xref: /openbmc/u-boot/README (revision 76abfa57)
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- Do compresssing for memory range:
1487		CONFIG_CMD_ZIP
1488
1489		If this option is set, it would use zlib deflate method
1490		to compress the specified memory at its best effort.
1491
1492- Compression support:
1493		CONFIG_BZIP2
1494
1495		If this option is set, support for bzip2 compressed
1496		images is included. If not, only uncompressed and gzip
1497		compressed images are supported.
1498
1499		NOTE: the bzip2 algorithm requires a lot of RAM, so
1500		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1501		be at least 4MB.
1502
1503		CONFIG_LZMA
1504
1505		If this option is set, support for lzma compressed
1506		images is included.
1507
1508		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1509		requires an amount of dynamic memory that is given by the
1510		formula:
1511
1512			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1513
1514		Where lc and lp stand for, respectively, Literal context bits
1515		and Literal pos bits.
1516
1517		This value is upper-bounded by 14MB in the worst case. Anyway,
1518		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1519		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1520		a very small buffer.
1521
1522		Use the lzmainfo tool to determinate the lc and lp values and
1523		then calculate the amount of needed dynamic memory (ensuring
1524		the appropriate CONFIG_SYS_MALLOC_LEN value).
1525
1526- MII/PHY support:
1527		CONFIG_PHY_ADDR
1528
1529		The address of PHY on MII bus.
1530
1531		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1532
1533		The clock frequency of the MII bus
1534
1535		CONFIG_PHY_GIGE
1536
1537		If this option is set, support for speed/duplex
1538		detection of gigabit PHY is included.
1539
1540		CONFIG_PHY_RESET_DELAY
1541
1542		Some PHY like Intel LXT971A need extra delay after
1543		reset before any MII register access is possible.
1544		For such PHY, set this option to the usec delay
1545		required. (minimum 300usec for LXT971A)
1546
1547		CONFIG_PHY_CMD_DELAY (ppc4xx)
1548
1549		Some PHY like Intel LXT971A need extra delay after
1550		command issued before MII status register can be read
1551
1552- Ethernet address:
1553		CONFIG_ETHADDR
1554		CONFIG_ETH1ADDR
1555		CONFIG_ETH2ADDR
1556		CONFIG_ETH3ADDR
1557		CONFIG_ETH4ADDR
1558		CONFIG_ETH5ADDR
1559
1560		Define a default value for Ethernet address to use
1561		for the respective Ethernet interface, in case this
1562		is not determined automatically.
1563
1564- IP address:
1565		CONFIG_IPADDR
1566
1567		Define a default value for the IP address to use for
1568		the default Ethernet interface, in case this is not
1569		determined through e.g. bootp.
1570		(Environment variable "ipaddr")
1571
1572- Server IP address:
1573		CONFIG_SERVERIP
1574
1575		Defines a default value for the IP address of a TFTP
1576		server to contact when using the "tftboot" command.
1577		(Environment variable "serverip")
1578
1579		CONFIG_KEEP_SERVERADDR
1580
1581		Keeps the server's MAC address, in the env 'serveraddr'
1582		for passing to bootargs (like Linux's netconsole option)
1583
1584- Gateway IP address:
1585		CONFIG_GATEWAYIP
1586
1587		Defines a default value for the IP address of the
1588		default router where packets to other networks are
1589		sent to.
1590		(Environment variable "gatewayip")
1591
1592- Subnet mask:
1593		CONFIG_NETMASK
1594
1595		Defines a default value for the subnet mask (or
1596		routing prefix) which is used to determine if an IP
1597		address belongs to the local subnet or needs to be
1598		forwarded through a router.
1599		(Environment variable "netmask")
1600
1601- Multicast TFTP Mode:
1602		CONFIG_MCAST_TFTP
1603
1604		Defines whether you want to support multicast TFTP as per
1605		rfc-2090; for example to work with atftp.  Lets lots of targets
1606		tftp down the same boot image concurrently.  Note: the Ethernet
1607		driver in use must provide a function: mcast() to join/leave a
1608		multicast group.
1609
1610- BOOTP Recovery Mode:
1611		CONFIG_BOOTP_RANDOM_DELAY
1612
1613		If you have many targets in a network that try to
1614		boot using BOOTP, you may want to avoid that all
1615		systems send out BOOTP requests at precisely the same
1616		moment (which would happen for instance at recovery
1617		from a power failure, when all systems will try to
1618		boot, thus flooding the BOOTP server. Defining
1619		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1620		inserted before sending out BOOTP requests. The
1621		following delays are inserted then:
1622
1623		1st BOOTP request:	delay 0 ... 1 sec
1624		2nd BOOTP request:	delay 0 ... 2 sec
1625		3rd BOOTP request:	delay 0 ... 4 sec
1626		4th and following
1627		BOOTP requests:		delay 0 ... 8 sec
1628
1629- DHCP Advanced Options:
1630		You can fine tune the DHCP functionality by defining
1631		CONFIG_BOOTP_* symbols:
1632
1633		CONFIG_BOOTP_SUBNETMASK
1634		CONFIG_BOOTP_GATEWAY
1635		CONFIG_BOOTP_HOSTNAME
1636		CONFIG_BOOTP_NISDOMAIN
1637		CONFIG_BOOTP_BOOTPATH
1638		CONFIG_BOOTP_BOOTFILESIZE
1639		CONFIG_BOOTP_DNS
1640		CONFIG_BOOTP_DNS2
1641		CONFIG_BOOTP_SEND_HOSTNAME
1642		CONFIG_BOOTP_NTPSERVER
1643		CONFIG_BOOTP_TIMEOFFSET
1644		CONFIG_BOOTP_VENDOREX
1645		CONFIG_BOOTP_MAY_FAIL
1646
1647		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1648		environment variable, not the BOOTP server.
1649
1650		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1651		after the configured retry count, the call will fail
1652		instead of starting over.  This can be used to fail over
1653		to Link-local IP address configuration if the DHCP server
1654		is not available.
1655
1656		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1657		serverip from a DHCP server, it is possible that more
1658		than one DNS serverip is offered to the client.
1659		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1660		serverip will be stored in the additional environment
1661		variable "dnsip2". The first DNS serverip is always
1662		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1663		is defined.
1664
1665		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1666		to do a dynamic update of a DNS server. To do this, they
1667		need the hostname of the DHCP requester.
1668		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1669		of the "hostname" environment variable is passed as
1670		option 12 to the DHCP server.
1671
1672		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1673
1674		A 32bit value in microseconds for a delay between
1675		receiving a "DHCP Offer" and sending the "DHCP Request".
1676		This fixes a problem with certain DHCP servers that don't
1677		respond 100% of the time to a "DHCP request". E.g. On an
1678		AT91RM9200 processor running at 180MHz, this delay needed
1679		to be *at least* 15,000 usec before a Windows Server 2003
1680		DHCP server would reply 100% of the time. I recommend at
1681		least 50,000 usec to be safe. The alternative is to hope
1682		that one of the retries will be successful but note that
1683		the DHCP timeout and retry process takes a longer than
1684		this delay.
1685
1686 - Link-local IP address negotiation:
1687		Negotiate with other link-local clients on the local network
1688		for an address that doesn't require explicit configuration.
1689		This is especially useful if a DHCP server cannot be guaranteed
1690		to exist in all environments that the device must operate.
1691
1692		See doc/README.link-local for more information.
1693
1694 - CDP Options:
1695		CONFIG_CDP_DEVICE_ID
1696
1697		The device id used in CDP trigger frames.
1698
1699		CONFIG_CDP_DEVICE_ID_PREFIX
1700
1701		A two character string which is prefixed to the MAC address
1702		of the device.
1703
1704		CONFIG_CDP_PORT_ID
1705
1706		A printf format string which contains the ascii name of
1707		the port. Normally is set to "eth%d" which sets
1708		eth0 for the first Ethernet, eth1 for the second etc.
1709
1710		CONFIG_CDP_CAPABILITIES
1711
1712		A 32bit integer which indicates the device capabilities;
1713		0x00000010 for a normal host which does not forwards.
1714
1715		CONFIG_CDP_VERSION
1716
1717		An ascii string containing the version of the software.
1718
1719		CONFIG_CDP_PLATFORM
1720
1721		An ascii string containing the name of the platform.
1722
1723		CONFIG_CDP_TRIGGER
1724
1725		A 32bit integer sent on the trigger.
1726
1727		CONFIG_CDP_POWER_CONSUMPTION
1728
1729		A 16bit integer containing the power consumption of the
1730		device in .1 of milliwatts.
1731
1732		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1733
1734		A byte containing the id of the VLAN.
1735
1736- Status LED:	CONFIG_STATUS_LED
1737
1738		Several configurations allow to display the current
1739		status using a LED. For instance, the LED will blink
1740		fast while running U-Boot code, stop blinking as
1741		soon as a reply to a BOOTP request was received, and
1742		start blinking slow once the Linux kernel is running
1743		(supported by a status LED driver in the Linux
1744		kernel). Defining CONFIG_STATUS_LED enables this
1745		feature in U-Boot.
1746
1747- CAN Support:	CONFIG_CAN_DRIVER
1748
1749		Defining CONFIG_CAN_DRIVER enables CAN driver support
1750		on those systems that support this (optional)
1751		feature, like the TQM8xxL modules.
1752
1753- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1754
1755		These enable I2C serial bus commands. Defining either of
1756		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1757		include the appropriate I2C driver for the selected CPU.
1758
1759		This will allow you to use i2c commands at the u-boot
1760		command line (as long as you set CONFIG_CMD_I2C in
1761		CONFIG_COMMANDS) and communicate with i2c based realtime
1762		clock chips. See common/cmd_i2c.c for a description of the
1763		command line interface.
1764
1765		CONFIG_HARD_I2C selects a hardware I2C controller.
1766
1767		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1768		bit-banging) driver instead of CPM or similar hardware
1769		support for I2C.
1770
1771		There are several other quantities that must also be
1772		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1773
1774		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1775		to be the frequency (in Hz) at which you wish your i2c bus
1776		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1777		the CPU's i2c node address).
1778
1779		Now, the u-boot i2c code for the mpc8xx
1780		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1781		and so its address should therefore be cleared to 0 (See,
1782		eg, MPC823e User's Manual p.16-473). So, set
1783		CONFIG_SYS_I2C_SLAVE to 0.
1784
1785		CONFIG_SYS_I2C_INIT_MPC5XXX
1786
1787		When a board is reset during an i2c bus transfer
1788		chips might think that the current transfer is still
1789		in progress.  Reset the slave devices by sending start
1790		commands until the slave device responds.
1791
1792		That's all that's required for CONFIG_HARD_I2C.
1793
1794		If you use the software i2c interface (CONFIG_SOFT_I2C)
1795		then the following macros need to be defined (examples are
1796		from include/configs/lwmon.h):
1797
1798		I2C_INIT
1799
1800		(Optional). Any commands necessary to enable the I2C
1801		controller or configure ports.
1802
1803		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1804
1805		I2C_PORT
1806
1807		(Only for MPC8260 CPU). The I/O port to use (the code
1808		assumes both bits are on the same port). Valid values
1809		are 0..3 for ports A..D.
1810
1811		I2C_ACTIVE
1812
1813		The code necessary to make the I2C data line active
1814		(driven).  If the data line is open collector, this
1815		define can be null.
1816
1817		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1818
1819		I2C_TRISTATE
1820
1821		The code necessary to make the I2C data line tri-stated
1822		(inactive).  If the data line is open collector, this
1823		define can be null.
1824
1825		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1826
1827		I2C_READ
1828
1829		Code that returns TRUE if the I2C data line is high,
1830		FALSE if it is low.
1831
1832		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1833
1834		I2C_SDA(bit)
1835
1836		If <bit> is TRUE, sets the I2C data line high. If it
1837		is FALSE, it clears it (low).
1838
1839		eg: #define I2C_SDA(bit) \
1840			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1841			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1842
1843		I2C_SCL(bit)
1844
1845		If <bit> is TRUE, sets the I2C clock line high. If it
1846		is FALSE, it clears it (low).
1847
1848		eg: #define I2C_SCL(bit) \
1849			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1850			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1851
1852		I2C_DELAY
1853
1854		This delay is invoked four times per clock cycle so this
1855		controls the rate of data transfer.  The data rate thus
1856		is 1 / (I2C_DELAY * 4). Often defined to be something
1857		like:
1858
1859		#define I2C_DELAY  udelay(2)
1860
1861		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1862
1863		If your arch supports the generic GPIO framework (asm/gpio.h),
1864		then you may alternatively define the two GPIOs that are to be
1865		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1866		have GPIO-based defaults assigned to them as appropriate.
1867
1868		You should define these to the GPIO value as given directly to
1869		the generic GPIO functions.
1870
1871		CONFIG_SYS_I2C_INIT_BOARD
1872
1873		When a board is reset during an i2c bus transfer
1874		chips might think that the current transfer is still
1875		in progress. On some boards it is possible to access
1876		the i2c SCLK line directly, either by using the
1877		processor pin as a GPIO or by having a second pin
1878		connected to the bus. If this option is defined a
1879		custom i2c_init_board() routine in boards/xxx/board.c
1880		is run early in the boot sequence.
1881
1882		CONFIG_SYS_I2C_BOARD_LATE_INIT
1883
1884		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1885		defined a custom i2c_board_late_init() routine in
1886		boards/xxx/board.c is run AFTER the operations in i2c_init()
1887		is completed. This callpoint can be used to unreset i2c bus
1888		using CPU i2c controller register accesses for CPUs whose i2c
1889		controller provide such a method. It is called at the end of
1890		i2c_init() to allow i2c_init operations to setup the i2c bus
1891		controller on the CPU (e.g. setting bus speed & slave address).
1892
1893		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1894
1895		This option enables configuration of bi_iic_fast[] flags
1896		in u-boot bd_info structure based on u-boot environment
1897		variable "i2cfast". (see also i2cfast)
1898
1899		CONFIG_I2C_MULTI_BUS
1900
1901		This option allows the use of multiple I2C buses, each of which
1902		must have a controller.	 At any point in time, only one bus is
1903		active.	 To switch to a different bus, use the 'i2c dev' command.
1904		Note that bus numbering is zero-based.
1905
1906		CONFIG_SYS_I2C_NOPROBES
1907
1908		This option specifies a list of I2C devices that will be skipped
1909		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1910		is set, specify a list of bus-device pairs.  Otherwise, specify
1911		a 1D array of device addresses
1912
1913		e.g.
1914			#undef	CONFIG_I2C_MULTI_BUS
1915			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1916
1917		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1918
1919			#define CONFIG_I2C_MULTI_BUS
1920			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1921
1922		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1923
1924		CONFIG_SYS_SPD_BUS_NUM
1925
1926		If defined, then this indicates the I2C bus number for DDR SPD.
1927		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1928
1929		CONFIG_SYS_RTC_BUS_NUM
1930
1931		If defined, then this indicates the I2C bus number for the RTC.
1932		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1933
1934		CONFIG_SYS_DTT_BUS_NUM
1935
1936		If defined, then this indicates the I2C bus number for the DTT.
1937		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1938
1939		CONFIG_SYS_I2C_DTT_ADDR:
1940
1941		If defined, specifies the I2C address of the DTT device.
1942		If not defined, then U-Boot uses predefined value for
1943		specified DTT device.
1944
1945		CONFIG_FSL_I2C
1946
1947		Define this option if you want to use Freescale's I2C driver in
1948		drivers/i2c/fsl_i2c.c.
1949
1950		CONFIG_I2C_MUX
1951
1952		Define this option if you have I2C devices reached over 1 .. n
1953		I2C Muxes like the pca9544a. This option addes a new I2C
1954		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1955		new I2C Bus to the existing I2C Busses. If you select the
1956		new Bus with "i2c dev", u-bbot sends first the commandos for
1957		the muxes to activate this new "bus".
1958
1959		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1960		feature!
1961
1962		Example:
1963		Adding a new I2C Bus reached over 2 pca9544a muxes
1964			The First mux with address 70 and channel 6
1965			The Second mux with address 71 and channel 4
1966
1967		=> i2c bus pca9544a:70:6:pca9544a:71:4
1968
1969		Use the "i2c bus" command without parameter, to get a list
1970		of I2C Busses with muxes:
1971
1972		=> i2c bus
1973		Busses reached over muxes:
1974		Bus ID: 2
1975		  reached over Mux(es):
1976		    pca9544a@70 ch: 4
1977		Bus ID: 3
1978		  reached over Mux(es):
1979		    pca9544a@70 ch: 6
1980		    pca9544a@71 ch: 4
1981		=>
1982
1983		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1984		u-boot first sends the command to the mux@70 to enable
1985		channel 6, and then the command to the mux@71 to enable
1986		the channel 4.
1987
1988		After that, you can use the "normal" i2c commands as
1989		usual to communicate with your I2C devices behind
1990		the 2 muxes.
1991
1992		This option is actually implemented for the bitbanging
1993		algorithm in common/soft_i2c.c and for the Hardware I2C
1994		Bus on the MPC8260. But it should be not so difficult
1995		to add this option to other architectures.
1996
1997		CONFIG_SOFT_I2C_READ_REPEATED_START
1998
1999		defining this will force the i2c_read() function in
2000		the soft_i2c driver to perform an I2C repeated start
2001		between writing the address pointer and reading the
2002		data.  If this define is omitted the default behaviour
2003		of doing a stop-start sequence will be used.  Most I2C
2004		devices can use either method, but some require one or
2005		the other.
2006
2007- SPI Support:	CONFIG_SPI
2008
2009		Enables SPI driver (so far only tested with
2010		SPI EEPROM, also an instance works with Crystal A/D and
2011		D/As on the SACSng board)
2012
2013		CONFIG_SH_SPI
2014
2015		Enables the driver for SPI controller on SuperH. Currently
2016		only SH7757 is supported.
2017
2018		CONFIG_SPI_X
2019
2020		Enables extended (16-bit) SPI EEPROM addressing.
2021		(symmetrical to CONFIG_I2C_X)
2022
2023		CONFIG_SOFT_SPI
2024
2025		Enables a software (bit-bang) SPI driver rather than
2026		using hardware support. This is a general purpose
2027		driver that only requires three general I/O port pins
2028		(two outputs, one input) to function. If this is
2029		defined, the board configuration must define several
2030		SPI configuration items (port pins to use, etc). For
2031		an example, see include/configs/sacsng.h.
2032
2033		CONFIG_HARD_SPI
2034
2035		Enables a hardware SPI driver for general-purpose reads
2036		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2037		must define a list of chip-select function pointers.
2038		Currently supported on some MPC8xxx processors.	 For an
2039		example, see include/configs/mpc8349emds.h.
2040
2041		CONFIG_MXC_SPI
2042
2043		Enables the driver for the SPI controllers on i.MX and MXC
2044		SoCs. Currently i.MX31/35/51 are supported.
2045
2046- FPGA Support: CONFIG_FPGA
2047
2048		Enables FPGA subsystem.
2049
2050		CONFIG_FPGA_<vendor>
2051
2052		Enables support for specific chip vendors.
2053		(ALTERA, XILINX)
2054
2055		CONFIG_FPGA_<family>
2056
2057		Enables support for FPGA family.
2058		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2059
2060		CONFIG_FPGA_COUNT
2061
2062		Specify the number of FPGA devices to support.
2063
2064		CONFIG_SYS_FPGA_PROG_FEEDBACK
2065
2066		Enable printing of hash marks during FPGA configuration.
2067
2068		CONFIG_SYS_FPGA_CHECK_BUSY
2069
2070		Enable checks on FPGA configuration interface busy
2071		status by the configuration function. This option
2072		will require a board or device specific function to
2073		be written.
2074
2075		CONFIG_FPGA_DELAY
2076
2077		If defined, a function that provides delays in the FPGA
2078		configuration driver.
2079
2080		CONFIG_SYS_FPGA_CHECK_CTRLC
2081		Allow Control-C to interrupt FPGA configuration
2082
2083		CONFIG_SYS_FPGA_CHECK_ERROR
2084
2085		Check for configuration errors during FPGA bitfile
2086		loading. For example, abort during Virtex II
2087		configuration if the INIT_B line goes low (which
2088		indicated a CRC error).
2089
2090		CONFIG_SYS_FPGA_WAIT_INIT
2091
2092		Maximum time to wait for the INIT_B line to deassert
2093		after PROB_B has been deasserted during a Virtex II
2094		FPGA configuration sequence. The default time is 500
2095		ms.
2096
2097		CONFIG_SYS_FPGA_WAIT_BUSY
2098
2099		Maximum time to wait for BUSY to deassert during
2100		Virtex II FPGA configuration. The default is 5 ms.
2101
2102		CONFIG_SYS_FPGA_WAIT_CONFIG
2103
2104		Time to wait after FPGA configuration. The default is
2105		200 ms.
2106
2107- Configuration Management:
2108		CONFIG_IDENT_STRING
2109
2110		If defined, this string will be added to the U-Boot
2111		version information (U_BOOT_VERSION)
2112
2113- Vendor Parameter Protection:
2114
2115		U-Boot considers the values of the environment
2116		variables "serial#" (Board Serial Number) and
2117		"ethaddr" (Ethernet Address) to be parameters that
2118		are set once by the board vendor / manufacturer, and
2119		protects these variables from casual modification by
2120		the user. Once set, these variables are read-only,
2121		and write or delete attempts are rejected. You can
2122		change this behaviour:
2123
2124		If CONFIG_ENV_OVERWRITE is #defined in your config
2125		file, the write protection for vendor parameters is
2126		completely disabled. Anybody can change or delete
2127		these parameters.
2128
2129		Alternatively, if you #define _both_ CONFIG_ETHADDR
2130		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2131		Ethernet address is installed in the environment,
2132		which can be changed exactly ONCE by the user. [The
2133		serial# is unaffected by this, i. e. it remains
2134		read-only.]
2135
2136- Protected RAM:
2137		CONFIG_PRAM
2138
2139		Define this variable to enable the reservation of
2140		"protected RAM", i. e. RAM which is not overwritten
2141		by U-Boot. Define CONFIG_PRAM to hold the number of
2142		kB you want to reserve for pRAM. You can overwrite
2143		this default value by defining an environment
2144		variable "pram" to the number of kB you want to
2145		reserve. Note that the board info structure will
2146		still show the full amount of RAM. If pRAM is
2147		reserved, a new environment variable "mem" will
2148		automatically be defined to hold the amount of
2149		remaining RAM in a form that can be passed as boot
2150		argument to Linux, for instance like that:
2151
2152			setenv bootargs ... mem=\${mem}
2153			saveenv
2154
2155		This way you can tell Linux not to use this memory,
2156		either, which results in a memory region that will
2157		not be affected by reboots.
2158
2159		*WARNING* If your board configuration uses automatic
2160		detection of the RAM size, you must make sure that
2161		this memory test is non-destructive. So far, the
2162		following board configurations are known to be
2163		"pRAM-clean":
2164
2165			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
2166			HERMES, IP860, RPXlite, LWMON, LANTEC,
2167			FLAGADM, TQM8260
2168
2169- Error Recovery:
2170		CONFIG_PANIC_HANG
2171
2172		Define this variable to stop the system in case of a
2173		fatal error, so that you have to reset it manually.
2174		This is probably NOT a good idea for an embedded
2175		system where you want the system to reboot
2176		automatically as fast as possible, but it may be
2177		useful during development since you can try to debug
2178		the conditions that lead to the situation.
2179
2180		CONFIG_NET_RETRY_COUNT
2181
2182		This variable defines the number of retries for
2183		network operations like ARP, RARP, TFTP, or BOOTP
2184		before giving up the operation. If not defined, a
2185		default value of 5 is used.
2186
2187		CONFIG_ARP_TIMEOUT
2188
2189		Timeout waiting for an ARP reply in milliseconds.
2190
2191		CONFIG_NFS_TIMEOUT
2192
2193		Timeout in milliseconds used in NFS protocol.
2194		If you encounter "ERROR: Cannot umount" in nfs command,
2195		try longer timeout such as
2196		#define CONFIG_NFS_TIMEOUT 10000UL
2197
2198- Command Interpreter:
2199		CONFIG_AUTO_COMPLETE
2200
2201		Enable auto completion of commands using TAB.
2202
2203		Note that this feature has NOT been implemented yet
2204		for the "hush" shell.
2205
2206
2207		CONFIG_SYS_HUSH_PARSER
2208
2209		Define this variable to enable the "hush" shell (from
2210		Busybox) as command line interpreter, thus enabling
2211		powerful command line syntax like
2212		if...then...else...fi conditionals or `&&' and '||'
2213		constructs ("shell scripts").
2214
2215		If undefined, you get the old, much simpler behaviour
2216		with a somewhat smaller memory footprint.
2217
2218
2219		CONFIG_SYS_PROMPT_HUSH_PS2
2220
2221		This defines the secondary prompt string, which is
2222		printed when the command interpreter needs more input
2223		to complete a command. Usually "> ".
2224
2225	Note:
2226
2227		In the current implementation, the local variables
2228		space and global environment variables space are
2229		separated. Local variables are those you define by
2230		simply typing `name=value'. To access a local
2231		variable later on, you have write `$name' or
2232		`${name}'; to execute the contents of a variable
2233		directly type `$name' at the command prompt.
2234
2235		Global environment variables are those you use
2236		setenv/printenv to work with. To run a command stored
2237		in such a variable, you need to use the run command,
2238		and you must not use the '$' sign to access them.
2239
2240		To store commands and special characters in a
2241		variable, please use double quotation marks
2242		surrounding the whole text of the variable, instead
2243		of the backslashes before semicolons and special
2244		symbols.
2245
2246- Commandline Editing and History:
2247		CONFIG_CMDLINE_EDITING
2248
2249		Enable editing and History functions for interactive
2250		commandline input operations
2251
2252- Default Environment:
2253		CONFIG_EXTRA_ENV_SETTINGS
2254
2255		Define this to contain any number of null terminated
2256		strings (variable = value pairs) that will be part of
2257		the default environment compiled into the boot image.
2258
2259		For example, place something like this in your
2260		board's config file:
2261
2262		#define CONFIG_EXTRA_ENV_SETTINGS \
2263			"myvar1=value1\0" \
2264			"myvar2=value2\0"
2265
2266		Warning: This method is based on knowledge about the
2267		internal format how the environment is stored by the
2268		U-Boot code. This is NOT an official, exported
2269		interface! Although it is unlikely that this format
2270		will change soon, there is no guarantee either.
2271		You better know what you are doing here.
2272
2273		Note: overly (ab)use of the default environment is
2274		discouraged. Make sure to check other ways to preset
2275		the environment like the "source" command or the
2276		boot command first.
2277
2278		CONFIG_ENV_VARS_UBOOT_CONFIG
2279
2280		Define this in order to add variables describing the
2281		U-Boot build configuration to the default environment.
2282		These will be named arch, cpu, board, vendor, and soc.
2283
2284		Enabling this option will cause the following to be defined:
2285
2286		- CONFIG_SYS_ARCH
2287		- CONFIG_SYS_CPU
2288		- CONFIG_SYS_BOARD
2289		- CONFIG_SYS_VENDOR
2290		- CONFIG_SYS_SOC
2291
2292- DataFlash Support:
2293		CONFIG_HAS_DATAFLASH
2294
2295		Defining this option enables DataFlash features and
2296		allows to read/write in Dataflash via the standard
2297		commands cp, md...
2298
2299- Serial Flash support
2300		CONFIG_CMD_SF
2301
2302		Defining this option enables SPI flash commands
2303		'sf probe/read/write/erase/update'.
2304
2305		Usage requires an initial 'probe' to define the serial
2306		flash parameters, followed by read/write/erase/update
2307		commands.
2308
2309		The following defaults may be provided by the platform
2310		to handle the common case when only a single serial
2311		flash is present on the system.
2312
2313		CONFIG_SF_DEFAULT_BUS		Bus identifier
2314		CONFIG_SF_DEFAULT_CS		Chip-select
2315		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2316		CONFIG_SF_DEFAULT_SPEED		in Hz
2317
2318- SystemACE Support:
2319		CONFIG_SYSTEMACE
2320
2321		Adding this option adds support for Xilinx SystemACE
2322		chips attached via some sort of local bus. The address
2323		of the chip must also be defined in the
2324		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2325
2326		#define CONFIG_SYSTEMACE
2327		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2328
2329		When SystemACE support is added, the "ace" device type
2330		becomes available to the fat commands, i.e. fatls.
2331
2332- TFTP Fixed UDP Port:
2333		CONFIG_TFTP_PORT
2334
2335		If this is defined, the environment variable tftpsrcp
2336		is used to supply the TFTP UDP source port value.
2337		If tftpsrcp isn't defined, the normal pseudo-random port
2338		number generator is used.
2339
2340		Also, the environment variable tftpdstp is used to supply
2341		the TFTP UDP destination port value.  If tftpdstp isn't
2342		defined, the normal port 69 is used.
2343
2344		The purpose for tftpsrcp is to allow a TFTP server to
2345		blindly start the TFTP transfer using the pre-configured
2346		target IP address and UDP port. This has the effect of
2347		"punching through" the (Windows XP) firewall, allowing
2348		the remainder of the TFTP transfer to proceed normally.
2349		A better solution is to properly configure the firewall,
2350		but sometimes that is not allowed.
2351
2352- Show boot progress:
2353		CONFIG_SHOW_BOOT_PROGRESS
2354
2355		Defining this option allows to add some board-
2356		specific code (calling a user-provided function
2357		"show_boot_progress(int)") that enables you to show
2358		the system's boot progress on some display (for
2359		example, some LED's) on your board. At the moment,
2360		the following checkpoints are implemented:
2361
2362- Detailed boot stage timing
2363		CONFIG_BOOTSTAGE
2364		Define this option to get detailed timing of each stage
2365		of the boot process.
2366
2367		CONFIG_BOOTSTAGE_USER_COUNT
2368		This is the number of available user bootstage records.
2369		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2370		a new ID will be allocated from this stash. If you exceed
2371		the limit, recording will stop.
2372
2373		CONFIG_BOOTSTAGE_REPORT
2374		Define this to print a report before boot, similar to this:
2375
2376		Timer summary in microseconds:
2377		       Mark    Elapsed  Stage
2378			  0          0  reset
2379		  3,575,678  3,575,678  board_init_f start
2380		  3,575,695         17  arch_cpu_init A9
2381		  3,575,777         82  arch_cpu_init done
2382		  3,659,598     83,821  board_init_r start
2383		  3,910,375    250,777  main_loop
2384		 29,916,167 26,005,792  bootm_start
2385		 30,361,327    445,160  start_kernel
2386
2387Legacy uImage format:
2388
2389  Arg	Where			When
2390    1	common/cmd_bootm.c	before attempting to boot an image
2391   -1	common/cmd_bootm.c	Image header has bad	 magic number
2392    2	common/cmd_bootm.c	Image header has correct magic number
2393   -2	common/cmd_bootm.c	Image header has bad	 checksum
2394    3	common/cmd_bootm.c	Image header has correct checksum
2395   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2396    4	common/cmd_bootm.c	Image data   has correct checksum
2397   -4	common/cmd_bootm.c	Image is for unsupported architecture
2398    5	common/cmd_bootm.c	Architecture check OK
2399   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2400    6	common/cmd_bootm.c	Image Type check OK
2401   -6	common/cmd_bootm.c	gunzip uncompression error
2402   -7	common/cmd_bootm.c	Unimplemented compression type
2403    7	common/cmd_bootm.c	Uncompression OK
2404    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2405   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2406
2407    9	common/image.c		Start initial ramdisk verification
2408  -10	common/image.c		Ramdisk header has bad	   magic number
2409  -11	common/image.c		Ramdisk header has bad	   checksum
2410   10	common/image.c		Ramdisk header is OK
2411  -12	common/image.c		Ramdisk data   has bad	   checksum
2412   11	common/image.c		Ramdisk data   has correct checksum
2413   12	common/image.c		Ramdisk verification complete, start loading
2414  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2415   13	common/image.c		Start multifile image verification
2416   14	common/image.c		No initial ramdisk, no multifile, continue.
2417
2418   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2419
2420  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2421  -31	post/post.c		POST test failed, detected by post_output_backlog()
2422  -32	post/post.c		POST test failed, detected by post_run_single()
2423
2424   34	common/cmd_doc.c	before loading a Image from a DOC device
2425  -35	common/cmd_doc.c	Bad usage of "doc" command
2426   35	common/cmd_doc.c	correct usage of "doc" command
2427  -36	common/cmd_doc.c	No boot device
2428   36	common/cmd_doc.c	correct boot device
2429  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2430   37	common/cmd_doc.c	correct chip ID found, device available
2431  -38	common/cmd_doc.c	Read Error on boot device
2432   38	common/cmd_doc.c	reading Image header from DOC device OK
2433  -39	common/cmd_doc.c	Image header has bad magic number
2434   39	common/cmd_doc.c	Image header has correct magic number
2435  -40	common/cmd_doc.c	Error reading Image from DOC device
2436   40	common/cmd_doc.c	Image header has correct magic number
2437   41	common/cmd_ide.c	before loading a Image from a IDE device
2438  -42	common/cmd_ide.c	Bad usage of "ide" command
2439   42	common/cmd_ide.c	correct usage of "ide" command
2440  -43	common/cmd_ide.c	No boot device
2441   43	common/cmd_ide.c	boot device found
2442  -44	common/cmd_ide.c	Device not available
2443   44	common/cmd_ide.c	Device available
2444  -45	common/cmd_ide.c	wrong partition selected
2445   45	common/cmd_ide.c	partition selected
2446  -46	common/cmd_ide.c	Unknown partition table
2447   46	common/cmd_ide.c	valid partition table found
2448  -47	common/cmd_ide.c	Invalid partition type
2449   47	common/cmd_ide.c	correct partition type
2450  -48	common/cmd_ide.c	Error reading Image Header on boot device
2451   48	common/cmd_ide.c	reading Image Header from IDE device OK
2452  -49	common/cmd_ide.c	Image header has bad magic number
2453   49	common/cmd_ide.c	Image header has correct magic number
2454  -50	common/cmd_ide.c	Image header has bad	 checksum
2455   50	common/cmd_ide.c	Image header has correct checksum
2456  -51	common/cmd_ide.c	Error reading Image from IDE device
2457   51	common/cmd_ide.c	reading Image from IDE device OK
2458   52	common/cmd_nand.c	before loading a Image from a NAND device
2459  -53	common/cmd_nand.c	Bad usage of "nand" command
2460   53	common/cmd_nand.c	correct usage of "nand" command
2461  -54	common/cmd_nand.c	No boot device
2462   54	common/cmd_nand.c	boot device found
2463  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2464   55	common/cmd_nand.c	correct chip ID found, device available
2465  -56	common/cmd_nand.c	Error reading Image Header on boot device
2466   56	common/cmd_nand.c	reading Image Header from NAND device OK
2467  -57	common/cmd_nand.c	Image header has bad magic number
2468   57	common/cmd_nand.c	Image header has correct magic number
2469  -58	common/cmd_nand.c	Error reading Image from NAND device
2470   58	common/cmd_nand.c	reading Image from NAND device OK
2471
2472  -60	common/env_common.c	Environment has a bad CRC, using default
2473
2474   64	net/eth.c		starting with Ethernet configuration.
2475  -64	net/eth.c		no Ethernet found.
2476   65	net/eth.c		Ethernet found.
2477
2478  -80	common/cmd_net.c	usage wrong
2479   80	common/cmd_net.c	before calling NetLoop()
2480  -81	common/cmd_net.c	some error in NetLoop() occurred
2481   81	common/cmd_net.c	NetLoop() back without error
2482  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2483   82	common/cmd_net.c	trying automatic boot
2484   83	common/cmd_net.c	running "source" command
2485  -83	common/cmd_net.c	some error in automatic boot or "source" command
2486   84	common/cmd_net.c	end without errors
2487
2488FIT uImage format:
2489
2490  Arg	Where			When
2491  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2492 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2493  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2494 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2495  102	common/cmd_bootm.c	Kernel unit name specified
2496 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2497  103	common/cmd_bootm.c	Found configuration node
2498  104	common/cmd_bootm.c	Got kernel subimage node offset
2499 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2500  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2501 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2502  106	common/cmd_bootm.c	Architecture check OK
2503 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2504  107	common/cmd_bootm.c	Kernel subimage type OK
2505 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2506  108	common/cmd_bootm.c	Got kernel subimage data/size
2507 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2508 -109	common/cmd_bootm.c	Can't get kernel subimage type
2509 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2510 -111	common/cmd_bootm.c	Can't get kernel subimage os
2511 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2512 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2513
2514  120	common/image.c		Start initial ramdisk verification
2515 -120	common/image.c		Ramdisk FIT image has incorrect format
2516  121	common/image.c		Ramdisk FIT image has correct format
2517  122	common/image.c		No ramdisk subimage unit name, using configuration
2518 -122	common/image.c		Can't get configuration for ramdisk subimage
2519  123	common/image.c		Ramdisk unit name specified
2520 -124	common/image.c		Can't get ramdisk subimage node offset
2521  125	common/image.c		Got ramdisk subimage node offset
2522 -125	common/image.c		Ramdisk subimage hash verification failed
2523  126	common/image.c		Ramdisk subimage hash verification OK
2524 -126	common/image.c		Ramdisk subimage for unsupported architecture
2525  127	common/image.c		Architecture check OK
2526 -127	common/image.c		Can't get ramdisk subimage data/size
2527  128	common/image.c		Got ramdisk subimage data/size
2528  129	common/image.c		Can't get ramdisk load address
2529 -129	common/image.c		Got ramdisk load address
2530
2531 -130	common/cmd_doc.c	Incorrect FIT image format
2532  131	common/cmd_doc.c	FIT image format OK
2533
2534 -140	common/cmd_ide.c	Incorrect FIT image format
2535  141	common/cmd_ide.c	FIT image format OK
2536
2537 -150	common/cmd_nand.c	Incorrect FIT image format
2538  151	common/cmd_nand.c	FIT image format OK
2539
2540- Standalone program support:
2541		CONFIG_STANDALONE_LOAD_ADDR
2542
2543		This option defines a board specific value for the
2544		address where standalone program gets loaded, thus
2545		overwriting the architecture dependent default
2546		settings.
2547
2548- Frame Buffer Address:
2549		CONFIG_FB_ADDR
2550
2551		Define CONFIG_FB_ADDR if you want to use specific
2552		address for frame buffer.
2553		Then system will reserve the frame buffer address to
2554		defined address instead of lcd_setmem (this function
2555		grabs the memory for frame buffer by panel's size).
2556
2557		Please see board_init_f function.
2558
2559- Automatic software updates via TFTP server
2560		CONFIG_UPDATE_TFTP
2561		CONFIG_UPDATE_TFTP_CNT_MAX
2562		CONFIG_UPDATE_TFTP_MSEC_MAX
2563
2564		These options enable and control the auto-update feature;
2565		for a more detailed description refer to doc/README.update.
2566
2567- MTD Support (mtdparts command, UBI support)
2568		CONFIG_MTD_DEVICE
2569
2570		Adds the MTD device infrastructure from the Linux kernel.
2571		Needed for mtdparts command support.
2572
2573		CONFIG_MTD_PARTITIONS
2574
2575		Adds the MTD partitioning infrastructure from the Linux
2576		kernel. Needed for UBI support.
2577
2578- SPL framework
2579		CONFIG_SPL
2580		Enable building of SPL globally.
2581
2582		CONFIG_SPL_LDSCRIPT
2583		LDSCRIPT for linking the SPL binary.
2584
2585		CONFIG_SPL_MAX_SIZE
2586		Maximum binary size (text, data and rodata) of the SPL binary.
2587
2588		CONFIG_SPL_TEXT_BASE
2589		TEXT_BASE for linking the SPL binary.
2590
2591		CONFIG_SPL_BSS_START_ADDR
2592		Link address for the BSS within the SPL binary.
2593
2594		CONFIG_SPL_BSS_MAX_SIZE
2595		Maximum binary size of the BSS section of the SPL binary.
2596
2597		CONFIG_SPL_STACK
2598		Adress of the start of the stack SPL will use
2599
2600		CONFIG_SYS_SPL_MALLOC_START
2601		Starting address of the malloc pool used in SPL.
2602
2603		CONFIG_SYS_SPL_MALLOC_SIZE
2604		The size of the malloc pool used in SPL.
2605
2606		CONFIG_SPL_FRAMEWORK
2607		Enable the SPL framework under common/.  This framework
2608		supports MMC, NAND and YMODEM loading of U-Boot and NAND
2609		NAND loading of the Linux Kernel.
2610
2611		CONFIG_SPL_DISPLAY_PRINT
2612		For ARM, enable an optional function to print more information
2613		about the running system.
2614
2615		CONFIG_SPL_LIBCOMMON_SUPPORT
2616		Support for common/libcommon.o in SPL binary
2617
2618		CONFIG_SPL_LIBDISK_SUPPORT
2619		Support for disk/libdisk.o in SPL binary
2620
2621		CONFIG_SPL_I2C_SUPPORT
2622		Support for drivers/i2c/libi2c.o in SPL binary
2623
2624		CONFIG_SPL_GPIO_SUPPORT
2625		Support for drivers/gpio/libgpio.o in SPL binary
2626
2627		CONFIG_SPL_MMC_SUPPORT
2628		Support for drivers/mmc/libmmc.o in SPL binary
2629
2630		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2631		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2632		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2633		Address, size and partition on the MMC to load U-Boot from
2634		when the MMC is being used in raw mode.
2635
2636		CONFIG_SPL_FAT_SUPPORT
2637		Support for fs/fat/libfat.o in SPL binary
2638
2639		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2640		Filename to read to load U-Boot when reading from FAT
2641
2642		CONFIG_SPL_NAND_SIMPLE
2643		Support for drivers/mtd/nand/libnand.o in SPL binary
2644
2645		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2646		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2647		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2648		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2649		CONFIG_SYS_NAND_ECCBYTES
2650		Defines the size and behavior of the NAND that SPL uses
2651		to read U-Boot with CONFIG_SPL_NAND_SIMPLE
2652
2653		CONFIG_SYS_NAND_U_BOOT_OFFS
2654		Location in NAND for CONFIG_SPL_NAND_SIMPLE to read U-Boot
2655		from.
2656
2657		CONFIG_SYS_NAND_U_BOOT_START
2658		Location in memory for CONFIG_SPL_NAND_SIMPLE to load U-Boot
2659		to.
2660
2661		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2662		Define this if you need to first read the OOB and then the
2663		data. This is used for example on davinci plattforms.
2664
2665		CONFIG_SPL_OMAP3_ID_NAND
2666		Support for an OMAP3-specific set of functions to return the
2667		ID and MFR of the first attached NAND chip, if present.
2668
2669		CONFIG_SPL_SERIAL_SUPPORT
2670		Support for drivers/serial/libserial.o in SPL binary
2671
2672		CONFIG_SPL_SPI_FLASH_SUPPORT
2673		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2674
2675		CONFIG_SPL_SPI_SUPPORT
2676		Support for drivers/spi/libspi.o in SPL binary
2677
2678		CONFIG_SPL_RAM_DEVICE
2679		Support for running image already present in ram, in SPL binary
2680
2681		CONFIG_SPL_LIBGENERIC_SUPPORT
2682		Support for lib/libgeneric.o in SPL binary
2683
2684Modem Support:
2685--------------
2686
2687[so far only for SMDK2400 boards]
2688
2689- Modem support enable:
2690		CONFIG_MODEM_SUPPORT
2691
2692- RTS/CTS Flow control enable:
2693		CONFIG_HWFLOW
2694
2695- Modem debug support:
2696		CONFIG_MODEM_SUPPORT_DEBUG
2697
2698		Enables debugging stuff (char screen[1024], dbg())
2699		for modem support. Useful only with BDI2000.
2700
2701- Interrupt support (PPC):
2702
2703		There are common interrupt_init() and timer_interrupt()
2704		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2705		for CPU specific initialization. interrupt_init_cpu()
2706		should set decrementer_count to appropriate value. If
2707		CPU resets decrementer automatically after interrupt
2708		(ppc4xx) it should set decrementer_count to zero.
2709		timer_interrupt() calls timer_interrupt_cpu() for CPU
2710		specific handling. If board has watchdog / status_led
2711		/ other_activity_monitor it works automatically from
2712		general timer_interrupt().
2713
2714- General:
2715
2716		In the target system modem support is enabled when a
2717		specific key (key combination) is pressed during
2718		power-on. Otherwise U-Boot will boot normally
2719		(autoboot). The key_pressed() function is called from
2720		board_init(). Currently key_pressed() is a dummy
2721		function, returning 1 and thus enabling modem
2722		initialization.
2723
2724		If there are no modem init strings in the
2725		environment, U-Boot proceed to autoboot; the
2726		previous output (banner, info printfs) will be
2727		suppressed, though.
2728
2729		See also: doc/README.Modem
2730
2731Board initialization settings:
2732------------------------------
2733
2734During Initialization u-boot calls a number of board specific functions
2735to allow the preparation of board specific prerequisites, e.g. pin setup
2736before drivers are initialized. To enable these callbacks the
2737following configuration macros have to be defined. Currently this is
2738architecture specific, so please check arch/your_architecture/lib/board.c
2739typically in board_init_f() and board_init_r().
2740
2741- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2742- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2743- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2744- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2745
2746Configuration Settings:
2747-----------------------
2748
2749- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2750		undefine this when you're short of memory.
2751
2752- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2753		width of the commands listed in the 'help' command output.
2754
2755- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2756		prompt for user input.
2757
2758- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2759
2760- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2761
2762- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2763
2764- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2765		the application (usually a Linux kernel) when it is
2766		booted
2767
2768- CONFIG_SYS_BAUDRATE_TABLE:
2769		List of legal baudrate settings for this board.
2770
2771- CONFIG_SYS_CONSOLE_INFO_QUIET
2772		Suppress display of console information at boot.
2773
2774- CONFIG_SYS_CONSOLE_IS_IN_ENV
2775		If the board specific function
2776			extern int overwrite_console (void);
2777		returns 1, the stdin, stderr and stdout are switched to the
2778		serial port, else the settings in the environment are used.
2779
2780- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2781		Enable the call to overwrite_console().
2782
2783- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2784		Enable overwrite of previous console environment settings.
2785
2786- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2787		Begin and End addresses of the area used by the
2788		simple memory test.
2789
2790- CONFIG_SYS_ALT_MEMTEST:
2791		Enable an alternate, more extensive memory test.
2792
2793- CONFIG_SYS_MEMTEST_SCRATCH:
2794		Scratch address used by the alternate memory test
2795		You only need to set this if address zero isn't writeable
2796
2797- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2798		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2799		this specified memory area will get subtracted from the top
2800		(end) of RAM and won't get "touched" at all by U-Boot. By
2801		fixing up gd->ram_size the Linux kernel should gets passed
2802		the now "corrected" memory size and won't touch it either.
2803		This should work for arch/ppc and arch/powerpc. Only Linux
2804		board ports in arch/powerpc with bootwrapper support that
2805		recalculate the memory size from the SDRAM controller setup
2806		will have to get fixed in Linux additionally.
2807
2808		This option can be used as a workaround for the 440EPx/GRx
2809		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2810		be touched.
2811
2812		WARNING: Please make sure that this value is a multiple of
2813		the Linux page size (normally 4k). If this is not the case,
2814		then the end address of the Linux memory will be located at a
2815		non page size aligned address and this could cause major
2816		problems.
2817
2818- CONFIG_SYS_TFTP_LOADADDR:
2819		Default load address for network file downloads
2820
2821- CONFIG_SYS_LOADS_BAUD_CHANGE:
2822		Enable temporary baudrate change while serial download
2823
2824- CONFIG_SYS_SDRAM_BASE:
2825		Physical start address of SDRAM. _Must_ be 0 here.
2826
2827- CONFIG_SYS_MBIO_BASE:
2828		Physical start address of Motherboard I/O (if using a
2829		Cogent motherboard)
2830
2831- CONFIG_SYS_FLASH_BASE:
2832		Physical start address of Flash memory.
2833
2834- CONFIG_SYS_MONITOR_BASE:
2835		Physical start address of boot monitor code (set by
2836		make config files to be same as the text base address
2837		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2838		CONFIG_SYS_FLASH_BASE when booting from flash.
2839
2840- CONFIG_SYS_MONITOR_LEN:
2841		Size of memory reserved for monitor code, used to
2842		determine _at_compile_time_ (!) if the environment is
2843		embedded within the U-Boot image, or in a separate
2844		flash sector.
2845
2846- CONFIG_SYS_MALLOC_LEN:
2847		Size of DRAM reserved for malloc() use.
2848
2849- CONFIG_SYS_BOOTM_LEN:
2850		Normally compressed uImages are limited to an
2851		uncompressed size of 8 MBytes. If this is not enough,
2852		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2853		to adjust this setting to your needs.
2854
2855- CONFIG_SYS_BOOTMAPSZ:
2856		Maximum size of memory mapped by the startup code of
2857		the Linux kernel; all data that must be processed by
2858		the Linux kernel (bd_info, boot arguments, FDT blob if
2859		used) must be put below this limit, unless "bootm_low"
2860		enviroment variable is defined and non-zero. In such case
2861		all data for the Linux kernel must be between "bootm_low"
2862		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2863		variable "bootm_mapsize" will override the value of
2864		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2865		then the value in "bootm_size" will be used instead.
2866
2867- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2868		Enable initrd_high functionality.  If defined then the
2869		initrd_high feature is enabled and the bootm ramdisk subcommand
2870		is enabled.
2871
2872- CONFIG_SYS_BOOT_GET_CMDLINE:
2873		Enables allocating and saving kernel cmdline in space between
2874		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2875
2876- CONFIG_SYS_BOOT_GET_KBD:
2877		Enables allocating and saving a kernel copy of the bd_info in
2878		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2879
2880- CONFIG_SYS_MAX_FLASH_BANKS:
2881		Max number of Flash memory banks
2882
2883- CONFIG_SYS_MAX_FLASH_SECT:
2884		Max number of sectors on a Flash chip
2885
2886- CONFIG_SYS_FLASH_ERASE_TOUT:
2887		Timeout for Flash erase operations (in ms)
2888
2889- CONFIG_SYS_FLASH_WRITE_TOUT:
2890		Timeout for Flash write operations (in ms)
2891
2892- CONFIG_SYS_FLASH_LOCK_TOUT
2893		Timeout for Flash set sector lock bit operation (in ms)
2894
2895- CONFIG_SYS_FLASH_UNLOCK_TOUT
2896		Timeout for Flash clear lock bits operation (in ms)
2897
2898- CONFIG_SYS_FLASH_PROTECTION
2899		If defined, hardware flash sectors protection is used
2900		instead of U-Boot software protection.
2901
2902- CONFIG_SYS_DIRECT_FLASH_TFTP:
2903
2904		Enable TFTP transfers directly to flash memory;
2905		without this option such a download has to be
2906		performed in two steps: (1) download to RAM, and (2)
2907		copy from RAM to flash.
2908
2909		The two-step approach is usually more reliable, since
2910		you can check if the download worked before you erase
2911		the flash, but in some situations (when system RAM is
2912		too limited to allow for a temporary copy of the
2913		downloaded image) this option may be very useful.
2914
2915- CONFIG_SYS_FLASH_CFI:
2916		Define if the flash driver uses extra elements in the
2917		common flash structure for storing flash geometry.
2918
2919- CONFIG_FLASH_CFI_DRIVER
2920		This option also enables the building of the cfi_flash driver
2921		in the drivers directory
2922
2923- CONFIG_FLASH_CFI_MTD
2924		This option enables the building of the cfi_mtd driver
2925		in the drivers directory. The driver exports CFI flash
2926		to the MTD layer.
2927
2928- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2929		Use buffered writes to flash.
2930
2931- CONFIG_FLASH_SPANSION_S29WS_N
2932		s29ws-n MirrorBit flash has non-standard addresses for buffered
2933		write commands.
2934
2935- CONFIG_SYS_FLASH_QUIET_TEST
2936		If this option is defined, the common CFI flash doesn't
2937		print it's warning upon not recognized FLASH banks. This
2938		is useful, if some of the configured banks are only
2939		optionally available.
2940
2941- CONFIG_FLASH_SHOW_PROGRESS
2942		If defined (must be an integer), print out countdown
2943		digits and dots.  Recommended value: 45 (9..1) for 80
2944		column displays, 15 (3..1) for 40 column displays.
2945
2946- CONFIG_SYS_RX_ETH_BUFFER:
2947		Defines the number of Ethernet receive buffers. On some
2948		Ethernet controllers it is recommended to set this value
2949		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2950		buffers can be full shortly after enabling the interface
2951		on high Ethernet traffic.
2952		Defaults to 4 if not defined.
2953
2954- CONFIG_ENV_MAX_ENTRIES
2955
2956	Maximum number of entries in the hash table that is used
2957	internally to store the environment settings. The default
2958	setting is supposed to be generous and should work in most
2959	cases. This setting can be used to tune behaviour; see
2960	lib/hashtable.c for details.
2961
2962The following definitions that deal with the placement and management
2963of environment data (variable area); in general, we support the
2964following configurations:
2965
2966- CONFIG_BUILD_ENVCRC:
2967
2968	Builds up envcrc with the target environment so that external utils
2969	may easily extract it and embed it in final U-Boot images.
2970
2971- CONFIG_ENV_IS_IN_FLASH:
2972
2973	Define this if the environment is in flash memory.
2974
2975	a) The environment occupies one whole flash sector, which is
2976	   "embedded" in the text segment with the U-Boot code. This
2977	   happens usually with "bottom boot sector" or "top boot
2978	   sector" type flash chips, which have several smaller
2979	   sectors at the start or the end. For instance, such a
2980	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2981	   such a case you would place the environment in one of the
2982	   4 kB sectors - with U-Boot code before and after it. With
2983	   "top boot sector" type flash chips, you would put the
2984	   environment in one of the last sectors, leaving a gap
2985	   between U-Boot and the environment.
2986
2987	- CONFIG_ENV_OFFSET:
2988
2989	   Offset of environment data (variable area) to the
2990	   beginning of flash memory; for instance, with bottom boot
2991	   type flash chips the second sector can be used: the offset
2992	   for this sector is given here.
2993
2994	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2995
2996	- CONFIG_ENV_ADDR:
2997
2998	   This is just another way to specify the start address of
2999	   the flash sector containing the environment (instead of
3000	   CONFIG_ENV_OFFSET).
3001
3002	- CONFIG_ENV_SECT_SIZE:
3003
3004	   Size of the sector containing the environment.
3005
3006
3007	b) Sometimes flash chips have few, equal sized, BIG sectors.
3008	   In such a case you don't want to spend a whole sector for
3009	   the environment.
3010
3011	- CONFIG_ENV_SIZE:
3012
3013	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3014	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3015	   of this flash sector for the environment. This saves
3016	   memory for the RAM copy of the environment.
3017
3018	   It may also save flash memory if you decide to use this
3019	   when your environment is "embedded" within U-Boot code,
3020	   since then the remainder of the flash sector could be used
3021	   for U-Boot code. It should be pointed out that this is
3022	   STRONGLY DISCOURAGED from a robustness point of view:
3023	   updating the environment in flash makes it always
3024	   necessary to erase the WHOLE sector. If something goes
3025	   wrong before the contents has been restored from a copy in
3026	   RAM, your target system will be dead.
3027
3028	- CONFIG_ENV_ADDR_REDUND
3029	  CONFIG_ENV_SIZE_REDUND
3030
3031	   These settings describe a second storage area used to hold
3032	   a redundant copy of the environment data, so that there is
3033	   a valid backup copy in case there is a power failure during
3034	   a "saveenv" operation.
3035
3036BE CAREFUL! Any changes to the flash layout, and some changes to the
3037source code will make it necessary to adapt <board>/u-boot.lds*
3038accordingly!
3039
3040
3041- CONFIG_ENV_IS_IN_NVRAM:
3042
3043	Define this if you have some non-volatile memory device
3044	(NVRAM, battery buffered SRAM) which you want to use for the
3045	environment.
3046
3047	- CONFIG_ENV_ADDR:
3048	- CONFIG_ENV_SIZE:
3049
3050	  These two #defines are used to determine the memory area you
3051	  want to use for environment. It is assumed that this memory
3052	  can just be read and written to, without any special
3053	  provision.
3054
3055BE CAREFUL! The first access to the environment happens quite early
3056in U-Boot initalization (when we try to get the setting of for the
3057console baudrate). You *MUST* have mapped your NVRAM area then, or
3058U-Boot will hang.
3059
3060Please note that even with NVRAM we still use a copy of the
3061environment in RAM: we could work on NVRAM directly, but we want to
3062keep settings there always unmodified except somebody uses "saveenv"
3063to save the current settings.
3064
3065
3066- CONFIG_ENV_IS_IN_EEPROM:
3067
3068	Use this if you have an EEPROM or similar serial access
3069	device and a driver for it.
3070
3071	- CONFIG_ENV_OFFSET:
3072	- CONFIG_ENV_SIZE:
3073
3074	  These two #defines specify the offset and size of the
3075	  environment area within the total memory of your EEPROM.
3076
3077	- CONFIG_SYS_I2C_EEPROM_ADDR:
3078	  If defined, specified the chip address of the EEPROM device.
3079	  The default address is zero.
3080
3081	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3082	  If defined, the number of bits used to address bytes in a
3083	  single page in the EEPROM device.  A 64 byte page, for example
3084	  would require six bits.
3085
3086	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3087	  If defined, the number of milliseconds to delay between
3088	  page writes.	The default is zero milliseconds.
3089
3090	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3091	  The length in bytes of the EEPROM memory array address.  Note
3092	  that this is NOT the chip address length!
3093
3094	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3095	  EEPROM chips that implement "address overflow" are ones
3096	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3097	  address and the extra bits end up in the "chip address" bit
3098	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3099	  byte chips.
3100
3101	  Note that we consider the length of the address field to
3102	  still be one byte because the extra address bits are hidden
3103	  in the chip address.
3104
3105	- CONFIG_SYS_EEPROM_SIZE:
3106	  The size in bytes of the EEPROM device.
3107
3108	- CONFIG_ENV_EEPROM_IS_ON_I2C
3109	  define this, if you have I2C and SPI activated, and your
3110	  EEPROM, which holds the environment, is on the I2C bus.
3111
3112	- CONFIG_I2C_ENV_EEPROM_BUS
3113	  if you have an Environment on an EEPROM reached over
3114	  I2C muxes, you can define here, how to reach this
3115	  EEPROM. For example:
3116
3117	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3118
3119	  EEPROM which holds the environment, is reached over
3120	  a pca9547 i2c mux with address 0x70, channel 3.
3121
3122- CONFIG_ENV_IS_IN_DATAFLASH:
3123
3124	Define this if you have a DataFlash memory device which you
3125	want to use for the environment.
3126
3127	- CONFIG_ENV_OFFSET:
3128	- CONFIG_ENV_ADDR:
3129	- CONFIG_ENV_SIZE:
3130
3131	  These three #defines specify the offset and size of the
3132	  environment area within the total memory of your DataFlash placed
3133	  at the specified address.
3134
3135- CONFIG_ENV_IS_IN_REMOTE:
3136
3137	Define this if you have a remote memory space which you
3138	want to use for the local device's environment.
3139
3140	- CONFIG_ENV_ADDR:
3141	- CONFIG_ENV_SIZE:
3142
3143	  These two #defines specify the address and size of the
3144	  environment area within the remote memory space. The
3145	  local device can get the environment from remote memory
3146	  space by SRIO or PCIE links.
3147
3148BE CAREFUL! For some special cases, the local device can not use
3149"saveenv" command. For example, the local device will get the
3150environment stored in a remote NOR flash by SRIO or PCIE link,
3151but it can not erase, write this NOR flash by SRIO or PCIE interface.
3152
3153- CONFIG_ENV_IS_IN_NAND:
3154
3155	Define this if you have a NAND device which you want to use
3156	for the environment.
3157
3158	- CONFIG_ENV_OFFSET:
3159	- CONFIG_ENV_SIZE:
3160
3161	  These two #defines specify the offset and size of the environment
3162	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3163	  aligned to an erase block boundary.
3164
3165	- CONFIG_ENV_OFFSET_REDUND (optional):
3166
3167	  This setting describes a second storage area of CONFIG_ENV_SIZE
3168	  size used to hold a redundant copy of the environment data, so
3169	  that there is a valid backup copy in case there is a power failure
3170	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3171	  aligned to an erase block boundary.
3172
3173	- CONFIG_ENV_RANGE (optional):
3174
3175	  Specifies the length of the region in which the environment
3176	  can be written.  This should be a multiple of the NAND device's
3177	  block size.  Specifying a range with more erase blocks than
3178	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3179	  the range to be avoided.
3180
3181	- CONFIG_ENV_OFFSET_OOB (optional):
3182
3183	  Enables support for dynamically retrieving the offset of the
3184	  environment from block zero's out-of-band data.  The
3185	  "nand env.oob" command can be used to record this offset.
3186	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3187	  using CONFIG_ENV_OFFSET_OOB.
3188
3189- CONFIG_NAND_ENV_DST
3190
3191	Defines address in RAM to which the nand_spl code should copy the
3192	environment. If redundant environment is used, it will be copied to
3193	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3194
3195- CONFIG_SYS_SPI_INIT_OFFSET
3196
3197	Defines offset to the initial SPI buffer area in DPRAM. The
3198	area is used at an early stage (ROM part) if the environment
3199	is configured to reside in the SPI EEPROM: We need a 520 byte
3200	scratch DPRAM area. It is used between the two initialization
3201	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3202	to be a good choice since it makes it far enough from the
3203	start of the data area as well as from the stack pointer.
3204
3205Please note that the environment is read-only until the monitor
3206has been relocated to RAM and a RAM copy of the environment has been
3207created; also, when using EEPROM you will have to use getenv_f()
3208until then to read environment variables.
3209
3210The environment is protected by a CRC32 checksum. Before the monitor
3211is relocated into RAM, as a result of a bad CRC you will be working
3212with the compiled-in default environment - *silently*!!! [This is
3213necessary, because the first environment variable we need is the
3214"baudrate" setting for the console - if we have a bad CRC, we don't
3215have any device yet where we could complain.]
3216
3217Note: once the monitor has been relocated, then it will complain if
3218the default environment is used; a new CRC is computed as soon as you
3219use the "saveenv" command to store a valid environment.
3220
3221- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3222		Echo the inverted Ethernet link state to the fault LED.
3223
3224		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3225		      also needs to be defined.
3226
3227- CONFIG_SYS_FAULT_MII_ADDR:
3228		MII address of the PHY to check for the Ethernet link state.
3229
3230- CONFIG_NS16550_MIN_FUNCTIONS:
3231		Define this if you desire to only have use of the NS16550_init
3232		and NS16550_putc functions for the serial driver located at
3233		drivers/serial/ns16550.c.  This option is useful for saving
3234		space for already greatly restricted images, including but not
3235		limited to NAND_SPL configurations.
3236
3237Low Level (hardware related) configuration options:
3238---------------------------------------------------
3239
3240- CONFIG_SYS_CACHELINE_SIZE:
3241		Cache Line Size of the CPU.
3242
3243- CONFIG_SYS_DEFAULT_IMMR:
3244		Default address of the IMMR after system reset.
3245
3246		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3247		and RPXsuper) to be able to adjust the position of
3248		the IMMR register after a reset.
3249
3250- CONFIG_SYS_CCSRBAR_DEFAULT:
3251		Default (power-on reset) physical address of CCSR on Freescale
3252		PowerPC SOCs.
3253
3254- CONFIG_SYS_CCSRBAR:
3255		Virtual address of CCSR.  On a 32-bit build, this is typically
3256		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3257
3258		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3259		for cross-platform code that uses that macro instead.
3260
3261- CONFIG_SYS_CCSRBAR_PHYS:
3262		Physical address of CCSR.  CCSR can be relocated to a new
3263		physical address, if desired.  In this case, this macro should
3264		be set to that address.	 Otherwise, it should be set to the
3265		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3266		is typically relocated on 36-bit builds.  It is recommended
3267		that this macro be defined via the _HIGH and _LOW macros:
3268
3269		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3270			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3271
3272- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3273		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3274		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3275		used in assembly code, so it must not contain typecasts or
3276		integer size suffixes (e.g. "ULL").
3277
3278- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3279		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3280		used in assembly code, so it must not contain typecasts or
3281		integer size suffixes (e.g. "ULL").
3282
3283- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3284		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3285		forced to a value that ensures that CCSR is not relocated.
3286
3287- Floppy Disk Support:
3288		CONFIG_SYS_FDC_DRIVE_NUMBER
3289
3290		the default drive number (default value 0)
3291
3292		CONFIG_SYS_ISA_IO_STRIDE
3293
3294		defines the spacing between FDC chipset registers
3295		(default value 1)
3296
3297		CONFIG_SYS_ISA_IO_OFFSET
3298
3299		defines the offset of register from address. It
3300		depends on which part of the data bus is connected to
3301		the FDC chipset. (default value 0)
3302
3303		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3304		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3305		default value.
3306
3307		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3308		fdc_hw_init() is called at the beginning of the FDC
3309		setup. fdc_hw_init() must be provided by the board
3310		source code. It is used to make hardware dependant
3311		initializations.
3312
3313- CONFIG_IDE_AHB:
3314		Most IDE controllers were designed to be connected with PCI
3315		interface. Only few of them were designed for AHB interface.
3316		When software is doing ATA command and data transfer to
3317		IDE devices through IDE-AHB controller, some additional
3318		registers accessing to these kind of IDE-AHB controller
3319		is requierd.
3320
3321- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3322		DO NOT CHANGE unless you know exactly what you're
3323		doing! (11-4) [MPC8xx/82xx systems only]
3324
3325- CONFIG_SYS_INIT_RAM_ADDR:
3326
3327		Start address of memory area that can be used for
3328		initial data and stack; please note that this must be
3329		writable memory that is working WITHOUT special
3330		initialization, i. e. you CANNOT use normal RAM which
3331		will become available only after programming the
3332		memory controller and running certain initialization
3333		sequences.
3334
3335		U-Boot uses the following memory types:
3336		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3337		- MPC824X: data cache
3338		- PPC4xx:  data cache
3339
3340- CONFIG_SYS_GBL_DATA_OFFSET:
3341
3342		Offset of the initial data structure in the memory
3343		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3344		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3345		data is located at the end of the available space
3346		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3347		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3348		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3349		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3350
3351	Note:
3352		On the MPC824X (or other systems that use the data
3353		cache for initial memory) the address chosen for
3354		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3355		point to an otherwise UNUSED address space between
3356		the top of RAM and the start of the PCI space.
3357
3358- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3359
3360- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3361
3362- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3363
3364- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3365
3366- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3367
3368- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3369
3370- CONFIG_SYS_OR_TIMING_SDRAM:
3371		SDRAM timing
3372
3373- CONFIG_SYS_MAMR_PTA:
3374		periodic timer for refresh
3375
3376- CONFIG_SYS_DER:	Debug Event Register (37-47)
3377
3378- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3379  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3380  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3381  CONFIG_SYS_BR1_PRELIM:
3382		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3383
3384- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3385  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3386  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3387		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3388
3389- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3390  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3391		Machine Mode Register and Memory Periodic Timer
3392		Prescaler definitions (SDRAM timing)
3393
3394- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3395		enable I2C microcode relocation patch (MPC8xx);
3396		define relocation offset in DPRAM [DSP2]
3397
3398- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3399		enable SMC microcode relocation patch (MPC8xx);
3400		define relocation offset in DPRAM [SMC1]
3401
3402- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3403		enable SPI microcode relocation patch (MPC8xx);
3404		define relocation offset in DPRAM [SCC4]
3405
3406- CONFIG_SYS_USE_OSCCLK:
3407		Use OSCM clock mode on MBX8xx board. Be careful,
3408		wrong setting might damage your board. Read
3409		doc/README.MBX before setting this variable!
3410
3411- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3412		Offset of the bootmode word in DPRAM used by post
3413		(Power On Self Tests). This definition overrides
3414		#define'd default value in commproc.h resp.
3415		cpm_8260.h.
3416
3417- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3418  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3419  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3420  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3421  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3422  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3423  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3424  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3425		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3426
3427- CONFIG_PCI_DISABLE_PCIE:
3428		Disable PCI-Express on systems where it is supported but not
3429		required.
3430
3431- CONFIG_PCI_ENUM_ONLY
3432		Only scan through and get the devices on the busses.
3433		Don't do any setup work, presumably because someone or
3434		something has already done it, and we don't need to do it
3435		a second time.	Useful for platforms that are pre-booted
3436		by coreboot or similar.
3437
3438- CONFIG_SYS_SRIO:
3439		Chip has SRIO or not
3440
3441- CONFIG_SRIO1:
3442		Board has SRIO 1 port available
3443
3444- CONFIG_SRIO2:
3445		Board has SRIO 2 port available
3446
3447- CONFIG_SYS_SRIOn_MEM_VIRT:
3448		Virtual Address of SRIO port 'n' memory region
3449
3450- CONFIG_SYS_SRIOn_MEM_PHYS:
3451		Physical Address of SRIO port 'n' memory region
3452
3453- CONFIG_SYS_SRIOn_MEM_SIZE:
3454		Size of SRIO port 'n' memory region
3455
3456- CONFIG_SYS_NDFC_16
3457		Defined to tell the NDFC that the NAND chip is using a
3458		16 bit bus.
3459
3460- CONFIG_SYS_NDFC_EBC0_CFG
3461		Sets the EBC0_CFG register for the NDFC. If not defined
3462		a default value will be used.
3463
3464- CONFIG_SPD_EEPROM
3465		Get DDR timing information from an I2C EEPROM. Common
3466		with pluggable memory modules such as SODIMMs
3467
3468  SPD_EEPROM_ADDRESS
3469		I2C address of the SPD EEPROM
3470
3471- CONFIG_SYS_SPD_BUS_NUM
3472		If SPD EEPROM is on an I2C bus other than the first
3473		one, specify here. Note that the value must resolve
3474		to something your driver can deal with.
3475
3476- CONFIG_SYS_DDR_RAW_TIMING
3477		Get DDR timing information from other than SPD. Common with
3478		soldered DDR chips onboard without SPD. DDR raw timing
3479		parameters are extracted from datasheet and hard-coded into
3480		header files or board specific files.
3481
3482- CONFIG_FSL_DDR_INTERACTIVE
3483		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3484
3485- CONFIG_SYS_83XX_DDR_USES_CS0
3486		Only for 83xx systems. If specified, then DDR should
3487		be configured using CS0 and CS1 instead of CS2 and CS3.
3488
3489- CONFIG_ETHER_ON_FEC[12]
3490		Define to enable FEC[12] on a 8xx series processor.
3491
3492- CONFIG_FEC[12]_PHY
3493		Define to the hardcoded PHY address which corresponds
3494		to the given FEC; i. e.
3495			#define CONFIG_FEC1_PHY 4
3496		means that the PHY with address 4 is connected to FEC1
3497
3498		When set to -1, means to probe for first available.
3499
3500- CONFIG_FEC[12]_PHY_NORXERR
3501		The PHY does not have a RXERR line (RMII only).
3502		(so program the FEC to ignore it).
3503
3504- CONFIG_RMII
3505		Enable RMII mode for all FECs.
3506		Note that this is a global option, we can't
3507		have one FEC in standard MII mode and another in RMII mode.
3508
3509- CONFIG_CRC32_VERIFY
3510		Add a verify option to the crc32 command.
3511		The syntax is:
3512
3513		=> crc32 -v <address> <count> <crc32>
3514
3515		Where address/count indicate a memory area
3516		and crc32 is the correct crc32 which the
3517		area should have.
3518
3519- CONFIG_LOOPW
3520		Add the "loopw" memory command. This only takes effect if
3521		the memory commands are activated globally (CONFIG_CMD_MEM).
3522
3523- CONFIG_MX_CYCLIC
3524		Add the "mdc" and "mwc" memory commands. These are cyclic
3525		"md/mw" commands.
3526		Examples:
3527
3528		=> mdc.b 10 4 500
3529		This command will print 4 bytes (10,11,12,13) each 500 ms.
3530
3531		=> mwc.l 100 12345678 10
3532		This command will write 12345678 to address 100 all 10 ms.
3533
3534		This only takes effect if the memory commands are activated
3535		globally (CONFIG_CMD_MEM).
3536
3537- CONFIG_SKIP_LOWLEVEL_INIT
3538		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3539		low level initializations (like setting up the memory
3540		controller) are omitted and/or U-Boot does not
3541		relocate itself into RAM.
3542
3543		Normally this variable MUST NOT be defined. The only
3544		exception is when U-Boot is loaded (to RAM) by some
3545		other boot loader or by a debugger which performs
3546		these initializations itself.
3547
3548- CONFIG_SPL_BUILD
3549		Modifies the behaviour of start.S when compiling a loader
3550		that is executed before the actual U-Boot. E.g. when
3551		compiling a NAND SPL.
3552
3553- CONFIG_USE_ARCH_MEMCPY
3554  CONFIG_USE_ARCH_MEMSET
3555		If these options are used a optimized version of memcpy/memset will
3556		be used if available. These functions may be faster under some
3557		conditions but may increase the binary size.
3558
3559Freescale QE/FMAN Firmware Support:
3560-----------------------------------
3561
3562The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3563loading of "firmware", which is encoded in the QE firmware binary format.
3564This firmware often needs to be loaded during U-Boot booting, so macros
3565are used to identify the storage device (NOR flash, SPI, etc) and the address
3566within that device.
3567
3568- CONFIG_SYS_QE_FMAN_FW_ADDR
3569	The address in the storage device where the firmware is located.  The
3570	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3571	is also specified.
3572
3573- CONFIG_SYS_QE_FMAN_FW_LENGTH
3574	The maximum possible size of the firmware.  The firmware binary format
3575	has a field that specifies the actual size of the firmware, but it
3576	might not be possible to read any part of the firmware unless some
3577	local storage is allocated to hold the entire firmware first.
3578
3579- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3580	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3581	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3582	virtual address in NOR flash.
3583
3584- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3585	Specifies that QE/FMAN firmware is located in NAND flash.
3586	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3587
3588- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3589	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3590	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3591
3592- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3593	Specifies that QE/FMAN firmware is located on the primary SPI
3594	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3595
3596- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3597	Specifies that QE/FMAN firmware is located in the remote (master)
3598	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3599	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3600	window->master inbound window->master LAW->the ucode address in
3601	master's memory space.
3602
3603Building the Software:
3604======================
3605
3606Building U-Boot has been tested in several native build environments
3607and in many different cross environments. Of course we cannot support
3608all possibly existing versions of cross development tools in all
3609(potentially obsolete) versions. In case of tool chain problems we
3610recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3611which is extensively used to build and test U-Boot.
3612
3613If you are not using a native environment, it is assumed that you
3614have GNU cross compiling tools available in your path. In this case,
3615you must set the environment variable CROSS_COMPILE in your shell.
3616Note that no changes to the Makefile or any other source files are
3617necessary. For example using the ELDK on a 4xx CPU, please enter:
3618
3619	$ CROSS_COMPILE=ppc_4xx-
3620	$ export CROSS_COMPILE
3621
3622Note: If you wish to generate Windows versions of the utilities in
3623      the tools directory you can use the MinGW toolchain
3624      (http://www.mingw.org).  Set your HOST tools to the MinGW
3625      toolchain and execute 'make tools'.  For example:
3626
3627       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3628
3629      Binaries such as tools/mkimage.exe will be created which can
3630      be executed on computers running Windows.
3631
3632U-Boot is intended to be simple to build. After installing the
3633sources you must configure U-Boot for one specific board type. This
3634is done by typing:
3635
3636	make NAME_config
3637
3638where "NAME_config" is the name of one of the existing configu-
3639rations; see boards.cfg for supported names.
3640
3641Note: for some board special configuration names may exist; check if
3642      additional information is available from the board vendor; for
3643      instance, the TQM823L systems are available without (standard)
3644      or with LCD support. You can select such additional "features"
3645      when choosing the configuration, i. e.
3646
3647      make TQM823L_config
3648	- will configure for a plain TQM823L, i. e. no LCD support
3649
3650      make TQM823L_LCD_config
3651	- will configure for a TQM823L with U-Boot console on LCD
3652
3653      etc.
3654
3655
3656Finally, type "make all", and you should get some working U-Boot
3657images ready for download to / installation on your system:
3658
3659- "u-boot.bin" is a raw binary image
3660- "u-boot" is an image in ELF binary format
3661- "u-boot.srec" is in Motorola S-Record format
3662
3663By default the build is performed locally and the objects are saved
3664in the source directory. One of the two methods can be used to change
3665this behavior and build U-Boot to some external directory:
3666
36671. Add O= to the make command line invocations:
3668
3669	make O=/tmp/build distclean
3670	make O=/tmp/build NAME_config
3671	make O=/tmp/build all
3672
36732. Set environment variable BUILD_DIR to point to the desired location:
3674
3675	export BUILD_DIR=/tmp/build
3676	make distclean
3677	make NAME_config
3678	make all
3679
3680Note that the command line "O=" setting overrides the BUILD_DIR environment
3681variable.
3682
3683
3684Please be aware that the Makefiles assume you are using GNU make, so
3685for instance on NetBSD you might need to use "gmake" instead of
3686native "make".
3687
3688
3689If the system board that you have is not listed, then you will need
3690to port U-Boot to your hardware platform. To do this, follow these
3691steps:
3692
36931.  Add a new configuration option for your board to the toplevel
3694    "boards.cfg" file, using the existing entries as examples.
3695    Follow the instructions there to keep the boards in order.
36962.  Create a new directory to hold your board specific code. Add any
3697    files you need. In your board directory, you will need at least
3698    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
36993.  Create a new configuration file "include/configs/<board>.h" for
3700    your board
37013.  If you're porting U-Boot to a new CPU, then also create a new
3702    directory to hold your CPU specific code. Add any files you need.
37034.  Run "make <board>_config" with your new name.
37045.  Type "make", and you should get a working "u-boot.srec" file
3705    to be installed on your target system.
37066.  Debug and solve any problems that might arise.
3707    [Of course, this last step is much harder than it sounds.]
3708
3709
3710Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3711==============================================================
3712
3713If you have modified U-Boot sources (for instance added a new board
3714or support for new devices, a new CPU, etc.) you are expected to
3715provide feedback to the other developers. The feedback normally takes
3716the form of a "patch", i. e. a context diff against a certain (latest
3717official or latest in the git repository) version of U-Boot sources.
3718
3719But before you submit such a patch, please verify that your modifi-
3720cation did not break existing code. At least make sure that *ALL* of
3721the supported boards compile WITHOUT ANY compiler warnings. To do so,
3722just run the "MAKEALL" script, which will configure and build U-Boot
3723for ALL supported system. Be warned, this will take a while. You can
3724select which (cross) compiler to use by passing a `CROSS_COMPILE'
3725environment variable to the script, i. e. to use the ELDK cross tools
3726you can type
3727
3728	CROSS_COMPILE=ppc_8xx- MAKEALL
3729
3730or to build on a native PowerPC system you can type
3731
3732	CROSS_COMPILE=' ' MAKEALL
3733
3734When using the MAKEALL script, the default behaviour is to build
3735U-Boot in the source directory. This location can be changed by
3736setting the BUILD_DIR environment variable. Also, for each target
3737built, the MAKEALL script saves two log files (<target>.ERR and
3738<target>.MAKEALL) in the <source dir>/LOG directory. This default
3739location can be changed by setting the MAKEALL_LOGDIR environment
3740variable. For example:
3741
3742	export BUILD_DIR=/tmp/build
3743	export MAKEALL_LOGDIR=/tmp/log
3744	CROSS_COMPILE=ppc_8xx- MAKEALL
3745
3746With the above settings build objects are saved in the /tmp/build,
3747log files are saved in the /tmp/log and the source tree remains clean
3748during the whole build process.
3749
3750
3751See also "U-Boot Porting Guide" below.
3752
3753
3754Monitor Commands - Overview:
3755============================
3756
3757go	- start application at address 'addr'
3758run	- run commands in an environment variable
3759bootm	- boot application image from memory
3760bootp	- boot image via network using BootP/TFTP protocol
3761bootz   - boot zImage from memory
3762tftpboot- boot image via network using TFTP protocol
3763	       and env variables "ipaddr" and "serverip"
3764	       (and eventually "gatewayip")
3765tftpput - upload a file via network using TFTP protocol
3766rarpboot- boot image via network using RARP/TFTP protocol
3767diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3768loads	- load S-Record file over serial line
3769loadb	- load binary file over serial line (kermit mode)
3770md	- memory display
3771mm	- memory modify (auto-incrementing)
3772nm	- memory modify (constant address)
3773mw	- memory write (fill)
3774cp	- memory copy
3775cmp	- memory compare
3776crc32	- checksum calculation
3777i2c	- I2C sub-system
3778sspi	- SPI utility commands
3779base	- print or set address offset
3780printenv- print environment variables
3781setenv	- set environment variables
3782saveenv - save environment variables to persistent storage
3783protect - enable or disable FLASH write protection
3784erase	- erase FLASH memory
3785flinfo	- print FLASH memory information
3786bdinfo	- print Board Info structure
3787iminfo	- print header information for application image
3788coninfo - print console devices and informations
3789ide	- IDE sub-system
3790loop	- infinite loop on address range
3791loopw	- infinite write loop on address range
3792mtest	- simple RAM test
3793icache	- enable or disable instruction cache
3794dcache	- enable or disable data cache
3795reset	- Perform RESET of the CPU
3796echo	- echo args to console
3797version - print monitor version
3798help	- print online help
3799?	- alias for 'help'
3800
3801
3802Monitor Commands - Detailed Description:
3803========================================
3804
3805TODO.
3806
3807For now: just type "help <command>".
3808
3809
3810Environment Variables:
3811======================
3812
3813U-Boot supports user configuration using Environment Variables which
3814can be made persistent by saving to Flash memory.
3815
3816Environment Variables are set using "setenv", printed using
3817"printenv", and saved to Flash using "saveenv". Using "setenv"
3818without a value can be used to delete a variable from the
3819environment. As long as you don't save the environment you are
3820working with an in-memory copy. In case the Flash area containing the
3821environment is erased by accident, a default environment is provided.
3822
3823Some configuration options can be set using Environment Variables.
3824
3825List of environment variables (most likely not complete):
3826
3827  baudrate	- see CONFIG_BAUDRATE
3828
3829  bootdelay	- see CONFIG_BOOTDELAY
3830
3831  bootcmd	- see CONFIG_BOOTCOMMAND
3832
3833  bootargs	- Boot arguments when booting an RTOS image
3834
3835  bootfile	- Name of the image to load with TFTP
3836
3837  bootm_low	- Memory range available for image processing in the bootm
3838		  command can be restricted. This variable is given as
3839		  a hexadecimal number and defines lowest address allowed
3840		  for use by the bootm command. See also "bootm_size"
3841		  environment variable. Address defined by "bootm_low" is
3842		  also the base of the initial memory mapping for the Linux
3843		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3844		  bootm_mapsize.
3845
3846  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3847		  This variable is given as a hexadecimal number and it
3848		  defines the size of the memory region starting at base
3849		  address bootm_low that is accessible by the Linux kernel
3850		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3851		  as the default value if it is defined, and bootm_size is
3852		  used otherwise.
3853
3854  bootm_size	- Memory range available for image processing in the bootm
3855		  command can be restricted. This variable is given as
3856		  a hexadecimal number and defines the size of the region
3857		  allowed for use by the bootm command. See also "bootm_low"
3858		  environment variable.
3859
3860  updatefile	- Location of the software update file on a TFTP server, used
3861		  by the automatic software update feature. Please refer to
3862		  documentation in doc/README.update for more details.
3863
3864  autoload	- if set to "no" (any string beginning with 'n'),
3865		  "bootp" will just load perform a lookup of the
3866		  configuration from the BOOTP server, but not try to
3867		  load any image using TFTP
3868
3869  autostart	- if set to "yes", an image loaded using the "bootp",
3870		  "rarpboot", "tftpboot" or "diskboot" commands will
3871		  be automatically started (by internally calling
3872		  "bootm")
3873
3874		  If set to "no", a standalone image passed to the
3875		  "bootm" command will be copied to the load address
3876		  (and eventually uncompressed), but NOT be started.
3877		  This can be used to load and uncompress arbitrary
3878		  data.
3879
3880  fdt_high	- if set this restricts the maximum address that the
3881		  flattened device tree will be copied into upon boot.
3882		  For example, if you have a system with 1 GB memory
3883		  at physical address 0x10000000, while Linux kernel
3884		  only recognizes the first 704 MB as low memory, you
3885		  may need to set fdt_high as 0x3C000000 to have the
3886		  device tree blob be copied to the maximum address
3887		  of the 704 MB low memory, so that Linux kernel can
3888		  access it during the boot procedure.
3889
3890		  If this is set to the special value 0xFFFFFFFF then
3891		  the fdt will not be copied at all on boot.  For this
3892		  to work it must reside in writable memory, have
3893		  sufficient padding on the end of it for u-boot to
3894		  add the information it needs into it, and the memory
3895		  must be accessible by the kernel.
3896
3897  fdtcontroladdr- if set this is the address of the control flattened
3898		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3899		  defined.
3900
3901  i2cfast	- (PPC405GP|PPC405EP only)
3902		  if set to 'y' configures Linux I2C driver for fast
3903		  mode (400kHZ). This environment variable is used in
3904		  initialization code. So, for changes to be effective
3905		  it must be saved and board must be reset.
3906
3907  initrd_high	- restrict positioning of initrd images:
3908		  If this variable is not set, initrd images will be
3909		  copied to the highest possible address in RAM; this
3910		  is usually what you want since it allows for
3911		  maximum initrd size. If for some reason you want to
3912		  make sure that the initrd image is loaded below the
3913		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3914		  variable to a value of "no" or "off" or "0".
3915		  Alternatively, you can set it to a maximum upper
3916		  address to use (U-Boot will still check that it
3917		  does not overwrite the U-Boot stack and data).
3918
3919		  For instance, when you have a system with 16 MB
3920		  RAM, and want to reserve 4 MB from use by Linux,
3921		  you can do this by adding "mem=12M" to the value of
3922		  the "bootargs" variable. However, now you must make
3923		  sure that the initrd image is placed in the first
3924		  12 MB as well - this can be done with
3925
3926		  setenv initrd_high 00c00000
3927
3928		  If you set initrd_high to 0xFFFFFFFF, this is an
3929		  indication to U-Boot that all addresses are legal
3930		  for the Linux kernel, including addresses in flash
3931		  memory. In this case U-Boot will NOT COPY the
3932		  ramdisk at all. This may be useful to reduce the
3933		  boot time on your system, but requires that this
3934		  feature is supported by your Linux kernel.
3935
3936  ipaddr	- IP address; needed for tftpboot command
3937
3938  loadaddr	- Default load address for commands like "bootp",
3939		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3940
3941  loads_echo	- see CONFIG_LOADS_ECHO
3942
3943  serverip	- TFTP server IP address; needed for tftpboot command
3944
3945  bootretry	- see CONFIG_BOOT_RETRY_TIME
3946
3947  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3948
3949  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3950
3951  ethprime	- controls which interface is used first.
3952
3953  ethact	- controls which interface is currently active.
3954		  For example you can do the following
3955
3956		  => setenv ethact FEC
3957		  => ping 192.168.0.1 # traffic sent on FEC
3958		  => setenv ethact SCC
3959		  => ping 10.0.0.1 # traffic sent on SCC
3960
3961  ethrotate	- When set to "no" U-Boot does not go through all
3962		  available network interfaces.
3963		  It just stays at the currently selected interface.
3964
3965  netretry	- When set to "no" each network operation will
3966		  either succeed or fail without retrying.
3967		  When set to "once" the network operation will
3968		  fail when all the available network interfaces
3969		  are tried once without success.
3970		  Useful on scripts which control the retry operation
3971		  themselves.
3972
3973  npe_ucode	- set load address for the NPE microcode
3974
3975  tftpsrcport	- If this is set, the value is used for TFTP's
3976		  UDP source port.
3977
3978  tftpdstport	- If this is set, the value is used for TFTP's UDP
3979		  destination port instead of the Well Know Port 69.
3980
3981  tftpblocksize - Block size to use for TFTP transfers; if not set,
3982		  we use the TFTP server's default block size
3983
3984  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
3985		  seconds, minimum value is 1000 = 1 second). Defines
3986		  when a packet is considered to be lost so it has to
3987		  be retransmitted. The default is 5000 = 5 seconds.
3988		  Lowering this value may make downloads succeed
3989		  faster in networks with high packet loss rates or
3990		  with unreliable TFTP servers.
3991
3992  vlan		- When set to a value < 4095 the traffic over
3993		  Ethernet is encapsulated/received over 802.1q
3994		  VLAN tagged frames.
3995
3996The following image location variables contain the location of images
3997used in booting. The "Image" column gives the role of the image and is
3998not an environment variable name. The other columns are environment
3999variable names. "File Name" gives the name of the file on a TFTP
4000server, "RAM Address" gives the location in RAM the image will be
4001loaded to, and "Flash Location" gives the image's address in NOR
4002flash or offset in NAND flash.
4003
4004*Note* - these variables don't have to be defined for all boards, some
4005boards currenlty use other variables for these purposes, and some
4006boards use these variables for other purposes.
4007
4008Image		    File Name	     RAM Address       Flash Location
4009-----		    ---------	     -----------       --------------
4010u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4011Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4012device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4013ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4014
4015The following environment variables may be used and automatically
4016updated by the network boot commands ("bootp" and "rarpboot"),
4017depending the information provided by your boot server:
4018
4019  bootfile	- see above
4020  dnsip		- IP address of your Domain Name Server
4021  dnsip2	- IP address of your secondary Domain Name Server
4022  gatewayip	- IP address of the Gateway (Router) to use
4023  hostname	- Target hostname
4024  ipaddr	- see above
4025  netmask	- Subnet Mask
4026  rootpath	- Pathname of the root filesystem on the NFS server
4027  serverip	- see above
4028
4029
4030There are two special Environment Variables:
4031
4032  serial#	- contains hardware identification information such
4033		  as type string and/or serial number
4034  ethaddr	- Ethernet address
4035
4036These variables can be set only once (usually during manufacturing of
4037the board). U-Boot refuses to delete or overwrite these variables
4038once they have been set once.
4039
4040
4041Further special Environment Variables:
4042
4043  ver		- Contains the U-Boot version string as printed
4044		  with the "version" command. This variable is
4045		  readonly (see CONFIG_VERSION_VARIABLE).
4046
4047
4048Please note that changes to some configuration parameters may take
4049only effect after the next boot (yes, that's just like Windoze :-).
4050
4051
4052Command Line Parsing:
4053=====================
4054
4055There are two different command line parsers available with U-Boot:
4056the old "simple" one, and the much more powerful "hush" shell:
4057
4058Old, simple command line parser:
4059--------------------------------
4060
4061- supports environment variables (through setenv / saveenv commands)
4062- several commands on one line, separated by ';'
4063- variable substitution using "... ${name} ..." syntax
4064- special characters ('$', ';') can be escaped by prefixing with '\',
4065  for example:
4066	setenv bootcmd bootm \${address}
4067- You can also escape text by enclosing in single apostrophes, for example:
4068	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4069
4070Hush shell:
4071-----------
4072
4073- similar to Bourne shell, with control structures like
4074  if...then...else...fi, for...do...done; while...do...done,
4075  until...do...done, ...
4076- supports environment ("global") variables (through setenv / saveenv
4077  commands) and local shell variables (through standard shell syntax
4078  "name=value"); only environment variables can be used with "run"
4079  command
4080
4081General rules:
4082--------------
4083
4084(1) If a command line (or an environment variable executed by a "run"
4085    command) contains several commands separated by semicolon, and
4086    one of these commands fails, then the remaining commands will be
4087    executed anyway.
4088
4089(2) If you execute several variables with one call to run (i. e.
4090    calling run with a list of variables as arguments), any failing
4091    command will cause "run" to terminate, i. e. the remaining
4092    variables are not executed.
4093
4094Note for Redundant Ethernet Interfaces:
4095=======================================
4096
4097Some boards come with redundant Ethernet interfaces; U-Boot supports
4098such configurations and is capable of automatic selection of a
4099"working" interface when needed. MAC assignment works as follows:
4100
4101Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4102MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4103"eth1addr" (=>eth1), "eth2addr", ...
4104
4105If the network interface stores some valid MAC address (for instance
4106in SROM), this is used as default address if there is NO correspon-
4107ding setting in the environment; if the corresponding environment
4108variable is set, this overrides the settings in the card; that means:
4109
4110o If the SROM has a valid MAC address, and there is no address in the
4111  environment, the SROM's address is used.
4112
4113o If there is no valid address in the SROM, and a definition in the
4114  environment exists, then the value from the environment variable is
4115  used.
4116
4117o If both the SROM and the environment contain a MAC address, and
4118  both addresses are the same, this MAC address is used.
4119
4120o If both the SROM and the environment contain a MAC address, and the
4121  addresses differ, the value from the environment is used and a
4122  warning is printed.
4123
4124o If neither SROM nor the environment contain a MAC address, an error
4125  is raised.
4126
4127If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4128will be programmed into hardware as part of the initialization process.	 This
4129may be skipped by setting the appropriate 'ethmacskip' environment variable.
4130The naming convention is as follows:
4131"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4132
4133Image Formats:
4134==============
4135
4136U-Boot is capable of booting (and performing other auxiliary operations on)
4137images in two formats:
4138
4139New uImage format (FIT)
4140-----------------------
4141
4142Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4143to Flattened Device Tree). It allows the use of images with multiple
4144components (several kernels, ramdisks, etc.), with contents protected by
4145SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4146
4147
4148Old uImage format
4149-----------------
4150
4151Old image format is based on binary files which can be basically anything,
4152preceded by a special header; see the definitions in include/image.h for
4153details; basically, the header defines the following image properties:
4154
4155* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4156  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4157  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4158  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4159  INTEGRITY).
4160* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4161  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4162  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4163* Compression Type (uncompressed, gzip, bzip2)
4164* Load Address
4165* Entry Point
4166* Image Name
4167* Image Timestamp
4168
4169The header is marked by a special Magic Number, and both the header
4170and the data portions of the image are secured against corruption by
4171CRC32 checksums.
4172
4173
4174Linux Support:
4175==============
4176
4177Although U-Boot should support any OS or standalone application
4178easily, the main focus has always been on Linux during the design of
4179U-Boot.
4180
4181U-Boot includes many features that so far have been part of some
4182special "boot loader" code within the Linux kernel. Also, any
4183"initrd" images to be used are no longer part of one big Linux image;
4184instead, kernel and "initrd" are separate images. This implementation
4185serves several purposes:
4186
4187- the same features can be used for other OS or standalone
4188  applications (for instance: using compressed images to reduce the
4189  Flash memory footprint)
4190
4191- it becomes much easier to port new Linux kernel versions because
4192  lots of low-level, hardware dependent stuff are done by U-Boot
4193
4194- the same Linux kernel image can now be used with different "initrd"
4195  images; of course this also means that different kernel images can
4196  be run with the same "initrd". This makes testing easier (you don't
4197  have to build a new "zImage.initrd" Linux image when you just
4198  change a file in your "initrd"). Also, a field-upgrade of the
4199  software is easier now.
4200
4201
4202Linux HOWTO:
4203============
4204
4205Porting Linux to U-Boot based systems:
4206---------------------------------------
4207
4208U-Boot cannot save you from doing all the necessary modifications to
4209configure the Linux device drivers for use with your target hardware
4210(no, we don't intend to provide a full virtual machine interface to
4211Linux :-).
4212
4213But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4214
4215Just make sure your machine specific header file (for instance
4216include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4217Information structure as we define in include/asm-<arch>/u-boot.h,
4218and make sure that your definition of IMAP_ADDR uses the same value
4219as your U-Boot configuration in CONFIG_SYS_IMMR.
4220
4221
4222Configuring the Linux kernel:
4223-----------------------------
4224
4225No specific requirements for U-Boot. Make sure you have some root
4226device (initial ramdisk, NFS) for your target system.
4227
4228
4229Building a Linux Image:
4230-----------------------
4231
4232With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4233not used. If you use recent kernel source, a new build target
4234"uImage" will exist which automatically builds an image usable by
4235U-Boot. Most older kernels also have support for a "pImage" target,
4236which was introduced for our predecessor project PPCBoot and uses a
4237100% compatible format.
4238
4239Example:
4240
4241	make TQM850L_config
4242	make oldconfig
4243	make dep
4244	make uImage
4245
4246The "uImage" build target uses a special tool (in 'tools/mkimage') to
4247encapsulate a compressed Linux kernel image with header	 information,
4248CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4249
4250* build a standard "vmlinux" kernel image (in ELF binary format):
4251
4252* convert the kernel into a raw binary image:
4253
4254	${CROSS_COMPILE}-objcopy -O binary \
4255				 -R .note -R .comment \
4256				 -S vmlinux linux.bin
4257
4258* compress the binary image:
4259
4260	gzip -9 linux.bin
4261
4262* package compressed binary image for U-Boot:
4263
4264	mkimage -A ppc -O linux -T kernel -C gzip \
4265		-a 0 -e 0 -n "Linux Kernel Image" \
4266		-d linux.bin.gz uImage
4267
4268
4269The "mkimage" tool can also be used to create ramdisk images for use
4270with U-Boot, either separated from the Linux kernel image, or
4271combined into one file. "mkimage" encapsulates the images with a 64
4272byte header containing information about target architecture,
4273operating system, image type, compression method, entry points, time
4274stamp, CRC32 checksums, etc.
4275
4276"mkimage" can be called in two ways: to verify existing images and
4277print the header information, or to build new images.
4278
4279In the first form (with "-l" option) mkimage lists the information
4280contained in the header of an existing U-Boot image; this includes
4281checksum verification:
4282
4283	tools/mkimage -l image
4284	  -l ==> list image header information
4285
4286The second form (with "-d" option) is used to build a U-Boot image
4287from a "data file" which is used as image payload:
4288
4289	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4290		      -n name -d data_file image
4291	  -A ==> set architecture to 'arch'
4292	  -O ==> set operating system to 'os'
4293	  -T ==> set image type to 'type'
4294	  -C ==> set compression type 'comp'
4295	  -a ==> set load address to 'addr' (hex)
4296	  -e ==> set entry point to 'ep' (hex)
4297	  -n ==> set image name to 'name'
4298	  -d ==> use image data from 'datafile'
4299
4300Right now, all Linux kernels for PowerPC systems use the same load
4301address (0x00000000), but the entry point address depends on the
4302kernel version:
4303
4304- 2.2.x kernels have the entry point at 0x0000000C,
4305- 2.3.x and later kernels have the entry point at 0x00000000.
4306
4307So a typical call to build a U-Boot image would read:
4308
4309	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4310	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4311	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4312	> examples/uImage.TQM850L
4313	Image Name:   2.4.4 kernel for TQM850L
4314	Created:      Wed Jul 19 02:34:59 2000
4315	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4316	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4317	Load Address: 0x00000000
4318	Entry Point:  0x00000000
4319
4320To verify the contents of the image (or check for corruption):
4321
4322	-> tools/mkimage -l examples/uImage.TQM850L
4323	Image Name:   2.4.4 kernel for TQM850L
4324	Created:      Wed Jul 19 02:34:59 2000
4325	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4326	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4327	Load Address: 0x00000000
4328	Entry Point:  0x00000000
4329
4330NOTE: for embedded systems where boot time is critical you can trade
4331speed for memory and install an UNCOMPRESSED image instead: this
4332needs more space in Flash, but boots much faster since it does not
4333need to be uncompressed:
4334
4335	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4336	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4337	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4338	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4339	> examples/uImage.TQM850L-uncompressed
4340	Image Name:   2.4.4 kernel for TQM850L
4341	Created:      Wed Jul 19 02:34:59 2000
4342	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4343	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4344	Load Address: 0x00000000
4345	Entry Point:  0x00000000
4346
4347
4348Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4349when your kernel is intended to use an initial ramdisk:
4350
4351	-> tools/mkimage -n 'Simple Ramdisk Image' \
4352	> -A ppc -O linux -T ramdisk -C gzip \
4353	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4354	Image Name:   Simple Ramdisk Image
4355	Created:      Wed Jan 12 14:01:50 2000
4356	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4357	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4358	Load Address: 0x00000000
4359	Entry Point:  0x00000000
4360
4361
4362Installing a Linux Image:
4363-------------------------
4364
4365To downloading a U-Boot image over the serial (console) interface,
4366you must convert the image to S-Record format:
4367
4368	objcopy -I binary -O srec examples/image examples/image.srec
4369
4370The 'objcopy' does not understand the information in the U-Boot
4371image header, so the resulting S-Record file will be relative to
4372address 0x00000000. To load it to a given address, you need to
4373specify the target address as 'offset' parameter with the 'loads'
4374command.
4375
4376Example: install the image to address 0x40100000 (which on the
4377TQM8xxL is in the first Flash bank):
4378
4379	=> erase 40100000 401FFFFF
4380
4381	.......... done
4382	Erased 8 sectors
4383
4384	=> loads 40100000
4385	## Ready for S-Record download ...
4386	~>examples/image.srec
4387	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4388	...
4389	15989 15990 15991 15992
4390	[file transfer complete]
4391	[connected]
4392	## Start Addr = 0x00000000
4393
4394
4395You can check the success of the download using the 'iminfo' command;
4396this includes a checksum verification so you can be sure no data
4397corruption happened:
4398
4399	=> imi 40100000
4400
4401	## Checking Image at 40100000 ...
4402	   Image Name:	 2.2.13 for initrd on TQM850L
4403	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4404	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4405	   Load Address: 00000000
4406	   Entry Point:	 0000000c
4407	   Verifying Checksum ... OK
4408
4409
4410Boot Linux:
4411-----------
4412
4413The "bootm" command is used to boot an application that is stored in
4414memory (RAM or Flash). In case of a Linux kernel image, the contents
4415of the "bootargs" environment variable is passed to the kernel as
4416parameters. You can check and modify this variable using the
4417"printenv" and "setenv" commands:
4418
4419
4420	=> printenv bootargs
4421	bootargs=root=/dev/ram
4422
4423	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4424
4425	=> printenv bootargs
4426	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4427
4428	=> bootm 40020000
4429	## Booting Linux kernel at 40020000 ...
4430	   Image Name:	 2.2.13 for NFS on TQM850L
4431	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4432	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4433	   Load Address: 00000000
4434	   Entry Point:	 0000000c
4435	   Verifying Checksum ... OK
4436	   Uncompressing Kernel Image ... OK
4437	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
4438	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4439	time_init: decrementer frequency = 187500000/60
4440	Calibrating delay loop... 49.77 BogoMIPS
4441	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4442	...
4443
4444If you want to boot a Linux kernel with initial RAM disk, you pass
4445the memory addresses of both the kernel and the initrd image (PPBCOOT
4446format!) to the "bootm" command:
4447
4448	=> imi 40100000 40200000
4449
4450	## Checking Image at 40100000 ...
4451	   Image Name:	 2.2.13 for initrd on TQM850L
4452	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4453	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4454	   Load Address: 00000000
4455	   Entry Point:	 0000000c
4456	   Verifying Checksum ... OK
4457
4458	## Checking Image at 40200000 ...
4459	   Image Name:	 Simple Ramdisk Image
4460	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4461	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4462	   Load Address: 00000000
4463	   Entry Point:	 00000000
4464	   Verifying Checksum ... OK
4465
4466	=> bootm 40100000 40200000
4467	## Booting Linux kernel at 40100000 ...
4468	   Image Name:	 2.2.13 for initrd on TQM850L
4469	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4470	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4471	   Load Address: 00000000
4472	   Entry Point:	 0000000c
4473	   Verifying Checksum ... OK
4474	   Uncompressing Kernel Image ... OK
4475	## Loading RAMDisk Image at 40200000 ...
4476	   Image Name:	 Simple Ramdisk Image
4477	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4478	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4479	   Load Address: 00000000
4480	   Entry Point:	 00000000
4481	   Verifying Checksum ... OK
4482	   Loading Ramdisk ... OK
4483	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
4484	Boot arguments: root=/dev/ram
4485	time_init: decrementer frequency = 187500000/60
4486	Calibrating delay loop... 49.77 BogoMIPS
4487	...
4488	RAMDISK: Compressed image found at block 0
4489	VFS: Mounted root (ext2 filesystem).
4490
4491	bash#
4492
4493Boot Linux and pass a flat device tree:
4494-----------
4495
4496First, U-Boot must be compiled with the appropriate defines. See the section
4497titled "Linux Kernel Interface" above for a more in depth explanation. The
4498following is an example of how to start a kernel and pass an updated
4499flat device tree:
4500
4501=> print oftaddr
4502oftaddr=0x300000
4503=> print oft
4504oft=oftrees/mpc8540ads.dtb
4505=> tftp $oftaddr $oft
4506Speed: 1000, full duplex
4507Using TSEC0 device
4508TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4509Filename 'oftrees/mpc8540ads.dtb'.
4510Load address: 0x300000
4511Loading: #
4512done
4513Bytes transferred = 4106 (100a hex)
4514=> tftp $loadaddr $bootfile
4515Speed: 1000, full duplex
4516Using TSEC0 device
4517TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4518Filename 'uImage'.
4519Load address: 0x200000
4520Loading:############
4521done
4522Bytes transferred = 1029407 (fb51f hex)
4523=> print loadaddr
4524loadaddr=200000
4525=> print oftaddr
4526oftaddr=0x300000
4527=> bootm $loadaddr - $oftaddr
4528## Booting image at 00200000 ...
4529   Image Name:	 Linux-2.6.17-dirty
4530   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4531   Data Size:	 1029343 Bytes = 1005.2 kB
4532   Load Address: 00000000
4533   Entry Point:	 00000000
4534   Verifying Checksum ... OK
4535   Uncompressing Kernel Image ... OK
4536Booting using flat device tree at 0x300000
4537Using MPC85xx ADS machine description
4538Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4539[snip]
4540
4541
4542More About U-Boot Image Types:
4543------------------------------
4544
4545U-Boot supports the following image types:
4546
4547   "Standalone Programs" are directly runnable in the environment
4548	provided by U-Boot; it is expected that (if they behave
4549	well) you can continue to work in U-Boot after return from
4550	the Standalone Program.
4551   "OS Kernel Images" are usually images of some Embedded OS which
4552	will take over control completely. Usually these programs
4553	will install their own set of exception handlers, device
4554	drivers, set up the MMU, etc. - this means, that you cannot
4555	expect to re-enter U-Boot except by resetting the CPU.
4556   "RAMDisk Images" are more or less just data blocks, and their
4557	parameters (address, size) are passed to an OS kernel that is
4558	being started.
4559   "Multi-File Images" contain several images, typically an OS
4560	(Linux) kernel image and one or more data images like
4561	RAMDisks. This construct is useful for instance when you want
4562	to boot over the network using BOOTP etc., where the boot
4563	server provides just a single image file, but you want to get
4564	for instance an OS kernel and a RAMDisk image.
4565
4566	"Multi-File Images" start with a list of image sizes, each
4567	image size (in bytes) specified by an "uint32_t" in network
4568	byte order. This list is terminated by an "(uint32_t)0".
4569	Immediately after the terminating 0 follow the images, one by
4570	one, all aligned on "uint32_t" boundaries (size rounded up to
4571	a multiple of 4 bytes).
4572
4573   "Firmware Images" are binary images containing firmware (like
4574	U-Boot or FPGA images) which usually will be programmed to
4575	flash memory.
4576
4577   "Script files" are command sequences that will be executed by
4578	U-Boot's command interpreter; this feature is especially
4579	useful when you configure U-Boot to use a real shell (hush)
4580	as command interpreter.
4581
4582Booting the Linux zImage:
4583-------------------------
4584
4585On some platforms, it's possible to boot Linux zImage. This is done
4586using the "bootz" command. The syntax of "bootz" command is the same
4587as the syntax of "bootm" command.
4588
4589Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4590kernel with raw initrd images. The syntax is slightly different, the
4591address of the initrd must be augmented by it's size, in the following
4592format: "<initrd addres>:<initrd size>".
4593
4594
4595Standalone HOWTO:
4596=================
4597
4598One of the features of U-Boot is that you can dynamically load and
4599run "standalone" applications, which can use some resources of
4600U-Boot like console I/O functions or interrupt services.
4601
4602Two simple examples are included with the sources:
4603
4604"Hello World" Demo:
4605-------------------
4606
4607'examples/hello_world.c' contains a small "Hello World" Demo
4608application; it is automatically compiled when you build U-Boot.
4609It's configured to run at address 0x00040004, so you can play with it
4610like that:
4611
4612	=> loads
4613	## Ready for S-Record download ...
4614	~>examples/hello_world.srec
4615	1 2 3 4 5 6 7 8 9 10 11 ...
4616	[file transfer complete]
4617	[connected]
4618	## Start Addr = 0x00040004
4619
4620	=> go 40004 Hello World! This is a test.
4621	## Starting application at 0x00040004 ...
4622	Hello World
4623	argc = 7
4624	argv[0] = "40004"
4625	argv[1] = "Hello"
4626	argv[2] = "World!"
4627	argv[3] = "This"
4628	argv[4] = "is"
4629	argv[5] = "a"
4630	argv[6] = "test."
4631	argv[7] = "<NULL>"
4632	Hit any key to exit ...
4633
4634	## Application terminated, rc = 0x0
4635
4636Another example, which demonstrates how to register a CPM interrupt
4637handler with the U-Boot code, can be found in 'examples/timer.c'.
4638Here, a CPM timer is set up to generate an interrupt every second.
4639The interrupt service routine is trivial, just printing a '.'
4640character, but this is just a demo program. The application can be
4641controlled by the following keys:
4642
4643	? - print current values og the CPM Timer registers
4644	b - enable interrupts and start timer
4645	e - stop timer and disable interrupts
4646	q - quit application
4647
4648	=> loads
4649	## Ready for S-Record download ...
4650	~>examples/timer.srec
4651	1 2 3 4 5 6 7 8 9 10 11 ...
4652	[file transfer complete]
4653	[connected]
4654	## Start Addr = 0x00040004
4655
4656	=> go 40004
4657	## Starting application at 0x00040004 ...
4658	TIMERS=0xfff00980
4659	Using timer 1
4660	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4661
4662Hit 'b':
4663	[q, b, e, ?] Set interval 1000000 us
4664	Enabling timer
4665Hit '?':
4666	[q, b, e, ?] ........
4667	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4668Hit '?':
4669	[q, b, e, ?] .
4670	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4671Hit '?':
4672	[q, b, e, ?] .
4673	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4674Hit '?':
4675	[q, b, e, ?] .
4676	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4677Hit 'e':
4678	[q, b, e, ?] ...Stopping timer
4679Hit 'q':
4680	[q, b, e, ?] ## Application terminated, rc = 0x0
4681
4682
4683Minicom warning:
4684================
4685
4686Over time, many people have reported problems when trying to use the
4687"minicom" terminal emulation program for serial download. I (wd)
4688consider minicom to be broken, and recommend not to use it. Under
4689Unix, I recommend to use C-Kermit for general purpose use (and
4690especially for kermit binary protocol download ("loadb" command), and
4691use "cu" for S-Record download ("loads" command).
4692
4693Nevertheless, if you absolutely want to use it try adding this
4694configuration to your "File transfer protocols" section:
4695
4696	   Name	   Program			Name U/D FullScr IO-Red. Multi
4697	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4698	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4699
4700
4701NetBSD Notes:
4702=============
4703
4704Starting at version 0.9.2, U-Boot supports NetBSD both as host
4705(build U-Boot) and target system (boots NetBSD/mpc8xx).
4706
4707Building requires a cross environment; it is known to work on
4708NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4709need gmake since the Makefiles are not compatible with BSD make).
4710Note that the cross-powerpc package does not install include files;
4711attempting to build U-Boot will fail because <machine/ansi.h> is
4712missing.  This file has to be installed and patched manually:
4713
4714	# cd /usr/pkg/cross/powerpc-netbsd/include
4715	# mkdir powerpc
4716	# ln -s powerpc machine
4717	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4718	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4719
4720Native builds *don't* work due to incompatibilities between native
4721and U-Boot include files.
4722
4723Booting assumes that (the first part of) the image booted is a
4724stage-2 loader which in turn loads and then invokes the kernel
4725proper. Loader sources will eventually appear in the NetBSD source
4726tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4727meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4728
4729
4730Implementation Internals:
4731=========================
4732
4733The following is not intended to be a complete description of every
4734implementation detail. However, it should help to understand the
4735inner workings of U-Boot and make it easier to port it to custom
4736hardware.
4737
4738
4739Initial Stack, Global Data:
4740---------------------------
4741
4742The implementation of U-Boot is complicated by the fact that U-Boot
4743starts running out of ROM (flash memory), usually without access to
4744system RAM (because the memory controller is not initialized yet).
4745This means that we don't have writable Data or BSS segments, and BSS
4746is not initialized as zero. To be able to get a C environment working
4747at all, we have to allocate at least a minimal stack. Implementation
4748options for this are defined and restricted by the CPU used: Some CPU
4749models provide on-chip memory (like the IMMR area on MPC8xx and
4750MPC826x processors), on others (parts of) the data cache can be
4751locked as (mis-) used as memory, etc.
4752
4753	Chris Hallinan posted a good summary of these issues to the
4754	U-Boot mailing list:
4755
4756	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4757	From: "Chris Hallinan" <clh@net1plus.com>
4758	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4759	...
4760
4761	Correct me if I'm wrong, folks, but the way I understand it
4762	is this: Using DCACHE as initial RAM for Stack, etc, does not
4763	require any physical RAM backing up the cache. The cleverness
4764	is that the cache is being used as a temporary supply of
4765	necessary storage before the SDRAM controller is setup. It's
4766	beyond the scope of this list to explain the details, but you
4767	can see how this works by studying the cache architecture and
4768	operation in the architecture and processor-specific manuals.
4769
4770	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4771	is another option for the system designer to use as an
4772	initial stack/RAM area prior to SDRAM being available. Either
4773	option should work for you. Using CS 4 should be fine if your
4774	board designers haven't used it for something that would
4775	cause you grief during the initial boot! It is frequently not
4776	used.
4777
4778	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4779	with your processor/board/system design. The default value
4780	you will find in any recent u-boot distribution in
4781	walnut.h should work for you. I'd set it to a value larger
4782	than your SDRAM module. If you have a 64MB SDRAM module, set
4783	it above 400_0000. Just make sure your board has no resources
4784	that are supposed to respond to that address! That code in
4785	start.S has been around a while and should work as is when
4786	you get the config right.
4787
4788	-Chris Hallinan
4789	DS4.COM, Inc.
4790
4791It is essential to remember this, since it has some impact on the C
4792code for the initialization procedures:
4793
4794* Initialized global data (data segment) is read-only. Do not attempt
4795  to write it.
4796
4797* Do not use any uninitialized global data (or implicitely initialized
4798  as zero data - BSS segment) at all - this is undefined, initiali-
4799  zation is performed later (when relocating to RAM).
4800
4801* Stack space is very limited. Avoid big data buffers or things like
4802  that.
4803
4804Having only the stack as writable memory limits means we cannot use
4805normal global data to share information beween the code. But it
4806turned out that the implementation of U-Boot can be greatly
4807simplified by making a global data structure (gd_t) available to all
4808functions. We could pass a pointer to this data as argument to _all_
4809functions, but this would bloat the code. Instead we use a feature of
4810the GCC compiler (Global Register Variables) to share the data: we
4811place a pointer (gd) to the global data into a register which we
4812reserve for this purpose.
4813
4814When choosing a register for such a purpose we are restricted by the
4815relevant  (E)ABI  specifications for the current architecture, and by
4816GCC's implementation.
4817
4818For PowerPC, the following registers have specific use:
4819	R1:	stack pointer
4820	R2:	reserved for system use
4821	R3-R4:	parameter passing and return values
4822	R5-R10: parameter passing
4823	R13:	small data area pointer
4824	R30:	GOT pointer
4825	R31:	frame pointer
4826
4827	(U-Boot also uses R12 as internal GOT pointer. r12
4828	is a volatile register so r12 needs to be reset when
4829	going back and forth between asm and C)
4830
4831    ==> U-Boot will use R2 to hold a pointer to the global data
4832
4833    Note: on PPC, we could use a static initializer (since the
4834    address of the global data structure is known at compile time),
4835    but it turned out that reserving a register results in somewhat
4836    smaller code - although the code savings are not that big (on
4837    average for all boards 752 bytes for the whole U-Boot image,
4838    624 text + 127 data).
4839
4840On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4841	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4842
4843    ==> U-Boot will use P3 to hold a pointer to the global data
4844
4845On ARM, the following registers are used:
4846
4847	R0:	function argument word/integer result
4848	R1-R3:	function argument word
4849	R9:	GOT pointer
4850	R10:	stack limit (used only if stack checking if enabled)
4851	R11:	argument (frame) pointer
4852	R12:	temporary workspace
4853	R13:	stack pointer
4854	R14:	link register
4855	R15:	program counter
4856
4857    ==> U-Boot will use R8 to hold a pointer to the global data
4858
4859On Nios II, the ABI is documented here:
4860	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4861
4862    ==> U-Boot will use gp to hold a pointer to the global data
4863
4864    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4865    to access small data sections, so gp is free.
4866
4867On NDS32, the following registers are used:
4868
4869	R0-R1:	argument/return
4870	R2-R5:	argument
4871	R15:	temporary register for assembler
4872	R16:	trampoline register
4873	R28:	frame pointer (FP)
4874	R29:	global pointer (GP)
4875	R30:	link register (LP)
4876	R31:	stack pointer (SP)
4877	PC:	program counter (PC)
4878
4879    ==> U-Boot will use R10 to hold a pointer to the global data
4880
4881NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4882or current versions of GCC may "optimize" the code too much.
4883
4884Memory Management:
4885------------------
4886
4887U-Boot runs in system state and uses physical addresses, i.e. the
4888MMU is not used either for address mapping nor for memory protection.
4889
4890The available memory is mapped to fixed addresses using the memory
4891controller. In this process, a contiguous block is formed for each
4892memory type (Flash, SDRAM, SRAM), even when it consists of several
4893physical memory banks.
4894
4895U-Boot is installed in the first 128 kB of the first Flash bank (on
4896TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4897booting and sizing and initializing DRAM, the code relocates itself
4898to the upper end of DRAM. Immediately below the U-Boot code some
4899memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4900configuration setting]. Below that, a structure with global Board
4901Info data is placed, followed by the stack (growing downward).
4902
4903Additionally, some exception handler code is copied to the low 8 kB
4904of DRAM (0x00000000 ... 0x00001FFF).
4905
4906So a typical memory configuration with 16 MB of DRAM could look like
4907this:
4908
4909	0x0000 0000	Exception Vector code
4910	      :
4911	0x0000 1FFF
4912	0x0000 2000	Free for Application Use
4913	      :
4914	      :
4915
4916	      :
4917	      :
4918	0x00FB FF20	Monitor Stack (Growing downward)
4919	0x00FB FFAC	Board Info Data and permanent copy of global data
4920	0x00FC 0000	Malloc Arena
4921	      :
4922	0x00FD FFFF
4923	0x00FE 0000	RAM Copy of Monitor Code
4924	...		eventually: LCD or video framebuffer
4925	...		eventually: pRAM (Protected RAM - unchanged by reset)
4926	0x00FF FFFF	[End of RAM]
4927
4928
4929System Initialization:
4930----------------------
4931
4932In the reset configuration, U-Boot starts at the reset entry point
4933(on most PowerPC systems at address 0x00000100). Because of the reset
4934configuration for CS0# this is a mirror of the onboard Flash memory.
4935To be able to re-map memory U-Boot then jumps to its link address.
4936To be able to implement the initialization code in C, a (small!)
4937initial stack is set up in the internal Dual Ported RAM (in case CPUs
4938which provide such a feature like MPC8xx or MPC8260), or in a locked
4939part of the data cache. After that, U-Boot initializes the CPU core,
4940the caches and the SIU.
4941
4942Next, all (potentially) available memory banks are mapped using a
4943preliminary mapping. For example, we put them on 512 MB boundaries
4944(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4945on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4946programmed for SDRAM access. Using the temporary configuration, a
4947simple memory test is run that determines the size of the SDRAM
4948banks.
4949
4950When there is more than one SDRAM bank, and the banks are of
4951different size, the largest is mapped first. For equal size, the first
4952bank (CS2#) is mapped first. The first mapping is always for address
49530x00000000, with any additional banks following immediately to create
4954contiguous memory starting from 0.
4955
4956Then, the monitor installs itself at the upper end of the SDRAM area
4957and allocates memory for use by malloc() and for the global Board
4958Info data; also, the exception vector code is copied to the low RAM
4959pages, and the final stack is set up.
4960
4961Only after this relocation will you have a "normal" C environment;
4962until that you are restricted in several ways, mostly because you are
4963running from ROM, and because the code will have to be relocated to a
4964new address in RAM.
4965
4966
4967U-Boot Porting Guide:
4968----------------------
4969
4970[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4971list, October 2002]
4972
4973
4974int main(int argc, char *argv[])
4975{
4976	sighandler_t no_more_time;
4977
4978	signal(SIGALRM, no_more_time);
4979	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4980
4981	if (available_money > available_manpower) {
4982		Pay consultant to port U-Boot;
4983		return 0;
4984	}
4985
4986	Download latest U-Boot source;
4987
4988	Subscribe to u-boot mailing list;
4989
4990	if (clueless)
4991		email("Hi, I am new to U-Boot, how do I get started?");
4992
4993	while (learning) {
4994		Read the README file in the top level directory;
4995		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4996		Read applicable doc/*.README;
4997		Read the source, Luke;
4998		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4999	}
5000
5001	if (available_money > toLocalCurrency ($2500))
5002		Buy a BDI3000;
5003	else
5004		Add a lot of aggravation and time;
5005
5006	if (a similar board exists) {	/* hopefully... */
5007		cp -a board/<similar> board/<myboard>
5008		cp include/configs/<similar>.h include/configs/<myboard>.h
5009	} else {
5010		Create your own board support subdirectory;
5011		Create your own board include/configs/<myboard>.h file;
5012	}
5013	Edit new board/<myboard> files
5014	Edit new include/configs/<myboard>.h
5015
5016	while (!accepted) {
5017		while (!running) {
5018			do {
5019				Add / modify source code;
5020			} until (compiles);
5021			Debug;
5022			if (clueless)
5023				email("Hi, I am having problems...");
5024		}
5025		Send patch file to the U-Boot email list;
5026		if (reasonable critiques)
5027			Incorporate improvements from email list code review;
5028		else
5029			Defend code as written;
5030	}
5031
5032	return 0;
5033}
5034
5035void no_more_time (int sig)
5036{
5037      hire_a_guru();
5038}
5039
5040
5041Coding Standards:
5042-----------------
5043
5044All contributions to U-Boot should conform to the Linux kernel
5045coding style; see the file "Documentation/CodingStyle" and the script
5046"scripts/Lindent" in your Linux kernel source directory.
5047
5048Source files originating from a different project (for example the
5049MTD subsystem) are generally exempt from these guidelines and are not
5050reformated to ease subsequent migration to newer versions of those
5051sources.
5052
5053Please note that U-Boot is implemented in C (and to some small parts in
5054Assembler); no C++ is used, so please do not use C++ style comments (//)
5055in your code.
5056
5057Please also stick to the following formatting rules:
5058- remove any trailing white space
5059- use TAB characters for indentation and vertical alignment, not spaces
5060- make sure NOT to use DOS '\r\n' line feeds
5061- do not add more than 2 consecutive empty lines to source files
5062- do not add trailing empty lines to source files
5063
5064Submissions which do not conform to the standards may be returned
5065with a request to reformat the changes.
5066
5067
5068Submitting Patches:
5069-------------------
5070
5071Since the number of patches for U-Boot is growing, we need to
5072establish some rules. Submissions which do not conform to these rules
5073may be rejected, even when they contain important and valuable stuff.
5074
5075Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5076
5077Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5078see http://lists.denx.de/mailman/listinfo/u-boot
5079
5080When you send a patch, please include the following information with
5081it:
5082
5083* For bug fixes: a description of the bug and how your patch fixes
5084  this bug. Please try to include a way of demonstrating that the
5085  patch actually fixes something.
5086
5087* For new features: a description of the feature and your
5088  implementation.
5089
5090* A CHANGELOG entry as plaintext (separate from the patch)
5091
5092* For major contributions, your entry to the CREDITS file
5093
5094* When you add support for a new board, don't forget to add this
5095  board to the MAINTAINERS file, too.
5096
5097* If your patch adds new configuration options, don't forget to
5098  document these in the README file.
5099
5100* The patch itself. If you are using git (which is *strongly*
5101  recommended) you can easily generate the patch using the
5102  "git format-patch". If you then use "git send-email" to send it to
5103  the U-Boot mailing list, you will avoid most of the common problems
5104  with some other mail clients.
5105
5106  If you cannot use git, use "diff -purN OLD NEW". If your version of
5107  diff does not support these options, then get the latest version of
5108  GNU diff.
5109
5110  The current directory when running this command shall be the parent
5111  directory of the U-Boot source tree (i. e. please make sure that
5112  your patch includes sufficient directory information for the
5113  affected files).
5114
5115  We prefer patches as plain text. MIME attachments are discouraged,
5116  and compressed attachments must not be used.
5117
5118* If one logical set of modifications affects or creates several
5119  files, all these changes shall be submitted in a SINGLE patch file.
5120
5121* Changesets that contain different, unrelated modifications shall be
5122  submitted as SEPARATE patches, one patch per changeset.
5123
5124
5125Notes:
5126
5127* Before sending the patch, run the MAKEALL script on your patched
5128  source tree and make sure that no errors or warnings are reported
5129  for any of the boards.
5130
5131* Keep your modifications to the necessary minimum: A patch
5132  containing several unrelated changes or arbitrary reformats will be
5133  returned with a request to re-formatting / split it.
5134
5135* If you modify existing code, make sure that your new code does not
5136  add to the memory footprint of the code ;-) Small is beautiful!
5137  When adding new features, these should compile conditionally only
5138  (using #ifdef), and the resulting code with the new feature
5139  disabled must not need more memory than the old code without your
5140  modification.
5141
5142* Remember that there is a size limit of 100 kB per message on the
5143  u-boot mailing list. Bigger patches will be moderated. If they are
5144  reasonable and not too big, they will be acknowledged. But patches
5145  bigger than the size limit should be avoided.
5146