flattened device tree will be copied into upon boot.
4921		  For example, if you have a system with 1 GB memory
4922		  at physical address 0x10000000, while Linux kernel
4923		  only recognizes the first 704 MB as low memory, you
4924		  may need to set fdt_high as 0x3C000000 to have the
4925		  device tree blob be copied to the maximum address
4926		  of the 704 MB low memory, so that Linux kernel can
4927		  access it during the boot procedure.
4928
4929		  If this is set to the special value 0xFFFFFFFF then
4930		  the fdt will not be copied at all on boot.  For this
4931		  to work it must reside in writable memory, have
4932		  sufficient padding on the end of it for u-boot to
4933		  add the information it needs into it, and the memory
4934		  must be accessible by the kernel.
4935
4936  fdtcontroladdr- if set this is the address of the control flattened
4937		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4938		  defined.
4939
4940  i2cfast	- (PPC405GP|PPC405EP only)
4941		  if set to 'y' configures Linux I2C driver for fast
4942		  mode (400kHZ). This environment variable is used in
4943		  initialization code. So, for changes to be effective
4944		  it must be saved and board must be reset.
4945
4946  initrd_high	- restrict positioning of initrd images:
4947		  If this variable is not set, initrd images will be
4948		  copied to the highest possible address in RAM; this
4949		  is usually what you want since it allows for
4950		  maximum initrd size. If for some reason you want to
4951		  make sure that the initrd image is loaded below the
4952		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4953		  variable to a value of "no" or "off" or "0".
4954		  Alternatively, you can set it to a maximum upper
4955		  address to use (U-Boot will still check that it
4956		  does not overwrite the U-Boot stack and data).
4957
4958		  For instance, when you have a system with 16 MB
4959		  RAM, and want to reserve 4 MB from use by Linux,
4960		  you can do this by adding "mem=12M" to the value of
4961		  the "bootargs" variable. However, now you must make
4962		  sure that the initrd image is placed in the first
4963		  12 MB as well - this can be done with
4964
4965		  setenv initrd_high 00c00000
4966
4967		  If you set initrd_high to 0xFFFFFFFF, this is an
4968		  indication to U-Boot that all addresses are legal
4969		  for the Linux kernel, including addresses in flash
4970		  memory. In this case U-Boot will NOT COPY the
4971		  ramdisk at all. This may be useful to reduce the
4972		  boot time on your system, but requires that this
4973		  feature is supported by your Linux kernel.
4974
4975  ipaddr	- IP address; needed for tftpboot command
4976
4977  loadaddr	- Default load address for commands like "bootp",
4978		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4979
4980  loads_echo	- see CONFIG_LOADS_ECHO
4981
4982  serverip	- TFTP server IP address; needed for tftpboot command
4983
4984  bootretry	- see CONFIG_BOOT_RETRY_TIME
4985
4986  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4987
4988  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4989
4990  ethprime	- controls which interface is used first.
4991
4992  ethact	- controls which interface is currently active.
4993		  For example you can do the following
4994
4995		  => setenv ethact FEC
4996		  => ping 192.168.0.1 # traffic sent on FEC
4997		  => setenv ethact SCC
4998		  => ping 10.0.0.1 # traffic sent on SCC
4999
5000  ethrotate	- When set to "no" U-Boot does not go through all
5001		  available network interfaces.
5002		  It just stays at the currently selected interface.
5003
5004  netretry	- When set to "no" each network operation will
5005		  either succeed or fail without retrying.
5006		  When set to "once" the network operation will
5007		  fail when all the available network interfaces
5008		  are tried once without success.
5009		  Useful on scripts which control the retry operation
5010		  themselves.
5011
5012  npe_ucode	- set load address for the NPE microcode
5013
5014  silent_linux  - If set then linux will be told to boot silently, by
5015		  changing the console to be empty. If "yes" it will be
5016		  made silent. If "no" it will not be made silent. If
5017		  unset, then it will be made silent if the U-Boot console
5018		  is silent.
5019
5020  tftpsrcport	- If this is set, the value is used for TFTP's
5021		  UDP source port.
5022
5023  tftpdstport	- If this is set, the value is used for TFTP's UDP
5024		  destination port instead of the Well Know Port 69.
5025
5026  tftpblocksize - Block size to use for TFTP transfers; if not set,
5027		  we use the TFTP server's default block size
5028
5029  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5030		  seconds, minimum value is 1000 = 1 second). Defines
5031		  when a packet is considered to be lost so it has to
5032		  be retransmitted. The default is 5000 = 5 seconds.
5033		  Lowering this value may make downloads succeed
5034		  faster in networks with high packet loss rates or
5035		  with unreliable TFTP servers.
5036
5037  vlan		- When set to a value < 4095 the traffic over
5038		  Ethernet is encapsulated/received over 802.1q
5039		  VLAN tagged frames.
5040
5041The following image location variables contain the location of images
5042used in booting. The "Image" column gives the role of the image and is
5043not an environment variable name. The other columns are environment
5044variable names. "File Name" gives the name of the file on a TFTP
5045server, "RAM Address" gives the location in RAM the image will be
5046loaded to, and "Flash Location" gives the image's address in NOR
5047flash or offset in NAND flash.
5048
5049*Note* - these variables don't have to be defined for all boards, some
5050boards currenlty use other variables for these purposes, and some
5051boards use these variables for other purposes.
5052
5053Image		    File Name	     RAM Address       Flash Location
5054-----		    ---------	     -----------       --------------
5055u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5056Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5057device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5058ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5059
5060The following environment variables may be used and automatically
5061updated by the network boot commands ("bootp" and "rarpboot"),
5062depending the information provided by your boot server:
5063
5064  bootfile	- see above
5065  dnsip		- IP address of your Domain Name Server
5066  dnsip2	- IP address of your secondary Domain Name Server
5067  gatewayip	- IP address of the Gateway (Router) to use
5068  hostname	- Target hostname
5069  ipaddr	- see above
5070  netmask	- Subnet Mask
5071  rootpath	- Pathname of the root filesystem on the NFS server
5072  serverip	- see above
5073
5074
5075There are two special Environment Variables:
5076
5077  serial#	- contains hardware identification information such
5078		  as type string and/or serial number
5079  ethaddr	- Ethernet address
5080
5081These variables can be set only once (usually during manufacturing of
5082the board). U-Boot refuses to delete or overwrite these variables
5083once they have been set once.
5084
5085
5086Further special Environment Variables:
5087
5088  ver		- Contains the U-Boot version string as printed
5089		  with the "version" command. This variable is
5090		  readonly (see CONFIG_VERSION_VARIABLE).
5091
5092
5093Please note that changes to some configuration parameters may take
5094only effect after the next boot (yes, that's just like Windoze :-).
5095
5096
5097Callback functions for environment variables:
5098---------------------------------------------
5099
5100For some environment variables, the behavior of u-boot needs to change
5101when their values are changed.  This functionailty allows functions to
5102be associated with arbitrary variables.  On creation, overwrite, or
5103deletion, the callback will provide the opportunity for some side
5104effect to happen or for the change to be rejected.
5105
5106The callbacks are named and associated with a function using the
5107U_BOOT_ENV_CALLBACK macro in your board or driver code.
5108
5109These callbacks are associated with variables in one of two ways.  The
5110static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5111in the board configuration to a string that defines a list of
5112associations.  The list must be in the following format:
5113
5114	entry = variable_name[:callback_name]
5115	list = entry[,list]
5116
5117If the callback name is not specified, then the callback is deleted.
5118Spaces are also allowed anywhere in the list.
5119
5120Callbacks can also be associated by defining the ".callbacks" variable
5121with the same list format above.  Any association in ".callbacks" will
5122override any association in the static list. You can define
5123CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5124".callbacks" envirnoment variable in the default or embedded environment.
5125
5126
5127Command Line Parsing:
5128=====================
5129
5130There are two different command line parsers available with U-Boot:
5131the old "simple" one, and the much more powerful "hush" shell:
5132
5133Old, simple command line parser:
5134--------------------------------
5135
5136- supports environment variables (through setenv / saveenv commands)
5137- several commands on one line, separated by ';'
5138- variable substitution using "... ${name} ..." syntax
5139- special characters ('$', ';') can be escaped by prefixing with '\',
5140  for example:
5141	setenv bootcmd bootm \${address}
5142- You can also escape text by enclosing in single apostrophes, for example:
5143	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5144
5145Hush shell:
5146-----------
5147
5148- similar to Bourne shell, with control structures like
5149  if...then...else...fi, for...do...done; while...do...done,
5150  until...do...done, ...
5151- supports environment ("global") variables (through setenv / saveenv
5152  commands) and local shell variables (through standard shell syntax
5153  "name=value"); only environment variables can be used with "run"
5154  command
5155
5156General rules:
5157--------------
5158
5159(1) If a command line (or an environment variable executed by a "run"
5160    command) contains several commands separated by semicolon, and
5161    one of these commands fails, then the remaining commands will be
5162    executed anyway.
5163
5164(2) If you execute several variables with one call to run (i. e.
5165    calling run with a list of variables as arguments), any failing
5166    command will cause "run" to terminate, i. e. the remaining
5167    variables are not executed.
5168
5169Note for Redundant Ethernet Interfaces:
5170=======================================
5171
5172Some boards come with redundant Ethernet interfaces; U-Boot supports
5173such configurations and is capable of automatic selection of a
5174"working" interface when needed. MAC assignment works as follows:
5175
5176Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5177MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5178"eth1addr" (=>eth1), "eth2addr", ...
5179
5180If the network interface stores some valid MAC address (for instance
5181in SROM), this is used as default address if there is NO correspon-
5182ding setting in the environment; if the corresponding environment
5183variable is set, this overrides the settings in the card; that means:
5184
5185o If the SROM has a valid MAC address, and there is no address in the
5186  environment, the SROM's address is used.
5187
5188o If there is no valid address in the SROM, and a definition in the
5189  environment exists, then the value from the environment variable is
5190  used.
5191
5192o If both the SROM and the environment contain a MAC address, and
5193  both addresses are the same, this MAC address is used.
5194
5195o If both the SROM and the environment contain a MAC address, and the
5196  addresses differ, the value from the environment is used and a
5197  warning is printed.
5198
5199o If neither SROM nor the environment contain a MAC address, an error
5200  is raised.
5201
5202If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5203will be programmed into hardware as part of the initialization process.	 This
5204may be skipped by setting the appropriate 'ethmacskip' environment variable.
5205The naming convention is as follows:
5206"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5207
5208Image Formats:
5209==============
5210
5211U-Boot is capable of booting (and performing other auxiliary operations on)
5212images in two formats:
5213
5214New uImage format (FIT)
5215-----------------------
5216
5217Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5218to Flattened Device Tree). It allows the use of images with multiple
5219components (several kernels, ramdisks, etc.), with contents protected by
5220SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5221
5222
5223Old uImage format
5224-----------------
5225
5226Old image format is based on binary files which can be basically anything,
5227preceded by a special header; see the definitions in include/image.h for
5228details; basically, the header defines the following image properties:
5229
5230* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5231  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5232  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5233  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5234  INTEGRITY).
5235* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5236  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5237  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5238* Compression Type (uncompressed, gzip, bzip2)
5239* Load Address
5240* Entry Point
5241* Image Name
5242* Image Timestamp
5243
5244The header is marked by a special Magic Number, and both the header
5245and the data portions of the image are secured against corruption by
5246CRC32 checksums.
5247
5248
5249Linux Support:
5250==============
5251
5252Although U-Boot should support any OS or standalone application
5253easily, the main focus has always been on Linux during the design of
5254U-Boot.
5255
5256U-Boot includes many features that so far have been part of some
5257special "boot loader" code within the Linux kernel. Also, any
5258"initrd" images to be used are no longer part of one big Linux image;
5259instead, kernel and "initrd" are separate images. This implementation
5260serves several purposes:
5261
5262- the same features can be used for other OS or standalone
5263  applications (for instance: using compressed images to reduce the
5264  Flash memory footprint)
5265
5266- it becomes much easier to port new Linux kernel versions because
5267  lots of low-level, hardware dependent stuff are done by U-Boot
5268
5269- the same Linux kernel image can now be used with different "initrd"
5270  images; of course this also means that different kernel images can
5271  be run with the same "initrd". This makes testing easier (you don't
5272  have to build a new "zImage.initrd" Linux image when you just
5273  change a file in your "initrd"). Also, a field-upgrade of the
5274  software is easier now.
5275
5276
5277Linux HOWTO:
5278============
5279
5280Porting Linux to U-Boot based systems:
5281---------------------------------------
5282
5283U-Boot cannot save you from doing all the necessary modifications to
5284configure the Linux device drivers for use with your target hardware
5285(no, we don't intend to provide a full virtual machine interface to
5286Linux :-).
5287
5288But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5289
5290Just make sure your machine specific header file (for instance
5291include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5292Information structure as we define in include/asm-<arch>/u-boot.h,
5293and make sure that your definition of IMAP_ADDR uses the same value
5294as your U-Boot configuration in CONFIG_SYS_IMMR.
5295
5296
5297Configuring the Linux kernel:
5298-----------------------------
5299
5300No specific requirements for U-Boot. Make sure you have some root
5301device (initial ramdisk, NFS) for your target system.
5302
5303
5304Building a Linux Image:
5305-----------------------
5306
5307With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5308not used. If you use recent kernel source, a new build target
5309"uImage" will exist which automatically builds an image usable by
5310U-Boot. Most older kernels also have support for a "pImage" target,
5311which was introduced for our predecessor project PPCBoot and uses a
5312100% compatible format.
5313
5314Example:
5315
5316	make TQM850L_config
5317	make oldconfig
5318	make dep
5319	make uImage
5320
5321The "uImage" build target uses a special tool (in 'tools/mkimage') to
5322encapsulate a compressed Linux kernel image with header	 information,
5323CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5324
5325* build a standard "vmlinux" kernel image (in ELF binary format):
5326
5327* convert the kernel into a raw binary image:
5328
5329	${CROSS_COMPILE}-objcopy -O binary \
5330				 -R .note -R .comment \
5331				 -S vmlinux linux.bin
5332
5333* compress the binary image:
5334
5335	gzip -9 linux.bin
5336
5337* package compressed binary image for U-Boot:
5338
5339	mkimage -A ppc -O linux -T kernel -C gzip \
5340		-a 0 -e 0 -n "Linux Kernel Image" \
5341		-d linux.bin.gz uImage
5342
5343
5344The "mkimage" tool can also be used to create ramdisk images for use
5345with U-Boot, either separated from the Linux kernel image, or
5346combined into one file. "mkimage" encapsulates the images with a 64
5347byte header containing information about target architecture,
5348operating system, image type, compression method, entry points, time
5349stamp, CRC32 checksums, etc.
5350
5351"mkimage" can be called in two ways: to verify existing images and
5352print the header information, or to build new images.
5353
5354In the first form (with "-l" option) mkimage lists the information
5355contained in the header of an existing U-Boot image; this includes
5356checksum verification:
5357
5358	tools/mkimage -l image
5359	  -l ==> list image header information
5360
5361The second form (with "-d" option) is used to build a U-Boot image
5362from a "data file" which is used as image payload:
5363
5364	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5365		      -n name -d data_file image
5366	  -A ==> set architecture to 'arch'
5367	  -O ==> set operating system to 'os'
5368	  -T ==> set image type to 'type'
5369	  -C ==> set compression type 'comp'
5370	  -a ==> set load address to 'addr' (hex)
5371	  -e ==> set entry point to 'ep' (hex)
5372	  -n ==> set image name to 'name'
5373	  -d ==> use image data from 'datafile'
5374
5375Right now, all Linux kernels for PowerPC systems use the same load
5376address (0x00000000), but the entry point address depends on the
5377kernel version:
5378
5379- 2.2.x kernels have the entry point at 0x0000000C,
5380- 2.3.x and later kernels have the entry point at 0x00000000.
5381
5382So a typical call to build a U-Boot image would read:
5383
5384	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5385	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5386	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5387	> examples/uImage.TQM850L
5388	Image Name:   2.4.4 kernel for TQM850L
5389	Created:      Wed Jul 19 02:34:59 2000
5390	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5391	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5392	Load Address: 0x00000000
5393	Entry Point:  0x00000000
5394
5395To verify the contents of the image (or check for corruption):
5396
5397	-> tools/mkimage -l examples/uImage.TQM850L
5398	Image Name:   2.4.4 kernel for TQM850L
5399	Created:      Wed Jul 19 02:34:59 2000
5400	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5401	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5402	Load Address: 0x00000000
5403	Entry Point:  0x00000000
5404
5405NOTE: for embedded systems where boot time is critical you can trade
5406speed for memory and install an UNCOMPRESSED image instead: this
5407needs more space in Flash, but boots much faster since it does not
5408need to be uncompressed:
5409
5410	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5411	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5412	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5413	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5414	> examples/uImage.TQM850L-uncompressed
5415	Image Name:   2.4.4 kernel for TQM850L
5416	Created:      Wed Jul 19 02:34:59 2000
5417	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5418	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5419	Load Address: 0x00000000
5420	Entry Point:  0x00000000
5421
5422
5423Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5424when your kernel is intended to use an initial ramdisk:
5425
5426	-> tools/mkimage -n 'Simple Ramdisk Image' \
5427	> -A ppc -O linux -T ramdisk -C gzip \
5428	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5429	Image Name:   Simple Ramdisk Image
5430	Created:      Wed Jan 12 14:01:50 2000
5431	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5432	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5433	Load Address: 0x00000000
5434	Entry Point:  0x00000000
5435
5436The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5437option performs the converse operation of the mkimage's second form (the "-d"
5438option). Given an image built by mkimage, the dumpimage extracts a "data file"
5439from the image:
5440
5441	tools/dumpimage -i image -p position data_file
5442	  -i ==> extract from the 'image' a specific 'data_file', \
5443	   indexed by 'position'
5444
5445
5446Installing a Linux Image:
5447-------------------------
5448
5449To downloading a U-Boot image over the serial (console) interface,
5450you must convert the image to S-Record format:
5451
5452	objcopy -I binary -O srec examples/image examples/image.srec
5453
5454The 'objcopy' does not understand the information in the U-Boot
5455image header, so the resulting S-Record file will be relative to
5456address 0x00000000. To load it to a given address, you need to
5457specify the target address as 'offset' parameter with the 'loads'
5458command.
5459
5460Example: install the image to address 0x40100000 (which on the
5461TQM8xxL is in the first Flash bank):
5462
5463	=> erase 40100000 401FFFFF
5464
5465	.......... done
5466	Erased 8 sectors
5467
5468	=> loads 40100000
5469	## Ready for S-Record download ...
5470	~>examples/image.srec
5471	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5472	...
5473	15989 15990 15991 15992
5474	[file transfer complete]
5475	[connected]
5476	## Start Addr = 0x00000000
5477
5478
5479You can check the success of the download using the 'iminfo' command;
5480this includes a checksum verification so you can be sure no data
5481corruption happened:
5482
5483	=> imi 40100000
5484
5485	## Checking Image at 40100000 ...
5486	   Image Name:	 2.2.13 for initrd on TQM850L
5487	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5488	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5489	   Load Address: 00000000
5490	   Entry Point:	 0000000c
5491	   Verifying Checksum ... OK
5492
5493
5494Boot Linux:
5495-----------
5496
5497The "bootm" command is used to boot an application that is stored in
5498memory (RAM or Flash). In case of a Linux kernel image, the contents
5499of the "bootargs" environment variable is passed to the kernel as
5500parameters. You can check and modify this variable using the
5501"printenv" and "setenv" commands:
5502
5503
5504	=> printenv bootargs
5505	bootargs=root=/dev/ram
5506
5507	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5508
5509	=> printenv bootargs
5510	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5511
5512	=> bootm 40020000
5513	## Booting Linux kernel at 40020000 ...
5514	   Image Name:	 2.2.13 for NFS on TQM850L
5515	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5516	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5517	   Load Address: 00000000
5518	   Entry Point:	 0000000c
5519	   Verifying Checksum ... OK
5520	   Uncompressing Kernel Image ... OK
5521	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
5522	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5523	time_init: decrementer frequency = 187500000/60
5524	Calibrating delay loop... 49.77 BogoMIPS
5525	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5526	...
5527
5528If you want to boot a Linux kernel with initial RAM disk, you pass
5529the memory addresses of both the kernel and the initrd image (PPBCOOT
5530format!) to the "bootm" command:
5531
5532	=> imi 40100000 40200000
5533
5534	## Checking Image at 40100000 ...
5535	   Image Name:	 2.2.13 for initrd on TQM850L
5536	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5537	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5538	   Load Address: 00000000
5539	   Entry Point:	 0000000c
5540	   Verifying Checksum ... OK
5541
5542	## Checking Image at 40200000 ...
5543	   Image Name:	 Simple Ramdisk Image
5544	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5545	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5546	   Load Address: 00000000
5547	   Entry Point:	 00000000
5548	   Verifying Checksum ... OK
5549
5550	=> bootm 40100000 40200000
5551	## Booting Linux kernel at 40100000 ...
5552	   Image Name:	 2.2.13 for initrd on TQM850L
5553	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5554	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5555	   Load Address: 00000000
5556	   Entry Point:	 0000000c
5557	   Verifying Checksum ... OK
5558	   Uncompressing Kernel Image ... OK
5559	## Loading RAMDisk Image at 40200000 ...
5560	   Image Name:	 Simple Ramdisk Image
5561	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5562	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5563	   Load Address: 00000000
5564	   Entry Point:	 00000000
5565	   Verifying Checksum ... OK
5566	   Loading Ramdisk ... OK
5567	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
5568	Boot arguments: root=/dev/ram
5569	time_init: decrementer frequency = 187500000/60
5570	Calibrating delay loop... 49.77 BogoMIPS
5571	...
5572	RAMDISK: Compressed image found at block 0
5573	VFS: Mounted root (ext2 filesystem).
5574
5575	bash#
5576
5577Boot Linux and pass a flat device tree:
5578-----------
5579
5580First, U-Boot must be compiled with the appropriate defines. See the section
5581titled "Linux Kernel Interface" above for a more in depth explanation. The
5582following is an example of how to start a kernel and pass an updated
5583flat device tree:
5584
5585=> print oftaddr
5586oftaddr=0x300000
5587=> print oft
5588oft=oftrees/mpc8540ads.dtb
5589=> tftp $oftaddr $oft
5590Speed: 1000, full duplex
5591Using TSEC0 device
5592TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5593Filename 'oftrees/mpc8540ads.dtb'.
5594Load address: 0x300000
5595Loading: #
5596done
5597Bytes transferred = 4106 (100a hex)
5598=> tftp $loadaddr $bootfile
5599Speed: 1000, full duplex
5600Using TSEC0 device
5601TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5602Filename 'uImage'.
5603Load address: 0x200000
5604Loading:############
5605done
5606Bytes transferred = 1029407 (fb51f hex)
5607=> print loadaddr
5608loadaddr=200000
5609=> print oftaddr
5610oftaddr=0x300000
5611=> bootm $loadaddr - $oftaddr
5612## Booting image at 00200000 ...
5613   Image Name:	 Linux-2.6.17-dirty
5614   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5615   Data Size:	 1029343 Bytes = 1005.2 kB
5616   Load Address: 00000000
5617   Entry Point:	 00000000
5618   Verifying Checksum ... OK
5619   Uncompressing Kernel Image ... OK
5620Booting using flat device tree at 0x300000
5621Using MPC85xx ADS machine description
5622Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5623[snip]
5624
5625
5626More About U-Boot Image Types:
5627------------------------------
5628
5629U-Boot supports the following image types:
5630
5631   "Standalone Programs" are directly runnable in the environment
5632	provided by U-Boot; it is expected that (if they behave
5633	well) you can continue to work in U-Boot after return from
5634	the Standalone Program.
5635   "OS Kernel Images" are usually images of some Embedded OS which
5636	will take over control completely. Usually these programs
5637	will install their own set of exception handlers, device
5638	drivers, set up the MMU, etc. - this means, that you cannot
5639	expect to re-enter U-Boot except by resetting the CPU.
5640   "RAMDisk Images" are more or less just data blocks, and their
5641	parameters (address, size) are passed to an OS kernel that is
5642	being started.
5643   "Multi-File Images" contain several images, typically an OS
5644	(Linux) kernel image and one or more data images like
5645	RAMDisks. This construct is useful for instance when you want
5646	to boot over the network using BOOTP etc., where the boot
5647	server provides just a single image file, but you want to get
5648	for instance an OS kernel and a RAMDisk image.
5649
5650	"Multi-File Images" start with a list of image sizes, each
5651	image size (in bytes) specified by an "uint32_t" in network
5652	byte order. This list is terminated by an "(uint32_t)0".
5653	Immediately after the terminating 0 follow the images, one by
5654	one, all aligned on "uint32_t" boundaries (size rounded up to
5655	a multiple of 4 bytes).
5656
5657   "Firmware Images" are binary images containing firmware (like
5658	U-Boot or FPGA images) which usually will be programmed to
5659	flash memory.
5660
5661   "Script files" are command sequences that will be executed by
5662	U-Boot's command interpreter; this feature is especially
5663	useful when you configure U-Boot to use a real shell (hush)
5664	as command interpreter.
5665
5666Booting the Linux zImage:
5667-------------------------
5668
5669On some platforms, it's possible to boot Linux zImage. This is done
5670using the "bootz" command. The syntax of "bootz" command is the same
5671as the syntax of "bootm" command.
5672
5673Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5674kernel with raw initrd images. The syntax is slightly different, the
5675address of the initrd must be augmented by it's size, in the following
5676format: "<initrd addres>:<initrd size>".
5677
5678
5679Standalone HOWTO:
5680=================
5681
5682One of the features of U-Boot is that you can dynamically load and
5683run "standalone" applications, which can use some resources of
5684U-Boot like console I/O functions or interrupt services.
5685
5686Two simple examples are included with the sources:
5687
5688"Hello World" Demo:
5689-------------------
5690
5691'examples/hello_world.c' contains a small "Hello World" Demo
5692application; it is automatically compiled when you build U-Boot.
5693It's configured to run at address 0x00040004, so you can play with it
5694like that:
5695
5696	=> loads
5697	## Ready for S-Record download ...
5698	~>examples/hello_world.srec
5699	1 2 3 4 5 6 7 8 9 10 11 ...
5700	[file transfer complete]
5701	[connected]
5702	## Start Addr = 0x00040004
5703
5704	=> go 40004 Hello World! This is a test.
5705	## Starting application at 0x00040004 ...
5706	Hello World
5707	argc = 7
5708	argv[0] = "40004"
5709	argv[1] = "Hello"
5710	argv[2] = "World!"
5711	argv[3] = "This"
5712	argv[4] = "is"
5713	argv[5] = "a"
5714	argv[6] = "test."
5715	argv[7] = "<NULL>"
5716	Hit any key to exit ...
5717
5718	## Application terminated, rc = 0x0
5719
5720Another example, which demonstrates how to register a CPM interrupt
5721handler with the U-Boot code, can be found in 'examples/timer.c'.
5722Here, a CPM timer is set up to generate an interrupt every second.
5723The interrupt service routine is trivial, just printing a '.'
5724character, but this is just a demo program. The application can be
5725controlled by the following keys:
5726
5727	? - print current values og the CPM Timer registers
5728	b - enable interrupts and start timer
5729	e - stop timer and disable interrupts
5730	q - quit application
5731
5732	=> loads
5733	## Ready for S-Record download ...
5734	~>examples/timer.srec
5735	1 2 3 4 5 6 7 8 9 10 11 ...
5736	[file transfer complete]
5737	[connected]
5738	## Start Addr = 0x00040004
5739
5740	=> go 40004
5741	## Starting application at 0x00040004 ...
5742	TIMERS=0xfff00980
5743	Using timer 1
5744	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5745
5746Hit 'b':
5747	[q, b, e, ?] Set interval 1000000 us
5748	Enabling timer
5749Hit '?':
5750	[q, b, e, ?] ........
5751	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5752Hit '?':
5753	[q, b, e, ?] .
5754	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5755Hit '?':
5756	[q, b, e, ?] .
5757	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5758Hit '?':
5759	[q, b, e, ?] .
5760	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5761Hit 'e':
5762	[q, b, e, ?] ...Stopping timer
5763Hit 'q':
5764	[q, b, e, ?] ## Application terminated, rc = 0x0
5765
5766
5767Minicom warning:
5768================
5769
5770Over time, many people have reported problems when trying to use the
5771"minicom" terminal emulation program for serial download. I (wd)
5772consider minicom to be broken, and recommend not to use it. Under
5773Unix, I recommend to use C-Kermit for general purpose use (and
5774especially for kermit binary protocol download ("loadb" command), and
5775use "cu" for S-Record download ("loads" command).  See
5776http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5777for help with kermit.
5778
5779
5780Nevertheless, if you absolutely want to use it try adding this
5781configuration to your "File transfer protocols" section:
5782
5783	   Name	   Program			Name U/D FullScr IO-Red. Multi
5784	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5785	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5786
5787
5788NetBSD Notes:
5789=============
5790
5791Starting at version 0.9.2, U-Boot supports NetBSD both as host
5792(build U-Boot) and target system (boots NetBSD/mpc8xx).
5793
5794Building requires a cross environment; it is known to work on
5795NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5796need gmake since the Makefiles are not compatible with BSD make).
5797Note that the cross-powerpc package does not install include files;
5798attempting to build U-Boot will fail because <machine/ansi.h> is
5799missing.  This file has to be installed and patched manually:
5800
5801	# cd /usr/pkg/cross/powerpc-netbsd/include
5802	# mkdir powerpc
5803	# ln -s powerpc machine
5804	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5805	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5806
5807Native builds *don't* work due to incompatibilities between native
5808and U-Boot include files.
5809
5810Booting assumes that (the first part of) the image booted is a
5811stage-2 loader which in turn loads and then invokes the kernel
5812proper. Loader sources will eventually appear in the NetBSD source
5813tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5814meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5815
5816
5817Implementation Internals:
5818=========================
5819
5820The following is not intended to be a complete description of every
5821implementation detail. However, it should help to understand the
5822inner workings of U-Boot and make it easier to port it to custom
5823hardware.
5824
5825
5826Initial Stack, Global Data:
5827---------------------------
5828
5829The implementation of U-Boot is complicated by the fact that U-Boot
5830starts running out of ROM (flash memory), usually without access to
5831system RAM (because the memory controller is not initialized yet).
5832This means that we don't have writable Data or BSS segments, and BSS
5833is not initialized as zero. To be able to get a C environment working
5834at all, we have to allocate at least a minimal stack. Implementation
5835options for this are defined and restricted by the CPU used: Some CPU
5836models provide on-chip memory (like the IMMR area on MPC8xx and
5837MPC826x processors), on others (parts of) the data cache can be
5838locked as (mis-) used as memory, etc.
5839
5840	Chris Hallinan posted a good summary of these issues to the
5841	U-Boot mailing list:
5842
5843	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5844	From: "Chris Hallinan" <clh@net1plus.com>
5845	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5846	...
5847
5848	Correct me if I'm wrong, folks, but the way I understand it
5849	is this: Using DCACHE as initial RAM for Stack, etc, does not
5850	require any physical RAM backing up the cache. The cleverness
5851	is that the cache is being used as a temporary supply of
5852	necessary storage before the SDRAM controller is setup. It's
5853	beyond the scope of this list to explain the details, but you
5854	can see how this works by studying the cache architecture and
5855	operation in the architecture and processor-specific manuals.
5856
5857	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5858	is another option for the system designer to use as an
5859	initial stack/RAM area prior to SDRAM being available. Either
5860	option should work for you. Using CS 4 should be fine if your
5861	board designers haven't used it for something that would
5862	cause you grief during the initial boot! It is frequently not
5863	used.
5864
5865	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5866	with your processor/board/system design. The default value
5867	you will find in any recent u-boot distribution in
5868	walnut.h should work for you. I'd set it to a value larger
5869	than your SDRAM module. If you have a 64MB SDRAM module, set
5870	it above 400_0000. Just make sure your board has no resources
5871	that are supposed to respond to that address! That code in
5872	start.S has been around a while and should work as is when
5873	you get the config right.
5874
5875	-Chris Hallinan
5876	DS4.COM, Inc.
5877
5878It is essential to remember this, since it has some impact on the C
5879code for the initialization procedures:
5880
5881* Initialized global data (data segment) is read-only. Do not attempt
5882  to write it.
5883
5884* Do not use any uninitialized global data (or implicitely initialized
5885  as zero data - BSS segment) at all - this is undefined, initiali-
5886  zation is performed later (when relocating to RAM).
5887
5888* Stack space is very limited. Avoid big data buffers or things like
5889  that.
5890
5891Having only the stack as writable memory limits means we cannot use
5892normal global data to share information beween the code. But it
5893turned out that the implementation of U-Boot can be greatly
5894simplified by making a global data structure (gd_t) available to all
5895functions. We could pass a pointer to this data as argument to _all_
5896functions, but this would bloat the code. Instead we use a feature of
5897the GCC compiler (Global Register Variables) to share the data: we
5898place a pointer (gd) to the global data into a register which we
5899reserve for this purpose.
5900
5901When choosing a register for such a purpose we are restricted by the
5902relevant  (E)ABI  specifications for the current architecture, and by
5903GCC's implementation.
5904
5905For PowerPC, the following registers have specific use:
5906	R1:	stack pointer
5907	R2:	reserved for system use
5908	R3-R4:	parameter passing and return values
5909	R5-R10: parameter passing
5910	R13:	small data area pointer
5911	R30:	GOT pointer
5912	R31:	frame pointer
5913
5914	(U-Boot also uses R12 as internal GOT pointer. r12
5915	is a volatile register so r12 needs to be reset when
5916	going back and forth between asm and C)
5917
5918    ==> U-Boot will use R2 to hold a pointer to the global data
5919
5920    Note: on PPC, we could use a static initializer (since the
5921    address of the global data structure is known at compile time),
5922    but it turned out that reserving a register results in somewhat
5923    smaller code - although the code savings are not that big (on
5924    average for all boards 752 bytes for the whole U-Boot image,
5925    624 text + 127 data).
5926
5927On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5928	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5929
5930    ==> U-Boot will use P3 to hold a pointer to the global data
5931
5932On ARM, the following registers are used:
5933
5934	R0:	function argument word/integer result
5935	R1-R3:	function argument word
5936	R9:	platform specific
5937	R10:	stack limit (used only if stack checking is enabled)
5938	R11:	argument (frame) pointer
5939	R12:	temporary workspace
5940	R13:	stack pointer
5941	R14:	link register
5942	R15:	program counter
5943
5944    ==> U-Boot will use R9 to hold a pointer to the global data
5945
5946    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5947
5948On Nios II, the ABI is documented here:
5949	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5950
5951    ==> U-Boot will use gp to hold a pointer to the global data
5952
5953    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5954    to access small data sections, so gp is free.
5955
5956On NDS32, the following registers are used:
5957
5958	R0-R1:	argument/return
5959	R2-R5:	argument
5960	R15:	temporary register for assembler
5961	R16:	trampoline register
5962	R28:	frame pointer (FP)
5963	R29:	global pointer (GP)
5964	R30:	link register (LP)
5965	R31:	stack pointer (SP)
5966	PC:	program counter (PC)
5967
5968    ==> U-Boot will use R10 to hold a pointer to the global data
5969
5970NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5971or current versions of GCC may "optimize" the code too much.
5972
5973Memory Management:
5974------------------
5975
5976U-Boot runs in system state and uses physical addresses, i.e. the
5977MMU is not used either for address mapping nor for memory protection.
5978
5979The available memory is mapped to fixed addresses using the memory
5980controller. In this process, a contiguous block is formed for each
5981memory type (Flash, SDRAM, SRAM), even when it consists of several
5982physical memory banks.
5983
5984U-Boot is installed in the first 128 kB of the first Flash bank (on
5985TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5986booting and sizing and initializing DRAM, the code relocates itself
5987to the upper end of DRAM. Immediately below the U-Boot code some
5988memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5989configuration setting]. Below that, a structure with global Board
5990Info data is placed, followed by the stack (growing downward).
5991
5992Additionally, some exception handler code is copied to the low 8 kB
5993of DRAM (0x00000000 ... 0x00001FFF).
5994
5995So a typical memory configuration with 16 MB of DRAM could look like
5996this:
5997
5998	0x0000 0000	Exception Vector code
5999	      :
6000	0x0000 1FFF
6001	0x0000 2000	Free for Application Use
6002	      :
6003	      :
6004
6005	      :
6006	      :
6007	0x00FB FF20	Monitor Stack (Growing downward)
6008	0x00FB FFAC	Board Info Data and permanent copy of global data
6009	0x00FC 0000	Malloc Arena
6010	      :
6011	0x00FD FFFF
6012	0x00FE 0000	RAM Copy of Monitor Code
6013	...		eventually: LCD or video framebuffer
6014	...		eventually: pRAM (Protected RAM - unchanged by reset)
6015	0x00FF FFFF	[End of RAM]
6016
6017
6018System Initialization:
6019----------------------
6020
6021In the reset configuration, U-Boot starts at the reset entry point
6022(on most PowerPC systems at address 0x00000100). Because of the reset
6023configuration for CS0# this is a mirror of the onboard Flash memory.
6024To be able to re-map memory U-Boot then jumps to its link address.
6025To be able to implement the initialization code in C, a (small!)
6026initial stack is set up in the internal Dual Ported RAM (in case CPUs
6027which provide such a feature like MPC8xx or MPC8260), or in a locked
6028part of the data cache. After that, U-Boot initializes the CPU core,
6029the caches and the SIU.
6030
6031Next, all (potentially) available memory banks are mapped using a
6032preliminary mapping. For example, we put them on 512 MB boundaries
6033(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6034on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6035programmed for SDRAM access. Using the temporary configuration, a
6036simple memory test is run that determines the size of the SDRAM
6037banks.
6038
6039When there is more than one SDRAM bank, and the banks are of
6040different size, the largest is mapped first. For equal size, the first
6041bank (CS2#) is mapped first. The first mapping is always for address
60420x00000000, with any additional banks following immediately to create
6043contiguous memory starting from 0.
6044
6045Then, the monitor installs itself at the upper end of the SDRAM area
6046and allocates memory for use by malloc() and for the global Board
6047Info data; also, the exception vector code is copied to the low RAM
6048pages, and the final stack is set up.
6049
6050Only after this relocation will you have a "normal" C environment;
6051until that you are restricted in several ways, mostly because you are
6052running from ROM, and because the code will have to be relocated to a
6053new address in RAM.
6054
6055
6056U-Boot Porting Guide:
6057----------------------
6058
6059[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6060list, October 2002]
6061
6062
6063int main(int argc, char *argv[])
6064{
6065	sighandler_t no_more_time;
6066
6067	signal(SIGALRM, no_more_time);
6068	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6069
6070	if (available_money > available_manpower) {
6071		Pay consultant to port U-Boot;
6072		return 0;
6073	}
6074
6075	Download latest U-Boot source;
6076
6077	Subscribe to u-boot mailing list;
6078
6079	if (clueless)
6080		email("Hi, I am new to U-Boot, how do I get started?");
6081
6082	while (learning) {
6083		Read the README file in the top level directory;
6084		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6085		Read applicable doc/*.README;
6086		Read the source, Luke;
6087		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6088	}
6089
6090	if (available_money > toLocalCurrency ($2500))
6091		Buy a BDI3000;
6092	else
6093		Add a lot of aggravation and time;
6094
6095	if (a similar board exists) {	/* hopefully... */
6096		cp -a board/<similar> board/<myboard>
6097		cp include/configs/<similar>.h include/configs/<myboard>.h
6098	} else {
6099		Create your own board support subdirectory;
6100		Create your own board include/configs/<myboard>.h file;
6101	}
6102	Edit new board/<myboard> files
6103	Edit new include/configs/<myboard>.h
6104
6105	while (!accepted) {
6106		while (!running) {
6107			do {
6108				Add / modify source code;
6109			} until (compiles);
6110			Debug;
6111			if (clueless)
6112				email("Hi, I am having problems...");
6113		}
6114		Send patch file to the U-Boot email list;
6115		if (reasonable critiques)
6116			Incorporate improvements from email list code review;
6117		else
6118			Defend code as written;
6119	}
6120
6121	return 0;
6122}
6123
6124void no_more_time (int sig)
6125{
6126      hire_a_guru();
6127}
6128
6129
6130Coding Standards:
6131-----------------
6132
6133All contributions to U-Boot should conform to the Linux kernel
6134coding style; see the file "Documentation/CodingStyle" and the script
6135"scripts/Lindent" in your Linux kernel source directory.
6136
6137Source files originating from a different project (for example the
6138MTD subsystem) are generally exempt from these guidelines and are not
6139reformated to ease subsequent migration to newer versions of those
6140sources.
6141
6142Please note that U-Boot is implemented in C (and to some small parts in
6143Assembler); no C++ is used, so please do not use C++ style comments (//)
6144in your code.
6145
6146Please also stick to the following formatting rules:
6147- remove any trailing white space
6148- use TAB characters for indentation and vertical alignment, not spaces
6149- make sure NOT to use DOS '\r\n' line feeds
6150- do not add more than 2 consecutive empty lines to source files
6151- do not add trailing empty lines to source files
6152
6153Submissions which do not conform to the standards may be returned
6154with a request to reformat the changes.
6155
6156
6157Submitting Patches:
6158-------------------
6159
6160Since the number of patches for U-Boot is growing, we need to
6161establish some rules. Submissions which do not conform to these rules
6162may be rejected, even when they contain important and valuable stuff.
6163
6164Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6165
6166Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6167see http://lists.denx.de/mailman/listinfo/u-boot
6168
6169When you send a patch, please include the following information with
6170it:
6171
6172* For bug fixes: a description of the bug and how your patch fixes
6173  this bug. Please try to include a way of demonstrating that the
6174  patch actually fixes something.
6175
6176* For new features: a description of the feature and your
6177  implementation.
6178
6179* A CHANGELOG entry as plaintext (separate from the patch)
6180
6181* For major contributions, your entry to the CREDITS file
6182
6183* When you add support for a new board, don't forget to add a
6184  maintainer e-mail address to the boards.cfg file, too.
6185
6186* If your patch adds new configuration options, don't forget to
6187  document these in the README file.
6188
6189* The patch itself. If you are using git (which is *strongly*
6190  recommended) you can easily generate the patch using the
6191  "git format-patch". If you then use "git send-email" to send it to
6192  the U-Boot mailing list, you will avoid most of the common problems
6193  with some other mail clients.
6194
6195  If you cannot use git, use "diff -purN OLD NEW". If your version of
6196  diff does not support these options, then get the latest version of
6197  GNU diff.
6198
6199  The current directory when running this command shall be the parent
6200  directory of the U-Boot source tree (i. e. please make sure that
6201  your patch includes sufficient directory information for the
6202  affected files).
6203
6204  We prefer patches as plain text. MIME attachments are discouraged,
6205  and compressed attachments must not be used.
6206
6207* If one logical set of modifications affects or creates several
6208  files, all these changes shall be submitted in a SINGLE patch file.
6209
6210* Changesets that contain different, unrelated modifications shall be
6211  submitted as SEPARATE patches, one patch per changeset.
6212
6213
6214Notes:
6215
6216* Before sending the patch, run the MAKEALL script on your patched
6217  source tree and make sure that no errors or warnings are reported
6218  for any of the boards.
6219
6220* Keep your modifications to the necessary minimum: A patch
6221  containing several unrelated changes or arbitrary reformats will be
6222  returned with a request to re-formatting / split it.
6223
6224* If you modify existing code, make sure that your new code does not
6225  add to the memory footprint of the code ;-) Small is beautiful!
6226  When adding new features, these should compile conditionally only
6227  (using #ifdef), and the resulting code with the new feature
6228  disabled must not need more memory than the old code without your
6229  modification.
6230
6231* Remember that there is a size limit of 100 kB per message on the
6232  u-boot mailing list. Bigger patches will be moderated. If they are
6233  reasonable and not too big, they will be acknowledged. But patches
6234  bigger than the size limit should be avoided.
6235