xref: /rk3399_rockchip-uboot/README (revision ba8dd7755ea53bb04bf148fefe6e438cbe34f45b)
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- legacy image format:
3204		CONFIG_IMAGE_FORMAT_LEGACY
3205		enables the legacy image format support in U-Boot.
3206
3207		Default:
3208		enabled if CONFIG_FIT_SIGNATURE is not defined.
3209
3210		CONFIG_DISABLE_IMAGE_LEGACY
3211		disable the legacy image format
3212
3213		This define is introduced, as the legacy image format is
3214		enabled per default for backward compatibility.
3215
3216- FIT image support:
3217		CONFIG_FIT
3218		Enable support for the FIT uImage format.
3219
3220		CONFIG_FIT_BEST_MATCH
3221		When no configuration is explicitly selected, default to the
3222		one whose fdt's compatibility field best matches that of
3223		U-Boot itself. A match is considered "best" if it matches the
3224		most specific compatibility entry of U-Boot's fdt's root node.
3225		The order of entries in the configuration's fdt is ignored.
3226
3227		CONFIG_FIT_SIGNATURE
3228		This option enables signature verification of FIT uImages,
3229		using a hash signed and verified using RSA. See
3230		doc/uImage.FIT/signature.txt for more details.
3231
3232		WARNING: When relying on signed FIT images with required
3233		signature check the legacy image format is default
3234		disabled. If a board need legacy image format support
3235		enable this through CONFIG_IMAGE_FORMAT_LEGACY
3236
3237- Standalone program support:
3238		CONFIG_STANDALONE_LOAD_ADDR
3239
3240		This option defines a board specific value for the
3241		address where standalone program gets loaded, thus
3242		overwriting the architecture dependent default
3243		settings.
3244
3245- Frame Buffer Address:
3246		CONFIG_FB_ADDR
3247
3248		Define CONFIG_FB_ADDR if you want to use specific
3249		address for frame buffer.  This is typically the case
3250		when using a graphics controller has separate video
3251		memory.  U-Boot will then place the frame buffer at
3252		the given address instead of dynamically reserving it
3253		in system RAM by calling lcd_setmem(), which grabs
3254		the memory for the frame buffer depending on the
3255		configured panel size.
3256
3257		Please see board_init_f function.
3258
3259- Automatic software updates via TFTP server
3260		CONFIG_UPDATE_TFTP
3261		CONFIG_UPDATE_TFTP_CNT_MAX
3262		CONFIG_UPDATE_TFTP_MSEC_MAX
3263
3264		These options enable and control the auto-update feature;
3265		for a more detailed description refer to doc/README.update.
3266
3267- MTD Support (mtdparts command, UBI support)
3268		CONFIG_MTD_DEVICE
3269
3270		Adds the MTD device infrastructure from the Linux kernel.
3271		Needed for mtdparts command support.
3272
3273		CONFIG_MTD_PARTITIONS
3274
3275		Adds the MTD partitioning infrastructure from the Linux
3276		kernel. Needed for UBI support.
3277
3278- UBI support
3279		CONFIG_CMD_UBI
3280
3281		Adds commands for interacting with MTD partitions formatted
3282		with the UBI flash translation layer
3283
3284		Requires also defining CONFIG_RBTREE
3285
3286		CONFIG_UBI_SILENCE_MSG
3287
3288		Make the verbose messages from UBI stop printing.  This leaves
3289		warnings and errors enabled.
3290
3291- UBIFS support
3292		CONFIG_CMD_UBIFS
3293
3294		Adds commands for interacting with UBI volumes formatted as
3295		UBIFS.  UBIFS is read-only in u-boot.
3296
3297		Requires UBI support as well as CONFIG_LZO
3298
3299		CONFIG_UBIFS_SILENCE_MSG
3300
3301		Make the verbose messages from UBIFS stop printing.  This leaves
3302		warnings and errors enabled.
3303
3304- SPL framework
3305		CONFIG_SPL
3306		Enable building of SPL globally.
3307
3308		CONFIG_SPL_LDSCRIPT
3309		LDSCRIPT for linking the SPL binary.
3310
3311		CONFIG_SPL_MAX_FOOTPRINT
3312		Maximum size in memory allocated to the SPL, BSS included.
3313		When defined, the linker checks that the actual memory
3314		used by SPL from _start to __bss_end does not exceed it.
3315		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3316		must not be both defined at the same time.
3317
3318		CONFIG_SPL_MAX_SIZE
3319		Maximum size of the SPL image (text, data, rodata, and
3320		linker lists sections), BSS excluded.
3321		When defined, the linker checks that the actual size does
3322		not exceed it.
3323
3324		CONFIG_SPL_TEXT_BASE
3325		TEXT_BASE for linking the SPL binary.
3326
3327		CONFIG_SPL_RELOC_TEXT_BASE
3328		Address to relocate to.  If unspecified, this is equal to
3329		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3330
3331		CONFIG_SPL_BSS_START_ADDR
3332		Link address for the BSS within the SPL binary.
3333
3334		CONFIG_SPL_BSS_MAX_SIZE
3335		Maximum size in memory allocated to the SPL BSS.
3336		When defined, the linker checks that the actual memory used
3337		by SPL from __bss_start to __bss_end does not exceed it.
3338		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3339		must not be both defined at the same time.
3340
3341		CONFIG_SPL_STACK
3342		Adress of the start of the stack SPL will use
3343
3344		CONFIG_SPL_RELOC_STACK
3345		Adress of the start of the stack SPL will use after
3346		relocation.  If unspecified, this is equal to
3347		CONFIG_SPL_STACK.
3348
3349		CONFIG_SYS_SPL_MALLOC_START
3350		Starting address of the malloc pool used in SPL.
3351
3352		CONFIG_SYS_SPL_MALLOC_SIZE
3353		The size of the malloc pool used in SPL.
3354
3355		CONFIG_SPL_FRAMEWORK
3356		Enable the SPL framework under common/.  This framework
3357		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3358		NAND loading of the Linux Kernel.
3359
3360		CONFIG_SPL_OS_BOOT
3361		Enable booting directly to an OS from SPL.
3362		See also: doc/README.falcon
3363
3364		CONFIG_SPL_DISPLAY_PRINT
3365		For ARM, enable an optional function to print more information
3366		about the running system.
3367
3368		CONFIG_SPL_INIT_MINIMAL
3369		Arch init code should be built for a very small image
3370
3371		CONFIG_SPL_LIBCOMMON_SUPPORT
3372		Support for common/libcommon.o in SPL binary
3373
3374		CONFIG_SPL_LIBDISK_SUPPORT
3375		Support for disk/libdisk.o in SPL binary
3376
3377		CONFIG_SPL_I2C_SUPPORT
3378		Support for drivers/i2c/libi2c.o in SPL binary
3379
3380		CONFIG_SPL_GPIO_SUPPORT
3381		Support for drivers/gpio/libgpio.o in SPL binary
3382
3383		CONFIG_SPL_MMC_SUPPORT
3384		Support for drivers/mmc/libmmc.o in SPL binary
3385
3386		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3387		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3388		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3389		Address, size and partition on the MMC to load U-Boot from
3390		when the MMC is being used in raw mode.
3391
3392		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3393		Sector to load kernel uImage from when MMC is being
3394		used in raw mode (for Falcon mode)
3395
3396		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3397		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3398		Sector and number of sectors to load kernel argument
3399		parameters from when MMC is being used in raw mode
3400		(for falcon mode)
3401
3402		CONFIG_SPL_FAT_SUPPORT
3403		Support for fs/fat/libfat.o in SPL binary
3404
3405		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3406		Filename to read to load U-Boot when reading from FAT
3407
3408		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3409		Filename to read to load kernel uImage when reading
3410		from FAT (for Falcon mode)
3411
3412		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3413		Filename to read to load kernel argument parameters
3414		when reading from FAT (for Falcon mode)
3415
3416		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3417		Set this for NAND SPL on PPC mpc83xx targets, so that
3418		start.S waits for the rest of the SPL to load before
3419		continuing (the hardware starts execution after just
3420		loading the first page rather than the full 4K).
3421
3422		CONFIG_SPL_SKIP_RELOCATE
3423		Avoid SPL relocation
3424
3425		CONFIG_SPL_NAND_BASE
3426		Include nand_base.c in the SPL.  Requires
3427		CONFIG_SPL_NAND_DRIVERS.
3428
3429		CONFIG_SPL_NAND_DRIVERS
3430		SPL uses normal NAND drivers, not minimal drivers.
3431
3432		CONFIG_SPL_NAND_ECC
3433		Include standard software ECC in the SPL
3434
3435		CONFIG_SPL_NAND_SIMPLE
3436		Support for NAND boot using simple NAND drivers that
3437		expose the cmd_ctrl() interface.
3438
3439		CONFIG_SPL_MTD_SUPPORT
3440		Support for the MTD subsystem within SPL.  Useful for
3441		environment on NAND support within SPL.
3442
3443		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3444		Set for the SPL on PPC mpc8xxx targets, support for
3445		drivers/ddr/fsl/libddr.o in SPL binary.
3446
3447		CONFIG_SPL_COMMON_INIT_DDR
3448		Set for common ddr init with serial presence detect in
3449		SPL binary.
3450
3451		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3452		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3453		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3454		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3455		CONFIG_SYS_NAND_ECCBYTES
3456		Defines the size and behavior of the NAND that SPL uses
3457		to read U-Boot
3458
3459		CONFIG_SPL_NAND_BOOT
3460		Add support NAND boot
3461
3462		CONFIG_SYS_NAND_U_BOOT_OFFS
3463		Location in NAND to read U-Boot from
3464
3465		CONFIG_SYS_NAND_U_BOOT_DST
3466		Location in memory to load U-Boot to
3467
3468		CONFIG_SYS_NAND_U_BOOT_SIZE
3469		Size of image to load
3470
3471		CONFIG_SYS_NAND_U_BOOT_START
3472		Entry point in loaded image to jump to
3473
3474		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3475		Define this if you need to first read the OOB and then the
3476		data. This is used for example on davinci plattforms.
3477
3478		CONFIG_SPL_OMAP3_ID_NAND
3479		Support for an OMAP3-specific set of functions to return the
3480		ID and MFR of the first attached NAND chip, if present.
3481
3482		CONFIG_SPL_SERIAL_SUPPORT
3483		Support for drivers/serial/libserial.o in SPL binary
3484
3485		CONFIG_SPL_SPI_FLASH_SUPPORT
3486		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3487
3488		CONFIG_SPL_SPI_SUPPORT
3489		Support for drivers/spi/libspi.o in SPL binary
3490
3491		CONFIG_SPL_RAM_DEVICE
3492		Support for running image already present in ram, in SPL binary
3493
3494		CONFIG_SPL_LIBGENERIC_SUPPORT
3495		Support for lib/libgeneric.o in SPL binary
3496
3497		CONFIG_SPL_ENV_SUPPORT
3498		Support for the environment operating in SPL binary
3499
3500		CONFIG_SPL_NET_SUPPORT
3501		Support for the net/libnet.o in SPL binary.
3502		It conflicts with SPL env from storage medium specified by
3503		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3504
3505		CONFIG_SPL_PAD_TO
3506		Image offset to which the SPL should be padded before appending
3507		the SPL payload. By default, this is defined as
3508		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3509		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3510		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3511
3512		CONFIG_SPL_TARGET
3513		Final target image containing SPL and payload.  Some SPLs
3514		use an arch-specific makefile fragment instead, for
3515		example if more than one image needs to be produced.
3516
3517		CONFIG_FIT_SPL_PRINT
3518		Printing information about a FIT image adds quite a bit of
3519		code to SPL. So this is normally disabled in SPL. Use this
3520		option to re-enable it. This will affect the output of the
3521		bootm command when booting a FIT image.
3522
3523- TPL framework
3524		CONFIG_TPL
3525		Enable building of TPL globally.
3526
3527		CONFIG_TPL_PAD_TO
3528		Image offset to which the TPL should be padded before appending
3529		the TPL payload. By default, this is defined as
3530		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3531		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3532		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3533
3534Modem Support:
3535--------------
3536
3537[so far only for SMDK2400 boards]
3538
3539- Modem support enable:
3540		CONFIG_MODEM_SUPPORT
3541
3542- RTS/CTS Flow control enable:
3543		CONFIG_HWFLOW
3544
3545- Modem debug support:
3546		CONFIG_MODEM_SUPPORT_DEBUG
3547
3548		Enables debugging stuff (char screen[1024], dbg())
3549		for modem support. Useful only with BDI2000.
3550
3551- Interrupt support (PPC):
3552
3553		There are common interrupt_init() and timer_interrupt()
3554		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3555		for CPU specific initialization. interrupt_init_cpu()
3556		should set decrementer_count to appropriate value. If
3557		CPU resets decrementer automatically after interrupt
3558		(ppc4xx) it should set decrementer_count to zero.
3559		timer_interrupt() calls timer_interrupt_cpu() for CPU
3560		specific handling. If board has watchdog / status_led
3561		/ other_activity_monitor it works automatically from
3562		general timer_interrupt().
3563
3564- General:
3565
3566		In the target system modem support is enabled when a
3567		specific key (key combination) is pressed during
3568		power-on. Otherwise U-Boot will boot normally
3569		(autoboot). The key_pressed() function is called from
3570		board_init(). Currently key_pressed() is a dummy
3571		function, returning 1 and thus enabling modem
3572		initialization.
3573
3574		If there are no modem init strings in the
3575		environment, U-Boot proceed to autoboot; the
3576		previous output (banner, info printfs) will be
3577		suppressed, though.
3578
3579		See also: doc/README.Modem
3580
3581Board initialization settings:
3582------------------------------
3583
3584During Initialization u-boot calls a number of board specific functions
3585to allow the preparation of board specific prerequisites, e.g. pin setup
3586before drivers are initialized. To enable these callbacks the
3587following configuration macros have to be defined. Currently this is
3588architecture specific, so please check arch/your_architecture/lib/board.c
3589typically in board_init_f() and board_init_r().
3590
3591- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3592- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3593- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3594- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3595
3596Configuration Settings:
3597-----------------------
3598
3599- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3600		Optionally it can be defined to support 64-bit memory commands.
3601
3602- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3603		undefine this when you're short of memory.
3604
3605- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3606		width of the commands listed in the 'help' command output.
3607
3608- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3609		prompt for user input.
3610
3611- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3612
3613- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3614
3615- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3616
3617- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3618		the application (usually a Linux kernel) when it is
3619		booted
3620
3621- CONFIG_SYS_BAUDRATE_TABLE:
3622		List of legal baudrate settings for this board.
3623
3624- CONFIG_SYS_CONSOLE_INFO_QUIET
3625		Suppress display of console information at boot.
3626
3627- CONFIG_SYS_CONSOLE_IS_IN_ENV
3628		If the board specific function
3629			extern int overwrite_console (void);
3630		returns 1, the stdin, stderr and stdout are switched to the
3631		serial port, else the settings in the environment are used.
3632
3633- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3634		Enable the call to overwrite_console().
3635
3636- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3637		Enable overwrite of previous console environment settings.
3638
3639- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3640		Begin and End addresses of the area used by the
3641		simple memory test.
3642
3643- CONFIG_SYS_ALT_MEMTEST:
3644		Enable an alternate, more extensive memory test.
3645
3646- CONFIG_SYS_MEMTEST_SCRATCH:
3647		Scratch address used by the alternate memory test
3648		You only need to set this if address zero isn't writeable
3649
3650- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3651		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3652		this specified memory area will get subtracted from the top
3653		(end) of RAM and won't get "touched" at all by U-Boot. By
3654		fixing up gd->ram_size the Linux kernel should gets passed
3655		the now "corrected" memory size and won't touch it either.
3656		This should work for arch/ppc and arch/powerpc. Only Linux
3657		board ports in arch/powerpc with bootwrapper support that
3658		recalculate the memory size from the SDRAM controller setup
3659		will have to get fixed in Linux additionally.
3660
3661		This option can be used as a workaround for the 440EPx/GRx
3662		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3663		be touched.
3664
3665		WARNING: Please make sure that this value is a multiple of
3666		the Linux page size (normally 4k). If this is not the case,
3667		then the end address of the Linux memory will be located at a
3668		non page size aligned address and this could cause major
3669		problems.
3670
3671- CONFIG_SYS_LOADS_BAUD_CHANGE:
3672		Enable temporary baudrate change while serial download
3673
3674- CONFIG_SYS_SDRAM_BASE:
3675		Physical start address of SDRAM. _Must_ be 0 here.
3676
3677- CONFIG_SYS_MBIO_BASE:
3678		Physical start address of Motherboard I/O (if using a
3679		Cogent motherboard)
3680
3681- CONFIG_SYS_FLASH_BASE:
3682		Physical start address of Flash memory.
3683
3684- CONFIG_SYS_MONITOR_BASE:
3685		Physical start address of boot monitor code (set by
3686		make config files to be same as the text base address
3687		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3688		CONFIG_SYS_FLASH_BASE when booting from flash.
3689
3690- CONFIG_SYS_MONITOR_LEN:
3691		Size of memory reserved for monitor code, used to
3692		determine _at_compile_time_ (!) if the environment is
3693		embedded within the U-Boot image, or in a separate
3694		flash sector.
3695
3696- CONFIG_SYS_MALLOC_LEN:
3697		Size of DRAM reserved for malloc() use.
3698
3699- CONFIG_SYS_BOOTM_LEN:
3700		Normally compressed uImages are limited to an
3701		uncompressed size of 8 MBytes. If this is not enough,
3702		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3703		to adjust this setting to your needs.
3704
3705- CONFIG_SYS_BOOTMAPSZ:
3706		Maximum size of memory mapped by the startup code of
3707		the Linux kernel; all data that must be processed by
3708		the Linux kernel (bd_info, boot arguments, FDT blob if
3709		used) must be put below this limit, unless "bootm_low"
3710		environment variable is defined and non-zero. In such case
3711		all data for the Linux kernel must be between "bootm_low"
3712		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3713		variable "bootm_mapsize" will override the value of
3714		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3715		then the value in "bootm_size" will be used instead.
3716
3717- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3718		Enable initrd_high functionality.  If defined then the
3719		initrd_high feature is enabled and the bootm ramdisk subcommand
3720		is enabled.
3721
3722- CONFIG_SYS_BOOT_GET_CMDLINE:
3723		Enables allocating and saving kernel cmdline in space between
3724		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3725
3726- CONFIG_SYS_BOOT_GET_KBD:
3727		Enables allocating and saving a kernel copy of the bd_info in
3728		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3729
3730- CONFIG_SYS_MAX_FLASH_BANKS:
3731		Max number of Flash memory banks
3732
3733- CONFIG_SYS_MAX_FLASH_SECT:
3734		Max number of sectors on a Flash chip
3735
3736- CONFIG_SYS_FLASH_ERASE_TOUT:
3737		Timeout for Flash erase operations (in ms)
3738
3739- CONFIG_SYS_FLASH_WRITE_TOUT:
3740		Timeout for Flash write operations (in ms)
3741
3742- CONFIG_SYS_FLASH_LOCK_TOUT
3743		Timeout for Flash set sector lock bit operation (in ms)
3744
3745- CONFIG_SYS_FLASH_UNLOCK_TOUT
3746		Timeout for Flash clear lock bits operation (in ms)
3747
3748- CONFIG_SYS_FLASH_PROTECTION
3749		If defined, hardware flash sectors protection is used
3750		instead of U-Boot software protection.
3751
3752- CONFIG_SYS_DIRECT_FLASH_TFTP:
3753
3754		Enable TFTP transfers directly to flash memory;
3755		without this option such a download has to be
3756		performed in two steps: (1) download to RAM, and (2)
3757		copy from RAM to flash.
3758
3759		The two-step approach is usually more reliable, since
3760		you can check if the download worked before you erase
3761		the flash, but in some situations (when system RAM is
3762		too limited to allow for a temporary copy of the
3763		downloaded image) this option may be very useful.
3764
3765- CONFIG_SYS_FLASH_CFI:
3766		Define if the flash driver uses extra elements in the
3767		common flash structure for storing flash geometry.
3768
3769- CONFIG_FLASH_CFI_DRIVER
3770		This option also enables the building of the cfi_flash driver
3771		in the drivers directory
3772
3773- CONFIG_FLASH_CFI_MTD
3774		This option enables the building of the cfi_mtd driver
3775		in the drivers directory. The driver exports CFI flash
3776		to the MTD layer.
3777
3778- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3779		Use buffered writes to flash.
3780
3781- CONFIG_FLASH_SPANSION_S29WS_N
3782		s29ws-n MirrorBit flash has non-standard addresses for buffered
3783		write commands.
3784
3785- CONFIG_SYS_FLASH_QUIET_TEST
3786		If this option is defined, the common CFI flash doesn't
3787		print it's warning upon not recognized FLASH banks. This
3788		is useful, if some of the configured banks are only
3789		optionally available.
3790
3791- CONFIG_FLASH_SHOW_PROGRESS
3792		If defined (must be an integer), print out countdown
3793		digits and dots.  Recommended value: 45 (9..1) for 80
3794		column displays, 15 (3..1) for 40 column displays.
3795
3796- CONFIG_FLASH_VERIFY
3797		If defined, the content of the flash (destination) is compared
3798		against the source after the write operation. An error message
3799		will be printed when the contents are not identical.
3800		Please note that this option is useless in nearly all cases,
3801		since such flash programming errors usually are detected earlier
3802		while unprotecting/erasing/programming. Please only enable
3803		this option if you really know what you are doing.
3804
3805- CONFIG_SYS_RX_ETH_BUFFER:
3806		Defines the number of Ethernet receive buffers. On some
3807		Ethernet controllers it is recommended to set this value
3808		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3809		buffers can be full shortly after enabling the interface
3810		on high Ethernet traffic.
3811		Defaults to 4 if not defined.
3812
3813- CONFIG_ENV_MAX_ENTRIES
3814
3815	Maximum number of entries in the hash table that is used
3816	internally to store the environment settings. The default
3817	setting is supposed to be generous and should work in most
3818	cases. This setting can be used to tune behaviour; see
3819	lib/hashtable.c for details.
3820
3821- CONFIG_ENV_FLAGS_LIST_DEFAULT
3822- CONFIG_ENV_FLAGS_LIST_STATIC
3823	Enable validation of the values given to environment variables when
3824	calling env set.  Variables can be restricted to only decimal,
3825	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3826	the variables can also be restricted to IP address or MAC address.
3827
3828	The format of the list is:
3829		type_attribute = [s|d|x|b|i|m]
3830		access_atribute = [a|r|o|c]
3831		attributes = type_attribute[access_atribute]
3832		entry = variable_name[:attributes]
3833		list = entry[,list]
3834
3835	The type attributes are:
3836		s - String (default)
3837		d - Decimal
3838		x - Hexadecimal
3839		b - Boolean ([1yYtT|0nNfF])
3840		i - IP address
3841		m - MAC address
3842
3843	The access attributes are:
3844		a - Any (default)
3845		r - Read-only
3846		o - Write-once
3847		c - Change-default
3848
3849	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3850		Define this to a list (string) to define the ".flags"
3851		envirnoment variable in the default or embedded environment.
3852
3853	- CONFIG_ENV_FLAGS_LIST_STATIC
3854		Define this to a list (string) to define validation that
3855		should be done if an entry is not found in the ".flags"
3856		environment variable.  To override a setting in the static
3857		list, simply add an entry for the same variable name to the
3858		".flags" variable.
3859
3860- CONFIG_ENV_ACCESS_IGNORE_FORCE
3861	If defined, don't allow the -f switch to env set override variable
3862	access flags.
3863
3864- CONFIG_SYS_GENERIC_BOARD
3865	This selects the architecture-generic board system instead of the
3866	architecture-specific board files. It is intended to move boards
3867	to this new framework over time. Defining this will disable the
3868	arch/foo/lib/board.c file and use common/board_f.c and
3869	common/board_r.c instead. To use this option your architecture
3870	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3871	its config.mk file). If you find problems enabling this option on
3872	your board please report the problem and send patches!
3873
3874- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3875	This is set by OMAP boards for the max time that reset should
3876	be asserted. See doc/README.omap-reset-time for details on how
3877	the value can be calulated on a given board.
3878
3879The following definitions that deal with the placement and management
3880of environment data (variable area); in general, we support the
3881following configurations:
3882
3883- CONFIG_BUILD_ENVCRC:
3884
3885	Builds up envcrc with the target environment so that external utils
3886	may easily extract it and embed it in final U-Boot images.
3887
3888- CONFIG_ENV_IS_IN_FLASH:
3889
3890	Define this if the environment is in flash memory.
3891
3892	a) The environment occupies one whole flash sector, which is
3893	   "embedded" in the text segment with the U-Boot code. This
3894	   happens usually with "bottom boot sector" or "top boot
3895	   sector" type flash chips, which have several smaller
3896	   sectors at the start or the end. For instance, such a
3897	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3898	   such a case you would place the environment in one of the
3899	   4 kB sectors - with U-Boot code before and after it. With
3900	   "top boot sector" type flash chips, you would put the
3901	   environment in one of the last sectors, leaving a gap
3902	   between U-Boot and the environment.
3903
3904	- CONFIG_ENV_OFFSET:
3905
3906	   Offset of environment data (variable area) to the
3907	   beginning of flash memory; for instance, with bottom boot
3908	   type flash chips the second sector can be used: the offset
3909	   for this sector is given here.
3910
3911	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3912
3913	- CONFIG_ENV_ADDR:
3914
3915	   This is just another way to specify the start address of
3916	   the flash sector containing the environment (instead of
3917	   CONFIG_ENV_OFFSET).
3918
3919	- CONFIG_ENV_SECT_SIZE:
3920
3921	   Size of the sector containing the environment.
3922
3923
3924	b) Sometimes flash chips have few, equal sized, BIG sectors.
3925	   In such a case you don't want to spend a whole sector for
3926	   the environment.
3927
3928	- CONFIG_ENV_SIZE:
3929
3930	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3931	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3932	   of this flash sector for the environment. This saves
3933	   memory for the RAM copy of the environment.
3934
3935	   It may also save flash memory if you decide to use this
3936	   when your environment is "embedded" within U-Boot code,
3937	   since then the remainder of the flash sector could be used
3938	   for U-Boot code. It should be pointed out that this is
3939	   STRONGLY DISCOURAGED from a robustness point of view:
3940	   updating the environment in flash makes it always
3941	   necessary to erase the WHOLE sector. If something goes
3942	   wrong before the contents has been restored from a copy in
3943	   RAM, your target system will be dead.
3944
3945	- CONFIG_ENV_ADDR_REDUND
3946	  CONFIG_ENV_SIZE_REDUND
3947
3948	   These settings describe a second storage area used to hold
3949	   a redundant copy of the environment data, so that there is
3950	   a valid backup copy in case there is a power failure during
3951	   a "saveenv" operation.
3952
3953BE CAREFUL! Any changes to the flash layout, and some changes to the
3954source code will make it necessary to adapt <board>/u-boot.lds*
3955accordingly!
3956
3957
3958- CONFIG_ENV_IS_IN_NVRAM:
3959
3960	Define this if you have some non-volatile memory device
3961	(NVRAM, battery buffered SRAM) which you want to use for the
3962	environment.
3963
3964	- CONFIG_ENV_ADDR:
3965	- CONFIG_ENV_SIZE:
3966
3967	  These two #defines are used to determine the memory area you
3968	  want to use for environment. It is assumed that this memory
3969	  can just be read and written to, without any special
3970	  provision.
3971
3972BE CAREFUL! The first access to the environment happens quite early
3973in U-Boot initalization (when we try to get the setting of for the
3974console baudrate). You *MUST* have mapped your NVRAM area then, or
3975U-Boot will hang.
3976
3977Please note that even with NVRAM we still use a copy of the
3978environment in RAM: we could work on NVRAM directly, but we want to
3979keep settings there always unmodified except somebody uses "saveenv"
3980to save the current settings.
3981
3982
3983- CONFIG_ENV_IS_IN_EEPROM:
3984
3985	Use this if you have an EEPROM or similar serial access
3986	device and a driver for it.
3987
3988	- CONFIG_ENV_OFFSET:
3989	- CONFIG_ENV_SIZE:
3990
3991	  These two #defines specify the offset and size of the
3992	  environment area within the total memory of your EEPROM.
3993
3994	- CONFIG_SYS_I2C_EEPROM_ADDR:
3995	  If defined, specified the chip address of the EEPROM device.
3996	  The default address is zero.
3997
3998	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3999	  If defined, the number of bits used to address bytes in a
4000	  single page in the EEPROM device.  A 64 byte page, for example
4001	  would require six bits.
4002
4003	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4004	  If defined, the number of milliseconds to delay between
4005	  page writes.	The default is zero milliseconds.
4006
4007	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4008	  The length in bytes of the EEPROM memory array address.  Note
4009	  that this is NOT the chip address length!
4010
4011	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4012	  EEPROM chips that implement "address overflow" are ones
4013	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4014	  address and the extra bits end up in the "chip address" bit
4015	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4016	  byte chips.
4017
4018	  Note that we consider the length of the address field to
4019	  still be one byte because the extra address bits are hidden
4020	  in the chip address.
4021
4022	- CONFIG_SYS_EEPROM_SIZE:
4023	  The size in bytes of the EEPROM device.
4024
4025	- CONFIG_ENV_EEPROM_IS_ON_I2C
4026	  define this, if you have I2C and SPI activated, and your
4027	  EEPROM, which holds the environment, is on the I2C bus.
4028
4029	- CONFIG_I2C_ENV_EEPROM_BUS
4030	  if you have an Environment on an EEPROM reached over
4031	  I2C muxes, you can define here, how to reach this
4032	  EEPROM. For example:
4033
4034	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4035
4036	  EEPROM which holds the environment, is reached over
4037	  a pca9547 i2c mux with address 0x70, channel 3.
4038
4039- CONFIG_ENV_IS_IN_DATAFLASH:
4040
4041	Define this if you have a DataFlash memory device which you
4042	want to use for the environment.
4043
4044	- CONFIG_ENV_OFFSET:
4045	- CONFIG_ENV_ADDR:
4046	- CONFIG_ENV_SIZE:
4047
4048	  These three #defines specify the offset and size of the
4049	  environment area within the total memory of your DataFlash placed
4050	  at the specified address.
4051
4052- CONFIG_ENV_IS_IN_REMOTE:
4053
4054	Define this if you have a remote memory space which you
4055	want to use for the local device's environment.
4056
4057	- CONFIG_ENV_ADDR:
4058	- CONFIG_ENV_SIZE:
4059
4060	  These two #defines specify the address and size of the
4061	  environment area within the remote memory space. The
4062	  local device can get the environment from remote memory
4063	  space by SRIO or PCIE links.
4064
4065BE CAREFUL! For some special cases, the local device can not use
4066"saveenv" command. For example, the local device will get the
4067environment stored in a remote NOR flash by SRIO or PCIE link,
4068but it can not erase, write this NOR flash by SRIO or PCIE interface.
4069
4070- CONFIG_ENV_IS_IN_NAND:
4071
4072	Define this if you have a NAND device which you want to use
4073	for the environment.
4074
4075	- CONFIG_ENV_OFFSET:
4076	- CONFIG_ENV_SIZE:
4077
4078	  These two #defines specify the offset and size of the environment
4079	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4080	  aligned to an erase block boundary.
4081
4082	- CONFIG_ENV_OFFSET_REDUND (optional):
4083
4084	  This setting describes a second storage area of CONFIG_ENV_SIZE
4085	  size used to hold a redundant copy of the environment data, so
4086	  that there is a valid backup copy in case there is a power failure
4087	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4088	  aligned to an erase block boundary.
4089
4090	- CONFIG_ENV_RANGE (optional):
4091
4092	  Specifies the length of the region in which the environment
4093	  can be written.  This should be a multiple of the NAND device's
4094	  block size.  Specifying a range with more erase blocks than
4095	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4096	  the range to be avoided.
4097
4098	- CONFIG_ENV_OFFSET_OOB (optional):
4099
4100	  Enables support for dynamically retrieving the offset of the
4101	  environment from block zero's out-of-band data.  The
4102	  "nand env.oob" command can be used to record this offset.
4103	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4104	  using CONFIG_ENV_OFFSET_OOB.
4105
4106- CONFIG_NAND_ENV_DST
4107
4108	Defines address in RAM to which the nand_spl code should copy the
4109	environment. If redundant environment is used, it will be copied to
4110	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4111
4112- CONFIG_ENV_IS_IN_UBI:
4113
4114	Define this if you have an UBI volume that you want to use for the
4115	environment.  This has the benefit of wear-leveling the environment
4116	accesses, which is important on NAND.
4117
4118	- CONFIG_ENV_UBI_PART:
4119
4120	  Define this to a string that is the mtd partition containing the UBI.
4121
4122	- CONFIG_ENV_UBI_VOLUME:
4123
4124	  Define this to the name of the volume that you want to store the
4125	  environment in.
4126
4127	- CONFIG_ENV_UBI_VOLUME_REDUND:
4128
4129	  Define this to the name of another volume to store a second copy of
4130	  the environment in.  This will enable redundant environments in UBI.
4131	  It is assumed that both volumes are in the same MTD partition.
4132
4133	- CONFIG_UBI_SILENCE_MSG
4134	- CONFIG_UBIFS_SILENCE_MSG
4135
4136	  You will probably want to define these to avoid a really noisy system
4137	  when storing the env in UBI.
4138
4139- CONFIG_ENV_IS_IN_MMC:
4140
4141	Define this if you have an MMC device which you want to use for the
4142	environment.
4143
4144	- CONFIG_SYS_MMC_ENV_DEV:
4145
4146	  Specifies which MMC device the environment is stored in.
4147
4148	- CONFIG_SYS_MMC_ENV_PART (optional):
4149
4150	  Specifies which MMC partition the environment is stored in. If not
4151	  set, defaults to partition 0, the user area. Common values might be
4152	  1 (first MMC boot partition), 2 (second MMC boot partition).
4153
4154	- CONFIG_ENV_OFFSET:
4155	- CONFIG_ENV_SIZE:
4156
4157	  These two #defines specify the offset and size of the environment
4158	  area within the specified MMC device.
4159
4160	  If offset is positive (the usual case), it is treated as relative to
4161	  the start of the MMC partition. If offset is negative, it is treated
4162	  as relative to the end of the MMC partition. This can be useful if
4163	  your board may be fitted with different MMC devices, which have
4164	  different sizes for the MMC partitions, and you always want the
4165	  environment placed at the very end of the partition, to leave the
4166	  maximum possible space before it, to store other data.
4167
4168	  These two values are in units of bytes, but must be aligned to an
4169	  MMC sector boundary.
4170
4171	- CONFIG_ENV_OFFSET_REDUND (optional):
4172
4173	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4174	  hold a redundant copy of the environment data. This provides a
4175	  valid backup copy in case the other copy is corrupted, e.g. due
4176	  to a power failure during a "saveenv" operation.
4177
4178	  This value may also be positive or negative; this is handled in the
4179	  same way as CONFIG_ENV_OFFSET.
4180
4181	  This value is also in units of bytes, but must also be aligned to
4182	  an MMC sector boundary.
4183
4184	- CONFIG_ENV_SIZE_REDUND (optional):
4185
4186	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4187	  set. If this value is set, it must be set to the same value as
4188	  CONFIG_ENV_SIZE.
4189
4190- CONFIG_SYS_SPI_INIT_OFFSET
4191
4192	Defines offset to the initial SPI buffer area in DPRAM. The
4193	area is used at an early stage (ROM part) if the environment
4194	is configured to reside in the SPI EEPROM: We need a 520 byte
4195	scratch DPRAM area. It is used between the two initialization
4196	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4197	to be a good choice since it makes it far enough from the
4198	start of the data area as well as from the stack pointer.
4199
4200Please note that the environment is read-only until the monitor
4201has been relocated to RAM and a RAM copy of the environment has been
4202created; also, when using EEPROM you will have to use getenv_f()
4203until then to read environment variables.
4204
4205The environment is protected by a CRC32 checksum. Before the monitor
4206is relocated into RAM, as a result of a bad CRC you will be working
4207with the compiled-in default environment - *silently*!!! [This is
4208necessary, because the first environment variable we need is the
4209"baudrate" setting for the console - if we have a bad CRC, we don't
4210have any device yet where we could complain.]
4211
4212Note: once the monitor has been relocated, then it will complain if
4213the default environment is used; a new CRC is computed as soon as you
4214use the "saveenv" command to store a valid environment.
4215
4216- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4217		Echo the inverted Ethernet link state to the fault LED.
4218
4219		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4220		      also needs to be defined.
4221
4222- CONFIG_SYS_FAULT_MII_ADDR:
4223		MII address of the PHY to check for the Ethernet link state.
4224
4225- CONFIG_NS16550_MIN_FUNCTIONS:
4226		Define this if you desire to only have use of the NS16550_init
4227		and NS16550_putc functions for the serial driver located at
4228		drivers/serial/ns16550.c.  This option is useful for saving
4229		space for already greatly restricted images, including but not
4230		limited to NAND_SPL configurations.
4231
4232- CONFIG_DISPLAY_BOARDINFO
4233		Display information about the board that U-Boot is running on
4234		when U-Boot starts up. The board function checkboard() is called
4235		to do this.
4236
4237- CONFIG_DISPLAY_BOARDINFO_LATE
4238		Similar to the previous option, but display this information
4239		later, once stdio is running and output goes to the LCD, if
4240		present.
4241
4242Low Level (hardware related) configuration options:
4243---------------------------------------------------
4244
4245- CONFIG_SYS_CACHELINE_SIZE:
4246		Cache Line Size of the CPU.
4247
4248- CONFIG_SYS_DEFAULT_IMMR:
4249		Default address of the IMMR after system reset.
4250
4251		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4252		and RPXsuper) to be able to adjust the position of
4253		the IMMR register after a reset.
4254
4255- CONFIG_SYS_CCSRBAR_DEFAULT:
4256		Default (power-on reset) physical address of CCSR on Freescale
4257		PowerPC SOCs.
4258
4259- CONFIG_SYS_CCSRBAR:
4260		Virtual address of CCSR.  On a 32-bit build, this is typically
4261		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4262
4263		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4264		for cross-platform code that uses that macro instead.
4265
4266- CONFIG_SYS_CCSRBAR_PHYS:
4267		Physical address of CCSR.  CCSR can be relocated to a new
4268		physical address, if desired.  In this case, this macro should
4269		be set to that address.	 Otherwise, it should be set to the
4270		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4271		is typically relocated on 36-bit builds.  It is recommended
4272		that this macro be defined via the _HIGH and _LOW macros:
4273
4274		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4275			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4276
4277- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4278		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4279		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4280		used in assembly code, so it must not contain typecasts or
4281		integer size suffixes (e.g. "ULL").
4282
4283- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4284		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4285		used in assembly code, so it must not contain typecasts or
4286		integer size suffixes (e.g. "ULL").
4287
4288- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4289		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4290		forced to a value that ensures that CCSR is not relocated.
4291
4292- Floppy Disk Support:
4293		CONFIG_SYS_FDC_DRIVE_NUMBER
4294
4295		the default drive number (default value 0)
4296
4297		CONFIG_SYS_ISA_IO_STRIDE
4298
4299		defines the spacing between FDC chipset registers
4300		(default value 1)
4301
4302		CONFIG_SYS_ISA_IO_OFFSET
4303
4304		defines the offset of register from address. It
4305		depends on which part of the data bus is connected to
4306		the FDC chipset. (default value 0)
4307
4308		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4309		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4310		default value.
4311
4312		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4313		fdc_hw_init() is called at the beginning of the FDC
4314		setup. fdc_hw_init() must be provided by the board
4315		source code. It is used to make hardware dependant
4316		initializations.
4317
4318- CONFIG_IDE_AHB:
4319		Most IDE controllers were designed to be connected with PCI
4320		interface. Only few of them were designed for AHB interface.
4321		When software is doing ATA command and data transfer to
4322		IDE devices through IDE-AHB controller, some additional
4323		registers accessing to these kind of IDE-AHB controller
4324		is requierd.
4325
4326- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4327		DO NOT CHANGE unless you know exactly what you're
4328		doing! (11-4) [MPC8xx/82xx systems only]
4329
4330- CONFIG_SYS_INIT_RAM_ADDR:
4331
4332		Start address of memory area that can be used for
4333		initial data and stack; please note that this must be
4334		writable memory that is working WITHOUT special
4335		initialization, i. e. you CANNOT use normal RAM which
4336		will become available only after programming the
4337		memory controller and running certain initialization
4338		sequences.
4339
4340		U-Boot uses the following memory types:
4341		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4342		- MPC824X: data cache
4343		- PPC4xx:  data cache
4344
4345- CONFIG_SYS_GBL_DATA_OFFSET:
4346
4347		Offset of the initial data structure in the memory
4348		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4349		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4350		data is located at the end of the available space
4351		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4352		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4353		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4354		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4355
4356	Note:
4357		On the MPC824X (or other systems that use the data
4358		cache for initial memory) the address chosen for
4359		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4360		point to an otherwise UNUSED address space between
4361		the top of RAM and the start of the PCI space.
4362
4363- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4364
4365- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4366
4367- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4368
4369- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4370
4371- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4372
4373- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4374
4375- CONFIG_SYS_OR_TIMING_SDRAM:
4376		SDRAM timing
4377
4378- CONFIG_SYS_MAMR_PTA:
4379		periodic timer for refresh
4380
4381- CONFIG_SYS_DER:	Debug Event Register (37-47)
4382
4383- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4384  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4385  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4386  CONFIG_SYS_BR1_PRELIM:
4387		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4388
4389- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4390  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4391  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4392		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4393
4394- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4395  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4396		Machine Mode Register and Memory Periodic Timer
4397		Prescaler definitions (SDRAM timing)
4398
4399- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4400		enable I2C microcode relocation patch (MPC8xx);
4401		define relocation offset in DPRAM [DSP2]
4402
4403- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4404		enable SMC microcode relocation patch (MPC8xx);
4405		define relocation offset in DPRAM [SMC1]
4406
4407- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4408		enable SPI microcode relocation patch (MPC8xx);
4409		define relocation offset in DPRAM [SCC4]
4410
4411- CONFIG_SYS_USE_OSCCLK:
4412		Use OSCM clock mode on MBX8xx board. Be careful,
4413		wrong setting might damage your board. Read
4414		doc/README.MBX before setting this variable!
4415
4416- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4417		Offset of the bootmode word in DPRAM used by post
4418		(Power On Self Tests). This definition overrides
4419		#define'd default value in commproc.h resp.
4420		cpm_8260.h.
4421
4422- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4423  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4424  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4425  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4426  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4427  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4428  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4429  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4430		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4431
4432- CONFIG_PCI_DISABLE_PCIE:
4433		Disable PCI-Express on systems where it is supported but not
4434		required.
4435
4436- CONFIG_PCI_ENUM_ONLY
4437		Only scan through and get the devices on the busses.
4438		Don't do any setup work, presumably because someone or
4439		something has already done it, and we don't need to do it
4440		a second time.	Useful for platforms that are pre-booted
4441		by coreboot or similar.
4442
4443- CONFIG_PCI_INDIRECT_BRIDGE:
4444		Enable support for indirect PCI bridges.
4445
4446- CONFIG_SYS_SRIO:
4447		Chip has SRIO or not
4448
4449- CONFIG_SRIO1:
4450		Board has SRIO 1 port available
4451
4452- CONFIG_SRIO2:
4453		Board has SRIO 2 port available
4454
4455- CONFIG_SRIO_PCIE_BOOT_MASTER
4456		Board can support master function for Boot from SRIO and PCIE
4457
4458- CONFIG_SYS_SRIOn_MEM_VIRT:
4459		Virtual Address of SRIO port 'n' memory region
4460
4461- CONFIG_SYS_SRIOn_MEM_PHYS:
4462		Physical Address of SRIO port 'n' memory region
4463
4464- CONFIG_SYS_SRIOn_MEM_SIZE:
4465		Size of SRIO port 'n' memory region
4466
4467- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4468		Defined to tell the NAND controller that the NAND chip is using
4469		a 16 bit bus.
4470		Not all NAND drivers use this symbol.
4471		Example of drivers that use it:
4472		- drivers/mtd/nand/ndfc.c
4473		- drivers/mtd/nand/mxc_nand.c
4474
4475- CONFIG_SYS_NDFC_EBC0_CFG
4476		Sets the EBC0_CFG register for the NDFC. If not defined
4477		a default value will be used.
4478
4479- CONFIG_SPD_EEPROM
4480		Get DDR timing information from an I2C EEPROM. Common
4481		with pluggable memory modules such as SODIMMs
4482
4483  SPD_EEPROM_ADDRESS
4484		I2C address of the SPD EEPROM
4485
4486- CONFIG_SYS_SPD_BUS_NUM
4487		If SPD EEPROM is on an I2C bus other than the first
4488		one, specify here. Note that the value must resolve
4489		to something your driver can deal with.
4490
4491- CONFIG_SYS_DDR_RAW_TIMING
4492		Get DDR timing information from other than SPD. Common with
4493		soldered DDR chips onboard without SPD. DDR raw timing
4494		parameters are extracted from datasheet and hard-coded into
4495		header files or board specific files.
4496
4497- CONFIG_FSL_DDR_INTERACTIVE
4498		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4499
4500- CONFIG_SYS_83XX_DDR_USES_CS0
4501		Only for 83xx systems. If specified, then DDR should
4502		be configured using CS0 and CS1 instead of CS2 and CS3.
4503
4504- CONFIG_ETHER_ON_FEC[12]
4505		Define to enable FEC[12] on a 8xx series processor.
4506
4507- CONFIG_FEC[12]_PHY
4508		Define to the hardcoded PHY address which corresponds
4509		to the given FEC; i. e.
4510			#define CONFIG_FEC1_PHY 4
4511		means that the PHY with address 4 is connected to FEC1
4512
4513		When set to -1, means to probe for first available.
4514
4515- CONFIG_FEC[12]_PHY_NORXERR
4516		The PHY does not have a RXERR line (RMII only).
4517		(so program the FEC to ignore it).
4518
4519- CONFIG_RMII
4520		Enable RMII mode for all FECs.
4521		Note that this is a global option, we can't
4522		have one FEC in standard MII mode and another in RMII mode.
4523
4524- CONFIG_CRC32_VERIFY
4525		Add a verify option to the crc32 command.
4526		The syntax is:
4527
4528		=> crc32 -v <address> <count> <crc32>
4529
4530		Where address/count indicate a memory area
4531		and crc32 is the correct crc32 which the
4532		area should have.
4533
4534- CONFIG_LOOPW
4535		Add the "loopw" memory command. This only takes effect if
4536		the memory commands are activated globally (CONFIG_CMD_MEM).
4537
4538- CONFIG_MX_CYCLIC
4539		Add the "mdc" and "mwc" memory commands. These are cyclic
4540		"md/mw" commands.
4541		Examples:
4542
4543		=> mdc.b 10 4 500
4544		This command will print 4 bytes (10,11,12,13) each 500 ms.
4545
4546		=> mwc.l 100 12345678 10
4547		This command will write 12345678 to address 100 all 10 ms.
4548
4549		This only takes effect if the memory commands are activated
4550		globally (CONFIG_CMD_MEM).
4551
4552- CONFIG_SKIP_LOWLEVEL_INIT
4553		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4554		low level initializations (like setting up the memory
4555		controller) are omitted and/or U-Boot does not
4556		relocate itself into RAM.
4557
4558		Normally this variable MUST NOT be defined. The only
4559		exception is when U-Boot is loaded (to RAM) by some
4560		other boot loader or by a debugger which performs
4561		these initializations itself.
4562
4563- CONFIG_SPL_BUILD
4564		Modifies the behaviour of start.S when compiling a loader
4565		that is executed before the actual U-Boot. E.g. when
4566		compiling a NAND SPL.
4567
4568- CONFIG_TPL_BUILD
4569		Modifies the behaviour of start.S  when compiling a loader
4570		that is executed after the SPL and before the actual U-Boot.
4571		It is loaded by the SPL.
4572
4573- CONFIG_SYS_MPC85XX_NO_RESETVEC
4574		Only for 85xx systems. If this variable is specified, the section
4575		.resetvec is not kept and the section .bootpg is placed in the
4576		previous 4k of the .text section.
4577
4578- CONFIG_ARCH_MAP_SYSMEM
4579		Generally U-Boot (and in particular the md command) uses
4580		effective address. It is therefore not necessary to regard
4581		U-Boot address as virtual addresses that need to be translated
4582		to physical addresses. However, sandbox requires this, since
4583		it maintains its own little RAM buffer which contains all
4584		addressable memory. This option causes some memory accesses
4585		to be mapped through map_sysmem() / unmap_sysmem().
4586
4587- CONFIG_USE_ARCH_MEMCPY
4588  CONFIG_USE_ARCH_MEMSET
4589		If these options are used a optimized version of memcpy/memset will
4590		be used if available. These functions may be faster under some
4591		conditions but may increase the binary size.
4592
4593- CONFIG_X86_RESET_VECTOR
4594		If defined, the x86 reset vector code is included. This is not
4595		needed when U-Boot is running from Coreboot.
4596
4597- CONFIG_SYS_MPUCLK
4598		Defines the MPU clock speed (in MHz).
4599
4600		NOTE : currently only supported on AM335x platforms.
4601
4602- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4603		Enables the RTC32K OSC on AM33xx based plattforms
4604
4605- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4606		Option to disable subpage write in NAND driver
4607		driver that uses this:
4608		drivers/mtd/nand/davinci_nand.c
4609
4610Freescale QE/FMAN Firmware Support:
4611-----------------------------------
4612
4613The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4614loading of "firmware", which is encoded in the QE firmware binary format.
4615This firmware often needs to be loaded during U-Boot booting, so macros
4616are used to identify the storage device (NOR flash, SPI, etc) and the address
4617within that device.
4618
4619- CONFIG_SYS_FMAN_FW_ADDR
4620	The address in the storage device where the FMAN microcode is located.  The
4621	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4622	is also specified.
4623
4624- CONFIG_SYS_QE_FW_ADDR
4625	The address in the storage device where the QE microcode is located.  The
4626	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4627	is also specified.
4628
4629- CONFIG_SYS_QE_FMAN_FW_LENGTH
4630	The maximum possible size of the firmware.  The firmware binary format
4631	has a field that specifies the actual size of the firmware, but it
4632	might not be possible to read any part of the firmware unless some
4633	local storage is allocated to hold the entire firmware first.
4634
4635- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4636	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4637	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4638	virtual address in NOR flash.
4639
4640- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4641	Specifies that QE/FMAN firmware is located in NAND flash.
4642	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4643
4644- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4645	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4646	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4647
4648- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4649	Specifies that QE/FMAN firmware is located on the primary SPI
4650	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4651
4652- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4653	Specifies that QE/FMAN firmware is located in the remote (master)
4654	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4655	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4656	window->master inbound window->master LAW->the ucode address in
4657	master's memory space.
4658
4659Building the Software:
4660======================
4661
4662Building U-Boot has been tested in several native build environments
4663and in many different cross environments. Of course we cannot support
4664all possibly existing versions of cross development tools in all
4665(potentially obsolete) versions. In case of tool chain problems we
4666recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4667which is extensively used to build and test U-Boot.
4668
4669If you are not using a native environment, it is assumed that you
4670have GNU cross compiling tools available in your path. In this case,
4671you must set the environment variable CROSS_COMPILE in your shell.
4672Note that no changes to the Makefile or any other source files are
4673necessary. For example using the ELDK on a 4xx CPU, please enter:
4674
4675	$ CROSS_COMPILE=ppc_4xx-
4676	$ export CROSS_COMPILE
4677
4678Note: If you wish to generate Windows versions of the utilities in
4679      the tools directory you can use the MinGW toolchain
4680      (http://www.mingw.org).  Set your HOST tools to the MinGW
4681      toolchain and execute 'make tools'.  For example:
4682
4683       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4684
4685      Binaries such as tools/mkimage.exe will be created which can
4686      be executed on computers running Windows.
4687
4688U-Boot is intended to be simple to build. After installing the
4689sources you must configure U-Boot for one specific board type. This
4690is done by typing:
4691
4692	make NAME_config
4693
4694where "NAME_config" is the name of one of the existing configu-
4695rations; see boards.cfg for supported names.
4696
4697Note: for some board special configuration names may exist; check if
4698      additional information is available from the board vendor; for
4699      instance, the TQM823L systems are available without (standard)
4700      or with LCD support. You can select such additional "features"
4701      when choosing the configuration, i. e.
4702
4703      make TQM823L_config
4704	- will configure for a plain TQM823L, i. e. no LCD support
4705
4706      make TQM823L_LCD_config
4707	- will configure for a TQM823L with U-Boot console on LCD
4708
4709      etc.
4710
4711
4712Finally, type "make all", and you should get some working U-Boot
4713images ready for download to / installation on your system:
4714
4715- "u-boot.bin" is a raw binary image
4716- "u-boot" is an image in ELF binary format
4717- "u-boot.srec" is in Motorola S-Record format
4718
4719By default the build is performed locally and the objects are saved
4720in the source directory. One of the two methods can be used to change
4721this behavior and build U-Boot to some external directory:
4722
47231. Add O= to the make command line invocations:
4724
4725	make O=/tmp/build distclean
4726	make O=/tmp/build NAME_config
4727	make O=/tmp/build all
4728
47292. Set environment variable BUILD_DIR to point to the desired location:
4730
4731	export BUILD_DIR=/tmp/build
4732	make distclean
4733	make NAME_config
4734	make all
4735
4736Note that the command line "O=" setting overrides the BUILD_DIR environment
4737variable.
4738
4739
4740Please be aware that the Makefiles assume you are using GNU make, so
4741for instance on NetBSD you might need to use "gmake" instead of
4742native "make".
4743
4744
4745If the system board that you have is not listed, then you will need
4746to port U-Boot to your hardware platform. To do this, follow these
4747steps:
4748
47491.  Add a new configuration option for your board to the toplevel
4750    "boards.cfg" file, using the existing entries as examples.
4751    Follow the instructions there to keep the boards in order.
47522.  Create a new directory to hold your board specific code. Add any
4753    files you need. In your board directory, you will need at least
4754    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
47553.  Create a new configuration file "include/configs/<board>.h" for
4756    your board
47573.  If you're porting U-Boot to a new CPU, then also create a new
4758    directory to hold your CPU specific code. Add any files you need.
47594.  Run "make <board>_config" with your new name.
47605.  Type "make", and you should get a working "u-boot.srec" file
4761    to be installed on your target system.
47626.  Debug and solve any problems that might arise.
4763    [Of course, this last step is much harder than it sounds.]
4764
4765
4766Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4767==============================================================
4768
4769If you have modified U-Boot sources (for instance added a new board
4770or support for new devices, a new CPU, etc.) you are expected to
4771provide feedback to the other developers. The feedback normally takes
4772the form of a "patch", i. e. a context diff against a certain (latest
4773official or latest in the git repository) version of U-Boot sources.
4774
4775But before you submit such a patch, please verify that your modifi-
4776cation did not break existing code. At least make sure that *ALL* of
4777the supported boards compile WITHOUT ANY compiler warnings. To do so,
4778just run the "MAKEALL" script, which will configure and build U-Boot
4779for ALL supported system. Be warned, this will take a while. You can
4780select which (cross) compiler to use by passing a `CROSS_COMPILE'
4781environment variable to the script, i. e. to use the ELDK cross tools
4782you can type
4783
4784	CROSS_COMPILE=ppc_8xx- MAKEALL
4785
4786or to build on a native PowerPC system you can type
4787
4788	CROSS_COMPILE=' ' MAKEALL
4789
4790When using the MAKEALL script, the default behaviour is to build
4791U-Boot in the source directory. This location can be changed by
4792setting the BUILD_DIR environment variable. Also, for each target
4793built, the MAKEALL script saves two log files (<target>.ERR and
4794<target>.MAKEALL) in the <source dir>/LOG directory. This default
4795location can be changed by setting the MAKEALL_LOGDIR environment
4796variable. For example:
4797
4798	export BUILD_DIR=/tmp/build
4799	export MAKEALL_LOGDIR=/tmp/log
4800	CROSS_COMPILE=ppc_8xx- MAKEALL
4801
4802With the above settings build objects are saved in the /tmp/build,
4803log files are saved in the /tmp/log and the source tree remains clean
4804during the whole build process.
4805
4806
4807See also "U-Boot Porting Guide" below.
4808
4809
4810Monitor Commands - Overview:
4811============================
4812
4813go	- start application at address 'addr'
4814run	- run commands in an environment variable
4815bootm	- boot application image from memory
4816bootp	- boot image via network using BootP/TFTP protocol
4817bootz   - boot zImage from memory
4818tftpboot- boot image via network using TFTP protocol
4819	       and env variables "ipaddr" and "serverip"
4820	       (and eventually "gatewayip")
4821tftpput - upload a file via network using TFTP protocol
4822rarpboot- boot image via network using RARP/TFTP protocol
4823diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4824loads	- load S-Record file over serial line
4825loadb	- load binary file over serial line (kermit mode)
4826md	- memory display
4827mm	- memory modify (auto-incrementing)
4828nm	- memory modify (constant address)
4829mw	- memory write (fill)
4830cp	- memory copy
4831cmp	- memory compare
4832crc32	- checksum calculation
4833i2c	- I2C sub-system
4834sspi	- SPI utility commands
4835base	- print or set address offset
4836printenv- print environment variables
4837setenv	- set environment variables
4838saveenv - save environment variables to persistent storage
4839protect - enable or disable FLASH write protection
4840erase	- erase FLASH memory
4841flinfo	- print FLASH memory information
4842nand	- NAND memory operations (see doc/README.nand)
4843bdinfo	- print Board Info structure
4844iminfo	- print header information for application image
4845coninfo - print console devices and informations
4846ide	- IDE sub-system
4847loop	- infinite loop on address range
4848loopw	- infinite write loop on address range
4849mtest	- simple RAM test
4850icache	- enable or disable instruction cache
4851dcache	- enable or disable data cache
4852reset	- Perform RESET of the CPU
4853echo	- echo args to console
4854version - print monitor version
4855help	- print online help
4856?	- alias for 'help'
4857
4858
4859Monitor Commands - Detailed Description:
4860========================================
4861
4862TODO.
4863
4864For now: just type "help <command>".
4865
4866
4867Environment Variables:
4868======================
4869
4870U-Boot supports user configuration using Environment Variables which
4871can be made persistent by saving to Flash memory.
4872
4873Environment Variables are set using "setenv", printed using
4874"printenv", and saved to Flash using "saveenv". Using "setenv"
4875without a value can be used to delete a variable from the
4876environment. As long as you don't save the environment you are
4877working with an in-memory copy. In case the Flash area containing the
4878environment is erased by accident, a default environment is provided.
4879
4880Some configuration options can be set using Environment Variables.
4881
4882List of environment variables (most likely not complete):
4883
4884  baudrate	- see CONFIG_BAUDRATE
4885
4886  bootdelay	- see CONFIG_BOOTDELAY
4887
4888  bootcmd	- see CONFIG_BOOTCOMMAND
4889
4890  bootargs	- Boot arguments when booting an RTOS image
4891
4892  bootfile	- Name of the image to load with TFTP
4893
4894  bootm_low	- Memory range available for image processing in the bootm
4895		  command can be restricted. This variable is given as
4896		  a hexadecimal number and defines lowest address allowed
4897		  for use by the bootm command. See also "bootm_size"
4898		  environment variable. Address defined by "bootm_low" is
4899		  also the base of the initial memory mapping for the Linux
4900		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4901		  bootm_mapsize.
4902
4903  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4904		  This variable is given as a hexadecimal number and it
4905		  defines the size of the memory region starting at base
4906		  address bootm_low that is accessible by the Linux kernel
4907		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4908		  as the default value if it is defined, and bootm_size is
4909		  used otherwise.
4910
4911  bootm_size	- Memory range available for image processing in the bootm
4912		  command can be restricted. This variable is given as
4913		  a hexadecimal number and defines the size of the region
4914		  allowed for use by the bootm command. See also "bootm_low"
4915		  environment variable.
4916
4917  updatefile	- Location of the software update file on a TFTP server, used
4918		  by the automatic software update feature. Please refer to
4919		  documentation in doc/README.update for more details.
4920
4921  autoload	- if set to "no" (any string beginning with 'n'),
4922		  "bootp" will just load perform a lookup of the
4923		  configuration from the BOOTP server, but not try to
4924		  load any image using TFTP
4925
4926  autostart	- if set to "yes", an image loaded using the "bootp",
4927		  "rarpboot", "tftpboot" or "diskboot" commands will
4928		  be automatically started (by internally calling
4929		  "bootm")
4930
4931		  If set to "no", a standalone image passed to the
4932		  "bootm" command will be copied to the load address
4933		  (and eventually uncompressed), but NOT be started.
4934		  This can be used to load and uncompress arbitrary
4935		  data.
4936
4937  fdt_high	- if set this restricts the maximum address that the
4938		  flattened device tree will be copied into upon boot.
4939		  For example, if you have a system with 1 GB memory
4940		  at physical address 0x10000000, while Linux kernel
4941		  only recognizes the first 704 MB as low memory, you
4942		  may need to set fdt_high as 0x3C000000 to have the
4943		  device tree blob be copied to the maximum address
4944		  of the 704 MB low memory, so that Linux kernel can
4945		  access it during the boot procedure.
4946
4947		  If this is set to the special value 0xFFFFFFFF then
4948		  the fdt will not be copied at all on boot.  For this
4949		  to work it must reside in writable memory, have
4950		  sufficient padding on the end of it for u-boot to
4951		  add the information it needs into it, and the memory
4952		  must be accessible by the kernel.
4953
4954  fdtcontroladdr- if set this is the address of the control flattened
4955		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4956		  defined.
4957
4958  i2cfast	- (PPC405GP|PPC405EP only)
4959		  if set to 'y' configures Linux I2C driver for fast
4960		  mode (400kHZ). This environment variable is used in
4961		  initialization code. So, for changes to be effective
4962		  it must be saved and board must be reset.
4963
4964  initrd_high	- restrict positioning of initrd images:
4965		  If this variable is not set, initrd images will be
4966		  copied to the highest possible address in RAM; this
4967		  is usually what you want since it allows for
4968		  maximum initrd size. If for some reason you want to
4969		  make sure that the initrd image is loaded below the
4970		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4971		  variable to a value of "no" or "off" or "0".
4972		  Alternatively, you can set it to a maximum upper
4973		  address to use (U-Boot will still check that it
4974		  does not overwrite the U-Boot stack and data).
4975
4976		  For instance, when you have a system with 16 MB
4977		  RAM, and want to reserve 4 MB from use by Linux,
4978		  you can do this by adding "mem=12M" to the value of
4979		  the "bootargs" variable. However, now you must make
4980		  sure that the initrd image is placed in the first
4981		  12 MB as well - this can be done with
4982
4983		  setenv initrd_high 00c00000
4984
4985		  If you set initrd_high to 0xFFFFFFFF, this is an
4986		  indication to U-Boot that all addresses are legal
4987		  for the Linux kernel, including addresses in flash
4988		  memory. In this case U-Boot will NOT COPY the
4989		  ramdisk at all. This may be useful to reduce the
4990		  boot time on your system, but requires that this
4991		  feature is supported by your Linux kernel.
4992
4993  ipaddr	- IP address; needed for tftpboot command
4994
4995  loadaddr	- Default load address for commands like "bootp",
4996		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4997
4998  loads_echo	- see CONFIG_LOADS_ECHO
4999
5000  serverip	- TFTP server IP address; needed for tftpboot command
5001
5002  bootretry	- see CONFIG_BOOT_RETRY_TIME
5003
5004  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5005
5006  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5007
5008  ethprime	- controls which interface is used first.
5009
5010  ethact	- controls which interface is currently active.
5011		  For example you can do the following
5012
5013		  => setenv ethact FEC
5014		  => ping 192.168.0.1 # traffic sent on FEC
5015		  => setenv ethact SCC
5016		  => ping 10.0.0.1 # traffic sent on SCC
5017
5018  ethrotate	- When set to "no" U-Boot does not go through all
5019		  available network interfaces.
5020		  It just stays at the currently selected interface.
5021
5022  netretry	- When set to "no" each network operation will
5023		  either succeed or fail without retrying.
5024		  When set to "once" the network operation will
5025		  fail when all the available network interfaces
5026		  are tried once without success.
5027		  Useful on scripts which control the retry operation
5028		  themselves.
5029
5030  npe_ucode	- set load address for the NPE microcode
5031
5032  silent_linux  - If set then linux will be told to boot silently, by
5033		  changing the console to be empty. If "yes" it will be
5034		  made silent. If "no" it will not be made silent. If
5035		  unset, then it will be made silent if the U-Boot console
5036		  is silent.
5037
5038  tftpsrcport	- If this is set, the value is used for TFTP's
5039		  UDP source port.
5040
5041  tftpdstport	- If this is set, the value is used for TFTP's UDP
5042		  destination port instead of the Well Know Port 69.
5043
5044  tftpblocksize - Block size to use for TFTP transfers; if not set,
5045		  we use the TFTP server's default block size
5046
5047  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5048		  seconds, minimum value is 1000 = 1 second). Defines
5049		  when a packet is considered to be lost so it has to
5050		  be retransmitted. The default is 5000 = 5 seconds.
5051		  Lowering this value may make downloads succeed
5052		  faster in networks with high packet loss rates or
5053		  with unreliable TFTP servers.
5054
5055  vlan		- When set to a value < 4095 the traffic over
5056		  Ethernet is encapsulated/received over 802.1q
5057		  VLAN tagged frames.
5058
5059The following image location variables contain the location of images
5060used in booting. The "Image" column gives the role of the image and is
5061not an environment variable name. The other columns are environment
5062variable names. "File Name" gives the name of the file on a TFTP
5063server, "RAM Address" gives the location in RAM the image will be
5064loaded to, and "Flash Location" gives the image's address in NOR
5065flash or offset in NAND flash.
5066
5067*Note* - these variables don't have to be defined for all boards, some
5068boards currenlty use other variables for these purposes, and some
5069boards use these variables for other purposes.
5070
5071Image		    File Name	     RAM Address       Flash Location
5072-----		    ---------	     -----------       --------------
5073u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5074Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5075device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5076ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5077
5078The following environment variables may be used and automatically
5079updated by the network boot commands ("bootp" and "rarpboot"),
5080depending the information provided by your boot server:
5081
5082  bootfile	- see above
5083  dnsip		- IP address of your Domain Name Server
5084  dnsip2	- IP address of your secondary Domain Name Server
5085  gatewayip	- IP address of the Gateway (Router) to use
5086  hostname	- Target hostname
5087  ipaddr	- see above
5088  netmask	- Subnet Mask
5089  rootpath	- Pathname of the root filesystem on the NFS server
5090  serverip	- see above
5091
5092
5093There are two special Environment Variables:
5094
5095  serial#	- contains hardware identification information such
5096		  as type string and/or serial number
5097  ethaddr	- Ethernet address
5098
5099These variables can be set only once (usually during manufacturing of
5100the board). U-Boot refuses to delete or overwrite these variables
5101once they have been set once.
5102
5103
5104Further special Environment Variables:
5105
5106  ver		- Contains the U-Boot version string as printed
5107		  with the "version" command. This variable is
5108		  readonly (see CONFIG_VERSION_VARIABLE).
5109
5110
5111Please note that changes to some configuration parameters may take
5112only effect after the next boot (yes, that's just like Windoze :-).
5113
5114
5115Callback functions for environment variables:
5116---------------------------------------------
5117
5118For some environment variables, the behavior of u-boot needs to change
5119when their values are changed.  This functionailty allows functions to
5120be associated with arbitrary variables.  On creation, overwrite, or
5121deletion, the callback will provide the opportunity for some side
5122effect to happen or for the change to be rejected.
5123
5124The callbacks are named and associated with a function using the
5125U_BOOT_ENV_CALLBACK macro in your board or driver code.
5126
5127These callbacks are associated with variables in one of two ways.  The
5128static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5129in the board configuration to a string that defines a list of
5130associations.  The list must be in the following format:
5131
5132	entry = variable_name[:callback_name]
5133	list = entry[,list]
5134
5135If the callback name is not specified, then the callback is deleted.
5136Spaces are also allowed anywhere in the list.
5137
5138Callbacks can also be associated by defining the ".callbacks" variable
5139with the same list format above.  Any association in ".callbacks" will
5140override any association in the static list. You can define
5141CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5142".callbacks" envirnoment variable in the default or embedded environment.
5143
5144
5145Command Line Parsing:
5146=====================
5147
5148There are two different command line parsers available with U-Boot:
5149the old "simple" one, and the much more powerful "hush" shell:
5150
5151Old, simple command line parser:
5152--------------------------------
5153
5154- supports environment variables (through setenv / saveenv commands)
5155- several commands on one line, separated by ';'
5156- variable substitution using "... ${name} ..." syntax
5157- special characters ('$', ';') can be escaped by prefixing with '\',
5158  for example:
5159	setenv bootcmd bootm \${address}
5160- You can also escape text by enclosing in single apostrophes, for example:
5161	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5162
5163Hush shell:
5164-----------
5165
5166- similar to Bourne shell, with control structures like
5167  if...then...else...fi, for...do...done; while...do...done,
5168  until...do...done, ...
5169- supports environment ("global") variables (through setenv / saveenv
5170  commands) and local shell variables (through standard shell syntax
5171  "name=value"); only environment variables can be used with "run"
5172  command
5173
5174General rules:
5175--------------
5176
5177(1) If a command line (or an environment variable executed by a "run"
5178    command) contains several commands separated by semicolon, and
5179    one of these commands fails, then the remaining commands will be
5180    executed anyway.
5181
5182(2) If you execute several variables with one call to run (i. e.
5183    calling run with a list of variables as arguments), any failing
5184    command will cause "run" to terminate, i. e. the remaining
5185    variables are not executed.
5186
5187Note for Redundant Ethernet Interfaces:
5188=======================================
5189
5190Some boards come with redundant Ethernet interfaces; U-Boot supports
5191such configurations and is capable of automatic selection of a
5192"working" interface when needed. MAC assignment works as follows:
5193
5194Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5195MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5196"eth1addr" (=>eth1), "eth2addr", ...
5197
5198If the network interface stores some valid MAC address (for instance
5199in SROM), this is used as default address if there is NO correspon-
5200ding setting in the environment; if the corresponding environment
5201variable is set, this overrides the settings in the card; that means:
5202
5203o If the SROM has a valid MAC address, and there is no address in the
5204  environment, the SROM's address is used.
5205
5206o If there is no valid address in the SROM, and a definition in the
5207  environment exists, then the value from the environment variable is
5208  used.
5209
5210o If both the SROM and the environment contain a MAC address, and
5211  both addresses are the same, this MAC address is used.
5212
5213o If both the SROM and the environment contain a MAC address, and the
5214  addresses differ, the value from the environment is used and a
5215  warning is printed.
5216
5217o If neither SROM nor the environment contain a MAC address, an error
5218  is raised.
5219
5220If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5221will be programmed into hardware as part of the initialization process.	 This
5222may be skipped by setting the appropriate 'ethmacskip' environment variable.
5223The naming convention is as follows:
5224"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5225
5226Image Formats:
5227==============
5228
5229U-Boot is capable of booting (and performing other auxiliary operations on)
5230images in two formats:
5231
5232New uImage format (FIT)
5233-----------------------
5234
5235Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5236to Flattened Device Tree). It allows the use of images with multiple
5237components (several kernels, ramdisks, etc.), with contents protected by
5238SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5239
5240
5241Old uImage format
5242-----------------
5243
5244Old image format is based on binary files which can be basically anything,
5245preceded by a special header; see the definitions in include/image.h for
5246details; basically, the header defines the following image properties:
5247
5248* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5249  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5250  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5251  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5252  INTEGRITY).
5253* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5254  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5255  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5256* Compression Type (uncompressed, gzip, bzip2)
5257* Load Address
5258* Entry Point
5259* Image Name
5260* Image Timestamp
5261
5262The header is marked by a special Magic Number, and both the header
5263and the data portions of the image are secured against corruption by
5264CRC32 checksums.
5265
5266
5267Linux Support:
5268==============
5269
5270Although U-Boot should support any OS or standalone application
5271easily, the main focus has always been on Linux during the design of
5272U-Boot.
5273
5274U-Boot includes many features that so far have been part of some
5275special "boot loader" code within the Linux kernel. Also, any
5276"initrd" images to be used are no longer part of one big Linux image;
5277instead, kernel and "initrd" are separate images. This implementation
5278serves several purposes:
5279
5280- the same features can be used for other OS or standalone
5281  applications (for instance: using compressed images to reduce the
5282  Flash memory footprint)
5283
5284- it becomes much easier to port new Linux kernel versions because
5285  lots of low-level, hardware dependent stuff are done by U-Boot
5286
5287- the same Linux kernel image can now be used with different "initrd"
5288  images; of course this also means that different kernel images can
5289  be run with the same "initrd". This makes testing easier (you don't
5290  have to build a new "zImage.initrd" Linux image when you just
5291  change a file in your "initrd"). Also, a field-upgrade of the
5292  software is easier now.
5293
5294
5295Linux HOWTO:
5296============
5297
5298Porting Linux to U-Boot based systems:
5299---------------------------------------
5300
5301U-Boot cannot save you from doing all the necessary modifications to
5302configure the Linux device drivers for use with your target hardware
5303(no, we don't intend to provide a full virtual machine interface to
5304Linux :-).
5305
5306But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5307
5308Just make sure your machine specific header file (for instance
5309include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5310Information structure as we define in include/asm-<arch>/u-boot.h,
5311and make sure that your definition of IMAP_ADDR uses the same value
5312as your U-Boot configuration in CONFIG_SYS_IMMR.
5313
5314
5315Configuring the Linux kernel:
5316-----------------------------
5317
5318No specific requirements for U-Boot. Make sure you have some root
5319device (initial ramdisk, NFS) for your target system.
5320
5321
5322Building a Linux Image:
5323-----------------------
5324
5325With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5326not used. If you use recent kernel source, a new build target
5327"uImage" will exist which automatically builds an image usable by
5328U-Boot. Most older kernels also have support for a "pImage" target,
5329which was introduced for our predecessor project PPCBoot and uses a
5330100% compatible format.
5331
5332Example:
5333
5334	make TQM850L_config
5335	make oldconfig
5336	make dep
5337	make uImage
5338
5339The "uImage" build target uses a special tool (in 'tools/mkimage') to
5340encapsulate a compressed Linux kernel image with header	 information,
5341CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5342
5343* build a standard "vmlinux" kernel image (in ELF binary format):
5344
5345* convert the kernel into a raw binary image:
5346
5347	${CROSS_COMPILE}-objcopy -O binary \
5348				 -R .note -R .comment \
5349				 -S vmlinux linux.bin
5350
5351* compress the binary image:
5352
5353	gzip -9 linux.bin
5354
5355* package compressed binary image for U-Boot:
5356
5357	mkimage -A ppc -O linux -T kernel -C gzip \
5358		-a 0 -e 0 -n "Linux Kernel Image" \
5359		-d linux.bin.gz uImage
5360
5361
5362The "mkimage" tool can also be used to create ramdisk images for use
5363with U-Boot, either separated from the Linux kernel image, or
5364combined into one file. "mkimage" encapsulates the images with a 64
5365byte header containing information about target architecture,
5366operating system, image type, compression method, entry points, time
5367stamp, CRC32 checksums, etc.
5368
5369"mkimage" can be called in two ways: to verify existing images and
5370print the header information, or to build new images.
5371
5372In the first form (with "-l" option) mkimage lists the information
5373contained in the header of an existing U-Boot image; this includes
5374checksum verification:
5375
5376	tools/mkimage -l image
5377	  -l ==> list image header information
5378
5379The second form (with "-d" option) is used to build a U-Boot image
5380from a "data file" which is used as image payload:
5381
5382	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5383		      -n name -d data_file image
5384	  -A ==> set architecture to 'arch'
5385	  -O ==> set operating system to 'os'
5386	  -T ==> set image type to 'type'
5387	  -C ==> set compression type 'comp'
5388	  -a ==> set load address to 'addr' (hex)
5389	  -e ==> set entry point to 'ep' (hex)
5390	  -n ==> set image name to 'name'
5391	  -d ==> use image data from 'datafile'
5392
5393Right now, all Linux kernels for PowerPC systems use the same load
5394address (0x00000000), but the entry point address depends on the
5395kernel version:
5396
5397- 2.2.x kernels have the entry point at 0x0000000C,
5398- 2.3.x and later kernels have the entry point at 0x00000000.
5399
5400So a typical call to build a U-Boot image would read:
5401
5402	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5403	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5404	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5405	> examples/uImage.TQM850L
5406	Image Name:   2.4.4 kernel for TQM850L
5407	Created:      Wed Jul 19 02:34:59 2000
5408	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5409	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5410	Load Address: 0x00000000
5411	Entry Point:  0x00000000
5412
5413To verify the contents of the image (or check for corruption):
5414
5415	-> tools/mkimage -l examples/uImage.TQM850L
5416	Image Name:   2.4.4 kernel for TQM850L
5417	Created:      Wed Jul 19 02:34:59 2000
5418	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5419	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5420	Load Address: 0x00000000
5421	Entry Point:  0x00000000
5422
5423NOTE: for embedded systems where boot time is critical you can trade
5424speed for memory and install an UNCOMPRESSED image instead: this
5425needs more space in Flash, but boots much faster since it does not
5426need to be uncompressed:
5427
5428	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5429	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5430	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5431	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5432	> examples/uImage.TQM850L-uncompressed
5433	Image Name:   2.4.4 kernel for TQM850L
5434	Created:      Wed Jul 19 02:34:59 2000
5435	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5436	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5437	Load Address: 0x00000000
5438	Entry Point:  0x00000000
5439
5440
5441Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5442when your kernel is intended to use an initial ramdisk:
5443
5444	-> tools/mkimage -n 'Simple Ramdisk Image' \
5445	> -A ppc -O linux -T ramdisk -C gzip \
5446	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5447	Image Name:   Simple Ramdisk Image
5448	Created:      Wed Jan 12 14:01:50 2000
5449	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5450	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5451	Load Address: 0x00000000
5452	Entry Point:  0x00000000
5453
5454The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5455option performs the converse operation of the mkimage's second form (the "-d"
5456option). Given an image built by mkimage, the dumpimage extracts a "data file"
5457from the image:
5458
5459	tools/dumpimage -i image -p position data_file
5460	  -i ==> extract from the 'image' a specific 'data_file', \
5461	   indexed by 'position'
5462
5463
5464Installing a Linux Image:
5465-------------------------
5466
5467To downloading a U-Boot image over the serial (console) interface,
5468you must convert the image to S-Record format:
5469
5470	objcopy -I binary -O srec examples/image examples/image.srec
5471
5472The 'objcopy' does not understand the information in the U-Boot
5473image header, so the resulting S-Record file will be relative to
5474address 0x00000000. To load it to a given address, you need to
5475specify the target address as 'offset' parameter with the 'loads'
5476command.
5477
5478Example: install the image to address 0x40100000 (which on the
5479TQM8xxL is in the first Flash bank):
5480
5481	=> erase 40100000 401FFFFF
5482
5483	.......... done
5484	Erased 8 sectors
5485
5486	=> loads 40100000
5487	## Ready for S-Record download ...
5488	~>examples/image.srec
5489	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5490	...
5491	15989 15990 15991 15992
5492	[file transfer complete]
5493	[connected]
5494	## Start Addr = 0x00000000
5495
5496
5497You can check the success of the download using the 'iminfo' command;
5498this includes a checksum verification so you can be sure no data
5499corruption happened:
5500
5501	=> imi 40100000
5502
5503	## Checking Image at 40100000 ...
5504	   Image Name:	 2.2.13 for initrd on TQM850L
5505	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5506	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5507	   Load Address: 00000000
5508	   Entry Point:	 0000000c
5509	   Verifying Checksum ... OK
5510
5511
5512Boot Linux:
5513-----------
5514
5515The "bootm" command is used to boot an application that is stored in
5516memory (RAM or Flash). In case of a Linux kernel image, the contents
5517of the "bootargs" environment variable is passed to the kernel as
5518parameters. You can check and modify this variable using the
5519"printenv" and "setenv" commands:
5520
5521
5522	=> printenv bootargs
5523	bootargs=root=/dev/ram
5524
5525	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5526
5527	=> printenv bootargs
5528	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5529
5530	=> bootm 40020000
5531	## Booting Linux kernel at 40020000 ...
5532	   Image Name:	 2.2.13 for NFS on TQM850L
5533	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5534	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5535	   Load Address: 00000000
5536	   Entry Point:	 0000000c
5537	   Verifying Checksum ... OK
5538	   Uncompressing Kernel Image ... OK
5539	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
5540	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5541	time_init: decrementer frequency = 187500000/60
5542	Calibrating delay loop... 49.77 BogoMIPS
5543	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5544	...
5545
5546If you want to boot a Linux kernel with initial RAM disk, you pass
5547the memory addresses of both the kernel and the initrd image (PPBCOOT
5548format!) to the "bootm" command:
5549
5550	=> imi 40100000 40200000
5551
5552	## Checking Image at 40100000 ...
5553	   Image Name:	 2.2.13 for initrd on TQM850L
5554	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5555	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5556	   Load Address: 00000000
5557	   Entry Point:	 0000000c
5558	   Verifying Checksum ... OK
5559
5560	## Checking Image at 40200000 ...
5561	   Image Name:	 Simple Ramdisk Image
5562	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5563	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5564	   Load Address: 00000000
5565	   Entry Point:	 00000000
5566	   Verifying Checksum ... OK
5567
5568	=> bootm 40100000 40200000
5569	## Booting Linux kernel at 40100000 ...
5570	   Image Name:	 2.2.13 for initrd on TQM850L
5571	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5572	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5573	   Load Address: 00000000
5574	   Entry Point:	 0000000c
5575	   Verifying Checksum ... OK
5576	   Uncompressing Kernel Image ... OK
5577	## Loading RAMDisk Image at 40200000 ...
5578	   Image Name:	 Simple Ramdisk Image
5579	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5580	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5581	   Load Address: 00000000
5582	   Entry Point:	 00000000
5583	   Verifying Checksum ... OK
5584	   Loading Ramdisk ... OK
5585	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
5586	Boot arguments: root=/dev/ram
5587	time_init: decrementer frequency = 187500000/60
5588	Calibrating delay loop... 49.77 BogoMIPS
5589	...
5590	RAMDISK: Compressed image found at block 0
5591	VFS: Mounted root (ext2 filesystem).
5592
5593	bash#
5594
5595Boot Linux and pass a flat device tree:
5596-----------
5597
5598First, U-Boot must be compiled with the appropriate defines. See the section
5599titled "Linux Kernel Interface" above for a more in depth explanation. The
5600following is an example of how to start a kernel and pass an updated
5601flat device tree:
5602
5603=> print oftaddr
5604oftaddr=0x300000
5605=> print oft
5606oft=oftrees/mpc8540ads.dtb
5607=> tftp $oftaddr $oft
5608Speed: 1000, full duplex
5609Using TSEC0 device
5610TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5611Filename 'oftrees/mpc8540ads.dtb'.
5612Load address: 0x300000
5613Loading: #
5614done
5615Bytes transferred = 4106 (100a hex)
5616=> tftp $loadaddr $bootfile
5617Speed: 1000, full duplex
5618Using TSEC0 device
5619TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5620Filename 'uImage'.
5621Load address: 0x200000
5622Loading:############
5623done
5624Bytes transferred = 1029407 (fb51f hex)
5625=> print loadaddr
5626loadaddr=200000
5627=> print oftaddr
5628oftaddr=0x300000
5629=> bootm $loadaddr - $oftaddr
5630## Booting image at 00200000 ...
5631   Image Name:	 Linux-2.6.17-dirty
5632   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5633   Data Size:	 1029343 Bytes = 1005.2 kB
5634   Load Address: 00000000
5635   Entry Point:	 00000000
5636   Verifying Checksum ... OK
5637   Uncompressing Kernel Image ... OK
5638Booting using flat device tree at 0x300000
5639Using MPC85xx ADS machine description
5640Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5641[snip]
5642
5643
5644More About U-Boot Image Types:
5645------------------------------
5646
5647U-Boot supports the following image types:
5648
5649   "Standalone Programs" are directly runnable in the environment
5650	provided by U-Boot; it is expected that (if they behave
5651	well) you can continue to work in U-Boot after return from
5652	the Standalone Program.
5653   "OS Kernel Images" are usually images of some Embedded OS which
5654	will take over control completely. Usually these programs
5655	will install their own set of exception handlers, device
5656	drivers, set up the MMU, etc. - this means, that you cannot
5657	expect to re-enter U-Boot except by resetting the CPU.
5658   "RAMDisk Images" are more or less just data blocks, and their
5659	parameters (address, size) are passed to an OS kernel that is
5660	being started.
5661   "Multi-File Images" contain several images, typically an OS
5662	(Linux) kernel image and one or more data images like
5663	RAMDisks. This construct is useful for instance when you want
5664	to boot over the network using BOOTP etc., where the boot
5665	server provides just a single image file, but you want to get
5666	for instance an OS kernel and a RAMDisk image.
5667
5668	"Multi-File Images" start with a list of image sizes, each
5669	image size (in bytes) specified by an "uint32_t" in network
5670	byte order. This list is terminated by an "(uint32_t)0".
5671	Immediately after the terminating 0 follow the images, one by
5672	one, all aligned on "uint32_t" boundaries (size rounded up to
5673	a multiple of 4 bytes).
5674
5675   "Firmware Images" are binary images containing firmware (like
5676	U-Boot or FPGA images) which usually will be programmed to
5677	flash memory.
5678
5679   "Script files" are command sequences that will be executed by
5680	U-Boot's command interpreter; this feature is especially
5681	useful when you configure U-Boot to use a real shell (hush)
5682	as command interpreter.
5683
5684Booting the Linux zImage:
5685-------------------------
5686
5687On some platforms, it's possible to boot Linux zImage. This is done
5688using the "bootz" command. The syntax of "bootz" command is the same
5689as the syntax of "bootm" command.
5690
5691Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5692kernel with raw initrd images. The syntax is slightly different, the
5693address of the initrd must be augmented by it's size, in the following
5694format: "<initrd addres>:<initrd size>".
5695
5696
5697Standalone HOWTO:
5698=================
5699
5700One of the features of U-Boot is that you can dynamically load and
5701run "standalone" applications, which can use some resources of
5702U-Boot like console I/O functions or interrupt services.
5703
5704Two simple examples are included with the sources:
5705
5706"Hello World" Demo:
5707-------------------
5708
5709'examples/hello_world.c' contains a small "Hello World" Demo
5710application; it is automatically compiled when you build U-Boot.
5711It's configured to run at address 0x00040004, so you can play with it
5712like that:
5713
5714	=> loads
5715	## Ready for S-Record download ...
5716	~>examples/hello_world.srec
5717	1 2 3 4 5 6 7 8 9 10 11 ...
5718	[file transfer complete]
5719	[connected]
5720	## Start Addr = 0x00040004
5721
5722	=> go 40004 Hello World! This is a test.
5723	## Starting application at 0x00040004 ...
5724	Hello World
5725	argc = 7
5726	argv[0] = "40004"
5727	argv[1] = "Hello"
5728	argv[2] = "World!"
5729	argv[3] = "This"
5730	argv[4] = "is"
5731	argv[5] = "a"
5732	argv[6] = "test."
5733	argv[7] = "<NULL>"
5734	Hit any key to exit ...
5735
5736	## Application terminated, rc = 0x0
5737
5738Another example, which demonstrates how to register a CPM interrupt
5739handler with the U-Boot code, can be found in 'examples/timer.c'.
5740Here, a CPM timer is set up to generate an interrupt every second.
5741The interrupt service routine is trivial, just printing a '.'
5742character, but this is just a demo program. The application can be
5743controlled by the following keys:
5744
5745	? - print current values og the CPM Timer registers
5746	b - enable interrupts and start timer
5747	e - stop timer and disable interrupts
5748	q - quit application
5749
5750	=> loads
5751	## Ready for S-Record download ...
5752	~>examples/timer.srec
5753	1 2 3 4 5 6 7 8 9 10 11 ...
5754	[file transfer complete]
5755	[connected]
5756	## Start Addr = 0x00040004
5757
5758	=> go 40004
5759	## Starting application at 0x00040004 ...
5760	TIMERS=0xfff00980
5761	Using timer 1
5762	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5763
5764Hit 'b':
5765	[q, b, e, ?] Set interval 1000000 us
5766	Enabling timer
5767Hit '?':
5768	[q, b, e, ?] ........
5769	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5770Hit '?':
5771	[q, b, e, ?] .
5772	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5773Hit '?':
5774	[q, b, e, ?] .
5775	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5776Hit '?':
5777	[q, b, e, ?] .
5778	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5779Hit 'e':
5780	[q, b, e, ?] ...Stopping timer
5781Hit 'q':
5782	[q, b, e, ?] ## Application terminated, rc = 0x0
5783
5784
5785Minicom warning:
5786================
5787
5788Over time, many people have reported problems when trying to use the
5789"minicom" terminal emulation program for serial download. I (wd)
5790consider minicom to be broken, and recommend not to use it. Under
5791Unix, I recommend to use C-Kermit for general purpose use (and
5792especially for kermit binary protocol download ("loadb" command), and
5793use "cu" for S-Record download ("loads" command).  See
5794http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5795for help with kermit.
5796
5797
5798Nevertheless, if you absolutely want to use it try adding this
5799configuration to your "File transfer protocols" section:
5800
5801	   Name	   Program			Name U/D FullScr IO-Red. Multi
5802	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5803	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5804
5805
5806NetBSD Notes:
5807=============
5808
5809Starting at version 0.9.2, U-Boot supports NetBSD both as host
5810(build U-Boot) and target system (boots NetBSD/mpc8xx).
5811
5812Building requires a cross environment; it is known to work on
5813NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5814need gmake since the Makefiles are not compatible with BSD make).
5815Note that the cross-powerpc package does not install include files;
5816attempting to build U-Boot will fail because <machine/ansi.h> is
5817missing.  This file has to be installed and patched manually:
5818
5819	# cd /usr/pkg/cross/powerpc-netbsd/include
5820	# mkdir powerpc
5821	# ln -s powerpc machine
5822	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5823	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5824
5825Native builds *don't* work due to incompatibilities between native
5826and U-Boot include files.
5827
5828Booting assumes that (the first part of) the image booted is a
5829stage-2 loader which in turn loads and then invokes the kernel
5830proper. Loader sources will eventually appear in the NetBSD source
5831tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5832meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5833
5834
5835Implementation Internals:
5836=========================
5837
5838The following is not intended to be a complete description of every
5839implementation detail. However, it should help to understand the
5840inner workings of U-Boot and make it easier to port it to custom
5841hardware.
5842
5843
5844Initial Stack, Global Data:
5845---------------------------
5846
5847The implementation of U-Boot is complicated by the fact that U-Boot
5848starts running out of ROM (flash memory), usually without access to
5849system RAM (because the memory controller is not initialized yet).
5850This means that we don't have writable Data or BSS segments, and BSS
5851is not initialized as zero. To be able to get a C environment working
5852at all, we have to allocate at least a minimal stack. Implementation
5853options for this are defined and restricted by the CPU used: Some CPU
5854models provide on-chip memory (like the IMMR area on MPC8xx and
5855MPC826x processors), on others (parts of) the data cache can be
5856locked as (mis-) used as memory, etc.
5857
5858	Chris Hallinan posted a good summary of these issues to the
5859	U-Boot mailing list:
5860
5861	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5862	From: "Chris Hallinan" <clh@net1plus.com>
5863	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5864	...
5865
5866	Correct me if I'm wrong, folks, but the way I understand it
5867	is this: Using DCACHE as initial RAM for Stack, etc, does not
5868	require any physical RAM backing up the cache. The cleverness
5869	is that the cache is being used as a temporary supply of
5870	necessary storage before the SDRAM controller is setup. It's
5871	beyond the scope of this list to explain the details, but you
5872	can see how this works by studying the cache architecture and
5873	operation in the architecture and processor-specific manuals.
5874
5875	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5876	is another option for the system designer to use as an
5877	initial stack/RAM area prior to SDRAM being available. Either
5878	option should work for you. Using CS 4 should be fine if your
5879	board designers haven't used it for something that would
5880	cause you grief during the initial boot! It is frequently not
5881	used.
5882
5883	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5884	with your processor/board/system design. The default value
5885	you will find in any recent u-boot distribution in
5886	walnut.h should work for you. I'd set it to a value larger
5887	than your SDRAM module. If you have a 64MB SDRAM module, set
5888	it above 400_0000. Just make sure your board has no resources
5889	that are supposed to respond to that address! That code in
5890	start.S has been around a while and should work as is when
5891	you get the config right.
5892
5893	-Chris Hallinan
5894	DS4.COM, Inc.
5895
5896It is essential to remember this, since it has some impact on the C
5897code for the initialization procedures:
5898
5899* Initialized global data (data segment) is read-only. Do not attempt
5900  to write it.
5901
5902* Do not use any uninitialized global data (or implicitely initialized
5903  as zero data - BSS segment) at all - this is undefined, initiali-
5904  zation is performed later (when relocating to RAM).
5905
5906* Stack space is very limited. Avoid big data buffers or things like
5907  that.
5908
5909Having only the stack as writable memory limits means we cannot use
5910normal global data to share information beween the code. But it
5911turned out that the implementation of U-Boot can be greatly
5912simplified by making a global data structure (gd_t) available to all
5913functions. We could pass a pointer to this data as argument to _all_
5914functions, but this would bloat the code. Instead we use a feature of
5915the GCC compiler (Global Register Variables) to share the data: we
5916place a pointer (gd) to the global data into a register which we
5917reserve for this purpose.
5918
5919When choosing a register for such a purpose we are restricted by the
5920relevant  (E)ABI  specifications for the current architecture, and by
5921GCC's implementation.
5922
5923For PowerPC, the following registers have specific use:
5924	R1:	stack pointer
5925	R2:	reserved for system use
5926	R3-R4:	parameter passing and return values
5927	R5-R10: parameter passing
5928	R13:	small data area pointer
5929	R30:	GOT pointer
5930	R31:	frame pointer
5931
5932	(U-Boot also uses R12 as internal GOT pointer. r12
5933	is a volatile register so r12 needs to be reset when
5934	going back and forth between asm and C)
5935
5936    ==> U-Boot will use R2 to hold a pointer to the global data
5937
5938    Note: on PPC, we could use a static initializer (since the
5939    address of the global data structure is known at compile time),
5940    but it turned out that reserving a register results in somewhat
5941    smaller code - although the code savings are not that big (on
5942    average for all boards 752 bytes for the whole U-Boot image,
5943    624 text + 127 data).
5944
5945On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5946	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5947
5948    ==> U-Boot will use P3 to hold a pointer to the global data
5949
5950On ARM, the following registers are used:
5951
5952	R0:	function argument word/integer result
5953	R1-R3:	function argument word
5954	R9:	platform specific
5955	R10:	stack limit (used only if stack checking is enabled)
5956	R11:	argument (frame) pointer
5957	R12:	temporary workspace
5958	R13:	stack pointer
5959	R14:	link register
5960	R15:	program counter
5961
5962    ==> U-Boot will use R9 to hold a pointer to the global data
5963
5964    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5965
5966On Nios II, the ABI is documented here:
5967	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5968
5969    ==> U-Boot will use gp to hold a pointer to the global data
5970
5971    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5972    to access small data sections, so gp is free.
5973
5974On NDS32, the following registers are used:
5975
5976	R0-R1:	argument/return
5977	R2-R5:	argument
5978	R15:	temporary register for assembler
5979	R16:	trampoline register
5980	R28:	frame pointer (FP)
5981	R29:	global pointer (GP)
5982	R30:	link register (LP)
5983	R31:	stack pointer (SP)
5984	PC:	program counter (PC)
5985
5986    ==> U-Boot will use R10 to hold a pointer to the global data
5987
5988NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5989or current versions of GCC may "optimize" the code too much.
5990
5991Memory Management:
5992------------------
5993
5994U-Boot runs in system state and uses physical addresses, i.e. the
5995MMU is not used either for address mapping nor for memory protection.
5996
5997The available memory is mapped to fixed addresses using the memory
5998controller. In this process, a contiguous block is formed for each
5999memory type (Flash, SDRAM, SRAM), even when it consists of several
6000physical memory banks.
6001
6002U-Boot is installed in the first 128 kB of the first Flash bank (on
6003TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6004booting and sizing and initializing DRAM, the code relocates itself
6005to the upper end of DRAM. Immediately below the U-Boot code some
6006memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6007configuration setting]. Below that, a structure with global Board
6008Info data is placed, followed by the stack (growing downward).
6009
6010Additionally, some exception handler code is copied to the low 8 kB
6011of DRAM (0x00000000 ... 0x00001FFF).
6012
6013So a typical memory configuration with 16 MB of DRAM could look like
6014this:
6015
6016	0x0000 0000	Exception Vector code
6017	      :
6018	0x0000 1FFF
6019	0x0000 2000	Free for Application Use
6020	      :
6021	      :
6022
6023	      :
6024	      :
6025	0x00FB FF20	Monitor Stack (Growing downward)
6026	0x00FB FFAC	Board Info Data and permanent copy of global data
6027	0x00FC 0000	Malloc Arena
6028	      :
6029	0x00FD FFFF
6030	0x00FE 0000	RAM Copy of Monitor Code
6031	...		eventually: LCD or video framebuffer
6032	...		eventually: pRAM (Protected RAM - unchanged by reset)
6033	0x00FF FFFF	[End of RAM]
6034
6035
6036System Initialization:
6037----------------------
6038
6039In the reset configuration, U-Boot starts at the reset entry point
6040(on most PowerPC systems at address 0x00000100). Because of the reset
6041configuration for CS0# this is a mirror of the onboard Flash memory.
6042To be able to re-map memory U-Boot then jumps to its link address.
6043To be able to implement the initialization code in C, a (small!)
6044initial stack is set up in the internal Dual Ported RAM (in case CPUs
6045which provide such a feature like MPC8xx or MPC8260), or in a locked
6046part of the data cache. After that, U-Boot initializes the CPU core,
6047the caches and the SIU.
6048
6049Next, all (potentially) available memory banks are mapped using a
6050preliminary mapping. For example, we put them on 512 MB boundaries
6051(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6052on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6053programmed for SDRAM access. Using the temporary configuration, a
6054simple memory test is run that determines the size of the SDRAM
6055banks.
6056
6057When there is more than one SDRAM bank, and the banks are of
6058different size, the largest is mapped first. For equal size, the first
6059bank (CS2#) is mapped first. The first mapping is always for address
60600x00000000, with any additional banks following immediately to create
6061contiguous memory starting from 0.
6062
6063Then, the monitor installs itself at the upper end of the SDRAM area
6064and allocates memory for use by malloc() and for the global Board
6065Info data; also, the exception vector code is copied to the low RAM
6066pages, and the final stack is set up.
6067
6068Only after this relocation will you have a "normal" C environment;
6069until that you are restricted in several ways, mostly because you are
6070running from ROM, and because the code will have to be relocated to a
6071new address in RAM.
6072
6073
6074U-Boot Porting Guide:
6075----------------------
6076
6077[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6078list, October 2002]
6079
6080
6081int main(int argc, char *argv[])
6082{
6083	sighandler_t no_more_time;
6084
6085	signal(SIGALRM, no_more_time);
6086	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6087
6088	if (available_money > available_manpower) {
6089		Pay consultant to port U-Boot;
6090		return 0;
6091	}
6092
6093	Download latest U-Boot source;
6094
6095	Subscribe to u-boot mailing list;
6096
6097	if (clueless)
6098		email("Hi, I am new to U-Boot, how do I get started?");
6099
6100	while (learning) {
6101		Read the README file in the top level directory;
6102		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6103		Read applicable doc/*.README;
6104		Read the source, Luke;
6105		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6106	}
6107
6108	if (available_money > toLocalCurrency ($2500))
6109		Buy a BDI3000;
6110	else
6111		Add a lot of aggravation and time;
6112
6113	if (a similar board exists) {	/* hopefully... */
6114		cp -a board/<similar> board/<myboard>
6115		cp include/configs/<similar>.h include/configs/<myboard>.h
6116	} else {
6117		Create your own board support subdirectory;
6118		Create your own board include/configs/<myboard>.h file;
6119	}
6120	Edit new board/<myboard> files
6121	Edit new include/configs/<myboard>.h
6122
6123	while (!accepted) {
6124		while (!running) {
6125			do {
6126				Add / modify source code;
6127			} until (compiles);
6128			Debug;
6129			if (clueless)
6130				email("Hi, I am having problems...");
6131		}
6132		Send patch file to the U-Boot email list;
6133		if (reasonable critiques)
6134			Incorporate improvements from email list code review;
6135		else
6136			Defend code as written;
6137	}
6138
6139	return 0;
6140}
6141
6142void no_more_time (int sig)
6143{
6144      hire_a_guru();
6145}
6146
6147
6148Coding Standards:
6149-----------------
6150
6151All contributions to U-Boot should conform to the Linux kernel
6152coding style; see the file "Documentation/CodingStyle" and the script
6153"scripts/Lindent" in your Linux kernel source directory.
6154
6155Source files originating from a different project (for example the
6156MTD subsystem) are generally exempt from these guidelines and are not
6157reformated to ease subsequent migration to newer versions of those
6158sources.
6159
6160Please note that U-Boot is implemented in C (and to some small parts in
6161Assembler); no C++ is used, so please do not use C++ style comments (//)
6162in your code.
6163
6164Please also stick to the following formatting rules:
6165- remove any trailing white space
6166- use TAB characters for indentation and vertical alignment, not spaces
6167- make sure NOT to use DOS '\r\n' line feeds
6168- do not add more than 2 consecutive empty lines to source files
6169- do not add trailing empty lines to source files
6170
6171Submissions which do not conform to the standards may be returned
6172with a request to reformat the changes.
6173
6174
6175Submitting Patches:
6176-------------------
6177
6178Since the number of patches for U-Boot is growing, we need to
6179establish some rules. Submissions which do not conform to these rules
6180may be rejected, even when they contain important and valuable stuff.
6181
6182Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6183
6184Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6185see http://lists.denx.de/mailman/listinfo/u-boot
6186
6187When you send a patch, please include the following information with
6188it:
6189
6190* For bug fixes: a description of the bug and how your patch fixes
6191  this bug. Please try to include a way of demonstrating that the
6192  patch actually fixes something.
6193
6194* For new features: a description of the feature and your
6195  implementation.
6196
6197* A CHANGELOG entry as plaintext (separate from the patch)
6198
6199* For major contributions, your entry to the CREDITS file
6200
6201* When you add support for a new board, don't forget to add a
6202  maintainer e-mail address to the boards.cfg file, too.
6203
6204* If your patch adds new configuration options, don't forget to
6205  document these in the README file.
6206
6207* The patch itself. If you are using git (which is *strongly*
6208  recommended) you can easily generate the patch using the
6209  "git format-patch". If you then use "git send-email" to send it to
6210  the U-Boot mailing list, you will avoid most of the common problems
6211  with some other mail clients.
6212
6213  If you cannot use git, use "diff -purN OLD NEW". If your version of
6214  diff does not support these options, then get the latest version of
6215  GNU diff.
6216
6217  The current directory when running this command shall be the parent
6218  directory of the U-Boot source tree (i. e. please make sure that
6219  your patch includes sufficient directory information for the
6220  affected files).
6221
6222  We prefer patches as plain text. MIME attachments are discouraged,
6223  and compressed attachments must not be used.
6224
6225* If one logical set of modifications affects or creates several
6226  files, all these changes shall be submitted in a SINGLE patch file.
6227
6228* Changesets that contain different, unrelated modifications shall be
6229  submitted as SEPARATE patches, one patch per changeset.
6230
6231
6232Notes:
6233
6234* Before sending the patch, run the MAKEALL script on your patched
6235  source tree and make sure that no errors or warnings are reported
6236  for any of the boards.
6237
6238* Keep your modifications to the necessary minimum: A patch
6239  containing several unrelated changes or arbitrary reformats will be
6240  returned with a request to re-formatting / split it.
6241
6242* If you modify existing code, make sure that your new code does not
6243  add to the memory footprint of the code ;-) Small is beautiful!
6244  When adding new features, these should compile conditionally only
6245  (using #ifdef), and the resulting code with the new feature
6246  disabled must not need more memory than the old code without your
6247  modification.
6248
6249* Remember that there is a size limit of 100 kB per message on the
6250  u-boot mailing list. Bigger patches will be moderated. If they are
6251  reasonable and not too big, they will be acknowledged. But patches
6252  bigger than the size limit should be avoided.
6253