xref: /openbmc/u-boot/README (revision 8a5f34ef)
1#
2# (C) Copyright 2000 - 2012
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port. The MAINTAINERS file lists board
55maintainers.
56
57
58Where to get help:
59==================
60
61In case you have questions about, problems with or contributions for
62U-Boot you should send a message to the U-Boot mailing list at
63<u-boot@lists.denx.de>. There is also an archive of previous traffic
64on the mailing list - please search the archive before asking FAQ's.
65Please see http://lists.denx.de/pipermail/u-boot and
66http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
67
68
69Where to get source code:
70=========================
71
72The U-Boot source code is maintained in the git repository at
73git://www.denx.de/git/u-boot.git ; you can browse it online at
74http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
75
76The "snapshot" links on this page allow you to download tarballs of
77any version you might be interested in. Official releases are also
78available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
79directory.
80
81Pre-built (and tested) images are available from
82ftp://ftp.denx.de/pub/u-boot/images/
83
84
85Where we come from:
86===================
87
88- start from 8xxrom sources
89- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
90- clean up code
91- make it easier to add custom boards
92- make it possible to add other [PowerPC] CPUs
93- extend functions, especially:
94  * Provide extended interface to Linux boot loader
95  * S-Record download
96  * network boot
97  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98- create ARMBoot project (http://sourceforge.net/projects/armboot)
99- add other CPU families (starting with ARM)
100- create U-Boot project (http://sourceforge.net/projects/u-boot)
101- current project page: see http://www.denx.de/wiki/U-Boot
102
103
104Names and Spelling:
105===================
106
107The "official" name of this project is "Das U-Boot". The spelling
108"U-Boot" shall be used in all written text (documentation, comments
109in source files etc.). Example:
110
111	This is the README file for the U-Boot project.
112
113File names etc. shall be based on the string "u-boot". Examples:
114
115	include/asm-ppc/u-boot.h
116
117	#include <asm/u-boot.h>
118
119Variable names, preprocessor constants etc. shall be either based on
120the string "u_boot" or on "U_BOOT". Example:
121
122	U_BOOT_VERSION		u_boot_logo
123	IH_OS_U_BOOT		u_boot_hush_start
124
125
126Versioning:
127===========
128
129Starting with the release in October 2008, the names of the releases
130were changed from numerical release numbers without deeper meaning
131into a time stamp based numbering. Regular releases are identified by
132names consisting of the calendar year and month of the release date.
133Additional fields (if present) indicate release candidates or bug fix
134releases in "stable" maintenance trees.
135
136Examples:
137	U-Boot v2009.11	    - Release November 2009
138	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
139	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
140
141
142Directory Hierarchy:
143====================
144
145/arch			Architecture specific files
146  /arm			Files generic to ARM architecture
147    /cpu		CPU specific files
148      /arm720t		Files specific to ARM 720 CPUs
149      /arm920t		Files specific to ARM 920 CPUs
150	/at91		Files specific to Atmel AT91RM9200 CPU
151	/imx		Files specific to Freescale MC9328 i.MX CPUs
152	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
153      /arm925t		Files specific to ARM 925 CPUs
154      /arm926ejs	Files specific to ARM 926 CPUs
155      /arm1136		Files specific to ARM 1136 CPUs
156      /ixp		Files specific to Intel XScale IXP CPUs
157      /pxa		Files specific to Intel XScale PXA CPUs
158      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
159      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
160    /lib		Architecture specific library files
161  /avr32		Files generic to AVR32 architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /blackfin		Files generic to Analog Devices Blackfin architecture
165    /cpu		CPU specific files
166    /lib		Architecture specific library files
167  /x86			Files generic to x86 architecture
168    /cpu		CPU specific files
169    /lib		Architecture specific library files
170  /m68k			Files generic to m68k architecture
171    /cpu		CPU specific files
172      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
173      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
174      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
175      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
176      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
177    /lib		Architecture specific library files
178  /microblaze		Files generic to microblaze architecture
179    /cpu		CPU specific files
180    /lib		Architecture specific library files
181  /mips			Files generic to MIPS architecture
182    /cpu		CPU specific files
183      /mips32		Files specific to MIPS32 CPUs
184      /xburst		Files specific to Ingenic XBurst CPUs
185    /lib		Architecture specific library files
186  /nds32		Files generic to NDS32 architecture
187    /cpu		CPU specific files
188      /n1213		Files specific to Andes Technology N1213 CPUs
189    /lib		Architecture specific library files
190  /nios2		Files generic to Altera NIOS2 architecture
191    /cpu		CPU specific files
192    /lib		Architecture specific library files
193  /powerpc		Files generic to PowerPC architecture
194    /cpu		CPU specific files
195      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
196      /mpc5xx		Files specific to Freescale MPC5xx CPUs
197      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
198      /mpc8xx		Files specific to Freescale MPC8xx CPUs
199      /mpc8220		Files specific to Freescale MPC8220 CPUs
200      /mpc824x		Files specific to Freescale MPC824x CPUs
201      /mpc8260		Files specific to Freescale MPC8260 CPUs
202      /mpc85xx		Files specific to Freescale MPC85xx CPUs
203      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
204    /lib		Architecture specific library files
205  /sh			Files generic to SH architecture
206    /cpu		CPU specific files
207      /sh2		Files specific to sh2 CPUs
208      /sh3		Files specific to sh3 CPUs
209      /sh4		Files specific to sh4 CPUs
210    /lib		Architecture specific library files
211  /sparc		Files generic to SPARC architecture
212    /cpu		CPU specific files
213      /leon2		Files specific to Gaisler LEON2 SPARC CPU
214      /leon3		Files specific to Gaisler LEON3 SPARC CPU
215    /lib		Architecture specific library files
216/api			Machine/arch independent API for external apps
217/board			Board dependent files
218/common			Misc architecture independent functions
219/disk			Code for disk drive partition handling
220/doc			Documentation (don't expect too much)
221/drivers		Commonly used device drivers
222/examples		Example code for standalone applications, etc.
223/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
224/include		Header Files
225/lib			Files generic to all architectures
226  /libfdt		Library files to support flattened device trees
227  /lzma			Library files to support LZMA decompression
228  /lzo			Library files to support LZO decompression
229/net			Networking code
230/post			Power On Self Test
231/rtc			Real Time Clock drivers
232/tools			Tools to build S-Record or U-Boot images, etc.
233
234Software Configuration:
235=======================
236
237Configuration is usually done using C preprocessor defines; the
238rationale behind that is to avoid dead code whenever possible.
239
240There are two classes of configuration variables:
241
242* Configuration _OPTIONS_:
243  These are selectable by the user and have names beginning with
244  "CONFIG_".
245
246* Configuration _SETTINGS_:
247  These depend on the hardware etc. and should not be meddled with if
248  you don't know what you're doing; they have names beginning with
249  "CONFIG_SYS_".
250
251Later we will add a configuration tool - probably similar to or even
252identical to what's used for the Linux kernel. Right now, we have to
253do the configuration by hand, which means creating some symbolic
254links and editing some configuration files. We use the TQM8xxL boards
255as an example here.
256
257
258Selection of Processor Architecture and Board Type:
259---------------------------------------------------
260
261For all supported boards there are ready-to-use default
262configurations available; just type "make <board_name>_config".
263
264Example: For a TQM823L module type:
265
266	cd u-boot
267	make TQM823L_config
268
269For the Cogent platform, you need to specify the CPU type as well;
270e.g. "make cogent_mpc8xx_config". And also configure the cogent
271directory according to the instructions in cogent/README.
272
273
274Configuration Options:
275----------------------
276
277Configuration depends on the combination of board and CPU type; all
278such information is kept in a configuration file
279"include/configs/<board_name>.h".
280
281Example: For a TQM823L module, all configuration settings are in
282"include/configs/TQM823L.h".
283
284
285Many of the options are named exactly as the corresponding Linux
286kernel configuration options. The intention is to make it easier to
287build a config tool - later.
288
289
290The following options need to be configured:
291
292- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
293
294- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
295
296- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
297		Define exactly one, e.g. CONFIG_ATSTK1002
298
299- CPU Module Type: (if CONFIG_COGENT is defined)
300		Define exactly one of
301		CONFIG_CMA286_60_OLD
302--- FIXME --- not tested yet:
303		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
304		CONFIG_CMA287_23, CONFIG_CMA287_50
305
306- Motherboard Type: (if CONFIG_COGENT is defined)
307		Define exactly one of
308		CONFIG_CMA101, CONFIG_CMA102
309
310- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
311		Define one or more of
312		CONFIG_CMA302
313
314- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
315		Define one or more of
316		CONFIG_LCD_HEARTBEAT	- update a character position on
317					  the LCD display every second with
318					  a "rotator" |\-/|\-/
319
320- Board flavour: (if CONFIG_MPC8260ADS is defined)
321		CONFIG_ADSTYPE
322		Possible values are:
323			CONFIG_SYS_8260ADS	- original MPC8260ADS
324			CONFIG_SYS_8266ADS	- MPC8266ADS
325			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
326			CONFIG_SYS_8272ADS	- MPC8272ADS
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- MPC824X Family Member (if CONFIG_MPC824X is defined)
334		Define exactly one of
335		CONFIG_MPC8240, CONFIG_MPC8245
336
337- 8xx CPU Options: (if using an MPC8xx CPU)
338		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
339					  get_gclk_freq() cannot work
340					  e.g. if there is no 32KHz
341					  reference PIT/RTC clock
342		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
343					  or XTAL/EXTAL)
344
345- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
346		CONFIG_SYS_8xx_CPUCLK_MIN
347		CONFIG_SYS_8xx_CPUCLK_MAX
348		CONFIG_8xx_CPUCLK_DEFAULT
349			See doc/README.MPC866
350
351		CONFIG_SYS_MEASURE_CPUCLK
352
353		Define this to measure the actual CPU clock instead
354		of relying on the correctness of the configured
355		values. Mostly useful for board bringup to make sure
356		the PLL is locked at the intended frequency. Note
357		that this requires a (stable) reference clock (32 kHz
358		RTC clock or CONFIG_SYS_8XX_XIN)
359
360		CONFIG_SYS_DELAYED_ICACHE
361
362		Define this option if you want to enable the
363		ICache only when Code runs from RAM.
364
365- 85xx CPU Options:
366		CONFIG_SYS_FSL_TBCLK_DIV
367
368		Defines the core time base clock divider ratio compared to the
369		system clock.  On most PQ3 devices this is 8, on newer QorIQ
370		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
371
372		CONFIG_SYS_FSL_PCIE_COMPAT
373
374		Defines the string to utilize when trying to match PCIe device
375		tree nodes for the given platform.
376
377		CONFIG_SYS_PPC_E500_DEBUG_TLB
378
379		Enables a temporary TLB entry to be used during boot to work
380		around limitations in e500v1 and e500v2 external debugger
381		support. This reduces the portions of the boot code where
382		breakpoints and single stepping do not work.  The value of this
383		symbol should be set to the TLB1 entry to be used for this
384		purpose.
385
386		CONFIG_SYS_FSL_ERRATUM_A004510
387
388		Enables a workaround for erratum A004510.  If set,
389		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
390		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
391
392		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
393		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
394
395		Defines one or two SoC revisions (low 8 bits of SVR)
396		for which the A004510 workaround should be applied.
397
398		The rest of SVR is either not relevant to the decision
399		of whether the erratum is present (e.g. p2040 versus
400		p2041) or is implied by the build target, which controls
401		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
402
403		See Freescale App Note 4493 for more information about
404		this erratum.
405
406		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
407
408		This is the value to write into CCSR offset 0x18600
409		according to the A004510 workaround.
410
411- Generic CPU options:
412		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
413
414		Defines the endianess of the CPU. Implementation of those
415		values is arch specific.
416
417- Intel Monahans options:
418		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
419
420		Defines the Monahans run mode to oscillator
421		ratio. Valid values are 8, 16, 24, 31. The core
422		frequency is this value multiplied by 13 MHz.
423
424		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
425
426		Defines the Monahans turbo mode to oscillator
427		ratio. Valid values are 1 (default if undefined) and
428		2. The core frequency as calculated above is multiplied
429		by this value.
430
431- MIPS CPU options:
432		CONFIG_SYS_INIT_SP_OFFSET
433
434		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
435		pointer. This is needed for the temporary stack before
436		relocation.
437
438		CONFIG_SYS_MIPS_CACHE_MODE
439
440		Cache operation mode for the MIPS CPU.
441		See also arch/mips/include/asm/mipsregs.h.
442		Possible values are:
443			CONF_CM_CACHABLE_NO_WA
444			CONF_CM_CACHABLE_WA
445			CONF_CM_UNCACHED
446			CONF_CM_CACHABLE_NONCOHERENT
447			CONF_CM_CACHABLE_CE
448			CONF_CM_CACHABLE_COW
449			CONF_CM_CACHABLE_CUW
450			CONF_CM_CACHABLE_ACCELERATED
451
452		CONFIG_SYS_XWAY_EBU_BOOTCFG
453
454		Special option for Lantiq XWAY SoCs for booting from NOR flash.
455		See also arch/mips/cpu/mips32/start.S.
456
457		CONFIG_XWAY_SWAP_BYTES
458
459		Enable compilation of tools/xway-swap-bytes needed for Lantiq
460		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
461		be swapped if a flash programmer is used.
462
463- ARM options:
464		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
465
466		Select high exception vectors of the ARM core, e.g., do not
467		clear the V bit of the c1 register of CP15.
468
469		CONFIG_SYS_THUMB_BUILD
470
471		Use this flag to build U-Boot using the Thumb instruction
472		set for ARM architectures. Thumb instruction set provides
473		better code density. For ARM architectures that support
474		Thumb2 this flag will result in Thumb2 code generated by
475		GCC.
476
477- Linux Kernel Interface:
478		CONFIG_CLOCKS_IN_MHZ
479
480		U-Boot stores all clock information in Hz
481		internally. For binary compatibility with older Linux
482		kernels (which expect the clocks passed in the
483		bd_info data to be in MHz) the environment variable
484		"clocks_in_mhz" can be defined so that U-Boot
485		converts clock data to MHZ before passing it to the
486		Linux kernel.
487		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
488		"clocks_in_mhz=1" is automatically included in the
489		default environment.
490
491		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
492
493		When transferring memsize parameter to linux, some versions
494		expect it to be in bytes, others in MB.
495		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
496
497		CONFIG_OF_LIBFDT
498
499		New kernel versions are expecting firmware settings to be
500		passed using flattened device trees (based on open firmware
501		concepts).
502
503		CONFIG_OF_LIBFDT
504		 * New libfdt-based support
505		 * Adds the "fdt" command
506		 * The bootm command automatically updates the fdt
507
508		OF_CPU - The proper name of the cpus node (only required for
509			MPC512X and MPC5xxx based boards).
510		OF_SOC - The proper name of the soc node (only required for
511			MPC512X and MPC5xxx based boards).
512		OF_TBCLK - The timebase frequency.
513		OF_STDOUT_PATH - The path to the console device
514
515		boards with QUICC Engines require OF_QE to set UCC MAC
516		addresses
517
518		CONFIG_OF_BOARD_SETUP
519
520		Board code has addition modification that it wants to make
521		to the flat device tree before handing it off to the kernel
522
523		CONFIG_OF_BOOT_CPU
524
525		This define fills in the correct boot CPU in the boot
526		param header, the default value is zero if undefined.
527
528		CONFIG_OF_IDE_FIXUP
529
530		U-Boot can detect if an IDE device is present or not.
531		If not, and this new config option is activated, U-Boot
532		removes the ATA node from the DTS before booting Linux,
533		so the Linux IDE driver does not probe the device and
534		crash. This is needed for buggy hardware (uc101) where
535		no pull down resistor is connected to the signal IDE5V_DD7.
536
537		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
538
539		This setting is mandatory for all boards that have only one
540		machine type and must be used to specify the machine type
541		number as it appears in the ARM machine registry
542		(see http://www.arm.linux.org.uk/developer/machines/).
543		Only boards that have multiple machine types supported
544		in a single configuration file and the machine type is
545		runtime discoverable, do not have to use this setting.
546
547- vxWorks boot parameters:
548
549		bootvx constructs a valid bootline using the following
550		environments variables: bootfile, ipaddr, serverip, hostname.
551		It loads the vxWorks image pointed bootfile.
552
553		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
554		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
555		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
556		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
557
558		CONFIG_SYS_VXWORKS_ADD_PARAMS
559
560		Add it at the end of the bootline. E.g "u=username pw=secret"
561
562		Note: If a "bootargs" environment is defined, it will overwride
563		the defaults discussed just above.
564
565- Cache Configuration:
566		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
567		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
568		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
569
570- Cache Configuration for ARM:
571		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
572				      controller
573		CONFIG_SYS_PL310_BASE - Physical base address of PL310
574					controller register space
575
576- Serial Ports:
577		CONFIG_PL010_SERIAL
578
579		Define this if you want support for Amba PrimeCell PL010 UARTs.
580
581		CONFIG_PL011_SERIAL
582
583		Define this if you want support for Amba PrimeCell PL011 UARTs.
584
585		CONFIG_PL011_CLOCK
586
587		If you have Amba PrimeCell PL011 UARTs, set this variable to
588		the clock speed of the UARTs.
589
590		CONFIG_PL01x_PORTS
591
592		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
593		define this to a list of base addresses for each (supported)
594		port. See e.g. include/configs/versatile.h
595
596		CONFIG_PL011_SERIAL_RLCR
597
598		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
599		have separate receive and transmit line control registers.  Set
600		this variable to initialize the extra register.
601
602		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
603
604		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
605		boot loader that has already initialized the UART.  Define this
606		variable to flush the UART at init time.
607
608
609- Console Interface:
610		Depending on board, define exactly one serial port
611		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
612		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
613		console by defining CONFIG_8xx_CONS_NONE
614
615		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
616		port routines must be defined elsewhere
617		(i.e. serial_init(), serial_getc(), ...)
618
619		CONFIG_CFB_CONSOLE
620		Enables console device for a color framebuffer. Needs following
621		defines (cf. smiLynxEM, i8042)
622			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
623						(default big endian)
624			VIDEO_HW_RECTFILL	graphic chip supports
625						rectangle fill
626						(cf. smiLynxEM)
627			VIDEO_HW_BITBLT		graphic chip supports
628						bit-blit (cf. smiLynxEM)
629			VIDEO_VISIBLE_COLS	visible pixel columns
630						(cols=pitch)
631			VIDEO_VISIBLE_ROWS	visible pixel rows
632			VIDEO_PIXEL_SIZE	bytes per pixel
633			VIDEO_DATA_FORMAT	graphic data format
634						(0-5, cf. cfb_console.c)
635			VIDEO_FB_ADRS		framebuffer address
636			VIDEO_KBD_INIT_FCT	keyboard int fct
637						(i.e. i8042_kbd_init())
638			VIDEO_TSTC_FCT		test char fct
639						(i.e. i8042_tstc)
640			VIDEO_GETC_FCT		get char fct
641						(i.e. i8042_getc)
642			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
643						(requires blink timer
644						cf. i8042.c)
645			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
646			CONFIG_CONSOLE_TIME	display time/date info in
647						upper right corner
648						(requires CONFIG_CMD_DATE)
649			CONFIG_VIDEO_LOGO	display Linux logo in
650						upper left corner
651			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
652						linux_logo.h for logo.
653						Requires CONFIG_VIDEO_LOGO
654			CONFIG_CONSOLE_EXTRA_INFO
655						additional board info beside
656						the logo
657
658		When CONFIG_CFB_CONSOLE is defined, video console is
659		default i/o. Serial console can be forced with
660		environment 'console=serial'.
661
662		When CONFIG_SILENT_CONSOLE is defined, all console
663		messages (by U-Boot and Linux!) can be silenced with
664		the "silent" environment variable. See
665		doc/README.silent for more information.
666
667- Console Baudrate:
668		CONFIG_BAUDRATE - in bps
669		Select one of the baudrates listed in
670		CONFIG_SYS_BAUDRATE_TABLE, see below.
671		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
672
673- Console Rx buffer length
674		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
675		the maximum receive buffer length for the SMC.
676		This option is actual only for 82xx and 8xx possible.
677		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
678		must be defined, to setup the maximum idle timeout for
679		the SMC.
680
681- Pre-Console Buffer:
682		Prior to the console being initialised (i.e. serial UART
683		initialised etc) all console output is silently discarded.
684		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
685		buffer any console messages prior to the console being
686		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
687		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
688		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
689		bytes are output before the console is initialised, the
690		earlier bytes are discarded.
691
692		'Sane' compilers will generate smaller code if
693		CONFIG_PRE_CON_BUF_SZ is a power of 2
694
695- Safe printf() functions
696		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
697		the printf() functions. These are defined in
698		include/vsprintf.h and include snprintf(), vsnprintf() and
699		so on. Code size increase is approximately 300-500 bytes.
700		If this option is not given then these functions will
701		silently discard their buffer size argument - this means
702		you are not getting any overflow checking in this case.
703
704- Boot Delay:	CONFIG_BOOTDELAY - in seconds
705		Delay before automatically booting the default image;
706		set to -1 to disable autoboot.
707
708		See doc/README.autoboot for these options that
709		work with CONFIG_BOOTDELAY. None are required.
710		CONFIG_BOOT_RETRY_TIME
711		CONFIG_BOOT_RETRY_MIN
712		CONFIG_AUTOBOOT_KEYED
713		CONFIG_AUTOBOOT_PROMPT
714		CONFIG_AUTOBOOT_DELAY_STR
715		CONFIG_AUTOBOOT_STOP_STR
716		CONFIG_AUTOBOOT_DELAY_STR2
717		CONFIG_AUTOBOOT_STOP_STR2
718		CONFIG_ZERO_BOOTDELAY_CHECK
719		CONFIG_RESET_TO_RETRY
720
721- Autoboot Command:
722		CONFIG_BOOTCOMMAND
723		Only needed when CONFIG_BOOTDELAY is enabled;
724		define a command string that is automatically executed
725		when no character is read on the console interface
726		within "Boot Delay" after reset.
727
728		CONFIG_BOOTARGS
729		This can be used to pass arguments to the bootm
730		command. The value of CONFIG_BOOTARGS goes into the
731		environment value "bootargs".
732
733		CONFIG_RAMBOOT and CONFIG_NFSBOOT
734		The value of these goes into the environment as
735		"ramboot" and "nfsboot" respectively, and can be used
736		as a convenience, when switching between booting from
737		RAM and NFS.
738
739- Pre-Boot Commands:
740		CONFIG_PREBOOT
741
742		When this option is #defined, the existence of the
743		environment variable "preboot" will be checked
744		immediately before starting the CONFIG_BOOTDELAY
745		countdown and/or running the auto-boot command resp.
746		entering interactive mode.
747
748		This feature is especially useful when "preboot" is
749		automatically generated or modified. For an example
750		see the LWMON board specific code: here "preboot" is
751		modified when the user holds down a certain
752		combination of keys on the (special) keyboard when
753		booting the systems
754
755- Serial Download Echo Mode:
756		CONFIG_LOADS_ECHO
757		If defined to 1, all characters received during a
758		serial download (using the "loads" command) are
759		echoed back. This might be needed by some terminal
760		emulations (like "cu"), but may as well just take
761		time on others. This setting #define's the initial
762		value of the "loads_echo" environment variable.
763
764- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
765		CONFIG_KGDB_BAUDRATE
766		Select one of the baudrates listed in
767		CONFIG_SYS_BAUDRATE_TABLE, see below.
768
769- Monitor Functions:
770		Monitor commands can be included or excluded
771		from the build by using the #include files
772		<config_cmd_all.h> and #undef'ing unwanted
773		commands, or using <config_cmd_default.h>
774		and augmenting with additional #define's
775		for wanted commands.
776
777		The default command configuration includes all commands
778		except those marked below with a "*".
779
780		CONFIG_CMD_ASKENV	* ask for env variable
781		CONFIG_CMD_BDI		  bdinfo
782		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
783		CONFIG_CMD_BMP		* BMP support
784		CONFIG_CMD_BSP		* Board specific commands
785		CONFIG_CMD_BOOTD	  bootd
786		CONFIG_CMD_CACHE	* icache, dcache
787		CONFIG_CMD_CONSOLE	  coninfo
788		CONFIG_CMD_CRC32	* crc32
789		CONFIG_CMD_DATE		* support for RTC, date/time...
790		CONFIG_CMD_DHCP		* DHCP support
791		CONFIG_CMD_DIAG		* Diagnostics
792		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
793		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
794		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
795		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
796		CONFIG_CMD_DTT		* Digital Therm and Thermostat
797		CONFIG_CMD_ECHO		  echo arguments
798		CONFIG_CMD_EDITENV	  edit env variable
799		CONFIG_CMD_EEPROM	* EEPROM read/write support
800		CONFIG_CMD_ELF		* bootelf, bootvx
801		CONFIG_CMD_EXPORTENV	* export the environment
802		CONFIG_CMD_SAVEENV	  saveenv
803		CONFIG_CMD_FDC		* Floppy Disk Support
804		CONFIG_CMD_FAT		* FAT partition support
805		CONFIG_CMD_FDOS		* Dos diskette Support
806		CONFIG_CMD_FLASH	  flinfo, erase, protect
807		CONFIG_CMD_FPGA		  FPGA device initialization support
808		CONFIG_CMD_GO		* the 'go' command (exec code)
809		CONFIG_CMD_GREPENV	* search environment
810		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
811		CONFIG_CMD_I2C		* I2C serial bus support
812		CONFIG_CMD_IDE		* IDE harddisk support
813		CONFIG_CMD_IMI		  iminfo
814		CONFIG_CMD_IMLS		  List all found images
815		CONFIG_CMD_IMMAP	* IMMR dump support
816		CONFIG_CMD_IMPORTENV	* import an environment
817		CONFIG_CMD_IRQ		* irqinfo
818		CONFIG_CMD_ITEST	  Integer/string test of 2 values
819		CONFIG_CMD_JFFS2	* JFFS2 Support
820		CONFIG_CMD_KGDB		* kgdb
821		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
822		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
823					  (169.254.*.*)
824		CONFIG_CMD_LOADB	  loadb
825		CONFIG_CMD_LOADS	  loads
826		CONFIG_CMD_MD5SUM	  print md5 message digest
827					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
828		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
829					  loop, loopw, mtest
830		CONFIG_CMD_MISC		  Misc functions like sleep etc
831		CONFIG_CMD_MMC		* MMC memory mapped support
832		CONFIG_CMD_MII		* MII utility commands
833		CONFIG_CMD_MTDPARTS	* MTD partition support
834		CONFIG_CMD_NAND		* NAND support
835		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
836		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
837		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
838		CONFIG_CMD_PCI		* pciinfo
839		CONFIG_CMD_PCMCIA		* PCMCIA support
840		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
841					  host
842		CONFIG_CMD_PORTIO	* Port I/O
843		CONFIG_CMD_REGINFO	* Register dump
844		CONFIG_CMD_RUN		  run command in env variable
845		CONFIG_CMD_SAVES	* save S record dump
846		CONFIG_CMD_SCSI		* SCSI Support
847		CONFIG_CMD_SDRAM	* print SDRAM configuration information
848					  (requires CONFIG_CMD_I2C)
849		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
850					  (4xx only)
851		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
852		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
853					  (requires CONFIG_CMD_MEMORY)
854		CONFIG_CMD_SOURCE	  "source" command Support
855		CONFIG_CMD_SPI		* SPI serial bus support
856		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
857		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
858		CONFIG_CMD_TIME		* run command and report execution time
859		CONFIG_CMD_USB		* USB support
860		CONFIG_CMD_CDP		* Cisco Discover Protocol support
861		CONFIG_CMD_MFSL		* Microblaze FSL support
862
863
864		EXAMPLE: If you want all functions except of network
865		support you can write:
866
867		#include "config_cmd_all.h"
868		#undef CONFIG_CMD_NET
869
870	Other Commands:
871		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
872
873	Note:	Don't enable the "icache" and "dcache" commands
874		(configuration option CONFIG_CMD_CACHE) unless you know
875		what you (and your U-Boot users) are doing. Data
876		cache cannot be enabled on systems like the 8xx or
877		8260 (where accesses to the IMMR region must be
878		uncached), and it cannot be disabled on all other
879		systems where we (mis-) use the data cache to hold an
880		initial stack and some data.
881
882
883		XXX - this list needs to get updated!
884
885- Device tree:
886		CONFIG_OF_CONTROL
887		If this variable is defined, U-Boot will use a device tree
888		to configure its devices, instead of relying on statically
889		compiled #defines in the board file. This option is
890		experimental and only available on a few boards. The device
891		tree is available in the global data as gd->fdt_blob.
892
893		U-Boot needs to get its device tree from somewhere. This can
894		be done using one of the two options below:
895
896		CONFIG_OF_EMBED
897		If this variable is defined, U-Boot will embed a device tree
898		binary in its image. This device tree file should be in the
899		board directory and called <soc>-<board>.dts. The binary file
900		is then picked up in board_init_f() and made available through
901		the global data structure as gd->blob.
902
903		CONFIG_OF_SEPARATE
904		If this variable is defined, U-Boot will build a device tree
905		binary. It will be called u-boot.dtb. Architecture-specific
906		code will locate it at run-time. Generally this works by:
907
908			cat u-boot.bin u-boot.dtb >image.bin
909
910		and in fact, U-Boot does this for you, creating a file called
911		u-boot-dtb.bin which is useful in the common case. You can
912		still use the individual files if you need something more
913		exotic.
914
915- Watchdog:
916		CONFIG_WATCHDOG
917		If this variable is defined, it enables watchdog
918		support for the SoC. There must be support in the SoC
919		specific code for a watchdog. For the 8xx and 8260
920		CPUs, the SIU Watchdog feature is enabled in the SYPCR
921		register.  When supported for a specific SoC is
922		available, then no further board specific code should
923		be needed to use it.
924
925		CONFIG_HW_WATCHDOG
926		When using a watchdog circuitry external to the used
927		SoC, then define this variable and provide board
928		specific code for the "hw_watchdog_reset" function.
929
930- U-Boot Version:
931		CONFIG_VERSION_VARIABLE
932		If this variable is defined, an environment variable
933		named "ver" is created by U-Boot showing the U-Boot
934		version as printed by the "version" command.
935		Any change to this variable will be reverted at the
936		next reset.
937
938- Real-Time Clock:
939
940		When CONFIG_CMD_DATE is selected, the type of the RTC
941		has to be selected, too. Define exactly one of the
942		following options:
943
944		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
945		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
946		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
947		CONFIG_RTC_MC146818	- use MC146818 RTC
948		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
949		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
950		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
951		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
952		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
953		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
954		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
955		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
956					  RV3029 RTC.
957
958		Note that if the RTC uses I2C, then the I2C interface
959		must also be configured. See I2C Support, below.
960
961- GPIO Support:
962		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
963		CONFIG_PCA953X_INFO	- enable pca953x info command
964
965		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
966		chip-ngpio pairs that tell the PCA953X driver the number of
967		pins supported by a particular chip.
968
969		Note that if the GPIO device uses I2C, then the I2C interface
970		must also be configured. See I2C Support, below.
971
972- Timestamp Support:
973
974		When CONFIG_TIMESTAMP is selected, the timestamp
975		(date and time) of an image is printed by image
976		commands like bootm or iminfo. This option is
977		automatically enabled when you select CONFIG_CMD_DATE .
978
979- Partition Labels (disklabels) Supported:
980		Zero or more of the following:
981		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
982		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
983				       Intel architecture, USB sticks, etc.
984		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
985		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
986				       bootloader.  Note 2TB partition limit; see
987				       disk/part_efi.c
988		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
989
990		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
991		CONFIG_CMD_SCSI) you must configure support for at
992		least one non-MTD partition type as well.
993
994- IDE Reset method:
995		CONFIG_IDE_RESET_ROUTINE - this is defined in several
996		board configurations files but used nowhere!
997
998		CONFIG_IDE_RESET - is this is defined, IDE Reset will
999		be performed by calling the function
1000			ide_set_reset(int reset)
1001		which has to be defined in a board specific file
1002
1003- ATAPI Support:
1004		CONFIG_ATAPI
1005
1006		Set this to enable ATAPI support.
1007
1008- LBA48 Support
1009		CONFIG_LBA48
1010
1011		Set this to enable support for disks larger than 137GB
1012		Also look at CONFIG_SYS_64BIT_LBA.
1013		Whithout these , LBA48 support uses 32bit variables and will 'only'
1014		support disks up to 2.1TB.
1015
1016		CONFIG_SYS_64BIT_LBA:
1017			When enabled, makes the IDE subsystem use 64bit sector addresses.
1018			Default is 32bit.
1019
1020- SCSI Support:
1021		At the moment only there is only support for the
1022		SYM53C8XX SCSI controller; define
1023		CONFIG_SCSI_SYM53C8XX to enable it.
1024
1025		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1026		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1027		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1028		maximum numbers of LUNs, SCSI ID's and target
1029		devices.
1030		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1031
1032- NETWORK Support (PCI):
1033		CONFIG_E1000
1034		Support for Intel 8254x/8257x gigabit chips.
1035
1036		CONFIG_E1000_SPI
1037		Utility code for direct access to the SPI bus on Intel 8257x.
1038		This does not do anything useful unless you set at least one
1039		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1040
1041		CONFIG_E1000_SPI_GENERIC
1042		Allow generic access to the SPI bus on the Intel 8257x, for
1043		example with the "sspi" command.
1044
1045		CONFIG_CMD_E1000
1046		Management command for E1000 devices.  When used on devices
1047		with SPI support you can reprogram the EEPROM from U-Boot.
1048
1049		CONFIG_E1000_FALLBACK_MAC
1050		default MAC for empty EEPROM after production.
1051
1052		CONFIG_EEPRO100
1053		Support for Intel 82557/82559/82559ER chips.
1054		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1055		write routine for first time initialisation.
1056
1057		CONFIG_TULIP
1058		Support for Digital 2114x chips.
1059		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1060		modem chip initialisation (KS8761/QS6611).
1061
1062		CONFIG_NATSEMI
1063		Support for National dp83815 chips.
1064
1065		CONFIG_NS8382X
1066		Support for National dp8382[01] gigabit chips.
1067
1068- NETWORK Support (other):
1069
1070		CONFIG_DRIVER_AT91EMAC
1071		Support for AT91RM9200 EMAC.
1072
1073			CONFIG_RMII
1074			Define this to use reduced MII inteface
1075
1076			CONFIG_DRIVER_AT91EMAC_QUIET
1077			If this defined, the driver is quiet.
1078			The driver doen't show link status messages.
1079
1080		CONFIG_CALXEDA_XGMAC
1081		Support for the Calxeda XGMAC device
1082
1083		CONFIG_DRIVER_LAN91C96
1084		Support for SMSC's LAN91C96 chips.
1085
1086			CONFIG_LAN91C96_BASE
1087			Define this to hold the physical address
1088			of the LAN91C96's I/O space
1089
1090			CONFIG_LAN91C96_USE_32_BIT
1091			Define this to enable 32 bit addressing
1092
1093		CONFIG_DRIVER_SMC91111
1094		Support for SMSC's LAN91C111 chip
1095
1096			CONFIG_SMC91111_BASE
1097			Define this to hold the physical address
1098			of the device (I/O space)
1099
1100			CONFIG_SMC_USE_32_BIT
1101			Define this if data bus is 32 bits
1102
1103			CONFIG_SMC_USE_IOFUNCS
1104			Define this to use i/o functions instead of macros
1105			(some hardware wont work with macros)
1106
1107		CONFIG_DRIVER_TI_EMAC
1108		Support for davinci emac
1109
1110			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1111			Define this if you have more then 3 PHYs.
1112
1113		CONFIG_FTGMAC100
1114		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1115
1116			CONFIG_FTGMAC100_EGIGA
1117			Define this to use GE link update with gigabit PHY.
1118			Define this if FTGMAC100 is connected to gigabit PHY.
1119			If your system has 10/100 PHY only, it might not occur
1120			wrong behavior. Because PHY usually return timeout or
1121			useless data when polling gigabit status and gigabit
1122			control registers. This behavior won't affect the
1123			correctnessof 10/100 link speed update.
1124
1125		CONFIG_SMC911X
1126		Support for SMSC's LAN911x and LAN921x chips
1127
1128			CONFIG_SMC911X_BASE
1129			Define this to hold the physical address
1130			of the device (I/O space)
1131
1132			CONFIG_SMC911X_32_BIT
1133			Define this if data bus is 32 bits
1134
1135			CONFIG_SMC911X_16_BIT
1136			Define this if data bus is 16 bits. If your processor
1137			automatically converts one 32 bit word to two 16 bit
1138			words you may also try CONFIG_SMC911X_32_BIT.
1139
1140		CONFIG_SH_ETHER
1141		Support for Renesas on-chip Ethernet controller
1142
1143			CONFIG_SH_ETHER_USE_PORT
1144			Define the number of ports to be used
1145
1146			CONFIG_SH_ETHER_PHY_ADDR
1147			Define the ETH PHY's address
1148
1149			CONFIG_SH_ETHER_CACHE_WRITEBACK
1150			If this option is set, the driver enables cache flush.
1151
1152- TPM Support:
1153		CONFIG_GENERIC_LPC_TPM
1154		Support for generic parallel port TPM devices. Only one device
1155		per system is supported at this time.
1156
1157			CONFIG_TPM_TIS_BASE_ADDRESS
1158			Base address where the generic TPM device is mapped
1159			to. Contemporary x86 systems usually map it at
1160			0xfed40000.
1161
1162- USB Support:
1163		At the moment only the UHCI host controller is
1164		supported (PIP405, MIP405, MPC5200); define
1165		CONFIG_USB_UHCI to enable it.
1166		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1167		and define CONFIG_USB_STORAGE to enable the USB
1168		storage devices.
1169		Note:
1170		Supported are USB Keyboards and USB Floppy drives
1171		(TEAC FD-05PUB).
1172		MPC5200 USB requires additional defines:
1173			CONFIG_USB_CLOCK
1174				for 528 MHz Clock: 0x0001bbbb
1175			CONFIG_PSC3_USB
1176				for USB on PSC3
1177			CONFIG_USB_CONFIG
1178				for differential drivers: 0x00001000
1179				for single ended drivers: 0x00005000
1180				for differential drivers on PSC3: 0x00000100
1181				for single ended drivers on PSC3: 0x00004100
1182			CONFIG_SYS_USB_EVENT_POLL
1183				May be defined to allow interrupt polling
1184				instead of using asynchronous interrupts
1185
1186		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1187		txfilltuning field in the EHCI controller on reset.
1188
1189- USB Device:
1190		Define the below if you wish to use the USB console.
1191		Once firmware is rebuilt from a serial console issue the
1192		command "setenv stdin usbtty; setenv stdout usbtty" and
1193		attach your USB cable. The Unix command "dmesg" should print
1194		it has found a new device. The environment variable usbtty
1195		can be set to gserial or cdc_acm to enable your device to
1196		appear to a USB host as a Linux gserial device or a
1197		Common Device Class Abstract Control Model serial device.
1198		If you select usbtty = gserial you should be able to enumerate
1199		a Linux host by
1200		# modprobe usbserial vendor=0xVendorID product=0xProductID
1201		else if using cdc_acm, simply setting the environment
1202		variable usbtty to be cdc_acm should suffice. The following
1203		might be defined in YourBoardName.h
1204
1205			CONFIG_USB_DEVICE
1206			Define this to build a UDC device
1207
1208			CONFIG_USB_TTY
1209			Define this to have a tty type of device available to
1210			talk to the UDC device
1211
1212			CONFIG_USBD_HS
1213			Define this to enable the high speed support for usb
1214			device and usbtty. If this feature is enabled, a routine
1215			int is_usbd_high_speed(void)
1216			also needs to be defined by the driver to dynamically poll
1217			whether the enumeration has succeded at high speed or full
1218			speed.
1219
1220			CONFIG_SYS_CONSOLE_IS_IN_ENV
1221			Define this if you want stdin, stdout &/or stderr to
1222			be set to usbtty.
1223
1224			mpc8xx:
1225				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1226				Derive USB clock from external clock "blah"
1227				- CONFIG_SYS_USB_EXTC_CLK 0x02
1228
1229				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1230				Derive USB clock from brgclk
1231				- CONFIG_SYS_USB_BRG_CLK 0x04
1232
1233		If you have a USB-IF assigned VendorID then you may wish to
1234		define your own vendor specific values either in BoardName.h
1235		or directly in usbd_vendor_info.h. If you don't define
1236		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1237		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1238		should pretend to be a Linux device to it's target host.
1239
1240			CONFIG_USBD_MANUFACTURER
1241			Define this string as the name of your company for
1242			- CONFIG_USBD_MANUFACTURER "my company"
1243
1244			CONFIG_USBD_PRODUCT_NAME
1245			Define this string as the name of your product
1246			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1247
1248			CONFIG_USBD_VENDORID
1249			Define this as your assigned Vendor ID from the USB
1250			Implementors Forum. This *must* be a genuine Vendor ID
1251			to avoid polluting the USB namespace.
1252			- CONFIG_USBD_VENDORID 0xFFFF
1253
1254			CONFIG_USBD_PRODUCTID
1255			Define this as the unique Product ID
1256			for your device
1257			- CONFIG_USBD_PRODUCTID 0xFFFF
1258
1259- ULPI Layer Support:
1260		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1261		the generic ULPI layer. The generic layer accesses the ULPI PHY
1262		via the platform viewport, so you need both the genric layer and
1263		the viewport enabled. Currently only Chipidea/ARC based
1264		viewport is supported.
1265		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1266		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1267
1268- MMC Support:
1269		The MMC controller on the Intel PXA is supported. To
1270		enable this define CONFIG_MMC. The MMC can be
1271		accessed from the boot prompt by mapping the device
1272		to physical memory similar to flash. Command line is
1273		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1274		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1275
1276		CONFIG_SH_MMCIF
1277		Support for Renesas on-chip MMCIF controller
1278
1279			CONFIG_SH_MMCIF_ADDR
1280			Define the base address of MMCIF registers
1281
1282			CONFIG_SH_MMCIF_CLK
1283			Define the clock frequency for MMCIF
1284
1285- Journaling Flash filesystem support:
1286		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1287		CONFIG_JFFS2_NAND_DEV
1288		Define these for a default partition on a NAND device
1289
1290		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1291		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1292		Define these for a default partition on a NOR device
1293
1294		CONFIG_SYS_JFFS_CUSTOM_PART
1295		Define this to create an own partition. You have to provide a
1296		function struct part_info* jffs2_part_info(int part_num)
1297
1298		If you define only one JFFS2 partition you may also want to
1299		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1300		to disable the command chpart. This is the default when you
1301		have not defined a custom partition
1302
1303- FAT(File Allocation Table) filesystem write function support:
1304		CONFIG_FAT_WRITE
1305
1306		Define this to enable support for saving memory data as a
1307		file in FAT formatted partition.
1308
1309		This will also enable the command "fatwrite" enabling the
1310		user to write files to FAT.
1311
1312- Keyboard Support:
1313		CONFIG_ISA_KEYBOARD
1314
1315		Define this to enable standard (PC-Style) keyboard
1316		support
1317
1318		CONFIG_I8042_KBD
1319		Standard PC keyboard driver with US (is default) and
1320		GERMAN key layout (switch via environment 'keymap=de') support.
1321		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1322		for cfb_console. Supports cursor blinking.
1323
1324- Video support:
1325		CONFIG_VIDEO
1326
1327		Define this to enable video support (for output to
1328		video).
1329
1330		CONFIG_VIDEO_CT69000
1331
1332		Enable Chips & Technologies 69000 Video chip
1333
1334		CONFIG_VIDEO_SMI_LYNXEM
1335		Enable Silicon Motion SMI 712/710/810 Video chip. The
1336		video output is selected via environment 'videoout'
1337		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1338		assumed.
1339
1340		For the CT69000 and SMI_LYNXEM drivers, videomode is
1341		selected via environment 'videomode'. Two different ways
1342		are possible:
1343		- "videomode=num"   'num' is a standard LiLo mode numbers.
1344		Following standard modes are supported	(* is default):
1345
1346		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1347		-------------+---------------------------------------------
1348		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1349		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1350		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1351		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1352		-------------+---------------------------------------------
1353		(i.e. setenv videomode 317; saveenv; reset;)
1354
1355		- "videomode=bootargs" all the video parameters are parsed
1356		from the bootargs. (See drivers/video/videomodes.c)
1357
1358
1359		CONFIG_VIDEO_SED13806
1360		Enable Epson SED13806 driver. This driver supports 8bpp
1361		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1362		or CONFIG_VIDEO_SED13806_16BPP
1363
1364		CONFIG_FSL_DIU_FB
1365		Enable the Freescale DIU video driver.	Reference boards for
1366		SOCs that have a DIU should define this macro to enable DIU
1367		support, and should also define these other macros:
1368
1369			CONFIG_SYS_DIU_ADDR
1370			CONFIG_VIDEO
1371			CONFIG_CMD_BMP
1372			CONFIG_CFB_CONSOLE
1373			CONFIG_VIDEO_SW_CURSOR
1374			CONFIG_VGA_AS_SINGLE_DEVICE
1375			CONFIG_VIDEO_LOGO
1376			CONFIG_VIDEO_BMP_LOGO
1377
1378		The DIU driver will look for the 'video-mode' environment
1379		variable, and if defined, enable the DIU as a console during
1380		boot.  See the documentation file README.video for a
1381		description of this variable.
1382
1383- Keyboard Support:
1384		CONFIG_KEYBOARD
1385
1386		Define this to enable a custom keyboard support.
1387		This simply calls drv_keyboard_init() which must be
1388		defined in your board-specific files.
1389		The only board using this so far is RBC823.
1390
1391- LCD Support:	CONFIG_LCD
1392
1393		Define this to enable LCD support (for output to LCD
1394		display); also select one of the supported displays
1395		by defining one of these:
1396
1397		CONFIG_ATMEL_LCD:
1398
1399			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1400
1401		CONFIG_NEC_NL6448AC33:
1402
1403			NEC NL6448AC33-18. Active, color, single scan.
1404
1405		CONFIG_NEC_NL6448BC20
1406
1407			NEC NL6448BC20-08. 6.5", 640x480.
1408			Active, color, single scan.
1409
1410		CONFIG_NEC_NL6448BC33_54
1411
1412			NEC NL6448BC33-54. 10.4", 640x480.
1413			Active, color, single scan.
1414
1415		CONFIG_SHARP_16x9
1416
1417			Sharp 320x240. Active, color, single scan.
1418			It isn't 16x9, and I am not sure what it is.
1419
1420		CONFIG_SHARP_LQ64D341
1421
1422			Sharp LQ64D341 display, 640x480.
1423			Active, color, single scan.
1424
1425		CONFIG_HLD1045
1426
1427			HLD1045 display, 640x480.
1428			Active, color, single scan.
1429
1430		CONFIG_OPTREX_BW
1431
1432			Optrex	 CBL50840-2 NF-FW 99 22 M5
1433			or
1434			Hitachi	 LMG6912RPFC-00T
1435			or
1436			Hitachi	 SP14Q002
1437
1438			320x240. Black & white.
1439
1440		Normally display is black on white background; define
1441		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1442
1443- Splash Screen Support: CONFIG_SPLASH_SCREEN
1444
1445		If this option is set, the environment is checked for
1446		a variable "splashimage". If found, the usual display
1447		of logo, copyright and system information on the LCD
1448		is suppressed and the BMP image at the address
1449		specified in "splashimage" is loaded instead. The
1450		console is redirected to the "nulldev", too. This
1451		allows for a "silent" boot where a splash screen is
1452		loaded very quickly after power-on.
1453
1454		CONFIG_SPLASH_SCREEN_ALIGN
1455
1456		If this option is set the splash image can be freely positioned
1457		on the screen. Environment variable "splashpos" specifies the
1458		position as "x,y". If a positive number is given it is used as
1459		number of pixel from left/top. If a negative number is given it
1460		is used as number of pixel from right/bottom. You can also
1461		specify 'm' for centering the image.
1462
1463		Example:
1464		setenv splashpos m,m
1465			=> image at center of screen
1466
1467		setenv splashpos 30,20
1468			=> image at x = 30 and y = 20
1469
1470		setenv splashpos -10,m
1471			=> vertically centered image
1472			   at x = dspWidth - bmpWidth - 9
1473
1474- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1475
1476		If this option is set, additionally to standard BMP
1477		images, gzipped BMP images can be displayed via the
1478		splashscreen support or the bmp command.
1479
1480- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1481
1482		If this option is set, 8-bit RLE compressed BMP images
1483		can be displayed via the splashscreen support or the
1484		bmp command.
1485
1486- Compression support:
1487		CONFIG_BZIP2
1488
1489		If this option is set, support for bzip2 compressed
1490		images is included. If not, only uncompressed and gzip
1491		compressed images are supported.
1492
1493		NOTE: the bzip2 algorithm requires a lot of RAM, so
1494		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1495		be at least 4MB.
1496
1497		CONFIG_LZMA
1498
1499		If this option is set, support for lzma compressed
1500		images is included.
1501
1502		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1503		requires an amount of dynamic memory that is given by the
1504		formula:
1505
1506			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1507
1508		Where lc and lp stand for, respectively, Literal context bits
1509		and Literal pos bits.
1510
1511		This value is upper-bounded by 14MB in the worst case. Anyway,
1512		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1513		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1514		a very small buffer.
1515
1516		Use the lzmainfo tool to determinate the lc and lp values and
1517		then calculate the amount of needed dynamic memory (ensuring
1518		the appropriate CONFIG_SYS_MALLOC_LEN value).
1519
1520- MII/PHY support:
1521		CONFIG_PHY_ADDR
1522
1523		The address of PHY on MII bus.
1524
1525		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1526
1527		The clock frequency of the MII bus
1528
1529		CONFIG_PHY_GIGE
1530
1531		If this option is set, support for speed/duplex
1532		detection of gigabit PHY is included.
1533
1534		CONFIG_PHY_RESET_DELAY
1535
1536		Some PHY like Intel LXT971A need extra delay after
1537		reset before any MII register access is possible.
1538		For such PHY, set this option to the usec delay
1539		required. (minimum 300usec for LXT971A)
1540
1541		CONFIG_PHY_CMD_DELAY (ppc4xx)
1542
1543		Some PHY like Intel LXT971A need extra delay after
1544		command issued before MII status register can be read
1545
1546- Ethernet address:
1547		CONFIG_ETHADDR
1548		CONFIG_ETH1ADDR
1549		CONFIG_ETH2ADDR
1550		CONFIG_ETH3ADDR
1551		CONFIG_ETH4ADDR
1552		CONFIG_ETH5ADDR
1553
1554		Define a default value for Ethernet address to use
1555		for the respective Ethernet interface, in case this
1556		is not determined automatically.
1557
1558- IP address:
1559		CONFIG_IPADDR
1560
1561		Define a default value for the IP address to use for
1562		the default Ethernet interface, in case this is not
1563		determined through e.g. bootp.
1564		(Environment variable "ipaddr")
1565
1566- Server IP address:
1567		CONFIG_SERVERIP
1568
1569		Defines a default value for the IP address of a TFTP
1570		server to contact when using the "tftboot" command.
1571		(Environment variable "serverip")
1572
1573		CONFIG_KEEP_SERVERADDR
1574
1575		Keeps the server's MAC address, in the env 'serveraddr'
1576		for passing to bootargs (like Linux's netconsole option)
1577
1578- Gateway IP address:
1579		CONFIG_GATEWAYIP
1580
1581		Defines a default value for the IP address of the
1582		default router where packets to other networks are
1583		sent to.
1584		(Environment variable "gatewayip")
1585
1586- Subnet mask:
1587		CONFIG_NETMASK
1588
1589		Defines a default value for the subnet mask (or
1590		routing prefix) which is used to determine if an IP
1591		address belongs to the local subnet or needs to be
1592		forwarded through a router.
1593		(Environment variable "netmask")
1594
1595- Multicast TFTP Mode:
1596		CONFIG_MCAST_TFTP
1597
1598		Defines whether you want to support multicast TFTP as per
1599		rfc-2090; for example to work with atftp.  Lets lots of targets
1600		tftp down the same boot image concurrently.  Note: the Ethernet
1601		driver in use must provide a function: mcast() to join/leave a
1602		multicast group.
1603
1604- BOOTP Recovery Mode:
1605		CONFIG_BOOTP_RANDOM_DELAY
1606
1607		If you have many targets in a network that try to
1608		boot using BOOTP, you may want to avoid that all
1609		systems send out BOOTP requests at precisely the same
1610		moment (which would happen for instance at recovery
1611		from a power failure, when all systems will try to
1612		boot, thus flooding the BOOTP server. Defining
1613		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1614		inserted before sending out BOOTP requests. The
1615		following delays are inserted then:
1616
1617		1st BOOTP request:	delay 0 ... 1 sec
1618		2nd BOOTP request:	delay 0 ... 2 sec
1619		3rd BOOTP request:	delay 0 ... 4 sec
1620		4th and following
1621		BOOTP requests:		delay 0 ... 8 sec
1622
1623- DHCP Advanced Options:
1624		You can fine tune the DHCP functionality by defining
1625		CONFIG_BOOTP_* symbols:
1626
1627		CONFIG_BOOTP_SUBNETMASK
1628		CONFIG_BOOTP_GATEWAY
1629		CONFIG_BOOTP_HOSTNAME
1630		CONFIG_BOOTP_NISDOMAIN
1631		CONFIG_BOOTP_BOOTPATH
1632		CONFIG_BOOTP_BOOTFILESIZE
1633		CONFIG_BOOTP_DNS
1634		CONFIG_BOOTP_DNS2
1635		CONFIG_BOOTP_SEND_HOSTNAME
1636		CONFIG_BOOTP_NTPSERVER
1637		CONFIG_BOOTP_TIMEOFFSET
1638		CONFIG_BOOTP_VENDOREX
1639		CONFIG_BOOTP_MAY_FAIL
1640
1641		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1642		environment variable, not the BOOTP server.
1643
1644		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1645		after the configured retry count, the call will fail
1646		instead of starting over.  This can be used to fail over
1647		to Link-local IP address configuration if the DHCP server
1648		is not available.
1649
1650		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1651		serverip from a DHCP server, it is possible that more
1652		than one DNS serverip is offered to the client.
1653		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1654		serverip will be stored in the additional environment
1655		variable "dnsip2". The first DNS serverip is always
1656		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1657		is defined.
1658
1659		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1660		to do a dynamic update of a DNS server. To do this, they
1661		need the hostname of the DHCP requester.
1662		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1663		of the "hostname" environment variable is passed as
1664		option 12 to the DHCP server.
1665
1666		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1667
1668		A 32bit value in microseconds for a delay between
1669		receiving a "DHCP Offer" and sending the "DHCP Request".
1670		This fixes a problem with certain DHCP servers that don't
1671		respond 100% of the time to a "DHCP request". E.g. On an
1672		AT91RM9200 processor running at 180MHz, this delay needed
1673		to be *at least* 15,000 usec before a Windows Server 2003
1674		DHCP server would reply 100% of the time. I recommend at
1675		least 50,000 usec to be safe. The alternative is to hope
1676		that one of the retries will be successful but note that
1677		the DHCP timeout and retry process takes a longer than
1678		this delay.
1679
1680 - Link-local IP address negotiation:
1681		Negotiate with other link-local clients on the local network
1682		for an address that doesn't require explicit configuration.
1683		This is especially useful if a DHCP server cannot be guaranteed
1684		to exist in all environments that the device must operate.
1685
1686		See doc/README.link-local for more information.
1687
1688 - CDP Options:
1689		CONFIG_CDP_DEVICE_ID
1690
1691		The device id used in CDP trigger frames.
1692
1693		CONFIG_CDP_DEVICE_ID_PREFIX
1694
1695		A two character string which is prefixed to the MAC address
1696		of the device.
1697
1698		CONFIG_CDP_PORT_ID
1699
1700		A printf format string which contains the ascii name of
1701		the port. Normally is set to "eth%d" which sets
1702		eth0 for the first Ethernet, eth1 for the second etc.
1703
1704		CONFIG_CDP_CAPABILITIES
1705
1706		A 32bit integer which indicates the device capabilities;
1707		0x00000010 for a normal host which does not forwards.
1708
1709		CONFIG_CDP_VERSION
1710
1711		An ascii string containing the version of the software.
1712
1713		CONFIG_CDP_PLATFORM
1714
1715		An ascii string containing the name of the platform.
1716
1717		CONFIG_CDP_TRIGGER
1718
1719		A 32bit integer sent on the trigger.
1720
1721		CONFIG_CDP_POWER_CONSUMPTION
1722
1723		A 16bit integer containing the power consumption of the
1724		device in .1 of milliwatts.
1725
1726		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1727
1728		A byte containing the id of the VLAN.
1729
1730- Status LED:	CONFIG_STATUS_LED
1731
1732		Several configurations allow to display the current
1733		status using a LED. For instance, the LED will blink
1734		fast while running U-Boot code, stop blinking as
1735		soon as a reply to a BOOTP request was received, and
1736		start blinking slow once the Linux kernel is running
1737		(supported by a status LED driver in the Linux
1738		kernel). Defining CONFIG_STATUS_LED enables this
1739		feature in U-Boot.
1740
1741- CAN Support:	CONFIG_CAN_DRIVER
1742
1743		Defining CONFIG_CAN_DRIVER enables CAN driver support
1744		on those systems that support this (optional)
1745		feature, like the TQM8xxL modules.
1746
1747- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1748
1749		These enable I2C serial bus commands. Defining either of
1750		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1751		include the appropriate I2C driver for the selected CPU.
1752
1753		This will allow you to use i2c commands at the u-boot
1754		command line (as long as you set CONFIG_CMD_I2C in
1755		CONFIG_COMMANDS) and communicate with i2c based realtime
1756		clock chips. See common/cmd_i2c.c for a description of the
1757		command line interface.
1758
1759		CONFIG_HARD_I2C selects a hardware I2C controller.
1760
1761		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1762		bit-banging) driver instead of CPM or similar hardware
1763		support for I2C.
1764
1765		There are several other quantities that must also be
1766		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1767
1768		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1769		to be the frequency (in Hz) at which you wish your i2c bus
1770		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1771		the CPU's i2c node address).
1772
1773		Now, the u-boot i2c code for the mpc8xx
1774		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1775		and so its address should therefore be cleared to 0 (See,
1776		eg, MPC823e User's Manual p.16-473). So, set
1777		CONFIG_SYS_I2C_SLAVE to 0.
1778
1779		CONFIG_SYS_I2C_INIT_MPC5XXX
1780
1781		When a board is reset during an i2c bus transfer
1782		chips might think that the current transfer is still
1783		in progress.  Reset the slave devices by sending start
1784		commands until the slave device responds.
1785
1786		That's all that's required for CONFIG_HARD_I2C.
1787
1788		If you use the software i2c interface (CONFIG_SOFT_I2C)
1789		then the following macros need to be defined (examples are
1790		from include/configs/lwmon.h):
1791
1792		I2C_INIT
1793
1794		(Optional). Any commands necessary to enable the I2C
1795		controller or configure ports.
1796
1797		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1798
1799		I2C_PORT
1800
1801		(Only for MPC8260 CPU). The I/O port to use (the code
1802		assumes both bits are on the same port). Valid values
1803		are 0..3 for ports A..D.
1804
1805		I2C_ACTIVE
1806
1807		The code necessary to make the I2C data line active
1808		(driven).  If the data line is open collector, this
1809		define can be null.
1810
1811		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1812
1813		I2C_TRISTATE
1814
1815		The code necessary to make the I2C data line tri-stated
1816		(inactive).  If the data line is open collector, this
1817		define can be null.
1818
1819		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1820
1821		I2C_READ
1822
1823		Code that returns TRUE if the I2C data line is high,
1824		FALSE if it is low.
1825
1826		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1827
1828		I2C_SDA(bit)
1829
1830		If <bit> is TRUE, sets the I2C data line high. If it
1831		is FALSE, it clears it (low).
1832
1833		eg: #define I2C_SDA(bit) \
1834			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1835			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1836
1837		I2C_SCL(bit)
1838
1839		If <bit> is TRUE, sets the I2C clock line high. If it
1840		is FALSE, it clears it (low).
1841
1842		eg: #define I2C_SCL(bit) \
1843			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1844			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1845
1846		I2C_DELAY
1847
1848		This delay is invoked four times per clock cycle so this
1849		controls the rate of data transfer.  The data rate thus
1850		is 1 / (I2C_DELAY * 4). Often defined to be something
1851		like:
1852
1853		#define I2C_DELAY  udelay(2)
1854
1855		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1856
1857		If your arch supports the generic GPIO framework (asm/gpio.h),
1858		then you may alternatively define the two GPIOs that are to be
1859		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1860		have GPIO-based defaults assigned to them as appropriate.
1861
1862		You should define these to the GPIO value as given directly to
1863		the generic GPIO functions.
1864
1865		CONFIG_SYS_I2C_INIT_BOARD
1866
1867		When a board is reset during an i2c bus transfer
1868		chips might think that the current transfer is still
1869		in progress. On some boards it is possible to access
1870		the i2c SCLK line directly, either by using the
1871		processor pin as a GPIO or by having a second pin
1872		connected to the bus. If this option is defined a
1873		custom i2c_init_board() routine in boards/xxx/board.c
1874		is run early in the boot sequence.
1875
1876		CONFIG_SYS_I2C_BOARD_LATE_INIT
1877
1878		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1879		defined a custom i2c_board_late_init() routine in
1880		boards/xxx/board.c is run AFTER the operations in i2c_init()
1881		is completed. This callpoint can be used to unreset i2c bus
1882		using CPU i2c controller register accesses for CPUs whose i2c
1883		controller provide such a method. It is called at the end of
1884		i2c_init() to allow i2c_init operations to setup the i2c bus
1885		controller on the CPU (e.g. setting bus speed & slave address).
1886
1887		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1888
1889		This option enables configuration of bi_iic_fast[] flags
1890		in u-boot bd_info structure based on u-boot environment
1891		variable "i2cfast". (see also i2cfast)
1892
1893		CONFIG_I2C_MULTI_BUS
1894
1895		This option allows the use of multiple I2C buses, each of which
1896		must have a controller.	 At any point in time, only one bus is
1897		active.	 To switch to a different bus, use the 'i2c dev' command.
1898		Note that bus numbering is zero-based.
1899
1900		CONFIG_SYS_I2C_NOPROBES
1901
1902		This option specifies a list of I2C devices that will be skipped
1903		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1904		is set, specify a list of bus-device pairs.  Otherwise, specify
1905		a 1D array of device addresses
1906
1907		e.g.
1908			#undef	CONFIG_I2C_MULTI_BUS
1909			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1910
1911		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1912
1913			#define CONFIG_I2C_MULTI_BUS
1914			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1915
1916		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1917
1918		CONFIG_SYS_SPD_BUS_NUM
1919
1920		If defined, then this indicates the I2C bus number for DDR SPD.
1921		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1922
1923		CONFIG_SYS_RTC_BUS_NUM
1924
1925		If defined, then this indicates the I2C bus number for the RTC.
1926		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1927
1928		CONFIG_SYS_DTT_BUS_NUM
1929
1930		If defined, then this indicates the I2C bus number for the DTT.
1931		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1932
1933		CONFIG_SYS_I2C_DTT_ADDR:
1934
1935		If defined, specifies the I2C address of the DTT device.
1936		If not defined, then U-Boot uses predefined value for
1937		specified DTT device.
1938
1939		CONFIG_FSL_I2C
1940
1941		Define this option if you want to use Freescale's I2C driver in
1942		drivers/i2c/fsl_i2c.c.
1943
1944		CONFIG_I2C_MUX
1945
1946		Define this option if you have I2C devices reached over 1 .. n
1947		I2C Muxes like the pca9544a. This option addes a new I2C
1948		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1949		new I2C Bus to the existing I2C Busses. If you select the
1950		new Bus with "i2c dev", u-bbot sends first the commandos for
1951		the muxes to activate this new "bus".
1952
1953		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1954		feature!
1955
1956		Example:
1957		Adding a new I2C Bus reached over 2 pca9544a muxes
1958			The First mux with address 70 and channel 6
1959			The Second mux with address 71 and channel 4
1960
1961		=> i2c bus pca9544a:70:6:pca9544a:71:4
1962
1963		Use the "i2c bus" command without parameter, to get a list
1964		of I2C Busses with muxes:
1965
1966		=> i2c bus
1967		Busses reached over muxes:
1968		Bus ID: 2
1969		  reached over Mux(es):
1970		    pca9544a@70 ch: 4
1971		Bus ID: 3
1972		  reached over Mux(es):
1973		    pca9544a@70 ch: 6
1974		    pca9544a@71 ch: 4
1975		=>
1976
1977		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1978		u-boot first sends the command to the mux@70 to enable
1979		channel 6, and then the command to the mux@71 to enable
1980		the channel 4.
1981
1982		After that, you can use the "normal" i2c commands as
1983		usual to communicate with your I2C devices behind
1984		the 2 muxes.
1985
1986		This option is actually implemented for the bitbanging
1987		algorithm in common/soft_i2c.c and for the Hardware I2C
1988		Bus on the MPC8260. But it should be not so difficult
1989		to add this option to other architectures.
1990
1991		CONFIG_SOFT_I2C_READ_REPEATED_START
1992
1993		defining this will force the i2c_read() function in
1994		the soft_i2c driver to perform an I2C repeated start
1995		between writing the address pointer and reading the
1996		data.  If this define is omitted the default behaviour
1997		of doing a stop-start sequence will be used.  Most I2C
1998		devices can use either method, but some require one or
1999		the other.
2000
2001- SPI Support:	CONFIG_SPI
2002
2003		Enables SPI driver (so far only tested with
2004		SPI EEPROM, also an instance works with Crystal A/D and
2005		D/As on the SACSng board)
2006
2007		CONFIG_SH_SPI
2008
2009		Enables the driver for SPI controller on SuperH. Currently
2010		only SH7757 is supported.
2011
2012		CONFIG_SPI_X
2013
2014		Enables extended (16-bit) SPI EEPROM addressing.
2015		(symmetrical to CONFIG_I2C_X)
2016
2017		CONFIG_SOFT_SPI
2018
2019		Enables a software (bit-bang) SPI driver rather than
2020		using hardware support. This is a general purpose
2021		driver that only requires three general I/O port pins
2022		(two outputs, one input) to function. If this is
2023		defined, the board configuration must define several
2024		SPI configuration items (port pins to use, etc). For
2025		an example, see include/configs/sacsng.h.
2026
2027		CONFIG_HARD_SPI
2028
2029		Enables a hardware SPI driver for general-purpose reads
2030		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2031		must define a list of chip-select function pointers.
2032		Currently supported on some MPC8xxx processors.	 For an
2033		example, see include/configs/mpc8349emds.h.
2034
2035		CONFIG_MXC_SPI
2036
2037		Enables the driver for the SPI controllers on i.MX and MXC
2038		SoCs. Currently i.MX31/35/51 are supported.
2039
2040- FPGA Support: CONFIG_FPGA
2041
2042		Enables FPGA subsystem.
2043
2044		CONFIG_FPGA_<vendor>
2045
2046		Enables support for specific chip vendors.
2047		(ALTERA, XILINX)
2048
2049		CONFIG_FPGA_<family>
2050
2051		Enables support for FPGA family.
2052		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2053
2054		CONFIG_FPGA_COUNT
2055
2056		Specify the number of FPGA devices to support.
2057
2058		CONFIG_SYS_FPGA_PROG_FEEDBACK
2059
2060		Enable printing of hash marks during FPGA configuration.
2061
2062		CONFIG_SYS_FPGA_CHECK_BUSY
2063
2064		Enable checks on FPGA configuration interface busy
2065		status by the configuration function. This option
2066		will require a board or device specific function to
2067		be written.
2068
2069		CONFIG_FPGA_DELAY
2070
2071		If defined, a function that provides delays in the FPGA
2072		configuration driver.
2073
2074		CONFIG_SYS_FPGA_CHECK_CTRLC
2075		Allow Control-C to interrupt FPGA configuration
2076
2077		CONFIG_SYS_FPGA_CHECK_ERROR
2078
2079		Check for configuration errors during FPGA bitfile
2080		loading. For example, abort during Virtex II
2081		configuration if the INIT_B line goes low (which
2082		indicated a CRC error).
2083
2084		CONFIG_SYS_FPGA_WAIT_INIT
2085
2086		Maximum time to wait for the INIT_B line to deassert
2087		after PROB_B has been deasserted during a Virtex II
2088		FPGA configuration sequence. The default time is 500
2089		ms.
2090
2091		CONFIG_SYS_FPGA_WAIT_BUSY
2092
2093		Maximum time to wait for BUSY to deassert during
2094		Virtex II FPGA configuration. The default is 5 ms.
2095
2096		CONFIG_SYS_FPGA_WAIT_CONFIG
2097
2098		Time to wait after FPGA configuration. The default is
2099		200 ms.
2100
2101- Configuration Management:
2102		CONFIG_IDENT_STRING
2103
2104		If defined, this string will be added to the U-Boot
2105		version information (U_BOOT_VERSION)
2106
2107- Vendor Parameter Protection:
2108
2109		U-Boot considers the values of the environment
2110		variables "serial#" (Board Serial Number) and
2111		"ethaddr" (Ethernet Address) to be parameters that
2112		are set once by the board vendor / manufacturer, and
2113		protects these variables from casual modification by
2114		the user. Once set, these variables are read-only,
2115		and write or delete attempts are rejected. You can
2116		change this behaviour:
2117
2118		If CONFIG_ENV_OVERWRITE is #defined in your config
2119		file, the write protection for vendor parameters is
2120		completely disabled. Anybody can change or delete
2121		these parameters.
2122
2123		Alternatively, if you #define _both_ CONFIG_ETHADDR
2124		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2125		Ethernet address is installed in the environment,
2126		which can be changed exactly ONCE by the user. [The
2127		serial# is unaffected by this, i. e. it remains
2128		read-only.]
2129
2130- Protected RAM:
2131		CONFIG_PRAM
2132
2133		Define this variable to enable the reservation of
2134		"protected RAM", i. e. RAM which is not overwritten
2135		by U-Boot. Define CONFIG_PRAM to hold the number of
2136		kB you want to reserve for pRAM. You can overwrite
2137		this default value by defining an environment
2138		variable "pram" to the number of kB you want to
2139		reserve. Note that the board info structure will
2140		still show the full amount of RAM. If pRAM is
2141		reserved, a new environment variable "mem" will
2142		automatically be defined to hold the amount of
2143		remaining RAM in a form that can be passed as boot
2144		argument to Linux, for instance like that:
2145
2146			setenv bootargs ... mem=\${mem}
2147			saveenv
2148
2149		This way you can tell Linux not to use this memory,
2150		either, which results in a memory region that will
2151		not be affected by reboots.
2152
2153		*WARNING* If your board configuration uses automatic
2154		detection of the RAM size, you must make sure that
2155		this memory test is non-destructive. So far, the
2156		following board configurations are known to be
2157		"pRAM-clean":
2158
2159			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
2160			HERMES, IP860, RPXlite, LWMON, LANTEC,
2161			FLAGADM, TQM8260
2162
2163- Error Recovery:
2164		CONFIG_PANIC_HANG
2165
2166		Define this variable to stop the system in case of a
2167		fatal error, so that you have to reset it manually.
2168		This is probably NOT a good idea for an embedded
2169		system where you want the system to reboot
2170		automatically as fast as possible, but it may be
2171		useful during development since you can try to debug
2172		the conditions that lead to the situation.
2173
2174		CONFIG_NET_RETRY_COUNT
2175
2176		This variable defines the number of retries for
2177		network operations like ARP, RARP, TFTP, or BOOTP
2178		before giving up the operation. If not defined, a
2179		default value of 5 is used.
2180
2181		CONFIG_ARP_TIMEOUT
2182
2183		Timeout waiting for an ARP reply in milliseconds.
2184
2185		CONFIG_NFS_TIMEOUT
2186
2187		Timeout in milliseconds used in NFS protocol.
2188		If you encounter "ERROR: Cannot umount" in nfs command,
2189		try longer timeout such as
2190		#define CONFIG_NFS_TIMEOUT 10000UL
2191
2192- Command Interpreter:
2193		CONFIG_AUTO_COMPLETE
2194
2195		Enable auto completion of commands using TAB.
2196
2197		Note that this feature has NOT been implemented yet
2198		for the "hush" shell.
2199
2200
2201		CONFIG_SYS_HUSH_PARSER
2202
2203		Define this variable to enable the "hush" shell (from
2204		Busybox) as command line interpreter, thus enabling
2205		powerful command line syntax like
2206		if...then...else...fi conditionals or `&&' and '||'
2207		constructs ("shell scripts").
2208
2209		If undefined, you get the old, much simpler behaviour
2210		with a somewhat smaller memory footprint.
2211
2212
2213		CONFIG_SYS_PROMPT_HUSH_PS2
2214
2215		This defines the secondary prompt string, which is
2216		printed when the command interpreter needs more input
2217		to complete a command. Usually "> ".
2218
2219	Note:
2220
2221		In the current implementation, the local variables
2222		space and global environment variables space are
2223		separated. Local variables are those you define by
2224		simply typing `name=value'. To access a local
2225		variable later on, you have write `$name' or
2226		`${name}'; to execute the contents of a variable
2227		directly type `$name' at the command prompt.
2228
2229		Global environment variables are those you use
2230		setenv/printenv to work with. To run a command stored
2231		in such a variable, you need to use the run command,
2232		and you must not use the '$' sign to access them.
2233
2234		To store commands and special characters in a
2235		variable, please use double quotation marks
2236		surrounding the whole text of the variable, instead
2237		of the backslashes before semicolons and special
2238		symbols.
2239
2240- Commandline Editing and History:
2241		CONFIG_CMDLINE_EDITING
2242
2243		Enable editing and History functions for interactive
2244		commandline input operations
2245
2246- Default Environment:
2247		CONFIG_EXTRA_ENV_SETTINGS
2248
2249		Define this to contain any number of null terminated
2250		strings (variable = value pairs) that will be part of
2251		the default environment compiled into the boot image.
2252
2253		For example, place something like this in your
2254		board's config file:
2255
2256		#define CONFIG_EXTRA_ENV_SETTINGS \
2257			"myvar1=value1\0" \
2258			"myvar2=value2\0"
2259
2260		Warning: This method is based on knowledge about the
2261		internal format how the environment is stored by the
2262		U-Boot code. This is NOT an official, exported
2263		interface! Although it is unlikely that this format
2264		will change soon, there is no guarantee either.
2265		You better know what you are doing here.
2266
2267		Note: overly (ab)use of the default environment is
2268		discouraged. Make sure to check other ways to preset
2269		the environment like the "source" command or the
2270		boot command first.
2271
2272		CONFIG_ENV_VARS_UBOOT_CONFIG
2273
2274		Define this in order to add variables describing the
2275		U-Boot build configuration to the default environment.
2276		These will be named arch, cpu, board, vendor, and soc.
2277
2278		Enabling this option will cause the following to be defined:
2279
2280		- CONFIG_SYS_ARCH
2281		- CONFIG_SYS_CPU
2282		- CONFIG_SYS_BOARD
2283		- CONFIG_SYS_VENDOR
2284		- CONFIG_SYS_SOC
2285
2286- DataFlash Support:
2287		CONFIG_HAS_DATAFLASH
2288
2289		Defining this option enables DataFlash features and
2290		allows to read/write in Dataflash via the standard
2291		commands cp, md...
2292
2293- Serial Flash support
2294		CONFIG_CMD_SF
2295
2296		Defining this option enables SPI flash commands
2297		'sf probe/read/write/erase/update'.
2298
2299		Usage requires an initial 'probe' to define the serial
2300		flash parameters, followed by read/write/erase/update
2301		commands.
2302
2303		The following defaults may be provided by the platform
2304		to handle the common case when only a single serial
2305		flash is present on the system.
2306
2307		CONFIG_SF_DEFAULT_BUS		Bus identifier
2308		CONFIG_SF_DEFAULT_CS		Chip-select
2309		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2310		CONFIG_SF_DEFAULT_SPEED		in Hz
2311
2312- SystemACE Support:
2313		CONFIG_SYSTEMACE
2314
2315		Adding this option adds support for Xilinx SystemACE
2316		chips attached via some sort of local bus. The address
2317		of the chip must also be defined in the
2318		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2319
2320		#define CONFIG_SYSTEMACE
2321		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2322
2323		When SystemACE support is added, the "ace" device type
2324		becomes available to the fat commands, i.e. fatls.
2325
2326- TFTP Fixed UDP Port:
2327		CONFIG_TFTP_PORT
2328
2329		If this is defined, the environment variable tftpsrcp
2330		is used to supply the TFTP UDP source port value.
2331		If tftpsrcp isn't defined, the normal pseudo-random port
2332		number generator is used.
2333
2334		Also, the environment variable tftpdstp is used to supply
2335		the TFTP UDP destination port value.  If tftpdstp isn't
2336		defined, the normal port 69 is used.
2337
2338		The purpose for tftpsrcp is to allow a TFTP server to
2339		blindly start the TFTP transfer using the pre-configured
2340		target IP address and UDP port. This has the effect of
2341		"punching through" the (Windows XP) firewall, allowing
2342		the remainder of the TFTP transfer to proceed normally.
2343		A better solution is to properly configure the firewall,
2344		but sometimes that is not allowed.
2345
2346- Show boot progress:
2347		CONFIG_SHOW_BOOT_PROGRESS
2348
2349		Defining this option allows to add some board-
2350		specific code (calling a user-provided function
2351		"show_boot_progress(int)") that enables you to show
2352		the system's boot progress on some display (for
2353		example, some LED's) on your board. At the moment,
2354		the following checkpoints are implemented:
2355
2356- Detailed boot stage timing
2357		CONFIG_BOOTSTAGE
2358		Define this option to get detailed timing of each stage
2359		of the boot process.
2360
2361		CONFIG_BOOTSTAGE_USER_COUNT
2362		This is the number of available user bootstage records.
2363		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2364		a new ID will be allocated from this stash. If you exceed
2365		the limit, recording will stop.
2366
2367		CONFIG_BOOTSTAGE_REPORT
2368		Define this to print a report before boot, similar to this:
2369
2370		Timer summary in microseconds:
2371		       Mark    Elapsed  Stage
2372			  0          0  reset
2373		  3,575,678  3,575,678  board_init_f start
2374		  3,575,695         17  arch_cpu_init A9
2375		  3,575,777         82  arch_cpu_init done
2376		  3,659,598     83,821  board_init_r start
2377		  3,910,375    250,777  main_loop
2378		 29,916,167 26,005,792  bootm_start
2379		 30,361,327    445,160  start_kernel
2380
2381Legacy uImage format:
2382
2383  Arg	Where			When
2384    1	common/cmd_bootm.c	before attempting to boot an image
2385   -1	common/cmd_bootm.c	Image header has bad	 magic number
2386    2	common/cmd_bootm.c	Image header has correct magic number
2387   -2	common/cmd_bootm.c	Image header has bad	 checksum
2388    3	common/cmd_bootm.c	Image header has correct checksum
2389   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2390    4	common/cmd_bootm.c	Image data   has correct checksum
2391   -4	common/cmd_bootm.c	Image is for unsupported architecture
2392    5	common/cmd_bootm.c	Architecture check OK
2393   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2394    6	common/cmd_bootm.c	Image Type check OK
2395   -6	common/cmd_bootm.c	gunzip uncompression error
2396   -7	common/cmd_bootm.c	Unimplemented compression type
2397    7	common/cmd_bootm.c	Uncompression OK
2398    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2399   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2400
2401    9	common/image.c		Start initial ramdisk verification
2402  -10	common/image.c		Ramdisk header has bad	   magic number
2403  -11	common/image.c		Ramdisk header has bad	   checksum
2404   10	common/image.c		Ramdisk header is OK
2405  -12	common/image.c		Ramdisk data   has bad	   checksum
2406   11	common/image.c		Ramdisk data   has correct checksum
2407   12	common/image.c		Ramdisk verification complete, start loading
2408  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2409   13	common/image.c		Start multifile image verification
2410   14	common/image.c		No initial ramdisk, no multifile, continue.
2411
2412   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2413
2414  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2415  -31	post/post.c		POST test failed, detected by post_output_backlog()
2416  -32	post/post.c		POST test failed, detected by post_run_single()
2417
2418   34	common/cmd_doc.c	before loading a Image from a DOC device
2419  -35	common/cmd_doc.c	Bad usage of "doc" command
2420   35	common/cmd_doc.c	correct usage of "doc" command
2421  -36	common/cmd_doc.c	No boot device
2422   36	common/cmd_doc.c	correct boot device
2423  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2424   37	common/cmd_doc.c	correct chip ID found, device available
2425  -38	common/cmd_doc.c	Read Error on boot device
2426   38	common/cmd_doc.c	reading Image header from DOC device OK
2427  -39	common/cmd_doc.c	Image header has bad magic number
2428   39	common/cmd_doc.c	Image header has correct magic number
2429  -40	common/cmd_doc.c	Error reading Image from DOC device
2430   40	common/cmd_doc.c	Image header has correct magic number
2431   41	common/cmd_ide.c	before loading a Image from a IDE device
2432  -42	common/cmd_ide.c	Bad usage of "ide" command
2433   42	common/cmd_ide.c	correct usage of "ide" command
2434  -43	common/cmd_ide.c	No boot device
2435   43	common/cmd_ide.c	boot device found
2436  -44	common/cmd_ide.c	Device not available
2437   44	common/cmd_ide.c	Device available
2438  -45	common/cmd_ide.c	wrong partition selected
2439   45	common/cmd_ide.c	partition selected
2440  -46	common/cmd_ide.c	Unknown partition table
2441   46	common/cmd_ide.c	valid partition table found
2442  -47	common/cmd_ide.c	Invalid partition type
2443   47	common/cmd_ide.c	correct partition type
2444  -48	common/cmd_ide.c	Error reading Image Header on boot device
2445   48	common/cmd_ide.c	reading Image Header from IDE device OK
2446  -49	common/cmd_ide.c	Image header has bad magic number
2447   49	common/cmd_ide.c	Image header has correct magic number
2448  -50	common/cmd_ide.c	Image header has bad	 checksum
2449   50	common/cmd_ide.c	Image header has correct checksum
2450  -51	common/cmd_ide.c	Error reading Image from IDE device
2451   51	common/cmd_ide.c	reading Image from IDE device OK
2452   52	common/cmd_nand.c	before loading a Image from a NAND device
2453  -53	common/cmd_nand.c	Bad usage of "nand" command
2454   53	common/cmd_nand.c	correct usage of "nand" command
2455  -54	common/cmd_nand.c	No boot device
2456   54	common/cmd_nand.c	boot device found
2457  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2458   55	common/cmd_nand.c	correct chip ID found, device available
2459  -56	common/cmd_nand.c	Error reading Image Header on boot device
2460   56	common/cmd_nand.c	reading Image Header from NAND device OK
2461  -57	common/cmd_nand.c	Image header has bad magic number
2462   57	common/cmd_nand.c	Image header has correct magic number
2463  -58	common/cmd_nand.c	Error reading Image from NAND device
2464   58	common/cmd_nand.c	reading Image from NAND device OK
2465
2466  -60	common/env_common.c	Environment has a bad CRC, using default
2467
2468   64	net/eth.c		starting with Ethernet configuration.
2469  -64	net/eth.c		no Ethernet found.
2470   65	net/eth.c		Ethernet found.
2471
2472  -80	common/cmd_net.c	usage wrong
2473   80	common/cmd_net.c	before calling NetLoop()
2474  -81	common/cmd_net.c	some error in NetLoop() occurred
2475   81	common/cmd_net.c	NetLoop() back without error
2476  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2477   82	common/cmd_net.c	trying automatic boot
2478   83	common/cmd_net.c	running "source" command
2479  -83	common/cmd_net.c	some error in automatic boot or "source" command
2480   84	common/cmd_net.c	end without errors
2481
2482FIT uImage format:
2483
2484  Arg	Where			When
2485  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2486 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2487  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2488 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2489  102	common/cmd_bootm.c	Kernel unit name specified
2490 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2491  103	common/cmd_bootm.c	Found configuration node
2492  104	common/cmd_bootm.c	Got kernel subimage node offset
2493 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2494  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2495 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2496  106	common/cmd_bootm.c	Architecture check OK
2497 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2498  107	common/cmd_bootm.c	Kernel subimage type OK
2499 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2500  108	common/cmd_bootm.c	Got kernel subimage data/size
2501 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2502 -109	common/cmd_bootm.c	Can't get kernel subimage type
2503 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2504 -111	common/cmd_bootm.c	Can't get kernel subimage os
2505 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2506 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2507
2508  120	common/image.c		Start initial ramdisk verification
2509 -120	common/image.c		Ramdisk FIT image has incorrect format
2510  121	common/image.c		Ramdisk FIT image has correct format
2511  122	common/image.c		No ramdisk subimage unit name, using configuration
2512 -122	common/image.c		Can't get configuration for ramdisk subimage
2513  123	common/image.c		Ramdisk unit name specified
2514 -124	common/image.c		Can't get ramdisk subimage node offset
2515  125	common/image.c		Got ramdisk subimage node offset
2516 -125	common/image.c		Ramdisk subimage hash verification failed
2517  126	common/image.c		Ramdisk subimage hash verification OK
2518 -126	common/image.c		Ramdisk subimage for unsupported architecture
2519  127	common/image.c		Architecture check OK
2520 -127	common/image.c		Can't get ramdisk subimage data/size
2521  128	common/image.c		Got ramdisk subimage data/size
2522  129	common/image.c		Can't get ramdisk load address
2523 -129	common/image.c		Got ramdisk load address
2524
2525 -130	common/cmd_doc.c	Incorrect FIT image format
2526  131	common/cmd_doc.c	FIT image format OK
2527
2528 -140	common/cmd_ide.c	Incorrect FIT image format
2529  141	common/cmd_ide.c	FIT image format OK
2530
2531 -150	common/cmd_nand.c	Incorrect FIT image format
2532  151	common/cmd_nand.c	FIT image format OK
2533
2534- Standalone program support:
2535		CONFIG_STANDALONE_LOAD_ADDR
2536
2537		This option defines a board specific value for the
2538		address where standalone program gets loaded, thus
2539		overwriting the architecture dependent default
2540		settings.
2541
2542- Frame Buffer Address:
2543		CONFIG_FB_ADDR
2544
2545		Define CONFIG_FB_ADDR if you want to use specific
2546		address for frame buffer.
2547		Then system will reserve the frame buffer address to
2548		defined address instead of lcd_setmem (this function
2549		grabs the memory for frame buffer by panel's size).
2550
2551		Please see board_init_f function.
2552
2553- Automatic software updates via TFTP server
2554		CONFIG_UPDATE_TFTP
2555		CONFIG_UPDATE_TFTP_CNT_MAX
2556		CONFIG_UPDATE_TFTP_MSEC_MAX
2557
2558		These options enable and control the auto-update feature;
2559		for a more detailed description refer to doc/README.update.
2560
2561- MTD Support (mtdparts command, UBI support)
2562		CONFIG_MTD_DEVICE
2563
2564		Adds the MTD device infrastructure from the Linux kernel.
2565		Needed for mtdparts command support.
2566
2567		CONFIG_MTD_PARTITIONS
2568
2569		Adds the MTD partitioning infrastructure from the Linux
2570		kernel. Needed for UBI support.
2571
2572- SPL framework
2573		CONFIG_SPL
2574		Enable building of SPL globally.
2575
2576		CONFIG_SPL_LDSCRIPT
2577		LDSCRIPT for linking the SPL binary.
2578
2579		CONFIG_SPL_MAX_SIZE
2580		Maximum binary size (text, data and rodata) of the SPL binary.
2581
2582		CONFIG_SPL_TEXT_BASE
2583		TEXT_BASE for linking the SPL binary.
2584
2585		CONFIG_SPL_BSS_START_ADDR
2586		Link address for the BSS within the SPL binary.
2587
2588		CONFIG_SPL_BSS_MAX_SIZE
2589		Maximum binary size of the BSS section of the SPL binary.
2590
2591		CONFIG_SPL_STACK
2592		Adress of the start of the stack SPL will use
2593
2594		CONFIG_SYS_SPL_MALLOC_START
2595		Starting address of the malloc pool used in SPL.
2596
2597		CONFIG_SYS_SPL_MALLOC_SIZE
2598		The size of the malloc pool used in SPL.
2599
2600		CONFIG_SPL_FRAMEWORK
2601		Enable the SPL framework under common/.  This framework
2602		supports MMC, NAND and YMODEM loading of U-Boot and NAND
2603		NAND loading of the Linux Kernel.
2604
2605		CONFIG_SPL_DISPLAY_PRINT
2606		For ARM, enable an optional function to print more information
2607		about the running system.
2608
2609		CONFIG_SPL_LIBCOMMON_SUPPORT
2610		Support for common/libcommon.o in SPL binary
2611
2612		CONFIG_SPL_LIBDISK_SUPPORT
2613		Support for disk/libdisk.o in SPL binary
2614
2615		CONFIG_SPL_I2C_SUPPORT
2616		Support for drivers/i2c/libi2c.o in SPL binary
2617
2618		CONFIG_SPL_GPIO_SUPPORT
2619		Support for drivers/gpio/libgpio.o in SPL binary
2620
2621		CONFIG_SPL_MMC_SUPPORT
2622		Support for drivers/mmc/libmmc.o in SPL binary
2623
2624		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2625		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2626		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2627		Address, size and partition on the MMC to load U-Boot from
2628		when the MMC is being used in raw mode.
2629
2630		CONFIG_SPL_FAT_SUPPORT
2631		Support for fs/fat/libfat.o in SPL binary
2632
2633		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2634		Filename to read to load U-Boot when reading from FAT
2635
2636		CONFIG_SPL_NAND_SIMPLE
2637		Support for drivers/mtd/nand/libnand.o in SPL binary
2638
2639		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2640		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2641		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2642		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2643		CONFIG_SYS_NAND_ECCBYTES
2644		Defines the size and behavior of the NAND that SPL uses
2645		to read U-Boot with CONFIG_SPL_NAND_SIMPLE
2646
2647		CONFIG_SYS_NAND_U_BOOT_OFFS
2648		Location in NAND for CONFIG_SPL_NAND_SIMPLE to read U-Boot
2649		from.
2650
2651		CONFIG_SYS_NAND_U_BOOT_START
2652		Location in memory for CONFIG_SPL_NAND_SIMPLE to load U-Boot
2653		to.
2654
2655		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2656		Define this if you need to first read the OOB and then the
2657		data. This is used for example on davinci plattforms.
2658
2659		CONFIG_SPL_OMAP3_ID_NAND
2660		Support for an OMAP3-specific set of functions to return the
2661		ID and MFR of the first attached NAND chip, if present.
2662
2663		CONFIG_SPL_SERIAL_SUPPORT
2664		Support for drivers/serial/libserial.o in SPL binary
2665
2666		CONFIG_SPL_SPI_FLASH_SUPPORT
2667		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2668
2669		CONFIG_SPL_SPI_SUPPORT
2670		Support for drivers/spi/libspi.o in SPL binary
2671
2672		CONFIG_SPL_RAM_DEVICE
2673		Support for running image already present in ram, in SPL binary
2674
2675		CONFIG_SPL_LIBGENERIC_SUPPORT
2676		Support for lib/libgeneric.o in SPL binary
2677
2678Modem Support:
2679--------------
2680
2681[so far only for SMDK2400 boards]
2682
2683- Modem support enable:
2684		CONFIG_MODEM_SUPPORT
2685
2686- RTS/CTS Flow control enable:
2687		CONFIG_HWFLOW
2688
2689- Modem debug support:
2690		CONFIG_MODEM_SUPPORT_DEBUG
2691
2692		Enables debugging stuff (char screen[1024], dbg())
2693		for modem support. Useful only with BDI2000.
2694
2695- Interrupt support (PPC):
2696
2697		There are common interrupt_init() and timer_interrupt()
2698		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2699		for CPU specific initialization. interrupt_init_cpu()
2700		should set decrementer_count to appropriate value. If
2701		CPU resets decrementer automatically after interrupt
2702		(ppc4xx) it should set decrementer_count to zero.
2703		timer_interrupt() calls timer_interrupt_cpu() for CPU
2704		specific handling. If board has watchdog / status_led
2705		/ other_activity_monitor it works automatically from
2706		general timer_interrupt().
2707
2708- General:
2709
2710		In the target system modem support is enabled when a
2711		specific key (key combination) is pressed during
2712		power-on. Otherwise U-Boot will boot normally
2713		(autoboot). The key_pressed() function is called from
2714		board_init(). Currently key_pressed() is a dummy
2715		function, returning 1 and thus enabling modem
2716		initialization.
2717
2718		If there are no modem init strings in the
2719		environment, U-Boot proceed to autoboot; the
2720		previous output (banner, info printfs) will be
2721		suppressed, though.
2722
2723		See also: doc/README.Modem
2724
2725Board initialization settings:
2726------------------------------
2727
2728During Initialization u-boot calls a number of board specific functions
2729to allow the preparation of board specific prerequisites, e.g. pin setup
2730before drivers are initialized. To enable these callbacks the
2731following configuration macros have to be defined. Currently this is
2732architecture specific, so please check arch/your_architecture/lib/board.c
2733typically in board_init_f() and board_init_r().
2734
2735- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2736- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2737- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2738- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2739
2740Configuration Settings:
2741-----------------------
2742
2743- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2744		undefine this when you're short of memory.
2745
2746- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2747		width of the commands listed in the 'help' command output.
2748
2749- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2750		prompt for user input.
2751
2752- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2753
2754- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2755
2756- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2757
2758- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2759		the application (usually a Linux kernel) when it is
2760		booted
2761
2762- CONFIG_SYS_BAUDRATE_TABLE:
2763		List of legal baudrate settings for this board.
2764
2765- CONFIG_SYS_CONSOLE_INFO_QUIET
2766		Suppress display of console information at boot.
2767
2768- CONFIG_SYS_CONSOLE_IS_IN_ENV
2769		If the board specific function
2770			extern int overwrite_console (void);
2771		returns 1, the stdin, stderr and stdout are switched to the
2772		serial port, else the settings in the environment are used.
2773
2774- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2775		Enable the call to overwrite_console().
2776
2777- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2778		Enable overwrite of previous console environment settings.
2779
2780- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2781		Begin and End addresses of the area used by the
2782		simple memory test.
2783
2784- CONFIG_SYS_ALT_MEMTEST:
2785		Enable an alternate, more extensive memory test.
2786
2787- CONFIG_SYS_MEMTEST_SCRATCH:
2788		Scratch address used by the alternate memory test
2789		You only need to set this if address zero isn't writeable
2790
2791- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2792		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2793		this specified memory area will get subtracted from the top
2794		(end) of RAM and won't get "touched" at all by U-Boot. By
2795		fixing up gd->ram_size the Linux kernel should gets passed
2796		the now "corrected" memory size and won't touch it either.
2797		This should work for arch/ppc and arch/powerpc. Only Linux
2798		board ports in arch/powerpc with bootwrapper support that
2799		recalculate the memory size from the SDRAM controller setup
2800		will have to get fixed in Linux additionally.
2801
2802		This option can be used as a workaround for the 440EPx/GRx
2803		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2804		be touched.
2805
2806		WARNING: Please make sure that this value is a multiple of
2807		the Linux page size (normally 4k). If this is not the case,
2808		then the end address of the Linux memory will be located at a
2809		non page size aligned address and this could cause major
2810		problems.
2811
2812- CONFIG_SYS_TFTP_LOADADDR:
2813		Default load address for network file downloads
2814
2815- CONFIG_SYS_LOADS_BAUD_CHANGE:
2816		Enable temporary baudrate change while serial download
2817
2818- CONFIG_SYS_SDRAM_BASE:
2819		Physical start address of SDRAM. _Must_ be 0 here.
2820
2821- CONFIG_SYS_MBIO_BASE:
2822		Physical start address of Motherboard I/O (if using a
2823		Cogent motherboard)
2824
2825- CONFIG_SYS_FLASH_BASE:
2826		Physical start address of Flash memory.
2827
2828- CONFIG_SYS_MONITOR_BASE:
2829		Physical start address of boot monitor code (set by
2830		make config files to be same as the text base address
2831		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2832		CONFIG_SYS_FLASH_BASE when booting from flash.
2833
2834- CONFIG_SYS_MONITOR_LEN:
2835		Size of memory reserved for monitor code, used to
2836		determine _at_compile_time_ (!) if the environment is
2837		embedded within the U-Boot image, or in a separate
2838		flash sector.
2839
2840- CONFIG_SYS_MALLOC_LEN:
2841		Size of DRAM reserved for malloc() use.
2842
2843- CONFIG_SYS_BOOTM_LEN:
2844		Normally compressed uImages are limited to an
2845		uncompressed size of 8 MBytes. If this is not enough,
2846		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2847		to adjust this setting to your needs.
2848
2849- CONFIG_SYS_BOOTMAPSZ:
2850		Maximum size of memory mapped by the startup code of
2851		the Linux kernel; all data that must be processed by
2852		the Linux kernel (bd_info, boot arguments, FDT blob if
2853		used) must be put below this limit, unless "bootm_low"
2854		enviroment variable is defined and non-zero. In such case
2855		all data for the Linux kernel must be between "bootm_low"
2856		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2857		variable "bootm_mapsize" will override the value of
2858		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2859		then the value in "bootm_size" will be used instead.
2860
2861- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2862		Enable initrd_high functionality.  If defined then the
2863		initrd_high feature is enabled and the bootm ramdisk subcommand
2864		is enabled.
2865
2866- CONFIG_SYS_BOOT_GET_CMDLINE:
2867		Enables allocating and saving kernel cmdline in space between
2868		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2869
2870- CONFIG_SYS_BOOT_GET_KBD:
2871		Enables allocating and saving a kernel copy of the bd_info in
2872		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2873
2874- CONFIG_SYS_MAX_FLASH_BANKS:
2875		Max number of Flash memory banks
2876
2877- CONFIG_SYS_MAX_FLASH_SECT:
2878		Max number of sectors on a Flash chip
2879
2880- CONFIG_SYS_FLASH_ERASE_TOUT:
2881		Timeout for Flash erase operations (in ms)
2882
2883- CONFIG_SYS_FLASH_WRITE_TOUT:
2884		Timeout for Flash write operations (in ms)
2885
2886- CONFIG_SYS_FLASH_LOCK_TOUT
2887		Timeout for Flash set sector lock bit operation (in ms)
2888
2889- CONFIG_SYS_FLASH_UNLOCK_TOUT
2890		Timeout for Flash clear lock bits operation (in ms)
2891
2892- CONFIG_SYS_FLASH_PROTECTION
2893		If defined, hardware flash sectors protection is used
2894		instead of U-Boot software protection.
2895
2896- CONFIG_SYS_DIRECT_FLASH_TFTP:
2897
2898		Enable TFTP transfers directly to flash memory;
2899		without this option such a download has to be
2900		performed in two steps: (1) download to RAM, and (2)
2901		copy from RAM to flash.
2902
2903		The two-step approach is usually more reliable, since
2904		you can check if the download worked before you erase
2905		the flash, but in some situations (when system RAM is
2906		too limited to allow for a temporary copy of the
2907		downloaded image) this option may be very useful.
2908
2909- CONFIG_SYS_FLASH_CFI:
2910		Define if the flash driver uses extra elements in the
2911		common flash structure for storing flash geometry.
2912
2913- CONFIG_FLASH_CFI_DRIVER
2914		This option also enables the building of the cfi_flash driver
2915		in the drivers directory
2916
2917- CONFIG_FLASH_CFI_MTD
2918		This option enables the building of the cfi_mtd driver
2919		in the drivers directory. The driver exports CFI flash
2920		to the MTD layer.
2921
2922- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2923		Use buffered writes to flash.
2924
2925- CONFIG_FLASH_SPANSION_S29WS_N
2926		s29ws-n MirrorBit flash has non-standard addresses for buffered
2927		write commands.
2928
2929- CONFIG_SYS_FLASH_QUIET_TEST
2930		If this option is defined, the common CFI flash doesn't
2931		print it's warning upon not recognized FLASH banks. This
2932		is useful, if some of the configured banks are only
2933		optionally available.
2934
2935- CONFIG_FLASH_SHOW_PROGRESS
2936		If defined (must be an integer), print out countdown
2937		digits and dots.  Recommended value: 45 (9..1) for 80
2938		column displays, 15 (3..1) for 40 column displays.
2939
2940- CONFIG_SYS_RX_ETH_BUFFER:
2941		Defines the number of Ethernet receive buffers. On some
2942		Ethernet controllers it is recommended to set this value
2943		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2944		buffers can be full shortly after enabling the interface
2945		on high Ethernet traffic.
2946		Defaults to 4 if not defined.
2947
2948- CONFIG_ENV_MAX_ENTRIES
2949
2950	Maximum number of entries in the hash table that is used
2951	internally to store the environment settings. The default
2952	setting is supposed to be generous and should work in most
2953	cases. This setting can be used to tune behaviour; see
2954	lib/hashtable.c for details.
2955
2956The following definitions that deal with the placement and management
2957of environment data (variable area); in general, we support the
2958following configurations:
2959
2960- CONFIG_BUILD_ENVCRC:
2961
2962	Builds up envcrc with the target environment so that external utils
2963	may easily extract it and embed it in final U-Boot images.
2964
2965- CONFIG_ENV_IS_IN_FLASH:
2966
2967	Define this if the environment is in flash memory.
2968
2969	a) The environment occupies one whole flash sector, which is
2970	   "embedded" in the text segment with the U-Boot code. This
2971	   happens usually with "bottom boot sector" or "top boot
2972	   sector" type flash chips, which have several smaller
2973	   sectors at the start or the end. For instance, such a
2974	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2975	   such a case you would place the environment in one of the
2976	   4 kB sectors - with U-Boot code before and after it. With
2977	   "top boot sector" type flash chips, you would put the
2978	   environment in one of the last sectors, leaving a gap
2979	   between U-Boot and the environment.
2980
2981	- CONFIG_ENV_OFFSET:
2982
2983	   Offset of environment data (variable area) to the
2984	   beginning of flash memory; for instance, with bottom boot
2985	   type flash chips the second sector can be used: the offset
2986	   for this sector is given here.
2987
2988	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2989
2990	- CONFIG_ENV_ADDR:
2991
2992	   This is just another way to specify the start address of
2993	   the flash sector containing the environment (instead of
2994	   CONFIG_ENV_OFFSET).
2995
2996	- CONFIG_ENV_SECT_SIZE:
2997
2998	   Size of the sector containing the environment.
2999
3000
3001	b) Sometimes flash chips have few, equal sized, BIG sectors.
3002	   In such a case you don't want to spend a whole sector for
3003	   the environment.
3004
3005	- CONFIG_ENV_SIZE:
3006
3007	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3008	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3009	   of this flash sector for the environment. This saves
3010	   memory for the RAM copy of the environment.
3011
3012	   It may also save flash memory if you decide to use this
3013	   when your environment is "embedded" within U-Boot code,
3014	   since then the remainder of the flash sector could be used
3015	   for U-Boot code. It should be pointed out that this is
3016	   STRONGLY DISCOURAGED from a robustness point of view:
3017	   updating the environment in flash makes it always
3018	   necessary to erase the WHOLE sector. If something goes
3019	   wrong before the contents has been restored from a copy in
3020	   RAM, your target system will be dead.
3021
3022	- CONFIG_ENV_ADDR_REDUND
3023	  CONFIG_ENV_SIZE_REDUND
3024
3025	   These settings describe a second storage area used to hold
3026	   a redundant copy of the environment data, so that there is
3027	   a valid backup copy in case there is a power failure during
3028	   a "saveenv" operation.
3029
3030BE CAREFUL! Any changes to the flash layout, and some changes to the
3031source code will make it necessary to adapt <board>/u-boot.lds*
3032accordingly!
3033
3034
3035- CONFIG_ENV_IS_IN_NVRAM:
3036
3037	Define this if you have some non-volatile memory device
3038	(NVRAM, battery buffered SRAM) which you want to use for the
3039	environment.
3040
3041	- CONFIG_ENV_ADDR:
3042	- CONFIG_ENV_SIZE:
3043
3044	  These two #defines are used to determine the memory area you
3045	  want to use for environment. It is assumed that this memory
3046	  can just be read and written to, without any special
3047	  provision.
3048
3049BE CAREFUL! The first access to the environment happens quite early
3050in U-Boot initalization (when we try to get the setting of for the
3051console baudrate). You *MUST* have mapped your NVRAM area then, or
3052U-Boot will hang.
3053
3054Please note that even with NVRAM we still use a copy of the
3055environment in RAM: we could work on NVRAM directly, but we want to
3056keep settings there always unmodified except somebody uses "saveenv"
3057to save the current settings.
3058
3059
3060- CONFIG_ENV_IS_IN_EEPROM:
3061
3062	Use this if you have an EEPROM or similar serial access
3063	device and a driver for it.
3064
3065	- CONFIG_ENV_OFFSET:
3066	- CONFIG_ENV_SIZE:
3067
3068	  These two #defines specify the offset and size of the
3069	  environment area within the total memory of your EEPROM.
3070
3071	- CONFIG_SYS_I2C_EEPROM_ADDR:
3072	  If defined, specified the chip address of the EEPROM device.
3073	  The default address is zero.
3074
3075	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3076	  If defined, the number of bits used to address bytes in a
3077	  single page in the EEPROM device.  A 64 byte page, for example
3078	  would require six bits.
3079
3080	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3081	  If defined, the number of milliseconds to delay between
3082	  page writes.	The default is zero milliseconds.
3083
3084	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3085	  The length in bytes of the EEPROM memory array address.  Note
3086	  that this is NOT the chip address length!
3087
3088	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3089	  EEPROM chips that implement "address overflow" are ones
3090	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3091	  address and the extra bits end up in the "chip address" bit
3092	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3093	  byte chips.
3094
3095	  Note that we consider the length of the address field to
3096	  still be one byte because the extra address bits are hidden
3097	  in the chip address.
3098
3099	- CONFIG_SYS_EEPROM_SIZE:
3100	  The size in bytes of the EEPROM device.
3101
3102	- CONFIG_ENV_EEPROM_IS_ON_I2C
3103	  define this, if you have I2C and SPI activated, and your
3104	  EEPROM, which holds the environment, is on the I2C bus.
3105
3106	- CONFIG_I2C_ENV_EEPROM_BUS
3107	  if you have an Environment on an EEPROM reached over
3108	  I2C muxes, you can define here, how to reach this
3109	  EEPROM. For example:
3110
3111	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3112
3113	  EEPROM which holds the environment, is reached over
3114	  a pca9547 i2c mux with address 0x70, channel 3.
3115
3116- CONFIG_ENV_IS_IN_DATAFLASH:
3117
3118	Define this if you have a DataFlash memory device which you
3119	want to use for the environment.
3120
3121	- CONFIG_ENV_OFFSET:
3122	- CONFIG_ENV_ADDR:
3123	- CONFIG_ENV_SIZE:
3124
3125	  These three #defines specify the offset and size of the
3126	  environment area within the total memory of your DataFlash placed
3127	  at the specified address.
3128
3129- CONFIG_ENV_IS_IN_REMOTE:
3130
3131	Define this if you have a remote memory space which you
3132	want to use for the local device's environment.
3133
3134	- CONFIG_ENV_ADDR:
3135	- CONFIG_ENV_SIZE:
3136
3137	  These two #defines specify the address and size of the
3138	  environment area within the remote memory space. The
3139	  local device can get the environment from remote memory
3140	  space by SRIO or PCIE links.
3141
3142BE CAREFUL! For some special cases, the local device can not use
3143"saveenv" command. For example, the local device will get the
3144environment stored in a remote NOR flash by SRIO or PCIE link,
3145but it can not erase, write this NOR flash by SRIO or PCIE interface.
3146
3147- CONFIG_ENV_IS_IN_NAND:
3148
3149	Define this if you have a NAND device which you want to use
3150	for the environment.
3151
3152	- CONFIG_ENV_OFFSET:
3153	- CONFIG_ENV_SIZE:
3154
3155	  These two #defines specify the offset and size of the environment
3156	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3157	  aligned to an erase block boundary.
3158
3159	- CONFIG_ENV_OFFSET_REDUND (optional):
3160
3161	  This setting describes a second storage area of CONFIG_ENV_SIZE
3162	  size used to hold a redundant copy of the environment data, so
3163	  that there is a valid backup copy in case there is a power failure
3164	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3165	  aligned to an erase block boundary.
3166
3167	- CONFIG_ENV_RANGE (optional):
3168
3169	  Specifies the length of the region in which the environment
3170	  can be written.  This should be a multiple of the NAND device's
3171	  block size.  Specifying a range with more erase blocks than
3172	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3173	  the range to be avoided.
3174
3175	- CONFIG_ENV_OFFSET_OOB (optional):
3176
3177	  Enables support for dynamically retrieving the offset of the
3178	  environment from block zero's out-of-band data.  The
3179	  "nand env.oob" command can be used to record this offset.
3180	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3181	  using CONFIG_ENV_OFFSET_OOB.
3182
3183- CONFIG_NAND_ENV_DST
3184
3185	Defines address in RAM to which the nand_spl code should copy the
3186	environment. If redundant environment is used, it will be copied to
3187	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3188
3189- CONFIG_SYS_SPI_INIT_OFFSET
3190
3191	Defines offset to the initial SPI buffer area in DPRAM. The
3192	area is used at an early stage (ROM part) if the environment
3193	is configured to reside in the SPI EEPROM: We need a 520 byte
3194	scratch DPRAM area. It is used between the two initialization
3195	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3196	to be a good choice since it makes it far enough from the
3197	start of the data area as well as from the stack pointer.
3198
3199Please note that the environment is read-only until the monitor
3200has been relocated to RAM and a RAM copy of the environment has been
3201created; also, when using EEPROM you will have to use getenv_f()
3202until then to read environment variables.
3203
3204The environment is protected by a CRC32 checksum. Before the monitor
3205is relocated into RAM, as a result of a bad CRC you will be working
3206with the compiled-in default environment - *silently*!!! [This is
3207necessary, because the first environment variable we need is the
3208"baudrate" setting for the console - if we have a bad CRC, we don't
3209have any device yet where we could complain.]
3210
3211Note: once the monitor has been relocated, then it will complain if
3212the default environment is used; a new CRC is computed as soon as you
3213use the "saveenv" command to store a valid environment.
3214
3215- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3216		Echo the inverted Ethernet link state to the fault LED.
3217
3218		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3219		      also needs to be defined.
3220
3221- CONFIG_SYS_FAULT_MII_ADDR:
3222		MII address of the PHY to check for the Ethernet link state.
3223
3224- CONFIG_NS16550_MIN_FUNCTIONS:
3225		Define this if you desire to only have use of the NS16550_init
3226		and NS16550_putc functions for the serial driver located at
3227		drivers/serial/ns16550.c.  This option is useful for saving
3228		space for already greatly restricted images, including but not
3229		limited to NAND_SPL configurations.
3230
3231Low Level (hardware related) configuration options:
3232---------------------------------------------------
3233
3234- CONFIG_SYS_CACHELINE_SIZE:
3235		Cache Line Size of the CPU.
3236
3237- CONFIG_SYS_DEFAULT_IMMR:
3238		Default address of the IMMR after system reset.
3239
3240		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3241		and RPXsuper) to be able to adjust the position of
3242		the IMMR register after a reset.
3243
3244- CONFIG_SYS_CCSRBAR_DEFAULT:
3245		Default (power-on reset) physical address of CCSR on Freescale
3246		PowerPC SOCs.
3247
3248- CONFIG_SYS_CCSRBAR:
3249		Virtual address of CCSR.  On a 32-bit build, this is typically
3250		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3251
3252		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3253		for cross-platform code that uses that macro instead.
3254
3255- CONFIG_SYS_CCSRBAR_PHYS:
3256		Physical address of CCSR.  CCSR can be relocated to a new
3257		physical address, if desired.  In this case, this macro should
3258		be set to that address.	 Otherwise, it should be set to the
3259		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3260		is typically relocated on 36-bit builds.  It is recommended
3261		that this macro be defined via the _HIGH and _LOW macros:
3262
3263		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3264			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3265
3266- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3267		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3268		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3269		used in assembly code, so it must not contain typecasts or
3270		integer size suffixes (e.g. "ULL").
3271
3272- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3273		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3274		used in assembly code, so it must not contain typecasts or
3275		integer size suffixes (e.g. "ULL").
3276
3277- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3278		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3279		forced to a value that ensures that CCSR is not relocated.
3280
3281- Floppy Disk Support:
3282		CONFIG_SYS_FDC_DRIVE_NUMBER
3283
3284		the default drive number (default value 0)
3285
3286		CONFIG_SYS_ISA_IO_STRIDE
3287
3288		defines the spacing between FDC chipset registers
3289		(default value 1)
3290
3291		CONFIG_SYS_ISA_IO_OFFSET
3292
3293		defines the offset of register from address. It
3294		depends on which part of the data bus is connected to
3295		the FDC chipset. (default value 0)
3296
3297		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3298		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3299		default value.
3300
3301		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3302		fdc_hw_init() is called at the beginning of the FDC
3303		setup. fdc_hw_init() must be provided by the board
3304		source code. It is used to make hardware dependant
3305		initializations.
3306
3307- CONFIG_IDE_AHB:
3308		Most IDE controllers were designed to be connected with PCI
3309		interface. Only few of them were designed for AHB interface.
3310		When software is doing ATA command and data transfer to
3311		IDE devices through IDE-AHB controller, some additional
3312		registers accessing to these kind of IDE-AHB controller
3313		is requierd.
3314
3315- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3316		DO NOT CHANGE unless you know exactly what you're
3317		doing! (11-4) [MPC8xx/82xx systems only]
3318
3319- CONFIG_SYS_INIT_RAM_ADDR:
3320
3321		Start address of memory area that can be used for
3322		initial data and stack; please note that this must be
3323		writable memory that is working WITHOUT special
3324		initialization, i. e. you CANNOT use normal RAM which
3325		will become available only after programming the
3326		memory controller and running certain initialization
3327		sequences.
3328
3329		U-Boot uses the following memory types:
3330		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3331		- MPC824X: data cache
3332		- PPC4xx:  data cache
3333
3334- CONFIG_SYS_GBL_DATA_OFFSET:
3335
3336		Offset of the initial data structure in the memory
3337		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3338		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3339		data is located at the end of the available space
3340		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3341		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3342		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3343		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3344
3345	Note:
3346		On the MPC824X (or other systems that use the data
3347		cache for initial memory) the address chosen for
3348		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3349		point to an otherwise UNUSED address space between
3350		the top of RAM and the start of the PCI space.
3351
3352- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3353
3354- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3355
3356- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3357
3358- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3359
3360- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3361
3362- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3363
3364- CONFIG_SYS_OR_TIMING_SDRAM:
3365		SDRAM timing
3366
3367- CONFIG_SYS_MAMR_PTA:
3368		periodic timer for refresh
3369
3370- CONFIG_SYS_DER:	Debug Event Register (37-47)
3371
3372- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3373  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3374  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3375  CONFIG_SYS_BR1_PRELIM:
3376		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3377
3378- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3379  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3380  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3381		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3382
3383- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3384  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3385		Machine Mode Register and Memory Periodic Timer
3386		Prescaler definitions (SDRAM timing)
3387
3388- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3389		enable I2C microcode relocation patch (MPC8xx);
3390		define relocation offset in DPRAM [DSP2]
3391
3392- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3393		enable SMC microcode relocation patch (MPC8xx);
3394		define relocation offset in DPRAM [SMC1]
3395
3396- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3397		enable SPI microcode relocation patch (MPC8xx);
3398		define relocation offset in DPRAM [SCC4]
3399
3400- CONFIG_SYS_USE_OSCCLK:
3401		Use OSCM clock mode on MBX8xx board. Be careful,
3402		wrong setting might damage your board. Read
3403		doc/README.MBX before setting this variable!
3404
3405- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3406		Offset of the bootmode word in DPRAM used by post
3407		(Power On Self Tests). This definition overrides
3408		#define'd default value in commproc.h resp.
3409		cpm_8260.h.
3410
3411- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3412  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3413  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3414  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3415  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3416  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3417  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3418  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3419		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3420
3421- CONFIG_PCI_DISABLE_PCIE:
3422		Disable PCI-Express on systems where it is supported but not
3423		required.
3424
3425- CONFIG_PCI_ENUM_ONLY
3426		Only scan through and get the devices on the busses.
3427		Don't do any setup work, presumably because someone or
3428		something has already done it, and we don't need to do it
3429		a second time.	Useful for platforms that are pre-booted
3430		by coreboot or similar.
3431
3432- CONFIG_SYS_SRIO:
3433		Chip has SRIO or not
3434
3435- CONFIG_SRIO1:
3436		Board has SRIO 1 port available
3437
3438- CONFIG_SRIO2:
3439		Board has SRIO 2 port available
3440
3441- CONFIG_SYS_SRIOn_MEM_VIRT:
3442		Virtual Address of SRIO port 'n' memory region
3443
3444- CONFIG_SYS_SRIOn_MEM_PHYS:
3445		Physical Address of SRIO port 'n' memory region
3446
3447- CONFIG_SYS_SRIOn_MEM_SIZE:
3448		Size of SRIO port 'n' memory region
3449
3450- CONFIG_SYS_NDFC_16
3451		Defined to tell the NDFC that the NAND chip is using a
3452		16 bit bus.
3453
3454- CONFIG_SYS_NDFC_EBC0_CFG
3455		Sets the EBC0_CFG register for the NDFC. If not defined
3456		a default value will be used.
3457
3458- CONFIG_SPD_EEPROM
3459		Get DDR timing information from an I2C EEPROM. Common
3460		with pluggable memory modules such as SODIMMs
3461
3462  SPD_EEPROM_ADDRESS
3463		I2C address of the SPD EEPROM
3464
3465- CONFIG_SYS_SPD_BUS_NUM
3466		If SPD EEPROM is on an I2C bus other than the first
3467		one, specify here. Note that the value must resolve
3468		to something your driver can deal with.
3469
3470- CONFIG_SYS_DDR_RAW_TIMING
3471		Get DDR timing information from other than SPD. Common with
3472		soldered DDR chips onboard without SPD. DDR raw timing
3473		parameters are extracted from datasheet and hard-coded into
3474		header files or board specific files.
3475
3476- CONFIG_FSL_DDR_INTERACTIVE
3477		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3478
3479- CONFIG_SYS_83XX_DDR_USES_CS0
3480		Only for 83xx systems. If specified, then DDR should
3481		be configured using CS0 and CS1 instead of CS2 and CS3.
3482
3483- CONFIG_ETHER_ON_FEC[12]
3484		Define to enable FEC[12] on a 8xx series processor.
3485
3486- CONFIG_FEC[12]_PHY
3487		Define to the hardcoded PHY address which corresponds
3488		to the given FEC; i. e.
3489			#define CONFIG_FEC1_PHY 4
3490		means that the PHY with address 4 is connected to FEC1
3491
3492		When set to -1, means to probe for first available.
3493
3494- CONFIG_FEC[12]_PHY_NORXERR
3495		The PHY does not have a RXERR line (RMII only).
3496		(so program the FEC to ignore it).
3497
3498- CONFIG_RMII
3499		Enable RMII mode for all FECs.
3500		Note that this is a global option, we can't
3501		have one FEC in standard MII mode and another in RMII mode.
3502
3503- CONFIG_CRC32_VERIFY
3504		Add a verify option to the crc32 command.
3505		The syntax is:
3506
3507		=> crc32 -v <address> <count> <crc32>
3508
3509		Where address/count indicate a memory area
3510		and crc32 is the correct crc32 which the
3511		area should have.
3512
3513- CONFIG_LOOPW
3514		Add the "loopw" memory command. This only takes effect if
3515		the memory commands are activated globally (CONFIG_CMD_MEM).
3516
3517- CONFIG_MX_CYCLIC
3518		Add the "mdc" and "mwc" memory commands. These are cyclic
3519		"md/mw" commands.
3520		Examples:
3521
3522		=> mdc.b 10 4 500
3523		This command will print 4 bytes (10,11,12,13) each 500 ms.
3524
3525		=> mwc.l 100 12345678 10
3526		This command will write 12345678 to address 100 all 10 ms.
3527
3528		This only takes effect if the memory commands are activated
3529		globally (CONFIG_CMD_MEM).
3530
3531- CONFIG_SKIP_LOWLEVEL_INIT
3532		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3533		low level initializations (like setting up the memory
3534		controller) are omitted and/or U-Boot does not
3535		relocate itself into RAM.
3536
3537		Normally this variable MUST NOT be defined. The only
3538		exception is when U-Boot is loaded (to RAM) by some
3539		other boot loader or by a debugger which performs
3540		these initializations itself.
3541
3542- CONFIG_SPL_BUILD
3543		Modifies the behaviour of start.S when compiling a loader
3544		that is executed before the actual U-Boot. E.g. when
3545		compiling a NAND SPL.
3546
3547- CONFIG_USE_ARCH_MEMCPY
3548  CONFIG_USE_ARCH_MEMSET
3549		If these options are used a optimized version of memcpy/memset will
3550		be used if available. These functions may be faster under some
3551		conditions but may increase the binary size.
3552
3553Freescale QE/FMAN Firmware Support:
3554-----------------------------------
3555
3556The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3557loading of "firmware", which is encoded in the QE firmware binary format.
3558This firmware often needs to be loaded during U-Boot booting, so macros
3559are used to identify the storage device (NOR flash, SPI, etc) and the address
3560within that device.
3561
3562- CONFIG_SYS_QE_FMAN_FW_ADDR
3563	The address in the storage device where the firmware is located.  The
3564	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3565	is also specified.
3566
3567- CONFIG_SYS_QE_FMAN_FW_LENGTH
3568	The maximum possible size of the firmware.  The firmware binary format
3569	has a field that specifies the actual size of the firmware, but it
3570	might not be possible to read any part of the firmware unless some
3571	local storage is allocated to hold the entire firmware first.
3572
3573- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3574	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3575	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3576	virtual address in NOR flash.
3577
3578- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3579	Specifies that QE/FMAN firmware is located in NAND flash.
3580	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3581
3582- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3583	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3584	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3585
3586- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3587	Specifies that QE/FMAN firmware is located on the primary SPI
3588	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3589
3590- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3591	Specifies that QE/FMAN firmware is located in the remote (master)
3592	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3593	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3594	window->master inbound window->master LAW->the ucode address in
3595	master's memory space.
3596
3597Building the Software:
3598======================
3599
3600Building U-Boot has been tested in several native build environments
3601and in many different cross environments. Of course we cannot support
3602all possibly existing versions of cross development tools in all
3603(potentially obsolete) versions. In case of tool chain problems we
3604recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3605which is extensively used to build and test U-Boot.
3606
3607If you are not using a native environment, it is assumed that you
3608have GNU cross compiling tools available in your path. In this case,
3609you must set the environment variable CROSS_COMPILE in your shell.
3610Note that no changes to the Makefile or any other source files are
3611necessary. For example using the ELDK on a 4xx CPU, please enter:
3612
3613	$ CROSS_COMPILE=ppc_4xx-
3614	$ export CROSS_COMPILE
3615
3616Note: If you wish to generate Windows versions of the utilities in
3617      the tools directory you can use the MinGW toolchain
3618      (http://www.mingw.org).  Set your HOST tools to the MinGW
3619      toolchain and execute 'make tools'.  For example:
3620
3621       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3622
3623      Binaries such as tools/mkimage.exe will be created which can
3624      be executed on computers running Windows.
3625
3626U-Boot is intended to be simple to build. After installing the
3627sources you must configure U-Boot for one specific board type. This
3628is done by typing:
3629
3630	make NAME_config
3631
3632where "NAME_config" is the name of one of the existing configu-
3633rations; see boards.cfg for supported names.
3634
3635Note: for some board special configuration names may exist; check if
3636      additional information is available from the board vendor; for
3637      instance, the TQM823L systems are available without (standard)
3638      or with LCD support. You can select such additional "features"
3639      when choosing the configuration, i. e.
3640
3641      make TQM823L_config
3642	- will configure for a plain TQM823L, i. e. no LCD support
3643
3644      make TQM823L_LCD_config
3645	- will configure for a TQM823L with U-Boot console on LCD
3646
3647      etc.
3648
3649
3650Finally, type "make all", and you should get some working U-Boot
3651images ready for download to / installation on your system:
3652
3653- "u-boot.bin" is a raw binary image
3654- "u-boot" is an image in ELF binary format
3655- "u-boot.srec" is in Motorola S-Record format
3656
3657By default the build is performed locally and the objects are saved
3658in the source directory. One of the two methods can be used to change
3659this behavior and build U-Boot to some external directory:
3660
36611. Add O= to the make command line invocations:
3662
3663	make O=/tmp/build distclean
3664	make O=/tmp/build NAME_config
3665	make O=/tmp/build all
3666
36672. Set environment variable BUILD_DIR to point to the desired location:
3668
3669	export BUILD_DIR=/tmp/build
3670	make distclean
3671	make NAME_config
3672	make all
3673
3674Note that the command line "O=" setting overrides the BUILD_DIR environment
3675variable.
3676
3677
3678Please be aware that the Makefiles assume you are using GNU make, so
3679for instance on NetBSD you might need to use "gmake" instead of
3680native "make".
3681
3682
3683If the system board that you have is not listed, then you will need
3684to port U-Boot to your hardware platform. To do this, follow these
3685steps:
3686
36871.  Add a new configuration option for your board to the toplevel
3688    "boards.cfg" file, using the existing entries as examples.
3689    Follow the instructions there to keep the boards in order.
36902.  Create a new directory to hold your board specific code. Add any
3691    files you need. In your board directory, you will need at least
3692    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
36933.  Create a new configuration file "include/configs/<board>.h" for
3694    your board
36953.  If you're porting U-Boot to a new CPU, then also create a new
3696    directory to hold your CPU specific code. Add any files you need.
36974.  Run "make <board>_config" with your new name.
36985.  Type "make", and you should get a working "u-boot.srec" file
3699    to be installed on your target system.
37006.  Debug and solve any problems that might arise.
3701    [Of course, this last step is much harder than it sounds.]
3702
3703
3704Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3705==============================================================
3706
3707If you have modified U-Boot sources (for instance added a new board
3708or support for new devices, a new CPU, etc.) you are expected to
3709provide feedback to the other developers. The feedback normally takes
3710the form of a "patch", i. e. a context diff against a certain (latest
3711official or latest in the git repository) version of U-Boot sources.
3712
3713But before you submit such a patch, please verify that your modifi-
3714cation did not break existing code. At least make sure that *ALL* of
3715the supported boards compile WITHOUT ANY compiler warnings. To do so,
3716just run the "MAKEALL" script, which will configure and build U-Boot
3717for ALL supported system. Be warned, this will take a while. You can
3718select which (cross) compiler to use by passing a `CROSS_COMPILE'
3719environment variable to the script, i. e. to use the ELDK cross tools
3720you can type
3721
3722	CROSS_COMPILE=ppc_8xx- MAKEALL
3723
3724or to build on a native PowerPC system you can type
3725
3726	CROSS_COMPILE=' ' MAKEALL
3727
3728When using the MAKEALL script, the default behaviour is to build
3729U-Boot in the source directory. This location can be changed by
3730setting the BUILD_DIR environment variable. Also, for each target
3731built, the MAKEALL script saves two log files (<target>.ERR and
3732<target>.MAKEALL) in the <source dir>/LOG directory. This default
3733location can be changed by setting the MAKEALL_LOGDIR environment
3734variable. For example:
3735
3736	export BUILD_DIR=/tmp/build
3737	export MAKEALL_LOGDIR=/tmp/log
3738	CROSS_COMPILE=ppc_8xx- MAKEALL
3739
3740With the above settings build objects are saved in the /tmp/build,
3741log files are saved in the /tmp/log and the source tree remains clean
3742during the whole build process.
3743
3744
3745See also "U-Boot Porting Guide" below.
3746
3747
3748Monitor Commands - Overview:
3749============================
3750
3751go	- start application at address 'addr'
3752run	- run commands in an environment variable
3753bootm	- boot application image from memory
3754bootp	- boot image via network using BootP/TFTP protocol
3755bootz   - boot zImage from memory
3756tftpboot- boot image via network using TFTP protocol
3757	       and env variables "ipaddr" and "serverip"
3758	       (and eventually "gatewayip")
3759tftpput - upload a file via network using TFTP protocol
3760rarpboot- boot image via network using RARP/TFTP protocol
3761diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3762loads	- load S-Record file over serial line
3763loadb	- load binary file over serial line (kermit mode)
3764md	- memory display
3765mm	- memory modify (auto-incrementing)
3766nm	- memory modify (constant address)
3767mw	- memory write (fill)
3768cp	- memory copy
3769cmp	- memory compare
3770crc32	- checksum calculation
3771i2c	- I2C sub-system
3772sspi	- SPI utility commands
3773base	- print or set address offset
3774printenv- print environment variables
3775setenv	- set environment variables
3776saveenv - save environment variables to persistent storage
3777protect - enable or disable FLASH write protection
3778erase	- erase FLASH memory
3779flinfo	- print FLASH memory information
3780bdinfo	- print Board Info structure
3781iminfo	- print header information for application image
3782coninfo - print console devices and informations
3783ide	- IDE sub-system
3784loop	- infinite loop on address range
3785loopw	- infinite write loop on address range
3786mtest	- simple RAM test
3787icache	- enable or disable instruction cache
3788dcache	- enable or disable data cache
3789reset	- Perform RESET of the CPU
3790echo	- echo args to console
3791version - print monitor version
3792help	- print online help
3793?	- alias for 'help'
3794
3795
3796Monitor Commands - Detailed Description:
3797========================================
3798
3799TODO.
3800
3801For now: just type "help <command>".
3802
3803
3804Environment Variables:
3805======================
3806
3807U-Boot supports user configuration using Environment Variables which
3808can be made persistent by saving to Flash memory.
3809
3810Environment Variables are set using "setenv", printed using
3811"printenv", and saved to Flash using "saveenv". Using "setenv"
3812without a value can be used to delete a variable from the
3813environment. As long as you don't save the environment you are
3814working with an in-memory copy. In case the Flash area containing the
3815environment is erased by accident, a default environment is provided.
3816
3817Some configuration options can be set using Environment Variables.
3818
3819List of environment variables (most likely not complete):
3820
3821  baudrate	- see CONFIG_BAUDRATE
3822
3823  bootdelay	- see CONFIG_BOOTDELAY
3824
3825  bootcmd	- see CONFIG_BOOTCOMMAND
3826
3827  bootargs	- Boot arguments when booting an RTOS image
3828
3829  bootfile	- Name of the image to load with TFTP
3830
3831  bootm_low	- Memory range available for image processing in the bootm
3832		  command can be restricted. This variable is given as
3833		  a hexadecimal number and defines lowest address allowed
3834		  for use by the bootm command. See also "bootm_size"
3835		  environment variable. Address defined by "bootm_low" is
3836		  also the base of the initial memory mapping for the Linux
3837		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3838		  bootm_mapsize.
3839
3840  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3841		  This variable is given as a hexadecimal number and it
3842		  defines the size of the memory region starting at base
3843		  address bootm_low that is accessible by the Linux kernel
3844		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3845		  as the default value if it is defined, and bootm_size is
3846		  used otherwise.
3847
3848  bootm_size	- Memory range available for image processing in the bootm
3849		  command can be restricted. This variable is given as
3850		  a hexadecimal number and defines the size of the region
3851		  allowed for use by the bootm command. See also "bootm_low"
3852		  environment variable.
3853
3854  updatefile	- Location of the software update file on a TFTP server, used
3855		  by the automatic software update feature. Please refer to
3856		  documentation in doc/README.update for more details.
3857
3858  autoload	- if set to "no" (any string beginning with 'n'),
3859		  "bootp" will just load perform a lookup of the
3860		  configuration from the BOOTP server, but not try to
3861		  load any image using TFTP
3862
3863  autostart	- if set to "yes", an image loaded using the "bootp",
3864		  "rarpboot", "tftpboot" or "diskboot" commands will
3865		  be automatically started (by internally calling
3866		  "bootm")
3867
3868		  If set to "no", a standalone image passed to the
3869		  "bootm" command will be copied to the load address
3870		  (and eventually uncompressed), but NOT be started.
3871		  This can be used to load and uncompress arbitrary
3872		  data.
3873
3874  fdt_high	- if set this restricts the maximum address that the
3875		  flattened device tree will be copied into upon boot.
3876		  For example, if you have a system with 1 GB memory
3877		  at physical address 0x10000000, while Linux kernel
3878		  only recognizes the first 704 MB as low memory, you
3879		  may need to set fdt_high as 0x3C000000 to have the
3880		  device tree blob be copied to the maximum address
3881		  of the 704 MB low memory, so that Linux kernel can
3882		  access it during the boot procedure.
3883
3884		  If this is set to the special value 0xFFFFFFFF then
3885		  the fdt will not be copied at all on boot.  For this
3886		  to work it must reside in writable memory, have
3887		  sufficient padding on the end of it for u-boot to
3888		  add the information it needs into it, and the memory
3889		  must be accessible by the kernel.
3890
3891  fdtcontroladdr- if set this is the address of the control flattened
3892		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3893		  defined.
3894
3895  i2cfast	- (PPC405GP|PPC405EP only)
3896		  if set to 'y' configures Linux I2C driver for fast
3897		  mode (400kHZ). This environment variable is used in
3898		  initialization code. So, for changes to be effective
3899		  it must be saved and board must be reset.
3900
3901  initrd_high	- restrict positioning of initrd images:
3902		  If this variable is not set, initrd images will be
3903		  copied to the highest possible address in RAM; this
3904		  is usually what you want since it allows for
3905		  maximum initrd size. If for some reason you want to
3906		  make sure that the initrd image is loaded below the
3907		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3908		  variable to a value of "no" or "off" or "0".
3909		  Alternatively, you can set it to a maximum upper
3910		  address to use (U-Boot will still check that it
3911		  does not overwrite the U-Boot stack and data).
3912
3913		  For instance, when you have a system with 16 MB
3914		  RAM, and want to reserve 4 MB from use by Linux,
3915		  you can do this by adding "mem=12M" to the value of
3916		  the "bootargs" variable. However, now you must make
3917		  sure that the initrd image is placed in the first
3918		  12 MB as well - this can be done with
3919
3920		  setenv initrd_high 00c00000
3921
3922		  If you set initrd_high to 0xFFFFFFFF, this is an
3923		  indication to U-Boot that all addresses are legal
3924		  for the Linux kernel, including addresses in flash
3925		  memory. In this case U-Boot will NOT COPY the
3926		  ramdisk at all. This may be useful to reduce the
3927		  boot time on your system, but requires that this
3928		  feature is supported by your Linux kernel.
3929
3930  ipaddr	- IP address; needed for tftpboot command
3931
3932  loadaddr	- Default load address for commands like "bootp",
3933		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3934
3935  loads_echo	- see CONFIG_LOADS_ECHO
3936
3937  serverip	- TFTP server IP address; needed for tftpboot command
3938
3939  bootretry	- see CONFIG_BOOT_RETRY_TIME
3940
3941  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3942
3943  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3944
3945  ethprime	- controls which interface is used first.
3946
3947  ethact	- controls which interface is currently active.
3948		  For example you can do the following
3949
3950		  => setenv ethact FEC
3951		  => ping 192.168.0.1 # traffic sent on FEC
3952		  => setenv ethact SCC
3953		  => ping 10.0.0.1 # traffic sent on SCC
3954
3955  ethrotate	- When set to "no" U-Boot does not go through all
3956		  available network interfaces.
3957		  It just stays at the currently selected interface.
3958
3959  netretry	- When set to "no" each network operation will
3960		  either succeed or fail without retrying.
3961		  When set to "once" the network operation will
3962		  fail when all the available network interfaces
3963		  are tried once without success.
3964		  Useful on scripts which control the retry operation
3965		  themselves.
3966
3967  npe_ucode	- set load address for the NPE microcode
3968
3969  tftpsrcport	- If this is set, the value is used for TFTP's
3970		  UDP source port.
3971
3972  tftpdstport	- If this is set, the value is used for TFTP's UDP
3973		  destination port instead of the Well Know Port 69.
3974
3975  tftpblocksize - Block size to use for TFTP transfers; if not set,
3976		  we use the TFTP server's default block size
3977
3978  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
3979		  seconds, minimum value is 1000 = 1 second). Defines
3980		  when a packet is considered to be lost so it has to
3981		  be retransmitted. The default is 5000 = 5 seconds.
3982		  Lowering this value may make downloads succeed
3983		  faster in networks with high packet loss rates or
3984		  with unreliable TFTP servers.
3985
3986  vlan		- When set to a value < 4095 the traffic over
3987		  Ethernet is encapsulated/received over 802.1q
3988		  VLAN tagged frames.
3989
3990The following image location variables contain the location of images
3991used in booting. The "Image" column gives the role of the image and is
3992not an environment variable name. The other columns are environment
3993variable names. "File Name" gives the name of the file on a TFTP
3994server, "RAM Address" gives the location in RAM the image will be
3995loaded to, and "Flash Location" gives the image's address in NOR
3996flash or offset in NAND flash.
3997
3998*Note* - these variables don't have to be defined for all boards, some
3999boards currenlty use other variables for these purposes, and some
4000boards use these variables for other purposes.
4001
4002Image		    File Name	     RAM Address       Flash Location
4003-----		    ---------	     -----------       --------------
4004u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4005Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4006device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4007ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4008
4009The following environment variables may be used and automatically
4010updated by the network boot commands ("bootp" and "rarpboot"),
4011depending the information provided by your boot server:
4012
4013  bootfile	- see above
4014  dnsip		- IP address of your Domain Name Server
4015  dnsip2	- IP address of your secondary Domain Name Server
4016  gatewayip	- IP address of the Gateway (Router) to use
4017  hostname	- Target hostname
4018  ipaddr	- see above
4019  netmask	- Subnet Mask
4020  rootpath	- Pathname of the root filesystem on the NFS server
4021  serverip	- see above
4022
4023
4024There are two special Environment Variables:
4025
4026  serial#	- contains hardware identification information such
4027		  as type string and/or serial number
4028  ethaddr	- Ethernet address
4029
4030These variables can be set only once (usually during manufacturing of
4031the board). U-Boot refuses to delete or overwrite these variables
4032once they have been set once.
4033
4034
4035Further special Environment Variables:
4036
4037  ver		- Contains the U-Boot version string as printed
4038		  with the "version" command. This variable is
4039		  readonly (see CONFIG_VERSION_VARIABLE).
4040
4041
4042Please note that changes to some configuration parameters may take
4043only effect after the next boot (yes, that's just like Windoze :-).
4044
4045
4046Command Line Parsing:
4047=====================
4048
4049There are two different command line parsers available with U-Boot:
4050the old "simple" one, and the much more powerful "hush" shell:
4051
4052Old, simple command line parser:
4053--------------------------------
4054
4055- supports environment variables (through setenv / saveenv commands)
4056- several commands on one line, separated by ';'
4057- variable substitution using "... ${name} ..." syntax
4058- special characters ('$', ';') can be escaped by prefixing with '\',
4059  for example:
4060	setenv bootcmd bootm \${address}
4061- You can also escape text by enclosing in single apostrophes, for example:
4062	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4063
4064Hush shell:
4065-----------
4066
4067- similar to Bourne shell, with control structures like
4068  if...then...else...fi, for...do...done; while...do...done,
4069  until...do...done, ...
4070- supports environment ("global") variables (through setenv / saveenv
4071  commands) and local shell variables (through standard shell syntax
4072  "name=value"); only environment variables can be used with "run"
4073  command
4074
4075General rules:
4076--------------
4077
4078(1) If a command line (or an environment variable executed by a "run"
4079    command) contains several commands separated by semicolon, and
4080    one of these commands fails, then the remaining commands will be
4081    executed anyway.
4082
4083(2) If you execute several variables with one call to run (i. e.
4084    calling run with a list of variables as arguments), any failing
4085    command will cause "run" to terminate, i. e. the remaining
4086    variables are not executed.
4087
4088Note for Redundant Ethernet Interfaces:
4089=======================================
4090
4091Some boards come with redundant Ethernet interfaces; U-Boot supports
4092such configurations and is capable of automatic selection of a
4093"working" interface when needed. MAC assignment works as follows:
4094
4095Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4096MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4097"eth1addr" (=>eth1), "eth2addr", ...
4098
4099If the network interface stores some valid MAC address (for instance
4100in SROM), this is used as default address if there is NO correspon-
4101ding setting in the environment; if the corresponding environment
4102variable is set, this overrides the settings in the card; that means:
4103
4104o If the SROM has a valid MAC address, and there is no address in the
4105  environment, the SROM's address is used.
4106
4107o If there is no valid address in the SROM, and a definition in the
4108  environment exists, then the value from the environment variable is
4109  used.
4110
4111o If both the SROM and the environment contain a MAC address, and
4112  both addresses are the same, this MAC address is used.
4113
4114o If both the SROM and the environment contain a MAC address, and the
4115  addresses differ, the value from the environment is used and a
4116  warning is printed.
4117
4118o If neither SROM nor the environment contain a MAC address, an error
4119  is raised.
4120
4121If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4122will be programmed into hardware as part of the initialization process.	 This
4123may be skipped by setting the appropriate 'ethmacskip' environment variable.
4124The naming convention is as follows:
4125"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4126
4127Image Formats:
4128==============
4129
4130U-Boot is capable of booting (and performing other auxiliary operations on)
4131images in two formats:
4132
4133New uImage format (FIT)
4134-----------------------
4135
4136Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4137to Flattened Device Tree). It allows the use of images with multiple
4138components (several kernels, ramdisks, etc.), with contents protected by
4139SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4140
4141
4142Old uImage format
4143-----------------
4144
4145Old image format is based on binary files which can be basically anything,
4146preceded by a special header; see the definitions in include/image.h for
4147details; basically, the header defines the following image properties:
4148
4149* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4150  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4151  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4152  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4153  INTEGRITY).
4154* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4155  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4156  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4157* Compression Type (uncompressed, gzip, bzip2)
4158* Load Address
4159* Entry Point
4160* Image Name
4161* Image Timestamp
4162
4163The header is marked by a special Magic Number, and both the header
4164and the data portions of the image are secured against corruption by
4165CRC32 checksums.
4166
4167
4168Linux Support:
4169==============
4170
4171Although U-Boot should support any OS or standalone application
4172easily, the main focus has always been on Linux during the design of
4173U-Boot.
4174
4175U-Boot includes many features that so far have been part of some
4176special "boot loader" code within the Linux kernel. Also, any
4177"initrd" images to be used are no longer part of one big Linux image;
4178instead, kernel and "initrd" are separate images. This implementation
4179serves several purposes:
4180
4181- the same features can be used for other OS or standalone
4182  applications (for instance: using compressed images to reduce the
4183  Flash memory footprint)
4184
4185- it becomes much easier to port new Linux kernel versions because
4186  lots of low-level, hardware dependent stuff are done by U-Boot
4187
4188- the same Linux kernel image can now be used with different "initrd"
4189  images; of course this also means that different kernel images can
4190  be run with the same "initrd". This makes testing easier (you don't
4191  have to build a new "zImage.initrd" Linux image when you just
4192  change a file in your "initrd"). Also, a field-upgrade of the
4193  software is easier now.
4194
4195
4196Linux HOWTO:
4197============
4198
4199Porting Linux to U-Boot based systems:
4200---------------------------------------
4201
4202U-Boot cannot save you from doing all the necessary modifications to
4203configure the Linux device drivers for use with your target hardware
4204(no, we don't intend to provide a full virtual machine interface to
4205Linux :-).
4206
4207But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4208
4209Just make sure your machine specific header file (for instance
4210include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4211Information structure as we define in include/asm-<arch>/u-boot.h,
4212and make sure that your definition of IMAP_ADDR uses the same value
4213as your U-Boot configuration in CONFIG_SYS_IMMR.
4214
4215
4216Configuring the Linux kernel:
4217-----------------------------
4218
4219No specific requirements for U-Boot. Make sure you have some root
4220device (initial ramdisk, NFS) for your target system.
4221
4222
4223Building a Linux Image:
4224-----------------------
4225
4226With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4227not used. If you use recent kernel source, a new build target
4228"uImage" will exist which automatically builds an image usable by
4229U-Boot. Most older kernels also have support for a "pImage" target,
4230which was introduced for our predecessor project PPCBoot and uses a
4231100% compatible format.
4232
4233Example:
4234
4235	make TQM850L_config
4236	make oldconfig
4237	make dep
4238	make uImage
4239
4240The "uImage" build target uses a special tool (in 'tools/mkimage') to
4241encapsulate a compressed Linux kernel image with header	 information,
4242CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4243
4244* build a standard "vmlinux" kernel image (in ELF binary format):
4245
4246* convert the kernel into a raw binary image:
4247
4248	${CROSS_COMPILE}-objcopy -O binary \
4249				 -R .note -R .comment \
4250				 -S vmlinux linux.bin
4251
4252* compress the binary image:
4253
4254	gzip -9 linux.bin
4255
4256* package compressed binary image for U-Boot:
4257
4258	mkimage -A ppc -O linux -T kernel -C gzip \
4259		-a 0 -e 0 -n "Linux Kernel Image" \
4260		-d linux.bin.gz uImage
4261
4262
4263The "mkimage" tool can also be used to create ramdisk images for use
4264with U-Boot, either separated from the Linux kernel image, or
4265combined into one file. "mkimage" encapsulates the images with a 64
4266byte header containing information about target architecture,
4267operating system, image type, compression method, entry points, time
4268stamp, CRC32 checksums, etc.
4269
4270"mkimage" can be called in two ways: to verify existing images and
4271print the header information, or to build new images.
4272
4273In the first form (with "-l" option) mkimage lists the information
4274contained in the header of an existing U-Boot image; this includes
4275checksum verification:
4276
4277	tools/mkimage -l image
4278	  -l ==> list image header information
4279
4280The second form (with "-d" option) is used to build a U-Boot image
4281from a "data file" which is used as image payload:
4282
4283	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4284		      -n name -d data_file image
4285	  -A ==> set architecture to 'arch'
4286	  -O ==> set operating system to 'os'
4287	  -T ==> set image type to 'type'
4288	  -C ==> set compression type 'comp'
4289	  -a ==> set load address to 'addr' (hex)
4290	  -e ==> set entry point to 'ep' (hex)
4291	  -n ==> set image name to 'name'
4292	  -d ==> use image data from 'datafile'
4293
4294Right now, all Linux kernels for PowerPC systems use the same load
4295address (0x00000000), but the entry point address depends on the
4296kernel version:
4297
4298- 2.2.x kernels have the entry point at 0x0000000C,
4299- 2.3.x and later kernels have the entry point at 0x00000000.
4300
4301So a typical call to build a U-Boot image would read:
4302
4303	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4304	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4305	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4306	> examples/uImage.TQM850L
4307	Image Name:   2.4.4 kernel for TQM850L
4308	Created:      Wed Jul 19 02:34:59 2000
4309	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4310	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4311	Load Address: 0x00000000
4312	Entry Point:  0x00000000
4313
4314To verify the contents of the image (or check for corruption):
4315
4316	-> tools/mkimage -l examples/uImage.TQM850L
4317	Image Name:   2.4.4 kernel for TQM850L
4318	Created:      Wed Jul 19 02:34:59 2000
4319	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4320	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4321	Load Address: 0x00000000
4322	Entry Point:  0x00000000
4323
4324NOTE: for embedded systems where boot time is critical you can trade
4325speed for memory and install an UNCOMPRESSED image instead: this
4326needs more space in Flash, but boots much faster since it does not
4327need to be uncompressed:
4328
4329	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4330	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4331	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4332	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4333	> examples/uImage.TQM850L-uncompressed
4334	Image Name:   2.4.4 kernel for TQM850L
4335	Created:      Wed Jul 19 02:34:59 2000
4336	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4337	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4338	Load Address: 0x00000000
4339	Entry Point:  0x00000000
4340
4341
4342Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4343when your kernel is intended to use an initial ramdisk:
4344
4345	-> tools/mkimage -n 'Simple Ramdisk Image' \
4346	> -A ppc -O linux -T ramdisk -C gzip \
4347	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4348	Image Name:   Simple Ramdisk Image
4349	Created:      Wed Jan 12 14:01:50 2000
4350	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4351	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4352	Load Address: 0x00000000
4353	Entry Point:  0x00000000
4354
4355
4356Installing a Linux Image:
4357-------------------------
4358
4359To downloading a U-Boot image over the serial (console) interface,
4360you must convert the image to S-Record format:
4361
4362	objcopy -I binary -O srec examples/image examples/image.srec
4363
4364The 'objcopy' does not understand the information in the U-Boot
4365image header, so the resulting S-Record file will be relative to
4366address 0x00000000. To load it to a given address, you need to
4367specify the target address as 'offset' parameter with the 'loads'
4368command.
4369
4370Example: install the image to address 0x40100000 (which on the
4371TQM8xxL is in the first Flash bank):
4372
4373	=> erase 40100000 401FFFFF
4374
4375	.......... done
4376	Erased 8 sectors
4377
4378	=> loads 40100000
4379	## Ready for S-Record download ...
4380	~>examples/image.srec
4381	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4382	...
4383	15989 15990 15991 15992
4384	[file transfer complete]
4385	[connected]
4386	## Start Addr = 0x00000000
4387
4388
4389You can check the success of the download using the 'iminfo' command;
4390this includes a checksum verification so you can be sure no data
4391corruption happened:
4392
4393	=> imi 40100000
4394
4395	## Checking Image at 40100000 ...
4396	   Image Name:	 2.2.13 for initrd on TQM850L
4397	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4398	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4399	   Load Address: 00000000
4400	   Entry Point:	 0000000c
4401	   Verifying Checksum ... OK
4402
4403
4404Boot Linux:
4405-----------
4406
4407The "bootm" command is used to boot an application that is stored in
4408memory (RAM or Flash). In case of a Linux kernel image, the contents
4409of the "bootargs" environment variable is passed to the kernel as
4410parameters. You can check and modify this variable using the
4411"printenv" and "setenv" commands:
4412
4413
4414	=> printenv bootargs
4415	bootargs=root=/dev/ram
4416
4417	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4418
4419	=> printenv bootargs
4420	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4421
4422	=> bootm 40020000
4423	## Booting Linux kernel at 40020000 ...
4424	   Image Name:	 2.2.13 for NFS on TQM850L
4425	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4426	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4427	   Load Address: 00000000
4428	   Entry Point:	 0000000c
4429	   Verifying Checksum ... OK
4430	   Uncompressing Kernel Image ... OK
4431	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
4432	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4433	time_init: decrementer frequency = 187500000/60
4434	Calibrating delay loop... 49.77 BogoMIPS
4435	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4436	...
4437
4438If you want to boot a Linux kernel with initial RAM disk, you pass
4439the memory addresses of both the kernel and the initrd image (PPBCOOT
4440format!) to the "bootm" command:
4441
4442	=> imi 40100000 40200000
4443
4444	## Checking Image at 40100000 ...
4445	   Image Name:	 2.2.13 for initrd on TQM850L
4446	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4447	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4448	   Load Address: 00000000
4449	   Entry Point:	 0000000c
4450	   Verifying Checksum ... OK
4451
4452	## Checking Image at 40200000 ...
4453	   Image Name:	 Simple Ramdisk Image
4454	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4455	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4456	   Load Address: 00000000
4457	   Entry Point:	 00000000
4458	   Verifying Checksum ... OK
4459
4460	=> bootm 40100000 40200000
4461	## Booting Linux kernel at 40100000 ...
4462	   Image Name:	 2.2.13 for initrd on TQM850L
4463	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4464	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4465	   Load Address: 00000000
4466	   Entry Point:	 0000000c
4467	   Verifying Checksum ... OK
4468	   Uncompressing Kernel Image ... OK
4469	## Loading RAMDisk Image at 40200000 ...
4470	   Image Name:	 Simple Ramdisk Image
4471	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4472	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4473	   Load Address: 00000000
4474	   Entry Point:	 00000000
4475	   Verifying Checksum ... OK
4476	   Loading Ramdisk ... OK
4477	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
4478	Boot arguments: root=/dev/ram
4479	time_init: decrementer frequency = 187500000/60
4480	Calibrating delay loop... 49.77 BogoMIPS
4481	...
4482	RAMDISK: Compressed image found at block 0
4483	VFS: Mounted root (ext2 filesystem).
4484
4485	bash#
4486
4487Boot Linux and pass a flat device tree:
4488-----------
4489
4490First, U-Boot must be compiled with the appropriate defines. See the section
4491titled "Linux Kernel Interface" above for a more in depth explanation. The
4492following is an example of how to start a kernel and pass an updated
4493flat device tree:
4494
4495=> print oftaddr
4496oftaddr=0x300000
4497=> print oft
4498oft=oftrees/mpc8540ads.dtb
4499=> tftp $oftaddr $oft
4500Speed: 1000, full duplex
4501Using TSEC0 device
4502TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4503Filename 'oftrees/mpc8540ads.dtb'.
4504Load address: 0x300000
4505Loading: #
4506done
4507Bytes transferred = 4106 (100a hex)
4508=> tftp $loadaddr $bootfile
4509Speed: 1000, full duplex
4510Using TSEC0 device
4511TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4512Filename 'uImage'.
4513Load address: 0x200000
4514Loading:############
4515done
4516Bytes transferred = 1029407 (fb51f hex)
4517=> print loadaddr
4518loadaddr=200000
4519=> print oftaddr
4520oftaddr=0x300000
4521=> bootm $loadaddr - $oftaddr
4522## Booting image at 00200000 ...
4523   Image Name:	 Linux-2.6.17-dirty
4524   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4525   Data Size:	 1029343 Bytes = 1005.2 kB
4526   Load Address: 00000000
4527   Entry Point:	 00000000
4528   Verifying Checksum ... OK
4529   Uncompressing Kernel Image ... OK
4530Booting using flat device tree at 0x300000
4531Using MPC85xx ADS machine description
4532Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4533[snip]
4534
4535
4536More About U-Boot Image Types:
4537------------------------------
4538
4539U-Boot supports the following image types:
4540
4541   "Standalone Programs" are directly runnable in the environment
4542	provided by U-Boot; it is expected that (if they behave
4543	well) you can continue to work in U-Boot after return from
4544	the Standalone Program.
4545   "OS Kernel Images" are usually images of some Embedded OS which
4546	will take over control completely. Usually these programs
4547	will install their own set of exception handlers, device
4548	drivers, set up the MMU, etc. - this means, that you cannot
4549	expect to re-enter U-Boot except by resetting the CPU.
4550   "RAMDisk Images" are more or less just data blocks, and their
4551	parameters (address, size) are passed to an OS kernel that is
4552	being started.
4553   "Multi-File Images" contain several images, typically an OS
4554	(Linux) kernel image and one or more data images like
4555	RAMDisks. This construct is useful for instance when you want
4556	to boot over the network using BOOTP etc., where the boot
4557	server provides just a single image file, but you want to get
4558	for instance an OS kernel and a RAMDisk image.
4559
4560	"Multi-File Images" start with a list of image sizes, each
4561	image size (in bytes) specified by an "uint32_t" in network
4562	byte order. This list is terminated by an "(uint32_t)0".
4563	Immediately after the terminating 0 follow the images, one by
4564	one, all aligned on "uint32_t" boundaries (size rounded up to
4565	a multiple of 4 bytes).
4566
4567   "Firmware Images" are binary images containing firmware (like
4568	U-Boot or FPGA images) which usually will be programmed to
4569	flash memory.
4570
4571   "Script files" are command sequences that will be executed by
4572	U-Boot's command interpreter; this feature is especially
4573	useful when you configure U-Boot to use a real shell (hush)
4574	as command interpreter.
4575
4576Booting the Linux zImage:
4577-------------------------
4578
4579On some platforms, it's possible to boot Linux zImage. This is done
4580using the "bootz" command. The syntax of "bootz" command is the same
4581as the syntax of "bootm" command.
4582
4583Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4584kernel with raw initrd images. The syntax is slightly different, the
4585address of the initrd must be augmented by it's size, in the following
4586format: "<initrd addres>:<initrd size>".
4587
4588
4589Standalone HOWTO:
4590=================
4591
4592One of the features of U-Boot is that you can dynamically load and
4593run "standalone" applications, which can use some resources of
4594U-Boot like console I/O functions or interrupt services.
4595
4596Two simple examples are included with the sources:
4597
4598"Hello World" Demo:
4599-------------------
4600
4601'examples/hello_world.c' contains a small "Hello World" Demo
4602application; it is automatically compiled when you build U-Boot.
4603It's configured to run at address 0x00040004, so you can play with it
4604like that:
4605
4606	=> loads
4607	## Ready for S-Record download ...
4608	~>examples/hello_world.srec
4609	1 2 3 4 5 6 7 8 9 10 11 ...
4610	[file transfer complete]
4611	[connected]
4612	## Start Addr = 0x00040004
4613
4614	=> go 40004 Hello World! This is a test.
4615	## Starting application at 0x00040004 ...
4616	Hello World
4617	argc = 7
4618	argv[0] = "40004"
4619	argv[1] = "Hello"
4620	argv[2] = "World!"
4621	argv[3] = "This"
4622	argv[4] = "is"
4623	argv[5] = "a"
4624	argv[6] = "test."
4625	argv[7] = "<NULL>"
4626	Hit any key to exit ...
4627
4628	## Application terminated, rc = 0x0
4629
4630Another example, which demonstrates how to register a CPM interrupt
4631handler with the U-Boot code, can be found in 'examples/timer.c'.
4632Here, a CPM timer is set up to generate an interrupt every second.
4633The interrupt service routine is trivial, just printing a '.'
4634character, but this is just a demo program. The application can be
4635controlled by the following keys:
4636
4637	? - print current values og the CPM Timer registers
4638	b - enable interrupts and start timer
4639	e - stop timer and disable interrupts
4640	q - quit application
4641
4642	=> loads
4643	## Ready for S-Record download ...
4644	~>examples/timer.srec
4645	1 2 3 4 5 6 7 8 9 10 11 ...
4646	[file transfer complete]
4647	[connected]
4648	## Start Addr = 0x00040004
4649
4650	=> go 40004
4651	## Starting application at 0x00040004 ...
4652	TIMERS=0xfff00980
4653	Using timer 1
4654	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4655
4656Hit 'b':
4657	[q, b, e, ?] Set interval 1000000 us
4658	Enabling timer
4659Hit '?':
4660	[q, b, e, ?] ........
4661	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4662Hit '?':
4663	[q, b, e, ?] .
4664	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4665Hit '?':
4666	[q, b, e, ?] .
4667	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4668Hit '?':
4669	[q, b, e, ?] .
4670	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4671Hit 'e':
4672	[q, b, e, ?] ...Stopping timer
4673Hit 'q':
4674	[q, b, e, ?] ## Application terminated, rc = 0x0
4675
4676
4677Minicom warning:
4678================
4679
4680Over time, many people have reported problems when trying to use the
4681"minicom" terminal emulation program for serial download. I (wd)
4682consider minicom to be broken, and recommend not to use it. Under
4683Unix, I recommend to use C-Kermit for general purpose use (and
4684especially for kermit binary protocol download ("loadb" command), and
4685use "cu" for S-Record download ("loads" command).
4686
4687Nevertheless, if you absolutely want to use it try adding this
4688configuration to your "File transfer protocols" section:
4689
4690	   Name	   Program			Name U/D FullScr IO-Red. Multi
4691	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4692	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4693
4694
4695NetBSD Notes:
4696=============
4697
4698Starting at version 0.9.2, U-Boot supports NetBSD both as host
4699(build U-Boot) and target system (boots NetBSD/mpc8xx).
4700
4701Building requires a cross environment; it is known to work on
4702NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4703need gmake since the Makefiles are not compatible with BSD make).
4704Note that the cross-powerpc package does not install include files;
4705attempting to build U-Boot will fail because <machine/ansi.h> is
4706missing.  This file has to be installed and patched manually:
4707
4708	# cd /usr/pkg/cross/powerpc-netbsd/include
4709	# mkdir powerpc
4710	# ln -s powerpc machine
4711	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4712	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4713
4714Native builds *don't* work due to incompatibilities between native
4715and U-Boot include files.
4716
4717Booting assumes that (the first part of) the image booted is a
4718stage-2 loader which in turn loads and then invokes the kernel
4719proper. Loader sources will eventually appear in the NetBSD source
4720tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4721meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4722
4723
4724Implementation Internals:
4725=========================
4726
4727The following is not intended to be a complete description of every
4728implementation detail. However, it should help to understand the
4729inner workings of U-Boot and make it easier to port it to custom
4730hardware.
4731
4732
4733Initial Stack, Global Data:
4734---------------------------
4735
4736The implementation of U-Boot is complicated by the fact that U-Boot
4737starts running out of ROM (flash memory), usually without access to
4738system RAM (because the memory controller is not initialized yet).
4739This means that we don't have writable Data or BSS segments, and BSS
4740is not initialized as zero. To be able to get a C environment working
4741at all, we have to allocate at least a minimal stack. Implementation
4742options for this are defined and restricted by the CPU used: Some CPU
4743models provide on-chip memory (like the IMMR area on MPC8xx and
4744MPC826x processors), on others (parts of) the data cache can be
4745locked as (mis-) used as memory, etc.
4746
4747	Chris Hallinan posted a good summary of these issues to the
4748	U-Boot mailing list:
4749
4750	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4751	From: "Chris Hallinan" <clh@net1plus.com>
4752	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4753	...
4754
4755	Correct me if I'm wrong, folks, but the way I understand it
4756	is this: Using DCACHE as initial RAM for Stack, etc, does not
4757	require any physical RAM backing up the cache. The cleverness
4758	is that the cache is being used as a temporary supply of
4759	necessary storage before the SDRAM controller is setup. It's
4760	beyond the scope of this list to explain the details, but you
4761	can see how this works by studying the cache architecture and
4762	operation in the architecture and processor-specific manuals.
4763
4764	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4765	is another option for the system designer to use as an
4766	initial stack/RAM area prior to SDRAM being available. Either
4767	option should work for you. Using CS 4 should be fine if your
4768	board designers haven't used it for something that would
4769	cause you grief during the initial boot! It is frequently not
4770	used.
4771
4772	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4773	with your processor/board/system design. The default value
4774	you will find in any recent u-boot distribution in
4775	walnut.h should work for you. I'd set it to a value larger
4776	than your SDRAM module. If you have a 64MB SDRAM module, set
4777	it above 400_0000. Just make sure your board has no resources
4778	that are supposed to respond to that address! That code in
4779	start.S has been around a while and should work as is when
4780	you get the config right.
4781
4782	-Chris Hallinan
4783	DS4.COM, Inc.
4784
4785It is essential to remember this, since it has some impact on the C
4786code for the initialization procedures:
4787
4788* Initialized global data (data segment) is read-only. Do not attempt
4789  to write it.
4790
4791* Do not use any uninitialized global data (or implicitely initialized
4792  as zero data - BSS segment) at all - this is undefined, initiali-
4793  zation is performed later (when relocating to RAM).
4794
4795* Stack space is very limited. Avoid big data buffers or things like
4796  that.
4797
4798Having only the stack as writable memory limits means we cannot use
4799normal global data to share information beween the code. But it
4800turned out that the implementation of U-Boot can be greatly
4801simplified by making a global data structure (gd_t) available to all
4802functions. We could pass a pointer to this data as argument to _all_
4803functions, but this would bloat the code. Instead we use a feature of
4804the GCC compiler (Global Register Variables) to share the data: we
4805place a pointer (gd) to the global data into a register which we
4806reserve for this purpose.
4807
4808When choosing a register for such a purpose we are restricted by the
4809relevant  (E)ABI  specifications for the current architecture, and by
4810GCC's implementation.
4811
4812For PowerPC, the following registers have specific use:
4813	R1:	stack pointer
4814	R2:	reserved for system use
4815	R3-R4:	parameter passing and return values
4816	R5-R10: parameter passing
4817	R13:	small data area pointer
4818	R30:	GOT pointer
4819	R31:	frame pointer
4820
4821	(U-Boot also uses R12 as internal GOT pointer. r12
4822	is a volatile register so r12 needs to be reset when
4823	going back and forth between asm and C)
4824
4825    ==> U-Boot will use R2 to hold a pointer to the global data
4826
4827    Note: on PPC, we could use a static initializer (since the
4828    address of the global data structure is known at compile time),
4829    but it turned out that reserving a register results in somewhat
4830    smaller code - although the code savings are not that big (on
4831    average for all boards 752 bytes for the whole U-Boot image,
4832    624 text + 127 data).
4833
4834On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4835	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4836
4837    ==> U-Boot will use P3 to hold a pointer to the global data
4838
4839On ARM, the following registers are used:
4840
4841	R0:	function argument word/integer result
4842	R1-R3:	function argument word
4843	R9:	GOT pointer
4844	R10:	stack limit (used only if stack checking if enabled)
4845	R11:	argument (frame) pointer
4846	R12:	temporary workspace
4847	R13:	stack pointer
4848	R14:	link register
4849	R15:	program counter
4850
4851    ==> U-Boot will use R8 to hold a pointer to the global data
4852
4853On Nios II, the ABI is documented here:
4854	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4855
4856    ==> U-Boot will use gp to hold a pointer to the global data
4857
4858    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4859    to access small data sections, so gp is free.
4860
4861On NDS32, the following registers are used:
4862
4863	R0-R1:	argument/return
4864	R2-R5:	argument
4865	R15:	temporary register for assembler
4866	R16:	trampoline register
4867	R28:	frame pointer (FP)
4868	R29:	global pointer (GP)
4869	R30:	link register (LP)
4870	R31:	stack pointer (SP)
4871	PC:	program counter (PC)
4872
4873    ==> U-Boot will use R10 to hold a pointer to the global data
4874
4875NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4876or current versions of GCC may "optimize" the code too much.
4877
4878Memory Management:
4879------------------
4880
4881U-Boot runs in system state and uses physical addresses, i.e. the
4882MMU is not used either for address mapping nor for memory protection.
4883
4884The available memory is mapped to fixed addresses using the memory
4885controller. In this process, a contiguous block is formed for each
4886memory type (Flash, SDRAM, SRAM), even when it consists of several
4887physical memory banks.
4888
4889U-Boot is installed in the first 128 kB of the first Flash bank (on
4890TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4891booting and sizing and initializing DRAM, the code relocates itself
4892to the upper end of DRAM. Immediately below the U-Boot code some
4893memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4894configuration setting]. Below that, a structure with global Board
4895Info data is placed, followed by the stack (growing downward).
4896
4897Additionally, some exception handler code is copied to the low 8 kB
4898of DRAM (0x00000000 ... 0x00001FFF).
4899
4900So a typical memory configuration with 16 MB of DRAM could look like
4901this:
4902
4903	0x0000 0000	Exception Vector code
4904	      :
4905	0x0000 1FFF
4906	0x0000 2000	Free for Application Use
4907	      :
4908	      :
4909
4910	      :
4911	      :
4912	0x00FB FF20	Monitor Stack (Growing downward)
4913	0x00FB FFAC	Board Info Data and permanent copy of global data
4914	0x00FC 0000	Malloc Arena
4915	      :
4916	0x00FD FFFF
4917	0x00FE 0000	RAM Copy of Monitor Code
4918	...		eventually: LCD or video framebuffer
4919	...		eventually: pRAM (Protected RAM - unchanged by reset)
4920	0x00FF FFFF	[End of RAM]
4921
4922
4923System Initialization:
4924----------------------
4925
4926In the reset configuration, U-Boot starts at the reset entry point
4927(on most PowerPC systems at address 0x00000100). Because of the reset
4928configuration for CS0# this is a mirror of the onboard Flash memory.
4929To be able to re-map memory U-Boot then jumps to its link address.
4930To be able to implement the initialization code in C, a (small!)
4931initial stack is set up in the internal Dual Ported RAM (in case CPUs
4932which provide such a feature like MPC8xx or MPC8260), or in a locked
4933part of the data cache. After that, U-Boot initializes the CPU core,
4934the caches and the SIU.
4935
4936Next, all (potentially) available memory banks are mapped using a
4937preliminary mapping. For example, we put them on 512 MB boundaries
4938(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4939on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4940programmed for SDRAM access. Using the temporary configuration, a
4941simple memory test is run that determines the size of the SDRAM
4942banks.
4943
4944When there is more than one SDRAM bank, and the banks are of
4945different size, the largest is mapped first. For equal size, the first
4946bank (CS2#) is mapped first. The first mapping is always for address
49470x00000000, with any additional banks following immediately to create
4948contiguous memory starting from 0.
4949
4950Then, the monitor installs itself at the upper end of the SDRAM area
4951and allocates memory for use by malloc() and for the global Board
4952Info data; also, the exception vector code is copied to the low RAM
4953pages, and the final stack is set up.
4954
4955Only after this relocation will you have a "normal" C environment;
4956until that you are restricted in several ways, mostly because you are
4957running from ROM, and because the code will have to be relocated to a
4958new address in RAM.
4959
4960
4961U-Boot Porting Guide:
4962----------------------
4963
4964[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4965list, October 2002]
4966
4967
4968int main(int argc, char *argv[])
4969{
4970	sighandler_t no_more_time;
4971
4972	signal(SIGALRM, no_more_time);
4973	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4974
4975	if (available_money > available_manpower) {
4976		Pay consultant to port U-Boot;
4977		return 0;
4978	}
4979
4980	Download latest U-Boot source;
4981
4982	Subscribe to u-boot mailing list;
4983
4984	if (clueless)
4985		email("Hi, I am new to U-Boot, how do I get started?");
4986
4987	while (learning) {
4988		Read the README file in the top level directory;
4989		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4990		Read applicable doc/*.README;
4991		Read the source, Luke;
4992		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4993	}
4994
4995	if (available_money > toLocalCurrency ($2500))
4996		Buy a BDI3000;
4997	else
4998		Add a lot of aggravation and time;
4999
5000	if (a similar board exists) {	/* hopefully... */
5001		cp -a board/<similar> board/<myboard>
5002		cp include/configs/<similar>.h include/configs/<myboard>.h
5003	} else {
5004		Create your own board support subdirectory;
5005		Create your own board include/configs/<myboard>.h file;
5006	}
5007	Edit new board/<myboard> files
5008	Edit new include/configs/<myboard>.h
5009
5010	while (!accepted) {
5011		while (!running) {
5012			do {
5013				Add / modify source code;
5014			} until (compiles);
5015			Debug;
5016			if (clueless)
5017				email("Hi, I am having problems...");
5018		}
5019		Send patch file to the U-Boot email list;
5020		if (reasonable critiques)
5021			Incorporate improvements from email list code review;
5022		else
5023			Defend code as written;
5024	}
5025
5026	return 0;
5027}
5028
5029void no_more_time (int sig)
5030{
5031      hire_a_guru();
5032}
5033
5034
5035Coding Standards:
5036-----------------
5037
5038All contributions to U-Boot should conform to the Linux kernel
5039coding style; see the file "Documentation/CodingStyle" and the script
5040"scripts/Lindent" in your Linux kernel source directory.
5041
5042Source files originating from a different project (for example the
5043MTD subsystem) are generally exempt from these guidelines and are not
5044reformated to ease subsequent migration to newer versions of those
5045sources.
5046
5047Please note that U-Boot is implemented in C (and to some small parts in
5048Assembler); no C++ is used, so please do not use C++ style comments (//)
5049in your code.
5050
5051Please also stick to the following formatting rules:
5052- remove any trailing white space
5053- use TAB characters for indentation and vertical alignment, not spaces
5054- make sure NOT to use DOS '\r\n' line feeds
5055- do not add more than 2 consecutive empty lines to source files
5056- do not add trailing empty lines to source files
5057
5058Submissions which do not conform to the standards may be returned
5059with a request to reformat the changes.
5060
5061
5062Submitting Patches:
5063-------------------
5064
5065Since the number of patches for U-Boot is growing, we need to
5066establish some rules. Submissions which do not conform to these rules
5067may be rejected, even when they contain important and valuable stuff.
5068
5069Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5070
5071Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5072see http://lists.denx.de/mailman/listinfo/u-boot
5073
5074When you send a patch, please include the following information with
5075it:
5076
5077* For bug fixes: a description of the bug and how your patch fixes
5078  this bug. Please try to include a way of demonstrating that the
5079  patch actually fixes something.
5080
5081* For new features: a description of the feature and your
5082  implementation.
5083
5084* A CHANGELOG entry as plaintext (separate from the patch)
5085
5086* For major contributions, your entry to the CREDITS file
5087
5088* When you add support for a new board, don't forget to add this
5089  board to the MAINTAINERS file, too.
5090
5091* If your patch adds new configuration options, don't forget to
5092  document these in the README file.
5093
5094* The patch itself. If you are using git (which is *strongly*
5095  recommended) you can easily generate the patch using the
5096  "git format-patch". If you then use "git send-email" to send it to
5097  the U-Boot mailing list, you will avoid most of the common problems
5098  with some other mail clients.
5099
5100  If you cannot use git, use "diff -purN OLD NEW". If your version of
5101  diff does not support these options, then get the latest version of
5102  GNU diff.
5103
5104  The current directory when running this command shall be the parent
5105  directory of the U-Boot source tree (i. e. please make sure that
5106  your patch includes sufficient directory information for the
5107  affected files).
5108
5109  We prefer patches as plain text. MIME attachments are discouraged,
5110  and compressed attachments must not be used.
5111
5112* If one logical set of modifications affects or creates several
5113  files, all these changes shall be submitted in a SINGLE patch file.
5114
5115* Changesets that contain different, unrelated modifications shall be
5116  submitted as SEPARATE patches, one patch per changeset.
5117
5118
5119Notes:
5120
5121* Before sending the patch, run the MAKEALL script on your patched
5122  source tree and make sure that no errors or warnings are reported
5123  for any of the boards.
5124
5125* Keep your modifications to the necessary minimum: A patch
5126  containing several unrelated changes or arbitrary reformats will be
5127  returned with a request to re-formatting / split it.
5128
5129* If you modify existing code, make sure that your new code does not
5130  add to the memory footprint of the code ;-) Small is beautiful!
5131  When adding new features, these should compile conditionally only
5132  (using #ifdef), and the resulting code with the new feature
5133  disabled must not need more memory than the old code without your
5134  modification.
5135
5136* Remember that there is a size limit of 100 kB per message on the
5137  u-boot mailing list. Bigger patches will be moderated. If they are
5138  reasonable and not too big, they will be acknowledged. But patches
5139  bigger than the size limit should be avoided.
5140