xref: /openbmc/u-boot/README (revision 06c53bea)
1#
2# (C) Copyright 2000 - 2008
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-users@lists.sourceforge.net>. There is also an archive of
64previous traffic on the mailing list - please search the archive
65before asking FAQ's. Please see
66http://lists.sourceforge.net/lists/listinfo/u-boot-users/
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/UBoot
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
129U-Boot uses a 3 level version number containing a version, a
130sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
131sub-version "34", and patchlevel "4".
132
133The patchlevel is used to indicate certain stages of development
134between released versions, i. e. officially released versions of
135U-Boot will always have a patchlevel of "0".
136
137
138Directory Hierarchy:
139====================
140
141- board		Board dependent files
142- common	Misc architecture independent functions
143- cpu		CPU specific files
144  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
145  - arm720t	Files specific to ARM 720 CPUs
146  - arm920t	Files specific to ARM 920 CPUs
147    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
148    - imx	Files specific to Freescale MC9328 i.MX CPUs
149    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
150  - arm925t	Files specific to ARM 925 CPUs
151  - arm926ejs	Files specific to ARM 926 CPUs
152  - arm1136	Files specific to ARM 1136 CPUs
153  - at32ap	Files specific to Atmel AVR32 AP CPUs
154  - i386	Files specific to i386 CPUs
155  - ixp		Files specific to Intel XScale IXP CPUs
156  - leon2	Files specific to Gaisler LEON2 SPARC CPU
157  - leon3	Files specific to Gaisler LEON3 SPARC CPU
158  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
159  - mcf5227x	Files specific to Freescale ColdFire MCF5227x CPUs
160  - mcf532x	Files specific to Freescale ColdFire MCF5329 CPUs
161  - mcf5445x	Files specific to Freescale ColdFire MCF5445x CPUs
162  - mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
163  - mips	Files specific to MIPS CPUs
164  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
165  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
166  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
167  - mpc8220	Files specific to Freescale MPC8220 CPUs
168  - mpc824x	Files specific to Freescale MPC824x CPUs
169  - mpc8260	Files specific to Freescale MPC8260 CPUs
170  - mpc85xx	Files specific to Freescale MPC85xx CPUs
171  - nios	Files specific to Altera NIOS CPUs
172  - nios2	Files specific to Altera Nios-II CPUs
173  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
174  - pxa		Files specific to Intel XScale PXA CPUs
175  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
176  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
177- disk		Code for disk drive partition handling
178- doc		Documentation (don't expect too much)
179- drivers	Commonly used device drivers
180- dtt		Digital Thermometer and Thermostat drivers
181- examples	Example code for standalone applications, etc.
182- include	Header Files
183- lib_arm	Files generic to ARM	 architecture
184- lib_avr32	Files generic to AVR32	 architecture
185- lib_generic	Files generic to all	 architectures
186- lib_i386	Files generic to i386	 architecture
187- lib_m68k	Files generic to m68k	 architecture
188- lib_mips	Files generic to MIPS	 architecture
189- lib_nios	Files generic to NIOS	 architecture
190- lib_ppc	Files generic to PowerPC architecture
191- lib_sparc	Files generic to SPARC	 architecture
192- libfdt	Library files to support flattened device trees
193- net		Networking code
194- post		Power On Self Test
195- rtc		Real Time Clock drivers
196- tools		Tools to build S-Record or U-Boot images, etc.
197
198Software Configuration:
199=======================
200
201Configuration is usually done using C preprocessor defines; the
202rationale behind that is to avoid dead code whenever possible.
203
204There are two classes of configuration variables:
205
206* Configuration _OPTIONS_:
207  These are selectable by the user and have names beginning with
208  "CONFIG_".
209
210* Configuration _SETTINGS_:
211  These depend on the hardware etc. and should not be meddled with if
212  you don't know what you're doing; they have names beginning with
213  "CFG_".
214
215Later we will add a configuration tool - probably similar to or even
216identical to what's used for the Linux kernel. Right now, we have to
217do the configuration by hand, which means creating some symbolic
218links and editing some configuration files. We use the TQM8xxL boards
219as an example here.
220
221
222Selection of Processor Architecture and Board Type:
223---------------------------------------------------
224
225For all supported boards there are ready-to-use default
226configurations available; just type "make <board_name>_config".
227
228Example: For a TQM823L module type:
229
230	cd u-boot
231	make TQM823L_config
232
233For the Cogent platform, you need to specify the CPU type as well;
234e.g. "make cogent_mpc8xx_config". And also configure the cogent
235directory according to the instructions in cogent/README.
236
237
238Configuration Options:
239----------------------
240
241Configuration depends on the combination of board and CPU type; all
242such information is kept in a configuration file
243"include/configs/<board_name>.h".
244
245Example: For a TQM823L module, all configuration settings are in
246"include/configs/TQM823L.h".
247
248
249Many of the options are named exactly as the corresponding Linux
250kernel configuration options. The intention is to make it easier to
251build a config tool - later.
252
253
254The following options need to be configured:
255
256- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
257
258- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
259
260- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
261		Define exactly one, e.g. CONFIG_ATSTK1002
262
263- CPU Module Type: (if CONFIG_COGENT is defined)
264		Define exactly one of
265		CONFIG_CMA286_60_OLD
266--- FIXME --- not tested yet:
267		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
268		CONFIG_CMA287_23, CONFIG_CMA287_50
269
270- Motherboard Type: (if CONFIG_COGENT is defined)
271		Define exactly one of
272		CONFIG_CMA101, CONFIG_CMA102
273
274- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
275		Define one or more of
276		CONFIG_CMA302
277
278- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
279		Define one or more of
280		CONFIG_LCD_HEARTBEAT	- update a character position on
281					  the LCD display every second with
282					  a "rotator" |\-/|\-/
283
284- Board flavour: (if CONFIG_MPC8260ADS is defined)
285		CONFIG_ADSTYPE
286		Possible values are:
287			CFG_8260ADS	- original MPC8260ADS
288			CFG_8266ADS	- MPC8266ADS
289			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
290			CFG_8272ADS	- MPC8272ADS
291
292- MPC824X Family Member (if CONFIG_MPC824X is defined)
293		Define exactly one of
294		CONFIG_MPC8240, CONFIG_MPC8245
295
296- 8xx CPU Options: (if using an MPC8xx CPU)
297		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
298					  get_gclk_freq() cannot work
299					  e.g. if there is no 32KHz
300					  reference PIT/RTC clock
301		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
302					  or XTAL/EXTAL)
303
304- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
305		CFG_8xx_CPUCLK_MIN
306		CFG_8xx_CPUCLK_MAX
307		CONFIG_8xx_CPUCLK_DEFAULT
308			See doc/README.MPC866
309
310		CFG_MEASURE_CPUCLK
311
312		Define this to measure the actual CPU clock instead
313		of relying on the correctness of the configured
314		values. Mostly useful for board bringup to make sure
315		the PLL is locked at the intended frequency. Note
316		that this requires a (stable) reference clock (32 kHz
317		RTC clock or CFG_8XX_XIN)
318
319- Intel Monahans options:
320		CFG_MONAHANS_RUN_MODE_OSC_RATIO
321
322		Defines the Monahans run mode to oscillator
323		ratio. Valid values are 8, 16, 24, 31. The core
324		frequency is this value multiplied by 13 MHz.
325
326		CFG_MONAHANS_TURBO_RUN_MODE_RATIO
327
328		Defines the Monahans turbo mode to oscillator
329		ratio. Valid values are 1 (default if undefined) and
330		2. The core frequency as calculated above is multiplied
331		by this value.
332
333- Linux Kernel Interface:
334		CONFIG_CLOCKS_IN_MHZ
335
336		U-Boot stores all clock information in Hz
337		internally. For binary compatibility with older Linux
338		kernels (which expect the clocks passed in the
339		bd_info data to be in MHz) the environment variable
340		"clocks_in_mhz" can be defined so that U-Boot
341		converts clock data to MHZ before passing it to the
342		Linux kernel.
343		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
344		"clocks_in_mhz=1" is automatically included in the
345		default environment.
346
347		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
348
349		When transferring memsize parameter to linux, some versions
350		expect it to be in bytes, others in MB.
351		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
352
353		CONFIG_OF_LIBFDT
354
355		New kernel versions are expecting firmware settings to be
356		passed using flattened device trees (based on open firmware
357		concepts).
358
359		CONFIG_OF_LIBFDT
360		 * New libfdt-based support
361		 * Adds the "fdt" command
362		 * The bootm command automatically updates the fdt
363
364		OF_CPU - The proper name of the cpus node.
365		OF_SOC - The proper name of the soc node.
366		OF_TBCLK - The timebase frequency.
367		OF_STDOUT_PATH - The path to the console device
368
369		boards with QUICC Engines require OF_QE to set UCC MAC
370		addresses
371
372		CONFIG_OF_BOARD_SETUP
373
374		Board code has addition modification that it wants to make
375		to the flat device tree before handing it off to the kernel
376
377		CONFIG_OF_BOOT_CPU
378
379		This define fills in the correct boot CPU in the boot
380		param header, the default value is zero if undefined.
381
382- Serial Ports:
383		CFG_PL010_SERIAL
384
385		Define this if you want support for Amba PrimeCell PL010 UARTs.
386
387		CFG_PL011_SERIAL
388
389		Define this if you want support for Amba PrimeCell PL011 UARTs.
390
391		CONFIG_PL011_CLOCK
392
393		If you have Amba PrimeCell PL011 UARTs, set this variable to
394		the clock speed of the UARTs.
395
396		CONFIG_PL01x_PORTS
397
398		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
399		define this to a list of base addresses for each (supported)
400		port. See e.g. include/configs/versatile.h
401
402
403- Console Interface:
404		Depending on board, define exactly one serial port
405		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
406		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
407		console by defining CONFIG_8xx_CONS_NONE
408
409		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
410		port routines must be defined elsewhere
411		(i.e. serial_init(), serial_getc(), ...)
412
413		CONFIG_CFB_CONSOLE
414		Enables console device for a color framebuffer. Needs following
415		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
416			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
417						(default big endian)
418			VIDEO_HW_RECTFILL	graphic chip supports
419						rectangle fill
420						(cf. smiLynxEM)
421			VIDEO_HW_BITBLT		graphic chip supports
422						bit-blit (cf. smiLynxEM)
423			VIDEO_VISIBLE_COLS	visible pixel columns
424						(cols=pitch)
425			VIDEO_VISIBLE_ROWS	visible pixel rows
426			VIDEO_PIXEL_SIZE	bytes per pixel
427			VIDEO_DATA_FORMAT	graphic data format
428						(0-5, cf. cfb_console.c)
429			VIDEO_FB_ADRS		framebuffer address
430			VIDEO_KBD_INIT_FCT	keyboard int fct
431						(i.e. i8042_kbd_init())
432			VIDEO_TSTC_FCT		test char fct
433						(i.e. i8042_tstc)
434			VIDEO_GETC_FCT		get char fct
435						(i.e. i8042_getc)
436			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
437						(requires blink timer
438						cf. i8042.c)
439			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
440			CONFIG_CONSOLE_TIME	display time/date info in
441						upper right corner
442						(requires CONFIG_CMD_DATE)
443			CONFIG_VIDEO_LOGO	display Linux logo in
444						upper left corner
445			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
446						linux_logo.h for logo.
447						Requires CONFIG_VIDEO_LOGO
448			CONFIG_CONSOLE_EXTRA_INFO
449						additional board info beside
450						the logo
451
452		When CONFIG_CFB_CONSOLE is defined, video console is
453		default i/o. Serial console can be forced with
454		environment 'console=serial'.
455
456		When CONFIG_SILENT_CONSOLE is defined, all console
457		messages (by U-Boot and Linux!) can be silenced with
458		the "silent" environment variable. See
459		doc/README.silent for more information.
460
461- Console Baudrate:
462		CONFIG_BAUDRATE - in bps
463		Select one of the baudrates listed in
464		CFG_BAUDRATE_TABLE, see below.
465		CFG_BRGCLK_PRESCALE, baudrate prescale
466
467- Interrupt driven serial port input:
468		CONFIG_SERIAL_SOFTWARE_FIFO
469
470		PPC405GP only.
471		Use an interrupt handler for receiving data on the
472		serial port. It also enables using hardware handshake
473		(RTS/CTS) and UART's built-in FIFO. Set the number of
474		bytes the interrupt driven input buffer should have.
475
476		Leave undefined to disable this feature, including
477		disable the buffer and hardware handshake.
478
479- Console UART Number:
480		CONFIG_UART1_CONSOLE
481
482		AMCC PPC4xx only.
483		If defined internal UART1 (and not UART0) is used
484		as default U-Boot console.
485
486- Boot Delay:	CONFIG_BOOTDELAY - in seconds
487		Delay before automatically booting the default image;
488		set to -1 to disable autoboot.
489
490		See doc/README.autoboot for these options that
491		work with CONFIG_BOOTDELAY. None are required.
492		CONFIG_BOOT_RETRY_TIME
493		CONFIG_BOOT_RETRY_MIN
494		CONFIG_AUTOBOOT_KEYED
495		CONFIG_AUTOBOOT_PROMPT
496		CONFIG_AUTOBOOT_DELAY_STR
497		CONFIG_AUTOBOOT_STOP_STR
498		CONFIG_AUTOBOOT_DELAY_STR2
499		CONFIG_AUTOBOOT_STOP_STR2
500		CONFIG_ZERO_BOOTDELAY_CHECK
501		CONFIG_RESET_TO_RETRY
502
503- Autoboot Command:
504		CONFIG_BOOTCOMMAND
505		Only needed when CONFIG_BOOTDELAY is enabled;
506		define a command string that is automatically executed
507		when no character is read on the console interface
508		within "Boot Delay" after reset.
509
510		CONFIG_BOOTARGS
511		This can be used to pass arguments to the bootm
512		command. The value of CONFIG_BOOTARGS goes into the
513		environment value "bootargs".
514
515		CONFIG_RAMBOOT and CONFIG_NFSBOOT
516		The value of these goes into the environment as
517		"ramboot" and "nfsboot" respectively, and can be used
518		as a convenience, when switching between booting from
519		RAM and NFS.
520
521- Pre-Boot Commands:
522		CONFIG_PREBOOT
523
524		When this option is #defined, the existence of the
525		environment variable "preboot" will be checked
526		immediately before starting the CONFIG_BOOTDELAY
527		countdown and/or running the auto-boot command resp.
528		entering interactive mode.
529
530		This feature is especially useful when "preboot" is
531		automatically generated or modified. For an example
532		see the LWMON board specific code: here "preboot" is
533		modified when the user holds down a certain
534		combination of keys on the (special) keyboard when
535		booting the systems
536
537- Serial Download Echo Mode:
538		CONFIG_LOADS_ECHO
539		If defined to 1, all characters received during a
540		serial download (using the "loads" command) are
541		echoed back. This might be needed by some terminal
542		emulations (like "cu"), but may as well just take
543		time on others. This setting #define's the initial
544		value of the "loads_echo" environment variable.
545
546- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
547		CONFIG_KGDB_BAUDRATE
548		Select one of the baudrates listed in
549		CFG_BAUDRATE_TABLE, see below.
550
551- Monitor Functions:
552		Monitor commands can be included or excluded
553		from the build by using the #include files
554		"config_cmd_all.h" and #undef'ing unwanted
555		commands, or using "config_cmd_default.h"
556		and augmenting with additional #define's
557		for wanted commands.
558
559		The default command configuration includes all commands
560		except those marked below with a "*".
561
562		CONFIG_CMD_ASKENV	* ask for env variable
563		CONFIG_CMD_AUTOSCRIPT	  Autoscript Support
564		CONFIG_CMD_BDI		  bdinfo
565		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
566		CONFIG_CMD_BMP		* BMP support
567		CONFIG_CMD_BSP		* Board specific commands
568		CONFIG_CMD_BOOTD	  bootd
569		CONFIG_CMD_CACHE	* icache, dcache
570		CONFIG_CMD_CONSOLE	  coninfo
571		CONFIG_CMD_DATE		* support for RTC, date/time...
572		CONFIG_CMD_DHCP		* DHCP support
573		CONFIG_CMD_DIAG		* Diagnostics
574		CONFIG_CMD_DOC		* Disk-On-Chip Support
575		CONFIG_CMD_DTT		* Digital Therm and Thermostat
576		CONFIG_CMD_ECHO		  echo arguments
577		CONFIG_CMD_EEPROM	* EEPROM read/write support
578		CONFIG_CMD_ELF		* bootelf, bootvx
579		CONFIG_CMD_ENV		  saveenv
580		CONFIG_CMD_FDC		* Floppy Disk Support
581		CONFIG_CMD_FAT		* FAT partition support
582		CONFIG_CMD_FDOS		* Dos diskette Support
583		CONFIG_CMD_FLASH	  flinfo, erase, protect
584		CONFIG_CMD_FPGA		  FPGA device initialization support
585		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
586		CONFIG_CMD_I2C		* I2C serial bus support
587		CONFIG_CMD_IDE		* IDE harddisk support
588		CONFIG_CMD_IMI		  iminfo
589		CONFIG_CMD_IMLS		  List all found images
590		CONFIG_CMD_IMMAP	* IMMR dump support
591		CONFIG_CMD_IRQ		* irqinfo
592		CONFIG_CMD_ITEST	  Integer/string test of 2 values
593		CONFIG_CMD_JFFS2	* JFFS2 Support
594		CONFIG_CMD_KGDB		* kgdb
595		CONFIG_CMD_LOADB	  loadb
596		CONFIG_CMD_LOADS	  loads
597		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
598					  loop, loopw, mtest
599		CONFIG_CMD_MISC		  Misc functions like sleep etc
600		CONFIG_CMD_MMC		* MMC memory mapped support
601		CONFIG_CMD_MII		* MII utility commands
602		CONFIG_CMD_NAND		* NAND support
603		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
604		CONFIG_CMD_PCI		* pciinfo
605		CONFIG_CMD_PCMCIA		* PCMCIA support
606		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
607					  host
608		CONFIG_CMD_PORTIO	* Port I/O
609		CONFIG_CMD_REGINFO	* Register dump
610		CONFIG_CMD_RUN		  run command in env variable
611		CONFIG_CMD_SAVES	* save S record dump
612		CONFIG_CMD_SCSI		* SCSI Support
613		CONFIG_CMD_SDRAM	* print SDRAM configuration information
614					  (requires CONFIG_CMD_I2C)
615		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
616					  (4xx only)
617		CONFIG_CMD_SPI		* SPI serial bus support
618		CONFIG_CMD_USB		* USB support
619		CONFIG_CMD_VFD		* VFD support (TRAB)
620		CONFIG_CMD_CDP		* Cisco Discover Protocol support
621		CONFIG_CMD_FSL		* Microblaze FSL support
622
623
624		EXAMPLE: If you want all functions except of network
625		support you can write:
626
627		#include "config_cmd_all.h"
628		#undef CONFIG_CMD_NET
629
630	Other Commands:
631		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
632
633	Note:	Don't enable the "icache" and "dcache" commands
634		(configuration option CONFIG_CMD_CACHE) unless you know
635		what you (and your U-Boot users) are doing. Data
636		cache cannot be enabled on systems like the 8xx or
637		8260 (where accesses to the IMMR region must be
638		uncached), and it cannot be disabled on all other
639		systems where we (mis-) use the data cache to hold an
640		initial stack and some data.
641
642
643		XXX - this list needs to get updated!
644
645- Watchdog:
646		CONFIG_WATCHDOG
647		If this variable is defined, it enables watchdog
648		support. There must be support in the platform specific
649		code for a watchdog. For the 8xx and 8260 CPUs, the
650		SIU Watchdog feature is enabled in the SYPCR
651		register.
652
653- U-Boot Version:
654		CONFIG_VERSION_VARIABLE
655		If this variable is defined, an environment variable
656		named "ver" is created by U-Boot showing the U-Boot
657		version as printed by the "version" command.
658		This variable is readonly.
659
660- Real-Time Clock:
661
662		When CONFIG_CMD_DATE is selected, the type of the RTC
663		has to be selected, too. Define exactly one of the
664		following options:
665
666		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
667		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
668		CONFIG_RTC_MC13783	- use MC13783 RTC
669		CONFIG_RTC_MC146818	- use MC146818 RTC
670		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
671		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
672		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
673		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
674		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
675		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
676		CFG_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
677
678		Note that if the RTC uses I2C, then the I2C interface
679		must also be configured. See I2C Support, below.
680
681- Timestamp Support:
682
683		When CONFIG_TIMESTAMP is selected, the timestamp
684		(date and time) of an image is printed by image
685		commands like bootm or iminfo. This option is
686		automatically enabled when you select CONFIG_CMD_DATE .
687
688- Partition Support:
689		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
690		and/or CONFIG_ISO_PARTITION
691
692		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
693		CONFIG_CMD_SCSI) you must configure support for at
694		least one partition type as well.
695
696- IDE Reset method:
697		CONFIG_IDE_RESET_ROUTINE - this is defined in several
698		board configurations files but used nowhere!
699
700		CONFIG_IDE_RESET - is this is defined, IDE Reset will
701		be performed by calling the function
702			ide_set_reset(int reset)
703		which has to be defined in a board specific file
704
705- ATAPI Support:
706		CONFIG_ATAPI
707
708		Set this to enable ATAPI support.
709
710- LBA48 Support
711		CONFIG_LBA48
712
713		Set this to enable support for disks larger than 137GB
714		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
715		Whithout these , LBA48 support uses 32bit variables and will 'only'
716		support disks up to 2.1TB.
717
718		CFG_64BIT_LBA:
719			When enabled, makes the IDE subsystem use 64bit sector addresses.
720			Default is 32bit.
721
722- SCSI Support:
723		At the moment only there is only support for the
724		SYM53C8XX SCSI controller; define
725		CONFIG_SCSI_SYM53C8XX to enable it.
726
727		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
728		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
729		CFG_SCSI_MAX_LUN] can be adjusted to define the
730		maximum numbers of LUNs, SCSI ID's and target
731		devices.
732		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
733
734- NETWORK Support (PCI):
735		CONFIG_E1000
736		Support for Intel 8254x gigabit chips.
737
738		CONFIG_E1000_FALLBACK_MAC
739		default MAC for empty EEPROM after production.
740
741		CONFIG_EEPRO100
742		Support for Intel 82557/82559/82559ER chips.
743		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
744		write routine for first time initialisation.
745
746		CONFIG_TULIP
747		Support for Digital 2114x chips.
748		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
749		modem chip initialisation (KS8761/QS6611).
750
751		CONFIG_NATSEMI
752		Support for National dp83815 chips.
753
754		CONFIG_NS8382X
755		Support for National dp8382[01] gigabit chips.
756
757- NETWORK Support (other):
758
759		CONFIG_DRIVER_LAN91C96
760		Support for SMSC's LAN91C96 chips.
761
762			CONFIG_LAN91C96_BASE
763			Define this to hold the physical address
764			of the LAN91C96's I/O space
765
766			CONFIG_LAN91C96_USE_32_BIT
767			Define this to enable 32 bit addressing
768
769		CONFIG_DRIVER_SMC91111
770		Support for SMSC's LAN91C111 chip
771
772			CONFIG_SMC91111_BASE
773			Define this to hold the physical address
774			of the device (I/O space)
775
776			CONFIG_SMC_USE_32_BIT
777			Define this if data bus is 32 bits
778
779			CONFIG_SMC_USE_IOFUNCS
780			Define this to use i/o functions instead of macros
781			(some hardware wont work with macros)
782
783		CONFIG_DRIVER_SMC911X
784		Support for SMSC's LAN911x and LAN921x chips
785
786			CONFIG_DRIVER_SMC911X_BASE
787			Define this to hold the physical address
788			of the device (I/O space)
789
790			CONFIG_DRIVER_SMC911X_32_BIT
791			Define this if data bus is 32 bits
792
793			CONFIG_DRIVER_SMC911X_16_BIT
794			Define this if data bus is 16 bits. If your processor
795			automatically converts one 32 bit word to two 16 bit
796			words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
797
798- USB Support:
799		At the moment only the UHCI host controller is
800		supported (PIP405, MIP405, MPC5200); define
801		CONFIG_USB_UHCI to enable it.
802		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
803		and define CONFIG_USB_STORAGE to enable the USB
804		storage devices.
805		Note:
806		Supported are USB Keyboards and USB Floppy drives
807		(TEAC FD-05PUB).
808		MPC5200 USB requires additional defines:
809			CONFIG_USB_CLOCK
810				for 528 MHz Clock: 0x0001bbbb
811			CONFIG_USB_CONFIG
812				for differential drivers: 0x00001000
813				for single ended drivers: 0x00005000
814			CFG_USB_EVENT_POLL
815				May be defined to allow interrupt polling
816				instead of using asynchronous interrupts
817
818- USB Device:
819		Define the below if you wish to use the USB console.
820		Once firmware is rebuilt from a serial console issue the
821		command "setenv stdin usbtty; setenv stdout usbtty" and
822		attach your USB cable. The Unix command "dmesg" should print
823		it has found a new device. The environment variable usbtty
824		can be set to gserial or cdc_acm to enable your device to
825		appear to a USB host as a Linux gserial device or a
826		Common Device Class Abstract Control Model serial device.
827		If you select usbtty = gserial you should be able to enumerate
828		a Linux host by
829		# modprobe usbserial vendor=0xVendorID product=0xProductID
830		else if using cdc_acm, simply setting the environment
831		variable usbtty to be cdc_acm should suffice. The following
832		might be defined in YourBoardName.h
833
834			CONFIG_USB_DEVICE
835			Define this to build a UDC device
836
837			CONFIG_USB_TTY
838			Define this to have a tty type of device available to
839			talk to the UDC device
840
841			CFG_CONSOLE_IS_IN_ENV
842			Define this if you want stdin, stdout &/or stderr to
843			be set to usbtty.
844
845			mpc8xx:
846				CFG_USB_EXTC_CLK 0xBLAH
847				Derive USB clock from external clock "blah"
848				- CFG_USB_EXTC_CLK 0x02
849
850				CFG_USB_BRG_CLK 0xBLAH
851				Derive USB clock from brgclk
852				- CFG_USB_BRG_CLK 0x04
853
854		If you have a USB-IF assigned VendorID then you may wish to
855		define your own vendor specific values either in BoardName.h
856		or directly in usbd_vendor_info.h. If you don't define
857		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
858		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
859		should pretend to be a Linux device to it's target host.
860
861			CONFIG_USBD_MANUFACTURER
862			Define this string as the name of your company for
863			- CONFIG_USBD_MANUFACTURER "my company"
864
865			CONFIG_USBD_PRODUCT_NAME
866			Define this string as the name of your product
867			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
868
869			CONFIG_USBD_VENDORID
870			Define this as your assigned Vendor ID from the USB
871			Implementors Forum. This *must* be a genuine Vendor ID
872			to avoid polluting the USB namespace.
873			- CONFIG_USBD_VENDORID 0xFFFF
874
875			CONFIG_USBD_PRODUCTID
876			Define this as the unique Product ID
877			for your device
878			- CONFIG_USBD_PRODUCTID 0xFFFF
879
880
881- MMC Support:
882		The MMC controller on the Intel PXA is supported. To
883		enable this define CONFIG_MMC. The MMC can be
884		accessed from the boot prompt by mapping the device
885		to physical memory similar to flash. Command line is
886		enabled with CONFIG_CMD_MMC. The MMC driver also works with
887		the FAT fs. This is enabled with CONFIG_CMD_FAT.
888
889- Journaling Flash filesystem support:
890		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
891		CONFIG_JFFS2_NAND_DEV
892		Define these for a default partition on a NAND device
893
894		CFG_JFFS2_FIRST_SECTOR,
895		CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
896		Define these for a default partition on a NOR device
897
898		CFG_JFFS_CUSTOM_PART
899		Define this to create an own partition. You have to provide a
900		function struct part_info* jffs2_part_info(int part_num)
901
902		If you define only one JFFS2 partition you may also want to
903		#define CFG_JFFS_SINGLE_PART	1
904		to disable the command chpart. This is the default when you
905		have not defined a custom partition
906
907- Keyboard Support:
908		CONFIG_ISA_KEYBOARD
909
910		Define this to enable standard (PC-Style) keyboard
911		support
912
913		CONFIG_I8042_KBD
914		Standard PC keyboard driver with US (is default) and
915		GERMAN key layout (switch via environment 'keymap=de') support.
916		Export function i8042_kbd_init, i8042_tstc and i8042_getc
917		for cfb_console. Supports cursor blinking.
918
919- Video support:
920		CONFIG_VIDEO
921
922		Define this to enable video support (for output to
923		video).
924
925		CONFIG_VIDEO_CT69000
926
927		Enable Chips & Technologies 69000 Video chip
928
929		CONFIG_VIDEO_SMI_LYNXEM
930		Enable Silicon Motion SMI 712/710/810 Video chip. The
931		video output is selected via environment 'videoout'
932		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
933		assumed.
934
935		For the CT69000 and SMI_LYNXEM drivers, videomode is
936		selected via environment 'videomode'. Two different ways
937		are possible:
938		- "videomode=num"   'num' is a standard LiLo mode numbers.
939		Following standard modes are supported	(* is default):
940
941		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
942		-------------+---------------------------------------------
943		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
944		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
945		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
946		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
947		-------------+---------------------------------------------
948		(i.e. setenv videomode 317; saveenv; reset;)
949
950		- "videomode=bootargs" all the video parameters are parsed
951		from the bootargs. (See drivers/video/videomodes.c)
952
953
954		CONFIG_VIDEO_SED13806
955		Enable Epson SED13806 driver. This driver supports 8bpp
956		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
957		or CONFIG_VIDEO_SED13806_16BPP
958
959- Keyboard Support:
960		CONFIG_KEYBOARD
961
962		Define this to enable a custom keyboard support.
963		This simply calls drv_keyboard_init() which must be
964		defined in your board-specific files.
965		The only board using this so far is RBC823.
966
967- LCD Support:	CONFIG_LCD
968
969		Define this to enable LCD support (for output to LCD
970		display); also select one of the supported displays
971		by defining one of these:
972
973		CONFIG_ATMEL_LCD:
974
975			HITACHI TX09D70VM1CCA, 3.5", 240x320.
976
977		CONFIG_NEC_NL6448AC33:
978
979			NEC NL6448AC33-18. Active, color, single scan.
980
981		CONFIG_NEC_NL6448BC20
982
983			NEC NL6448BC20-08. 6.5", 640x480.
984			Active, color, single scan.
985
986		CONFIG_NEC_NL6448BC33_54
987
988			NEC NL6448BC33-54. 10.4", 640x480.
989			Active, color, single scan.
990
991		CONFIG_SHARP_16x9
992
993			Sharp 320x240. Active, color, single scan.
994			It isn't 16x9, and I am not sure what it is.
995
996		CONFIG_SHARP_LQ64D341
997
998			Sharp LQ64D341 display, 640x480.
999			Active, color, single scan.
1000
1001		CONFIG_HLD1045
1002
1003			HLD1045 display, 640x480.
1004			Active, color, single scan.
1005
1006		CONFIG_OPTREX_BW
1007
1008			Optrex	 CBL50840-2 NF-FW 99 22 M5
1009			or
1010			Hitachi	 LMG6912RPFC-00T
1011			or
1012			Hitachi	 SP14Q002
1013
1014			320x240. Black & white.
1015
1016		Normally display is black on white background; define
1017		CFG_WHITE_ON_BLACK to get it inverted.
1018
1019- Splash Screen Support: CONFIG_SPLASH_SCREEN
1020
1021		If this option is set, the environment is checked for
1022		a variable "splashimage". If found, the usual display
1023		of logo, copyright and system information on the LCD
1024		is suppressed and the BMP image at the address
1025		specified in "splashimage" is loaded instead. The
1026		console is redirected to the "nulldev", too. This
1027		allows for a "silent" boot where a splash screen is
1028		loaded very quickly after power-on.
1029
1030- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1031
1032		If this option is set, additionally to standard BMP
1033		images, gzipped BMP images can be displayed via the
1034		splashscreen support or the bmp command.
1035
1036- Compression support:
1037		CONFIG_BZIP2
1038
1039		If this option is set, support for bzip2 compressed
1040		images is included. If not, only uncompressed and gzip
1041		compressed images are supported.
1042
1043		NOTE: the bzip2 algorithm requires a lot of RAM, so
1044		the malloc area (as defined by CFG_MALLOC_LEN) should
1045		be at least 4MB.
1046
1047- MII/PHY support:
1048		CONFIG_PHY_ADDR
1049
1050		The address of PHY on MII bus.
1051
1052		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1053
1054		The clock frequency of the MII bus
1055
1056		CONFIG_PHY_GIGE
1057
1058		If this option is set, support for speed/duplex
1059		detection of gigabit PHY is included.
1060
1061		CONFIG_PHY_RESET_DELAY
1062
1063		Some PHY like Intel LXT971A need extra delay after
1064		reset before any MII register access is possible.
1065		For such PHY, set this option to the usec delay
1066		required. (minimum 300usec for LXT971A)
1067
1068		CONFIG_PHY_CMD_DELAY (ppc4xx)
1069
1070		Some PHY like Intel LXT971A need extra delay after
1071		command issued before MII status register can be read
1072
1073- Ethernet address:
1074		CONFIG_ETHADDR
1075		CONFIG_ETH2ADDR
1076		CONFIG_ETH3ADDR
1077
1078		Define a default value for Ethernet address to use
1079		for the respective Ethernet interface, in case this
1080		is not determined automatically.
1081
1082- IP address:
1083		CONFIG_IPADDR
1084
1085		Define a default value for the IP address to use for
1086		the default Ethernet interface, in case this is not
1087		determined through e.g. bootp.
1088
1089- Server IP address:
1090		CONFIG_SERVERIP
1091
1092		Defines a default value for the IP address of a TFTP
1093		server to contact when using the "tftboot" command.
1094
1095- Multicast TFTP Mode:
1096		CONFIG_MCAST_TFTP
1097
1098		Defines whether you want to support multicast TFTP as per
1099		rfc-2090; for example to work with atftp.  Lets lots of targets
1100		tftp down the same boot image concurrently.  Note: the Ethernet
1101		driver in use must provide a function: mcast() to join/leave a
1102		multicast group.
1103
1104		CONFIG_BOOTP_RANDOM_DELAY
1105- BOOTP Recovery Mode:
1106		CONFIG_BOOTP_RANDOM_DELAY
1107
1108		If you have many targets in a network that try to
1109		boot using BOOTP, you may want to avoid that all
1110		systems send out BOOTP requests at precisely the same
1111		moment (which would happen for instance at recovery
1112		from a power failure, when all systems will try to
1113		boot, thus flooding the BOOTP server. Defining
1114		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1115		inserted before sending out BOOTP requests. The
1116		following delays are inserted then:
1117
1118		1st BOOTP request:	delay 0 ... 1 sec
1119		2nd BOOTP request:	delay 0 ... 2 sec
1120		3rd BOOTP request:	delay 0 ... 4 sec
1121		4th and following
1122		BOOTP requests:		delay 0 ... 8 sec
1123
1124- DHCP Advanced Options:
1125		You can fine tune the DHCP functionality by defining
1126		CONFIG_BOOTP_* symbols:
1127
1128		CONFIG_BOOTP_SUBNETMASK
1129		CONFIG_BOOTP_GATEWAY
1130		CONFIG_BOOTP_HOSTNAME
1131		CONFIG_BOOTP_NISDOMAIN
1132		CONFIG_BOOTP_BOOTPATH
1133		CONFIG_BOOTP_BOOTFILESIZE
1134		CONFIG_BOOTP_DNS
1135		CONFIG_BOOTP_DNS2
1136		CONFIG_BOOTP_SEND_HOSTNAME
1137		CONFIG_BOOTP_NTPSERVER
1138		CONFIG_BOOTP_TIMEOFFSET
1139		CONFIG_BOOTP_VENDOREX
1140
1141		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1142		environment variable, not the BOOTP server.
1143
1144		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1145		serverip from a DHCP server, it is possible that more
1146		than one DNS serverip is offered to the client.
1147		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1148		serverip will be stored in the additional environment
1149		variable "dnsip2". The first DNS serverip is always
1150		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1151		is defined.
1152
1153		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1154		to do a dynamic update of a DNS server. To do this, they
1155		need the hostname of the DHCP requester.
1156		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1157		of the "hostname" environment variable is passed as
1158		option 12 to the DHCP server.
1159
1160		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1161
1162		A 32bit value in microseconds for a delay between
1163		receiving a "DHCP Offer" and sending the "DHCP Request".
1164		This fixes a problem with certain DHCP servers that don't
1165		respond 100% of the time to a "DHCP request". E.g. On an
1166		AT91RM9200 processor running at 180MHz, this delay needed
1167		to be *at least* 15,000 usec before a Windows Server 2003
1168		DHCP server would reply 100% of the time. I recommend at
1169		least 50,000 usec to be safe. The alternative is to hope
1170		that one of the retries will be successful but note that
1171		the DHCP timeout and retry process takes a longer than
1172		this delay.
1173
1174 - CDP Options:
1175		CONFIG_CDP_DEVICE_ID
1176
1177		The device id used in CDP trigger frames.
1178
1179		CONFIG_CDP_DEVICE_ID_PREFIX
1180
1181		A two character string which is prefixed to the MAC address
1182		of the device.
1183
1184		CONFIG_CDP_PORT_ID
1185
1186		A printf format string which contains the ascii name of
1187		the port. Normally is set to "eth%d" which sets
1188		eth0 for the first Ethernet, eth1 for the second etc.
1189
1190		CONFIG_CDP_CAPABILITIES
1191
1192		A 32bit integer which indicates the device capabilities;
1193		0x00000010 for a normal host which does not forwards.
1194
1195		CONFIG_CDP_VERSION
1196
1197		An ascii string containing the version of the software.
1198
1199		CONFIG_CDP_PLATFORM
1200
1201		An ascii string containing the name of the platform.
1202
1203		CONFIG_CDP_TRIGGER
1204
1205		A 32bit integer sent on the trigger.
1206
1207		CONFIG_CDP_POWER_CONSUMPTION
1208
1209		A 16bit integer containing the power consumption of the
1210		device in .1 of milliwatts.
1211
1212		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1213
1214		A byte containing the id of the VLAN.
1215
1216- Status LED:	CONFIG_STATUS_LED
1217
1218		Several configurations allow to display the current
1219		status using a LED. For instance, the LED will blink
1220		fast while running U-Boot code, stop blinking as
1221		soon as a reply to a BOOTP request was received, and
1222		start blinking slow once the Linux kernel is running
1223		(supported by a status LED driver in the Linux
1224		kernel). Defining CONFIG_STATUS_LED enables this
1225		feature in U-Boot.
1226
1227- CAN Support:	CONFIG_CAN_DRIVER
1228
1229		Defining CONFIG_CAN_DRIVER enables CAN driver support
1230		on those systems that support this (optional)
1231		feature, like the TQM8xxL modules.
1232
1233- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1234
1235		These enable I2C serial bus commands. Defining either of
1236		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1237		include the appropriate I2C driver for the selected CPU.
1238
1239		This will allow you to use i2c commands at the u-boot
1240		command line (as long as you set CONFIG_CMD_I2C in
1241		CONFIG_COMMANDS) and communicate with i2c based realtime
1242		clock chips. See common/cmd_i2c.c for a description of the
1243		command line interface.
1244
1245		CONFIG_I2C_CMD_TREE is a recommended option that places
1246		all I2C commands under a single 'i2c' root command.  The
1247		older 'imm', 'imd', 'iprobe' etc. commands are considered
1248		deprecated and may disappear in the future.
1249
1250		CONFIG_HARD_I2C selects a hardware I2C controller.
1251
1252		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1253		bit-banging) driver instead of CPM or similar hardware
1254		support for I2C.
1255
1256		There are several other quantities that must also be
1257		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1258
1259		In both cases you will need to define CFG_I2C_SPEED
1260		to be the frequency (in Hz) at which you wish your i2c bus
1261		to run and CFG_I2C_SLAVE to be the address of this node (ie
1262		the CPU's i2c node address).
1263
1264		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1265		sets the CPU up as a master node and so its address should
1266		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1267		p.16-473). So, set CFG_I2C_SLAVE to 0.
1268
1269		That's all that's required for CONFIG_HARD_I2C.
1270
1271		If you use the software i2c interface (CONFIG_SOFT_I2C)
1272		then the following macros need to be defined (examples are
1273		from include/configs/lwmon.h):
1274
1275		I2C_INIT
1276
1277		(Optional). Any commands necessary to enable the I2C
1278		controller or configure ports.
1279
1280		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1281
1282		I2C_PORT
1283
1284		(Only for MPC8260 CPU). The I/O port to use (the code
1285		assumes both bits are on the same port). Valid values
1286		are 0..3 for ports A..D.
1287
1288		I2C_ACTIVE
1289
1290		The code necessary to make the I2C data line active
1291		(driven).  If the data line is open collector, this
1292		define can be null.
1293
1294		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1295
1296		I2C_TRISTATE
1297
1298		The code necessary to make the I2C data line tri-stated
1299		(inactive).  If the data line is open collector, this
1300		define can be null.
1301
1302		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1303
1304		I2C_READ
1305
1306		Code that returns TRUE if the I2C data line is high,
1307		FALSE if it is low.
1308
1309		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1310
1311		I2C_SDA(bit)
1312
1313		If <bit> is TRUE, sets the I2C data line high. If it
1314		is FALSE, it clears it (low).
1315
1316		eg: #define I2C_SDA(bit) \
1317			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1318			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1319
1320		I2C_SCL(bit)
1321
1322		If <bit> is TRUE, sets the I2C clock line high. If it
1323		is FALSE, it clears it (low).
1324
1325		eg: #define I2C_SCL(bit) \
1326			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1327			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1328
1329		I2C_DELAY
1330
1331		This delay is invoked four times per clock cycle so this
1332		controls the rate of data transfer.  The data rate thus
1333		is 1 / (I2C_DELAY * 4). Often defined to be something
1334		like:
1335
1336		#define I2C_DELAY  udelay(2)
1337
1338		CFG_I2C_INIT_BOARD
1339
1340		When a board is reset during an i2c bus transfer
1341		chips might think that the current transfer is still
1342		in progress. On some boards it is possible to access
1343		the i2c SCLK line directly, either by using the
1344		processor pin as a GPIO or by having a second pin
1345		connected to the bus. If this option is defined a
1346		custom i2c_init_board() routine in boards/xxx/board.c
1347		is run early in the boot sequence.
1348
1349		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1350
1351		This option enables configuration of bi_iic_fast[] flags
1352		in u-boot bd_info structure based on u-boot environment
1353		variable "i2cfast". (see also i2cfast)
1354
1355		CONFIG_I2C_MULTI_BUS
1356
1357		This option allows the use of multiple I2C buses, each of which
1358		must have a controller.  At any point in time, only one bus is
1359		active.  To switch to a different bus, use the 'i2c dev' command.
1360		Note that bus numbering is zero-based.
1361
1362		CFG_I2C_NOPROBES
1363
1364		This option specifies a list of I2C devices that will be skipped
1365		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1366		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1367		pairs.	Otherwise, specify a 1D array of device addresses
1368
1369		e.g.
1370			#undef	CONFIG_I2C_MULTI_BUS
1371			#define CFG_I2C_NOPROBES	{0x50,0x68}
1372
1373		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1374
1375			#define	CONFIG_I2C_MULTI_BUS
1376			#define CFG_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1377
1378		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1379
1380		CFG_SPD_BUS_NUM
1381
1382		If defined, then this indicates the I2C bus number for DDR SPD.
1383		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1384
1385		CFG_RTC_BUS_NUM
1386
1387		If defined, then this indicates the I2C bus number for the RTC.
1388		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1389
1390		CFG_DTT_BUS_NUM
1391
1392		If defined, then this indicates the I2C bus number for the DTT.
1393		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1394
1395		CONFIG_FSL_I2C
1396
1397		Define this option if you want to use Freescale's I2C driver in
1398		drivers/i2c/fsl_i2c.c.
1399
1400
1401- SPI Support:	CONFIG_SPI
1402
1403		Enables SPI driver (so far only tested with
1404		SPI EEPROM, also an instance works with Crystal A/D and
1405		D/As on the SACSng board)
1406
1407		CONFIG_SPI_X
1408
1409		Enables extended (16-bit) SPI EEPROM addressing.
1410		(symmetrical to CONFIG_I2C_X)
1411
1412		CONFIG_SOFT_SPI
1413
1414		Enables a software (bit-bang) SPI driver rather than
1415		using hardware support. This is a general purpose
1416		driver that only requires three general I/O port pins
1417		(two outputs, one input) to function. If this is
1418		defined, the board configuration must define several
1419		SPI configuration items (port pins to use, etc). For
1420		an example, see include/configs/sacsng.h.
1421
1422		CONFIG_HARD_SPI
1423
1424		Enables a hardware SPI driver for general-purpose reads
1425		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1426		must define a list of chip-select function pointers.
1427		Currently supported on some MPC8xxx processors.  For an
1428		example, see include/configs/mpc8349emds.h.
1429
1430		CONFIG_MXC_SPI
1431
1432		Enables the driver for the SPI controllers on i.MX and MXC
1433		SoCs. Currently only i.MX31 is supported.
1434
1435- FPGA Support: CONFIG_FPGA
1436
1437		Enables FPGA subsystem.
1438
1439		CONFIG_FPGA_<vendor>
1440
1441		Enables support for specific chip vendors.
1442		(ALTERA, XILINX)
1443
1444		CONFIG_FPGA_<family>
1445
1446		Enables support for FPGA family.
1447		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1448
1449		CONFIG_FPGA_COUNT
1450
1451		Specify the number of FPGA devices to support.
1452
1453		CFG_FPGA_PROG_FEEDBACK
1454
1455		Enable printing of hash marks during FPGA configuration.
1456
1457		CFG_FPGA_CHECK_BUSY
1458
1459		Enable checks on FPGA configuration interface busy
1460		status by the configuration function. This option
1461		will require a board or device specific function to
1462		be written.
1463
1464		CONFIG_FPGA_DELAY
1465
1466		If defined, a function that provides delays in the FPGA
1467		configuration driver.
1468
1469		CFG_FPGA_CHECK_CTRLC
1470		Allow Control-C to interrupt FPGA configuration
1471
1472		CFG_FPGA_CHECK_ERROR
1473
1474		Check for configuration errors during FPGA bitfile
1475		loading. For example, abort during Virtex II
1476		configuration if the INIT_B line goes low (which
1477		indicated a CRC error).
1478
1479		CFG_FPGA_WAIT_INIT
1480
1481		Maximum time to wait for the INIT_B line to deassert
1482		after PROB_B has been deasserted during a Virtex II
1483		FPGA configuration sequence. The default time is 500
1484		ms.
1485
1486		CFG_FPGA_WAIT_BUSY
1487
1488		Maximum time to wait for BUSY to deassert during
1489		Virtex II FPGA configuration. The default is 5 ms.
1490
1491		CFG_FPGA_WAIT_CONFIG
1492
1493		Time to wait after FPGA configuration. The default is
1494		200 ms.
1495
1496- Configuration Management:
1497		CONFIG_IDENT_STRING
1498
1499		If defined, this string will be added to the U-Boot
1500		version information (U_BOOT_VERSION)
1501
1502- Vendor Parameter Protection:
1503
1504		U-Boot considers the values of the environment
1505		variables "serial#" (Board Serial Number) and
1506		"ethaddr" (Ethernet Address) to be parameters that
1507		are set once by the board vendor / manufacturer, and
1508		protects these variables from casual modification by
1509		the user. Once set, these variables are read-only,
1510		and write or delete attempts are rejected. You can
1511		change this behaviour:
1512
1513		If CONFIG_ENV_OVERWRITE is #defined in your config
1514		file, the write protection for vendor parameters is
1515		completely disabled. Anybody can change or delete
1516		these parameters.
1517
1518		Alternatively, if you #define _both_ CONFIG_ETHADDR
1519		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1520		Ethernet address is installed in the environment,
1521		which can be changed exactly ONCE by the user. [The
1522		serial# is unaffected by this, i. e. it remains
1523		read-only.]
1524
1525- Protected RAM:
1526		CONFIG_PRAM
1527
1528		Define this variable to enable the reservation of
1529		"protected RAM", i. e. RAM which is not overwritten
1530		by U-Boot. Define CONFIG_PRAM to hold the number of
1531		kB you want to reserve for pRAM. You can overwrite
1532		this default value by defining an environment
1533		variable "pram" to the number of kB you want to
1534		reserve. Note that the board info structure will
1535		still show the full amount of RAM. If pRAM is
1536		reserved, a new environment variable "mem" will
1537		automatically be defined to hold the amount of
1538		remaining RAM in a form that can be passed as boot
1539		argument to Linux, for instance like that:
1540
1541			setenv bootargs ... mem=\${mem}
1542			saveenv
1543
1544		This way you can tell Linux not to use this memory,
1545		either, which results in a memory region that will
1546		not be affected by reboots.
1547
1548		*WARNING* If your board configuration uses automatic
1549		detection of the RAM size, you must make sure that
1550		this memory test is non-destructive. So far, the
1551		following board configurations are known to be
1552		"pRAM-clean":
1553
1554			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1555			HERMES, IP860, RPXlite, LWMON, LANTEC,
1556			PCU_E, FLAGADM, TQM8260
1557
1558- Error Recovery:
1559		CONFIG_PANIC_HANG
1560
1561		Define this variable to stop the system in case of a
1562		fatal error, so that you have to reset it manually.
1563		This is probably NOT a good idea for an embedded
1564		system where you want the system to reboot
1565		automatically as fast as possible, but it may be
1566		useful during development since you can try to debug
1567		the conditions that lead to the situation.
1568
1569		CONFIG_NET_RETRY_COUNT
1570
1571		This variable defines the number of retries for
1572		network operations like ARP, RARP, TFTP, or BOOTP
1573		before giving up the operation. If not defined, a
1574		default value of 5 is used.
1575
1576		CONFIG_ARP_TIMEOUT
1577
1578		Timeout waiting for an ARP reply in milliseconds.
1579
1580- Command Interpreter:
1581		CONFIG_AUTO_COMPLETE
1582
1583		Enable auto completion of commands using TAB.
1584
1585		Note that this feature has NOT been implemented yet
1586		for the "hush" shell.
1587
1588
1589		CFG_HUSH_PARSER
1590
1591		Define this variable to enable the "hush" shell (from
1592		Busybox) as command line interpreter, thus enabling
1593		powerful command line syntax like
1594		if...then...else...fi conditionals or `&&' and '||'
1595		constructs ("shell scripts").
1596
1597		If undefined, you get the old, much simpler behaviour
1598		with a somewhat smaller memory footprint.
1599
1600
1601		CFG_PROMPT_HUSH_PS2
1602
1603		This defines the secondary prompt string, which is
1604		printed when the command interpreter needs more input
1605		to complete a command. Usually "> ".
1606
1607	Note:
1608
1609		In the current implementation, the local variables
1610		space and global environment variables space are
1611		separated. Local variables are those you define by
1612		simply typing `name=value'. To access a local
1613		variable later on, you have write `$name' or
1614		`${name}'; to execute the contents of a variable
1615		directly type `$name' at the command prompt.
1616
1617		Global environment variables are those you use
1618		setenv/printenv to work with. To run a command stored
1619		in such a variable, you need to use the run command,
1620		and you must not use the '$' sign to access them.
1621
1622		To store commands and special characters in a
1623		variable, please use double quotation marks
1624		surrounding the whole text of the variable, instead
1625		of the backslashes before semicolons and special
1626		symbols.
1627
1628- Commandline Editing and History:
1629		CONFIG_CMDLINE_EDITING
1630
1631		Enable editing and History functions for interactive
1632		commandline input operations
1633
1634- Default Environment:
1635		CONFIG_EXTRA_ENV_SETTINGS
1636
1637		Define this to contain any number of null terminated
1638		strings (variable = value pairs) that will be part of
1639		the default environment compiled into the boot image.
1640
1641		For example, place something like this in your
1642		board's config file:
1643
1644		#define CONFIG_EXTRA_ENV_SETTINGS \
1645			"myvar1=value1\0" \
1646			"myvar2=value2\0"
1647
1648		Warning: This method is based on knowledge about the
1649		internal format how the environment is stored by the
1650		U-Boot code. This is NOT an official, exported
1651		interface! Although it is unlikely that this format
1652		will change soon, there is no guarantee either.
1653		You better know what you are doing here.
1654
1655		Note: overly (ab)use of the default environment is
1656		discouraged. Make sure to check other ways to preset
1657		the environment like the autoscript function or the
1658		boot command first.
1659
1660- DataFlash Support:
1661		CONFIG_HAS_DATAFLASH
1662
1663		Defining this option enables DataFlash features and
1664		allows to read/write in Dataflash via the standard
1665		commands cp, md...
1666
1667- SystemACE Support:
1668		CONFIG_SYSTEMACE
1669
1670		Adding this option adds support for Xilinx SystemACE
1671		chips attached via some sort of local bus. The address
1672		of the chip must also be defined in the
1673		CFG_SYSTEMACE_BASE macro. For example:
1674
1675		#define CONFIG_SYSTEMACE
1676		#define CFG_SYSTEMACE_BASE 0xf0000000
1677
1678		When SystemACE support is added, the "ace" device type
1679		becomes available to the fat commands, i.e. fatls.
1680
1681- TFTP Fixed UDP Port:
1682		CONFIG_TFTP_PORT
1683
1684		If this is defined, the environment variable tftpsrcp
1685		is used to supply the TFTP UDP source port value.
1686		If tftpsrcp isn't defined, the normal pseudo-random port
1687		number generator is used.
1688
1689		Also, the environment variable tftpdstp is used to supply
1690		the TFTP UDP destination port value.  If tftpdstp isn't
1691		defined, the normal port 69 is used.
1692
1693		The purpose for tftpsrcp is to allow a TFTP server to
1694		blindly start the TFTP transfer using the pre-configured
1695		target IP address and UDP port. This has the effect of
1696		"punching through" the (Windows XP) firewall, allowing
1697		the remainder of the TFTP transfer to proceed normally.
1698		A better solution is to properly configure the firewall,
1699		but sometimes that is not allowed.
1700
1701- Show boot progress:
1702		CONFIG_SHOW_BOOT_PROGRESS
1703
1704		Defining this option allows to add some board-
1705		specific code (calling a user-provided function
1706		"show_boot_progress(int)") that enables you to show
1707		the system's boot progress on some display (for
1708		example, some LED's) on your board. At the moment,
1709		the following checkpoints are implemented:
1710
1711Legacy uImage format:
1712
1713  Arg	Where			When
1714    1	common/cmd_bootm.c	before attempting to boot an image
1715   -1	common/cmd_bootm.c	Image header has bad	 magic number
1716    2	common/cmd_bootm.c	Image header has correct magic number
1717   -2	common/cmd_bootm.c	Image header has bad	 checksum
1718    3	common/cmd_bootm.c	Image header has correct checksum
1719   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1720    4	common/cmd_bootm.c	Image data   has correct checksum
1721   -4	common/cmd_bootm.c	Image is for unsupported architecture
1722    5	common/cmd_bootm.c	Architecture check OK
1723   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1724    6	common/cmd_bootm.c	Image Type check OK
1725   -6	common/cmd_bootm.c	gunzip uncompression error
1726   -7	common/cmd_bootm.c	Unimplemented compression type
1727    7	common/cmd_bootm.c	Uncompression OK
1728    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1729   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1730
1731    9	common/image.c		Start initial ramdisk verification
1732  -10	common/image.c		Ramdisk header has bad	   magic number
1733  -11	common/image.c		Ramdisk header has bad	   checksum
1734   10	common/image.c		Ramdisk header is OK
1735  -12	common/image.c		Ramdisk data   has bad	   checksum
1736   11	common/image.c		Ramdisk data   has correct checksum
1737   12	common/image.c		Ramdisk verification complete, start loading
1738  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
1739   13	common/image.c		Start multifile image verification
1740   14	common/image.c		No initial ramdisk, no multifile, continue.
1741
1742   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1743
1744  -30	lib_ppc/board.c		Fatal error, hang the system
1745  -31	post/post.c		POST test failed, detected by post_output_backlog()
1746  -32	post/post.c		POST test failed, detected by post_run_single()
1747
1748   34	common/cmd_doc.c	before loading a Image from a DOC device
1749  -35	common/cmd_doc.c	Bad usage of "doc" command
1750   35	common/cmd_doc.c	correct usage of "doc" command
1751  -36	common/cmd_doc.c	No boot device
1752   36	common/cmd_doc.c	correct boot device
1753  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1754   37	common/cmd_doc.c	correct chip ID found, device available
1755  -38	common/cmd_doc.c	Read Error on boot device
1756   38	common/cmd_doc.c	reading Image header from DOC device OK
1757  -39	common/cmd_doc.c	Image header has bad magic number
1758   39	common/cmd_doc.c	Image header has correct magic number
1759  -40	common/cmd_doc.c	Error reading Image from DOC device
1760   40	common/cmd_doc.c	Image header has correct magic number
1761   41	common/cmd_ide.c	before loading a Image from a IDE device
1762  -42	common/cmd_ide.c	Bad usage of "ide" command
1763   42	common/cmd_ide.c	correct usage of "ide" command
1764  -43	common/cmd_ide.c	No boot device
1765   43	common/cmd_ide.c	boot device found
1766  -44	common/cmd_ide.c	Device not available
1767   44	common/cmd_ide.c	Device available
1768  -45	common/cmd_ide.c	wrong partition selected
1769   45	common/cmd_ide.c	partition selected
1770  -46	common/cmd_ide.c	Unknown partition table
1771   46	common/cmd_ide.c	valid partition table found
1772  -47	common/cmd_ide.c	Invalid partition type
1773   47	common/cmd_ide.c	correct partition type
1774  -48	common/cmd_ide.c	Error reading Image Header on boot device
1775   48	common/cmd_ide.c	reading Image Header from IDE device OK
1776  -49	common/cmd_ide.c	Image header has bad magic number
1777   49	common/cmd_ide.c	Image header has correct magic number
1778  -50	common/cmd_ide.c	Image header has bad	 checksum
1779   50	common/cmd_ide.c	Image header has correct checksum
1780  -51	common/cmd_ide.c	Error reading Image from IDE device
1781   51	common/cmd_ide.c	reading Image from IDE device OK
1782   52	common/cmd_nand.c	before loading a Image from a NAND device
1783  -53	common/cmd_nand.c	Bad usage of "nand" command
1784   53	common/cmd_nand.c	correct usage of "nand" command
1785  -54	common/cmd_nand.c	No boot device
1786   54	common/cmd_nand.c	boot device found
1787  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1788   55	common/cmd_nand.c	correct chip ID found, device available
1789  -56	common/cmd_nand.c	Error reading Image Header on boot device
1790   56	common/cmd_nand.c	reading Image Header from NAND device OK
1791  -57	common/cmd_nand.c	Image header has bad magic number
1792   57	common/cmd_nand.c	Image header has correct magic number
1793  -58	common/cmd_nand.c	Error reading Image from NAND device
1794   58	common/cmd_nand.c	reading Image from NAND device OK
1795
1796  -60	common/env_common.c	Environment has a bad CRC, using default
1797
1798   64	net/eth.c		starting with Ethernet configuration.
1799  -64	net/eth.c		no Ethernet found.
1800   65	net/eth.c		Ethernet found.
1801
1802  -80	common/cmd_net.c	usage wrong
1803   80	common/cmd_net.c	before calling NetLoop()
1804  -81	common/cmd_net.c	some error in NetLoop() occurred
1805   81	common/cmd_net.c	NetLoop() back without error
1806  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1807   82	common/cmd_net.c	trying automatic boot
1808   83	common/cmd_net.c	running autoscript
1809  -83	common/cmd_net.c	some error in automatic boot or autoscript
1810   84	common/cmd_net.c	end without errors
1811
1812FIT uImage format:
1813
1814  Arg	Where			When
1815  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1816 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1817  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1818 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
1819  102	common/cmd_bootm.c	Kernel unit name specified
1820 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
1821  103	common/cmd_bootm.c	Found configuration node
1822  104	common/cmd_bootm.c	Got kernel subimage node offset
1823 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
1824  105	common/cmd_bootm.c	Kernel subimage hash verification OK
1825 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
1826  106	common/cmd_bootm.c	Architecture check OK
1827 -106	common/cmd_bootm.c	Kernel subimage has wrong type
1828  107	common/cmd_bootm.c	Kernel subimage type OK
1829 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
1830  108	common/cmd_bootm.c	Got kernel subimage data/size
1831 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
1832 -109	common/cmd_bootm.c	Can't get kernel subimage type
1833 -110	common/cmd_bootm.c	Can't get kernel subimage comp
1834 -111	common/cmd_bootm.c	Can't get kernel subimage os
1835 -112	common/cmd_bootm.c	Can't get kernel subimage load address
1836 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
1837
1838  120	common/image.c		Start initial ramdisk verification
1839 -120	common/image.c		Ramdisk FIT image has incorrect format
1840  121	common/image.c		Ramdisk FIT image has correct format
1841  122	common/image.c		No ramdisk subimage unit name, using configuration
1842 -122	common/image.c		Can't get configuration for ramdisk subimage
1843  123	common/image.c		Ramdisk unit name specified
1844 -124	common/image.c		Can't get ramdisk subimage node offset
1845  125	common/image.c		Got ramdisk subimage node offset
1846 -125	common/image.c		Ramdisk subimage hash verification failed
1847  126	common/image.c		Ramdisk subimage hash verification OK
1848 -126	common/image.c		Ramdisk subimage for unsupported architecture
1849  127	common/image.c		Architecture check OK
1850 -127	common/image.c		Can't get ramdisk subimage data/size
1851  128	common/image.c		Got ramdisk subimage data/size
1852  129	common/image.c		Can't get ramdisk load address
1853 -129	common/image.c		Got ramdisk load address
1854
1855 -130	common/cmd_doc.c	Incorrect FIT image format
1856  131	common/cmd_doc.c	FIT image format OK
1857
1858 -140	common/cmd_ide.c	Incorrect FIT image format
1859  141	common/cmd_ide.c	FIT image format OK
1860
1861 -150	common/cmd_nand.c	Incorrect FIT image format
1862  151	common/cmd_nand.c	FIT image format OK
1863
1864
1865Modem Support:
1866--------------
1867
1868[so far only for SMDK2400 and TRAB boards]
1869
1870- Modem support enable:
1871		CONFIG_MODEM_SUPPORT
1872
1873- RTS/CTS Flow control enable:
1874		CONFIG_HWFLOW
1875
1876- Modem debug support:
1877		CONFIG_MODEM_SUPPORT_DEBUG
1878
1879		Enables debugging stuff (char screen[1024], dbg())
1880		for modem support. Useful only with BDI2000.
1881
1882- Interrupt support (PPC):
1883
1884		There are common interrupt_init() and timer_interrupt()
1885		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1886		for CPU specific initialization. interrupt_init_cpu()
1887		should set decrementer_count to appropriate value. If
1888		CPU resets decrementer automatically after interrupt
1889		(ppc4xx) it should set decrementer_count to zero.
1890		timer_interrupt() calls timer_interrupt_cpu() for CPU
1891		specific handling. If board has watchdog / status_led
1892		/ other_activity_monitor it works automatically from
1893		general timer_interrupt().
1894
1895- General:
1896
1897		In the target system modem support is enabled when a
1898		specific key (key combination) is pressed during
1899		power-on. Otherwise U-Boot will boot normally
1900		(autoboot). The key_pressed() function is called from
1901		board_init(). Currently key_pressed() is a dummy
1902		function, returning 1 and thus enabling modem
1903		initialization.
1904
1905		If there are no modem init strings in the
1906		environment, U-Boot proceed to autoboot; the
1907		previous output (banner, info printfs) will be
1908		suppressed, though.
1909
1910		See also: doc/README.Modem
1911
1912
1913Configuration Settings:
1914-----------------------
1915
1916- CFG_LONGHELP: Defined when you want long help messages included;
1917		undefine this when you're short of memory.
1918
1919- CFG_PROMPT:	This is what U-Boot prints on the console to
1920		prompt for user input.
1921
1922- CFG_CBSIZE:	Buffer size for input from the Console
1923
1924- CFG_PBSIZE:	Buffer size for Console output
1925
1926- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1927
1928- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1929		the application (usually a Linux kernel) when it is
1930		booted
1931
1932- CFG_BAUDRATE_TABLE:
1933		List of legal baudrate settings for this board.
1934
1935- CFG_CONSOLE_INFO_QUIET
1936		Suppress display of console information at boot.
1937
1938- CFG_CONSOLE_IS_IN_ENV
1939		If the board specific function
1940			extern int overwrite_console (void);
1941		returns 1, the stdin, stderr and stdout are switched to the
1942		serial port, else the settings in the environment are used.
1943
1944- CFG_CONSOLE_OVERWRITE_ROUTINE
1945		Enable the call to overwrite_console().
1946
1947- CFG_CONSOLE_ENV_OVERWRITE
1948		Enable overwrite of previous console environment settings.
1949
1950- CFG_MEMTEST_START, CFG_MEMTEST_END:
1951		Begin and End addresses of the area used by the
1952		simple memory test.
1953
1954- CFG_ALT_MEMTEST:
1955		Enable an alternate, more extensive memory test.
1956
1957- CFG_MEMTEST_SCRATCH:
1958		Scratch address used by the alternate memory test
1959		You only need to set this if address zero isn't writeable
1960
1961- CFG_MEM_TOP_HIDE (PPC only):
1962		If CFG_MEM_TOP_HIDE is defined in the board config header,
1963		this specified memory area will get subtracted from the top
1964		(end) of RAM and won't get "touched" at all by U-Boot. By
1965		fixing up gd->ram_size the Linux kernel should gets passed
1966		the now "corrected" memory size and won't touch it either.
1967		This should work for arch/ppc and arch/powerpc. Only Linux
1968		board ports in arch/powerpc with bootwrapper support that
1969		recalculate the memory size from the SDRAM controller setup
1970		will have to get fixed in Linux additionally.
1971
1972		This option can be used as a workaround for the 440EPx/GRx
1973		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
1974		be touched.
1975
1976		WARNING: Please make sure that this value is a multiple of
1977		the Linux page size (normally 4k). If this is not the case,
1978		then the end address of the Linux memory will be located at a
1979		non page size aligned address and this could cause major
1980		problems.
1981
1982- CFG_TFTP_LOADADDR:
1983		Default load address for network file downloads
1984
1985- CFG_LOADS_BAUD_CHANGE:
1986		Enable temporary baudrate change while serial download
1987
1988- CFG_SDRAM_BASE:
1989		Physical start address of SDRAM. _Must_ be 0 here.
1990
1991- CFG_MBIO_BASE:
1992		Physical start address of Motherboard I/O (if using a
1993		Cogent motherboard)
1994
1995- CFG_FLASH_BASE:
1996		Physical start address of Flash memory.
1997
1998- CFG_MONITOR_BASE:
1999		Physical start address of boot monitor code (set by
2000		make config files to be same as the text base address
2001		(TEXT_BASE) used when linking) - same as
2002		CFG_FLASH_BASE when booting from flash.
2003
2004- CFG_MONITOR_LEN:
2005		Size of memory reserved for monitor code, used to
2006		determine _at_compile_time_ (!) if the environment is
2007		embedded within the U-Boot image, or in a separate
2008		flash sector.
2009
2010- CFG_MALLOC_LEN:
2011		Size of DRAM reserved for malloc() use.
2012
2013- CFG_BOOTM_LEN:
2014		Normally compressed uImages are limited to an
2015		uncompressed size of 8 MBytes. If this is not enough,
2016		you can define CFG_BOOTM_LEN in your board config file
2017		to adjust this setting to your needs.
2018
2019- CFG_BOOTMAPSZ:
2020		Maximum size of memory mapped by the startup code of
2021		the Linux kernel; all data that must be processed by
2022		the Linux kernel (bd_info, boot arguments, FDT blob if
2023		used) must be put below this limit, unless "bootm_low"
2024		enviroment variable is defined and non-zero. In such case
2025		all data for the Linux kernel must be between "bootm_low"
2026		and "bootm_low" + CFG_BOOTMAPSZ.
2027
2028- CFG_MAX_FLASH_BANKS:
2029		Max number of Flash memory banks
2030
2031- CFG_MAX_FLASH_SECT:
2032		Max number of sectors on a Flash chip
2033
2034- CFG_FLASH_ERASE_TOUT:
2035		Timeout for Flash erase operations (in ms)
2036
2037- CFG_FLASH_WRITE_TOUT:
2038		Timeout for Flash write operations (in ms)
2039
2040- CFG_FLASH_LOCK_TOUT
2041		Timeout for Flash set sector lock bit operation (in ms)
2042
2043- CFG_FLASH_UNLOCK_TOUT
2044		Timeout for Flash clear lock bits operation (in ms)
2045
2046- CFG_FLASH_PROTECTION
2047		If defined, hardware flash sectors protection is used
2048		instead of U-Boot software protection.
2049
2050- CFG_DIRECT_FLASH_TFTP:
2051
2052		Enable TFTP transfers directly to flash memory;
2053		without this option such a download has to be
2054		performed in two steps: (1) download to RAM, and (2)
2055		copy from RAM to flash.
2056
2057		The two-step approach is usually more reliable, since
2058		you can check if the download worked before you erase
2059		the flash, but in some situations (when system RAM is
2060		too limited to allow for a temporary copy of the
2061		downloaded image) this option may be very useful.
2062
2063- CFG_FLASH_CFI:
2064		Define if the flash driver uses extra elements in the
2065		common flash structure for storing flash geometry.
2066
2067- CFG_FLASH_CFI_DRIVER
2068		This option also enables the building of the cfi_flash driver
2069		in the drivers directory
2070
2071- CFG_FLASH_USE_BUFFER_WRITE
2072		Use buffered writes to flash.
2073
2074- CONFIG_FLASH_SPANSION_S29WS_N
2075		s29ws-n MirrorBit flash has non-standard addresses for buffered
2076		write commands.
2077
2078- CFG_FLASH_QUIET_TEST
2079		If this option is defined, the common CFI flash doesn't
2080		print it's warning upon not recognized FLASH banks. This
2081		is useful, if some of the configured banks are only
2082		optionally available.
2083
2084- CONFIG_FLASH_SHOW_PROGRESS
2085		If defined (must be an integer), print out countdown
2086		digits and dots.  Recommended value: 45 (9..1) for 80
2087		column displays, 15 (3..1) for 40 column displays.
2088
2089- CFG_RX_ETH_BUFFER:
2090		Defines the number of Ethernet receive buffers. On some
2091		Ethernet controllers it is recommended to set this value
2092		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2093		buffers can be full shortly after enabling the interface
2094		on high Ethernet traffic.
2095		Defaults to 4 if not defined.
2096
2097The following definitions that deal with the placement and management
2098of environment data (variable area); in general, we support the
2099following configurations:
2100
2101- CFG_ENV_IS_IN_FLASH:
2102
2103	Define this if the environment is in flash memory.
2104
2105	a) The environment occupies one whole flash sector, which is
2106	   "embedded" in the text segment with the U-Boot code. This
2107	   happens usually with "bottom boot sector" or "top boot
2108	   sector" type flash chips, which have several smaller
2109	   sectors at the start or the end. For instance, such a
2110	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2111	   such a case you would place the environment in one of the
2112	   4 kB sectors - with U-Boot code before and after it. With
2113	   "top boot sector" type flash chips, you would put the
2114	   environment in one of the last sectors, leaving a gap
2115	   between U-Boot and the environment.
2116
2117	- CFG_ENV_OFFSET:
2118
2119	   Offset of environment data (variable area) to the
2120	   beginning of flash memory; for instance, with bottom boot
2121	   type flash chips the second sector can be used: the offset
2122	   for this sector is given here.
2123
2124	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
2125
2126	- CFG_ENV_ADDR:
2127
2128	   This is just another way to specify the start address of
2129	   the flash sector containing the environment (instead of
2130	   CFG_ENV_OFFSET).
2131
2132	- CFG_ENV_SECT_SIZE:
2133
2134	   Size of the sector containing the environment.
2135
2136
2137	b) Sometimes flash chips have few, equal sized, BIG sectors.
2138	   In such a case you don't want to spend a whole sector for
2139	   the environment.
2140
2141	- CFG_ENV_SIZE:
2142
2143	   If you use this in combination with CFG_ENV_IS_IN_FLASH
2144	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
2145	   of this flash sector for the environment. This saves
2146	   memory for the RAM copy of the environment.
2147
2148	   It may also save flash memory if you decide to use this
2149	   when your environment is "embedded" within U-Boot code,
2150	   since then the remainder of the flash sector could be used
2151	   for U-Boot code. It should be pointed out that this is
2152	   STRONGLY DISCOURAGED from a robustness point of view:
2153	   updating the environment in flash makes it always
2154	   necessary to erase the WHOLE sector. If something goes
2155	   wrong before the contents has been restored from a copy in
2156	   RAM, your target system will be dead.
2157
2158	- CFG_ENV_ADDR_REDUND
2159	  CFG_ENV_SIZE_REDUND
2160
2161	   These settings describe a second storage area used to hold
2162	   a redundant copy of the environment data, so that there is
2163	   a valid backup copy in case there is a power failure during
2164	   a "saveenv" operation.
2165
2166BE CAREFUL! Any changes to the flash layout, and some changes to the
2167source code will make it necessary to adapt <board>/u-boot.lds*
2168accordingly!
2169
2170
2171- CFG_ENV_IS_IN_NVRAM:
2172
2173	Define this if you have some non-volatile memory device
2174	(NVRAM, battery buffered SRAM) which you want to use for the
2175	environment.
2176
2177	- CFG_ENV_ADDR:
2178	- CFG_ENV_SIZE:
2179
2180	  These two #defines are used to determine the memory area you
2181	  want to use for environment. It is assumed that this memory
2182	  can just be read and written to, without any special
2183	  provision.
2184
2185BE CAREFUL! The first access to the environment happens quite early
2186in U-Boot initalization (when we try to get the setting of for the
2187console baudrate). You *MUST* have mapped your NVRAM area then, or
2188U-Boot will hang.
2189
2190Please note that even with NVRAM we still use a copy of the
2191environment in RAM: we could work on NVRAM directly, but we want to
2192keep settings there always unmodified except somebody uses "saveenv"
2193to save the current settings.
2194
2195
2196- CFG_ENV_IS_IN_EEPROM:
2197
2198	Use this if you have an EEPROM or similar serial access
2199	device and a driver for it.
2200
2201	- CFG_ENV_OFFSET:
2202	- CFG_ENV_SIZE:
2203
2204	  These two #defines specify the offset and size of the
2205	  environment area within the total memory of your EEPROM.
2206
2207	- CFG_I2C_EEPROM_ADDR:
2208	  If defined, specified the chip address of the EEPROM device.
2209	  The default address is zero.
2210
2211	- CFG_EEPROM_PAGE_WRITE_BITS:
2212	  If defined, the number of bits used to address bytes in a
2213	  single page in the EEPROM device.  A 64 byte page, for example
2214	  would require six bits.
2215
2216	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2217	  If defined, the number of milliseconds to delay between
2218	  page writes.	The default is zero milliseconds.
2219
2220	- CFG_I2C_EEPROM_ADDR_LEN:
2221	  The length in bytes of the EEPROM memory array address.  Note
2222	  that this is NOT the chip address length!
2223
2224	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2225	  EEPROM chips that implement "address overflow" are ones
2226	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2227	  address and the extra bits end up in the "chip address" bit
2228	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2229	  byte chips.
2230
2231	  Note that we consider the length of the address field to
2232	  still be one byte because the extra address bits are hidden
2233	  in the chip address.
2234
2235	- CFG_EEPROM_SIZE:
2236	  The size in bytes of the EEPROM device.
2237
2238
2239- CFG_ENV_IS_IN_DATAFLASH:
2240
2241	Define this if you have a DataFlash memory device which you
2242	want to use for the environment.
2243
2244	- CFG_ENV_OFFSET:
2245	- CFG_ENV_ADDR:
2246	- CFG_ENV_SIZE:
2247
2248	  These three #defines specify the offset and size of the
2249	  environment area within the total memory of your DataFlash placed
2250	  at the specified address.
2251
2252- CFG_ENV_IS_IN_NAND:
2253
2254	Define this if you have a NAND device which you want to use
2255	for the environment.
2256
2257	- CFG_ENV_OFFSET:
2258	- CFG_ENV_SIZE:
2259
2260	  These two #defines specify the offset and size of the environment
2261	  area within the first NAND device.
2262
2263	- CFG_ENV_OFFSET_REDUND
2264
2265	  This setting describes a second storage area of CFG_ENV_SIZE
2266	  size used to hold a redundant copy of the environment data,
2267	  so that there is a valid backup copy in case there is a
2268	  power failure during a "saveenv" operation.
2269
2270	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2271	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2272	the NAND devices block size.
2273
2274- CFG_SPI_INIT_OFFSET
2275
2276	Defines offset to the initial SPI buffer area in DPRAM. The
2277	area is used at an early stage (ROM part) if the environment
2278	is configured to reside in the SPI EEPROM: We need a 520 byte
2279	scratch DPRAM area. It is used between the two initialization
2280	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2281	to be a good choice since it makes it far enough from the
2282	start of the data area as well as from the stack pointer.
2283
2284Please note that the environment is read-only until the monitor
2285has been relocated to RAM and a RAM copy of the environment has been
2286created; also, when using EEPROM you will have to use getenv_r()
2287until then to read environment variables.
2288
2289The environment is protected by a CRC32 checksum. Before the monitor
2290is relocated into RAM, as a result of a bad CRC you will be working
2291with the compiled-in default environment - *silently*!!! [This is
2292necessary, because the first environment variable we need is the
2293"baudrate" setting for the console - if we have a bad CRC, we don't
2294have any device yet where we could complain.]
2295
2296Note: once the monitor has been relocated, then it will complain if
2297the default environment is used; a new CRC is computed as soon as you
2298use the "saveenv" command to store a valid environment.
2299
2300- CFG_FAULT_ECHO_LINK_DOWN:
2301		Echo the inverted Ethernet link state to the fault LED.
2302
2303		Note: If this option is active, then CFG_FAULT_MII_ADDR
2304		      also needs to be defined.
2305
2306- CFG_FAULT_MII_ADDR:
2307		MII address of the PHY to check for the Ethernet link state.
2308
2309- CFG_64BIT_VSPRINTF:
2310		Makes vsprintf (and all *printf functions) support printing
2311		of 64bit values by using the L quantifier
2312
2313- CFG_64BIT_STRTOUL:
2314		Adds simple_strtoull that returns a 64bit value
2315
2316Low Level (hardware related) configuration options:
2317---------------------------------------------------
2318
2319- CFG_CACHELINE_SIZE:
2320		Cache Line Size of the CPU.
2321
2322- CFG_DEFAULT_IMMR:
2323		Default address of the IMMR after system reset.
2324
2325		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2326		and RPXsuper) to be able to adjust the position of
2327		the IMMR register after a reset.
2328
2329- Floppy Disk Support:
2330		CFG_FDC_DRIVE_NUMBER
2331
2332		the default drive number (default value 0)
2333
2334		CFG_ISA_IO_STRIDE
2335
2336		defines the spacing between FDC chipset registers
2337		(default value 1)
2338
2339		CFG_ISA_IO_OFFSET
2340
2341		defines the offset of register from address. It
2342		depends on which part of the data bus is connected to
2343		the FDC chipset. (default value 0)
2344
2345		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2346		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2347		default value.
2348
2349		if CFG_FDC_HW_INIT is defined, then the function
2350		fdc_hw_init() is called at the beginning of the FDC
2351		setup. fdc_hw_init() must be provided by the board
2352		source code. It is used to make hardware dependant
2353		initializations.
2354
2355- CFG_IMMR:	Physical address of the Internal Memory.
2356		DO NOT CHANGE unless you know exactly what you're
2357		doing! (11-4) [MPC8xx/82xx systems only]
2358
2359- CFG_INIT_RAM_ADDR:
2360
2361		Start address of memory area that can be used for
2362		initial data and stack; please note that this must be
2363		writable memory that is working WITHOUT special
2364		initialization, i. e. you CANNOT use normal RAM which
2365		will become available only after programming the
2366		memory controller and running certain initialization
2367		sequences.
2368
2369		U-Boot uses the following memory types:
2370		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2371		- MPC824X: data cache
2372		- PPC4xx:  data cache
2373
2374- CFG_GBL_DATA_OFFSET:
2375
2376		Offset of the initial data structure in the memory
2377		area defined by CFG_INIT_RAM_ADDR. Usually
2378		CFG_GBL_DATA_OFFSET is chosen such that the initial
2379		data is located at the end of the available space
2380		(sometimes written as (CFG_INIT_RAM_END -
2381		CFG_INIT_DATA_SIZE), and the initial stack is just
2382		below that area (growing from (CFG_INIT_RAM_ADDR +
2383		CFG_GBL_DATA_OFFSET) downward.
2384
2385	Note:
2386		On the MPC824X (or other systems that use the data
2387		cache for initial memory) the address chosen for
2388		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2389		point to an otherwise UNUSED address space between
2390		the top of RAM and the start of the PCI space.
2391
2392- CFG_SIUMCR:	SIU Module Configuration (11-6)
2393
2394- CFG_SYPCR:	System Protection Control (11-9)
2395
2396- CFG_TBSCR:	Time Base Status and Control (11-26)
2397
2398- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2399
2400- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2401
2402- CFG_SCCR:	System Clock and reset Control Register (15-27)
2403
2404- CFG_OR_TIMING_SDRAM:
2405		SDRAM timing
2406
2407- CFG_MAMR_PTA:
2408		periodic timer for refresh
2409
2410- CFG_DER:	Debug Event Register (37-47)
2411
2412- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2413  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2414  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2415  CFG_BR1_PRELIM:
2416		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2417
2418- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2419  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2420  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2421		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2422
2423- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2424  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2425		Machine Mode Register and Memory Periodic Timer
2426		Prescaler definitions (SDRAM timing)
2427
2428- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2429		enable I2C microcode relocation patch (MPC8xx);
2430		define relocation offset in DPRAM [DSP2]
2431
2432- CFG_SMC_UCODE_PATCH, CFG_SMC_DPMEM_OFFSET [0x1FC0]:
2433		enable SMC microcode relocation patch (MPC8xx);
2434		define relocation offset in DPRAM [SMC1]
2435
2436- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2437		enable SPI microcode relocation patch (MPC8xx);
2438		define relocation offset in DPRAM [SCC4]
2439
2440- CFG_USE_OSCCLK:
2441		Use OSCM clock mode on MBX8xx board. Be careful,
2442		wrong setting might damage your board. Read
2443		doc/README.MBX before setting this variable!
2444
2445- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2446		Offset of the bootmode word in DPRAM used by post
2447		(Power On Self Tests). This definition overrides
2448		#define'd default value in commproc.h resp.
2449		cpm_8260.h.
2450
2451- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2452  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2453  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2454  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2455  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2456  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2457  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2458  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2459		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2460
2461- CONFIG_SPD_EEPROM
2462		Get DDR timing information from an I2C EEPROM. Common
2463		with pluggable memory modules such as SODIMMs
2464
2465  SPD_EEPROM_ADDRESS
2466		I2C address of the SPD EEPROM
2467
2468- CFG_SPD_BUS_NUM
2469		If SPD EEPROM is on an I2C bus other than the first
2470		one, specify here. Note that the value must resolve
2471		to something your driver can deal with.
2472
2473- CFG_83XX_DDR_USES_CS0
2474		Only for 83xx systems. If specified, then DDR should
2475		be configured using CS0 and CS1 instead of CS2 and CS3.
2476
2477- CFG_83XX_DDR_USES_CS0
2478		Only for 83xx systems. If specified, then DDR should
2479		be configured using CS0 and CS1 instead of CS2 and CS3.
2480
2481- CONFIG_ETHER_ON_FEC[12]
2482		Define to enable FEC[12] on a 8xx series processor.
2483
2484- CONFIG_FEC[12]_PHY
2485		Define to the hardcoded PHY address which corresponds
2486		to the given FEC; i. e.
2487			#define CONFIG_FEC1_PHY 4
2488		means that the PHY with address 4 is connected to FEC1
2489
2490		When set to -1, means to probe for first available.
2491
2492- CONFIG_FEC[12]_PHY_NORXERR
2493		The PHY does not have a RXERR line (RMII only).
2494		(so program the FEC to ignore it).
2495
2496- CONFIG_RMII
2497		Enable RMII mode for all FECs.
2498		Note that this is a global option, we can't
2499		have one FEC in standard MII mode and another in RMII mode.
2500
2501- CONFIG_CRC32_VERIFY
2502		Add a verify option to the crc32 command.
2503		The syntax is:
2504
2505		=> crc32 -v <address> <count> <crc32>
2506
2507		Where address/count indicate a memory area
2508		and crc32 is the correct crc32 which the
2509		area should have.
2510
2511- CONFIG_LOOPW
2512		Add the "loopw" memory command. This only takes effect if
2513		the memory commands are activated globally (CONFIG_CMD_MEM).
2514
2515- CONFIG_MX_CYCLIC
2516		Add the "mdc" and "mwc" memory commands. These are cyclic
2517		"md/mw" commands.
2518		Examples:
2519
2520		=> mdc.b 10 4 500
2521		This command will print 4 bytes (10,11,12,13) each 500 ms.
2522
2523		=> mwc.l 100 12345678 10
2524		This command will write 12345678 to address 100 all 10 ms.
2525
2526		This only takes effect if the memory commands are activated
2527		globally (CONFIG_CMD_MEM).
2528
2529- CONFIG_SKIP_LOWLEVEL_INIT
2530- CONFIG_SKIP_RELOCATE_UBOOT
2531
2532		[ARM only] If these variables are defined, then
2533		certain low level initializations (like setting up
2534		the memory controller) are omitted and/or U-Boot does
2535		not relocate itself into RAM.
2536		Normally these variables MUST NOT be defined. The
2537		only exception is when U-Boot is loaded (to RAM) by
2538		some other boot loader or by a debugger which
2539		performs these initializations itself.
2540
2541
2542Building the Software:
2543======================
2544
2545Building U-Boot has been tested in several native build environments
2546and in many different cross environments. Of course we cannot support
2547all possibly existing versions of cross development tools in all
2548(potentially obsolete) versions. In case of tool chain problems we
2549recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2550which is extensively used to build and test U-Boot.
2551
2552If you are not using a native environment, it is assumed that you
2553have GNU cross compiling tools available in your path. In this case,
2554you must set the environment variable CROSS_COMPILE in your shell.
2555Note that no changes to the Makefile or any other source files are
2556necessary. For example using the ELDK on a 4xx CPU, please enter:
2557
2558	$ CROSS_COMPILE=ppc_4xx-
2559	$ export CROSS_COMPILE
2560
2561U-Boot is intended to be simple to build. After installing the
2562sources you must configure U-Boot for one specific board type. This
2563is done by typing:
2564
2565	make NAME_config
2566
2567where "NAME_config" is the name of one of the existing configu-
2568rations; see the main Makefile for supported names.
2569
2570Note: for some board special configuration names may exist; check if
2571      additional information is available from the board vendor; for
2572      instance, the TQM823L systems are available without (standard)
2573      or with LCD support. You can select such additional "features"
2574      when choosing the configuration, i. e.
2575
2576      make TQM823L_config
2577	- will configure for a plain TQM823L, i. e. no LCD support
2578
2579      make TQM823L_LCD_config
2580	- will configure for a TQM823L with U-Boot console on LCD
2581
2582      etc.
2583
2584
2585Finally, type "make all", and you should get some working U-Boot
2586images ready for download to / installation on your system:
2587
2588- "u-boot.bin" is a raw binary image
2589- "u-boot" is an image in ELF binary format
2590- "u-boot.srec" is in Motorola S-Record format
2591
2592By default the build is performed locally and the objects are saved
2593in the source directory. One of the two methods can be used to change
2594this behavior and build U-Boot to some external directory:
2595
25961. Add O= to the make command line invocations:
2597
2598	make O=/tmp/build distclean
2599	make O=/tmp/build NAME_config
2600	make O=/tmp/build all
2601
26022. Set environment variable BUILD_DIR to point to the desired location:
2603
2604	export BUILD_DIR=/tmp/build
2605	make distclean
2606	make NAME_config
2607	make all
2608
2609Note that the command line "O=" setting overrides the BUILD_DIR environment
2610variable.
2611
2612
2613Please be aware that the Makefiles assume you are using GNU make, so
2614for instance on NetBSD you might need to use "gmake" instead of
2615native "make".
2616
2617
2618If the system board that you have is not listed, then you will need
2619to port U-Boot to your hardware platform. To do this, follow these
2620steps:
2621
26221.  Add a new configuration option for your board to the toplevel
2623    "Makefile" and to the "MAKEALL" script, using the existing
2624    entries as examples. Note that here and at many other places
2625    boards and other names are listed in alphabetical sort order. Please
2626    keep this order.
26272.  Create a new directory to hold your board specific code. Add any
2628    files you need. In your board directory, you will need at least
2629    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
26303.  Create a new configuration file "include/configs/<board>.h" for
2631    your board
26323.  If you're porting U-Boot to a new CPU, then also create a new
2633    directory to hold your CPU specific code. Add any files you need.
26344.  Run "make <board>_config" with your new name.
26355.  Type "make", and you should get a working "u-boot.srec" file
2636    to be installed on your target system.
26376.  Debug and solve any problems that might arise.
2638    [Of course, this last step is much harder than it sounds.]
2639
2640
2641Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2642==============================================================
2643
2644If you have modified U-Boot sources (for instance added a new board
2645or support for new devices, a new CPU, etc.) you are expected to
2646provide feedback to the other developers. The feedback normally takes
2647the form of a "patch", i. e. a context diff against a certain (latest
2648official or latest in the git repository) version of U-Boot sources.
2649
2650But before you submit such a patch, please verify that your modifi-
2651cation did not break existing code. At least make sure that *ALL* of
2652the supported boards compile WITHOUT ANY compiler warnings. To do so,
2653just run the "MAKEALL" script, which will configure and build U-Boot
2654for ALL supported system. Be warned, this will take a while. You can
2655select which (cross) compiler to use by passing a `CROSS_COMPILE'
2656environment variable to the script, i. e. to use the ELDK cross tools
2657you can type
2658
2659	CROSS_COMPILE=ppc_8xx- MAKEALL
2660
2661or to build on a native PowerPC system you can type
2662
2663	CROSS_COMPILE=' ' MAKEALL
2664
2665When using the MAKEALL script, the default behaviour is to build
2666U-Boot in the source directory. This location can be changed by
2667setting the BUILD_DIR environment variable. Also, for each target
2668built, the MAKEALL script saves two log files (<target>.ERR and
2669<target>.MAKEALL) in the <source dir>/LOG directory. This default
2670location can be changed by setting the MAKEALL_LOGDIR environment
2671variable. For example:
2672
2673	export BUILD_DIR=/tmp/build
2674	export MAKEALL_LOGDIR=/tmp/log
2675	CROSS_COMPILE=ppc_8xx- MAKEALL
2676
2677With the above settings build objects are saved in the /tmp/build,
2678log files are saved in the /tmp/log and the source tree remains clean
2679during the whole build process.
2680
2681
2682See also "U-Boot Porting Guide" below.
2683
2684
2685Monitor Commands - Overview:
2686============================
2687
2688go	- start application at address 'addr'
2689run	- run commands in an environment variable
2690bootm	- boot application image from memory
2691bootp	- boot image via network using BootP/TFTP protocol
2692tftpboot- boot image via network using TFTP protocol
2693	       and env variables "ipaddr" and "serverip"
2694	       (and eventually "gatewayip")
2695rarpboot- boot image via network using RARP/TFTP protocol
2696diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2697loads	- load S-Record file over serial line
2698loadb	- load binary file over serial line (kermit mode)
2699md	- memory display
2700mm	- memory modify (auto-incrementing)
2701nm	- memory modify (constant address)
2702mw	- memory write (fill)
2703cp	- memory copy
2704cmp	- memory compare
2705crc32	- checksum calculation
2706imd	- i2c memory display
2707imm	- i2c memory modify (auto-incrementing)
2708inm	- i2c memory modify (constant address)
2709imw	- i2c memory write (fill)
2710icrc32	- i2c checksum calculation
2711iprobe	- probe to discover valid I2C chip addresses
2712iloop	- infinite loop on address range
2713isdram	- print SDRAM configuration information
2714sspi	- SPI utility commands
2715base	- print or set address offset
2716printenv- print environment variables
2717setenv	- set environment variables
2718saveenv - save environment variables to persistent storage
2719protect - enable or disable FLASH write protection
2720erase	- erase FLASH memory
2721flinfo	- print FLASH memory information
2722bdinfo	- print Board Info structure
2723iminfo	- print header information for application image
2724coninfo - print console devices and informations
2725ide	- IDE sub-system
2726loop	- infinite loop on address range
2727loopw	- infinite write loop on address range
2728mtest	- simple RAM test
2729icache	- enable or disable instruction cache
2730dcache	- enable or disable data cache
2731reset	- Perform RESET of the CPU
2732echo	- echo args to console
2733version - print monitor version
2734help	- print online help
2735?	- alias for 'help'
2736
2737
2738Monitor Commands - Detailed Description:
2739========================================
2740
2741TODO.
2742
2743For now: just type "help <command>".
2744
2745
2746Environment Variables:
2747======================
2748
2749U-Boot supports user configuration using Environment Variables which
2750can be made persistent by saving to Flash memory.
2751
2752Environment Variables are set using "setenv", printed using
2753"printenv", and saved to Flash using "saveenv". Using "setenv"
2754without a value can be used to delete a variable from the
2755environment. As long as you don't save the environment you are
2756working with an in-memory copy. In case the Flash area containing the
2757environment is erased by accident, a default environment is provided.
2758
2759Some configuration options can be set using Environment Variables:
2760
2761  baudrate	- see CONFIG_BAUDRATE
2762
2763  bootdelay	- see CONFIG_BOOTDELAY
2764
2765  bootcmd	- see CONFIG_BOOTCOMMAND
2766
2767  bootargs	- Boot arguments when booting an RTOS image
2768
2769  bootfile	- Name of the image to load with TFTP
2770
2771  bootm_low	- Memory range available for image processing in the bootm
2772		  command can be restricted. This variable is given as
2773		  a hexadecimal number and defines lowest address allowed
2774		  for use by the bootm command. See also "bootm_size"
2775		  environment variable. Address defined by "bootm_low" is
2776		  also the base of the initial memory mapping for the Linux
2777		  kernel -- see the description of CFG_BOOTMAPSZ.
2778
2779  bootm_size	- Memory range available for image processing in the bootm
2780		  command can be restricted. This variable is given as
2781		  a hexadecimal number and defines the size of the region
2782		  allowed for use by the bootm command. See also "bootm_low"
2783		  environment variable.
2784
2785  autoload	- if set to "no" (any string beginning with 'n'),
2786		  "bootp" will just load perform a lookup of the
2787		  configuration from the BOOTP server, but not try to
2788		  load any image using TFTP
2789
2790  autoscript	- if set to "yes" commands like "loadb", "loady",
2791		  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2792		  to automatically run script images (by internally
2793		  calling "autoscript").
2794
2795  autoscript_uname - if script image is in a format (FIT) this
2796		     variable is used to get script subimage unit name.
2797
2798  autostart	- if set to "yes", an image loaded using the "bootp",
2799		  "rarpboot", "tftpboot" or "diskboot" commands will
2800		  be automatically started (by internally calling
2801		  "bootm")
2802
2803		  If set to "no", a standalone image passed to the
2804		  "bootm" command will be copied to the load address
2805		  (and eventually uncompressed), but NOT be started.
2806		  This can be used to load and uncompress arbitrary
2807		  data.
2808
2809  i2cfast	- (PPC405GP|PPC405EP only)
2810		  if set to 'y' configures Linux I2C driver for fast
2811		  mode (400kHZ). This environment variable is used in
2812		  initialization code. So, for changes to be effective
2813		  it must be saved and board must be reset.
2814
2815  initrd_high	- restrict positioning of initrd images:
2816		  If this variable is not set, initrd images will be
2817		  copied to the highest possible address in RAM; this
2818		  is usually what you want since it allows for
2819		  maximum initrd size. If for some reason you want to
2820		  make sure that the initrd image is loaded below the
2821		  CFG_BOOTMAPSZ limit, you can set this environment
2822		  variable to a value of "no" or "off" or "0".
2823		  Alternatively, you can set it to a maximum upper
2824		  address to use (U-Boot will still check that it
2825		  does not overwrite the U-Boot stack and data).
2826
2827		  For instance, when you have a system with 16 MB
2828		  RAM, and want to reserve 4 MB from use by Linux,
2829		  you can do this by adding "mem=12M" to the value of
2830		  the "bootargs" variable. However, now you must make
2831		  sure that the initrd image is placed in the first
2832		  12 MB as well - this can be done with
2833
2834		  setenv initrd_high 00c00000
2835
2836		  If you set initrd_high to 0xFFFFFFFF, this is an
2837		  indication to U-Boot that all addresses are legal
2838		  for the Linux kernel, including addresses in flash
2839		  memory. In this case U-Boot will NOT COPY the
2840		  ramdisk at all. This may be useful to reduce the
2841		  boot time on your system, but requires that this
2842		  feature is supported by your Linux kernel.
2843
2844  ipaddr	- IP address; needed for tftpboot command
2845
2846  loadaddr	- Default load address for commands like "bootp",
2847		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2848
2849  loads_echo	- see CONFIG_LOADS_ECHO
2850
2851  serverip	- TFTP server IP address; needed for tftpboot command
2852
2853  bootretry	- see CONFIG_BOOT_RETRY_TIME
2854
2855  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2856
2857  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2858
2859  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2860		  interface is used first.
2861
2862  ethact	- When CONFIG_NET_MULTI is enabled controls which
2863		  interface is currently active. For example you
2864		  can do the following
2865
2866		  => setenv ethact FEC ETHERNET
2867		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2868		  => setenv ethact SCC ETHERNET
2869		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2870
2871  ethrotate	- When set to "no" U-Boot does not go through all
2872		  available network interfaces.
2873		  It just stays at the currently selected interface.
2874
2875   netretry	- When set to "no" each network operation will
2876		  either succeed or fail without retrying.
2877		  When set to "once" the network operation will
2878		  fail when all the available network interfaces
2879		  are tried once without success.
2880		  Useful on scripts which control the retry operation
2881		  themselves.
2882
2883  npe_ucode	- see CONFIG_IXP4XX_NPE_EXT_UCOD
2884		  if set load address for the NPE microcode
2885
2886  tftpsrcport	- If this is set, the value is used for TFTP's
2887		  UDP source port.
2888
2889  tftpdstport	- If this is set, the value is used for TFTP's UDP
2890		  destination port instead of the Well Know Port 69.
2891
2892   vlan		- When set to a value < 4095 the traffic over
2893		  Ethernet is encapsulated/received over 802.1q
2894		  VLAN tagged frames.
2895
2896The following environment variables may be used and automatically
2897updated by the network boot commands ("bootp" and "rarpboot"),
2898depending the information provided by your boot server:
2899
2900  bootfile	- see above
2901  dnsip		- IP address of your Domain Name Server
2902  dnsip2	- IP address of your secondary Domain Name Server
2903  gatewayip	- IP address of the Gateway (Router) to use
2904  hostname	- Target hostname
2905  ipaddr	- see above
2906  netmask	- Subnet Mask
2907  rootpath	- Pathname of the root filesystem on the NFS server
2908  serverip	- see above
2909
2910
2911There are two special Environment Variables:
2912
2913  serial#	- contains hardware identification information such
2914		  as type string and/or serial number
2915  ethaddr	- Ethernet address
2916
2917These variables can be set only once (usually during manufacturing of
2918the board). U-Boot refuses to delete or overwrite these variables
2919once they have been set once.
2920
2921
2922Further special Environment Variables:
2923
2924  ver		- Contains the U-Boot version string as printed
2925		  with the "version" command. This variable is
2926		  readonly (see CONFIG_VERSION_VARIABLE).
2927
2928
2929Please note that changes to some configuration parameters may take
2930only effect after the next boot (yes, that's just like Windoze :-).
2931
2932
2933Command Line Parsing:
2934=====================
2935
2936There are two different command line parsers available with U-Boot:
2937the old "simple" one, and the much more powerful "hush" shell:
2938
2939Old, simple command line parser:
2940--------------------------------
2941
2942- supports environment variables (through setenv / saveenv commands)
2943- several commands on one line, separated by ';'
2944- variable substitution using "... ${name} ..." syntax
2945- special characters ('$', ';') can be escaped by prefixing with '\',
2946  for example:
2947	setenv bootcmd bootm \${address}
2948- You can also escape text by enclosing in single apostrophes, for example:
2949	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2950
2951Hush shell:
2952-----------
2953
2954- similar to Bourne shell, with control structures like
2955  if...then...else...fi, for...do...done; while...do...done,
2956  until...do...done, ...
2957- supports environment ("global") variables (through setenv / saveenv
2958  commands) and local shell variables (through standard shell syntax
2959  "name=value"); only environment variables can be used with "run"
2960  command
2961
2962General rules:
2963--------------
2964
2965(1) If a command line (or an environment variable executed by a "run"
2966    command) contains several commands separated by semicolon, and
2967    one of these commands fails, then the remaining commands will be
2968    executed anyway.
2969
2970(2) If you execute several variables with one call to run (i. e.
2971    calling run with a list of variables as arguments), any failing
2972    command will cause "run" to terminate, i. e. the remaining
2973    variables are not executed.
2974
2975Note for Redundant Ethernet Interfaces:
2976=======================================
2977
2978Some boards come with redundant Ethernet interfaces; U-Boot supports
2979such configurations and is capable of automatic selection of a
2980"working" interface when needed. MAC assignment works as follows:
2981
2982Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2983MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2984"eth1addr" (=>eth1), "eth2addr", ...
2985
2986If the network interface stores some valid MAC address (for instance
2987in SROM), this is used as default address if there is NO correspon-
2988ding setting in the environment; if the corresponding environment
2989variable is set, this overrides the settings in the card; that means:
2990
2991o If the SROM has a valid MAC address, and there is no address in the
2992  environment, the SROM's address is used.
2993
2994o If there is no valid address in the SROM, and a definition in the
2995  environment exists, then the value from the environment variable is
2996  used.
2997
2998o If both the SROM and the environment contain a MAC address, and
2999  both addresses are the same, this MAC address is used.
3000
3001o If both the SROM and the environment contain a MAC address, and the
3002  addresses differ, the value from the environment is used and a
3003  warning is printed.
3004
3005o If neither SROM nor the environment contain a MAC address, an error
3006  is raised.
3007
3008
3009Image Formats:
3010==============
3011
3012U-Boot is capable of booting (and performing other auxiliary operations on)
3013images in two formats:
3014
3015New uImage format (FIT)
3016-----------------------
3017
3018Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3019to Flattened Device Tree). It allows the use of images with multiple
3020components (several kernels, ramdisks, etc.), with contents protected by
3021SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3022
3023
3024Old uImage format
3025-----------------
3026
3027Old image format is based on binary files which can be basically anything,
3028preceded by a special header; see the definitions in include/image.h for
3029details; basically, the header defines the following image properties:
3030
3031* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3032  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3033  LynxOS, pSOS, QNX, RTEMS, ARTOS;
3034  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
3035* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3036  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3037  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3038* Compression Type (uncompressed, gzip, bzip2)
3039* Load Address
3040* Entry Point
3041* Image Name
3042* Image Timestamp
3043
3044The header is marked by a special Magic Number, and both the header
3045and the data portions of the image are secured against corruption by
3046CRC32 checksums.
3047
3048
3049Linux Support:
3050==============
3051
3052Although U-Boot should support any OS or standalone application
3053easily, the main focus has always been on Linux during the design of
3054U-Boot.
3055
3056U-Boot includes many features that so far have been part of some
3057special "boot loader" code within the Linux kernel. Also, any
3058"initrd" images to be used are no longer part of one big Linux image;
3059instead, kernel and "initrd" are separate images. This implementation
3060serves several purposes:
3061
3062- the same features can be used for other OS or standalone
3063  applications (for instance: using compressed images to reduce the
3064  Flash memory footprint)
3065
3066- it becomes much easier to port new Linux kernel versions because
3067  lots of low-level, hardware dependent stuff are done by U-Boot
3068
3069- the same Linux kernel image can now be used with different "initrd"
3070  images; of course this also means that different kernel images can
3071  be run with the same "initrd". This makes testing easier (you don't
3072  have to build a new "zImage.initrd" Linux image when you just
3073  change a file in your "initrd"). Also, a field-upgrade of the
3074  software is easier now.
3075
3076
3077Linux HOWTO:
3078============
3079
3080Porting Linux to U-Boot based systems:
3081---------------------------------------
3082
3083U-Boot cannot save you from doing all the necessary modifications to
3084configure the Linux device drivers for use with your target hardware
3085(no, we don't intend to provide a full virtual machine interface to
3086Linux :-).
3087
3088But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3089
3090Just make sure your machine specific header file (for instance
3091include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3092Information structure as we define in include/u-boot.h, and make
3093sure that your definition of IMAP_ADDR uses the same value as your
3094U-Boot configuration in CFG_IMMR.
3095
3096
3097Configuring the Linux kernel:
3098-----------------------------
3099
3100No specific requirements for U-Boot. Make sure you have some root
3101device (initial ramdisk, NFS) for your target system.
3102
3103
3104Building a Linux Image:
3105-----------------------
3106
3107With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3108not used. If you use recent kernel source, a new build target
3109"uImage" will exist which automatically builds an image usable by
3110U-Boot. Most older kernels also have support for a "pImage" target,
3111which was introduced for our predecessor project PPCBoot and uses a
3112100% compatible format.
3113
3114Example:
3115
3116	make TQM850L_config
3117	make oldconfig
3118	make dep
3119	make uImage
3120
3121The "uImage" build target uses a special tool (in 'tools/mkimage') to
3122encapsulate a compressed Linux kernel image with header	 information,
3123CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3124
3125* build a standard "vmlinux" kernel image (in ELF binary format):
3126
3127* convert the kernel into a raw binary image:
3128
3129	${CROSS_COMPILE}-objcopy -O binary \
3130				 -R .note -R .comment \
3131				 -S vmlinux linux.bin
3132
3133* compress the binary image:
3134
3135	gzip -9 linux.bin
3136
3137* package compressed binary image for U-Boot:
3138
3139	mkimage -A ppc -O linux -T kernel -C gzip \
3140		-a 0 -e 0 -n "Linux Kernel Image" \
3141		-d linux.bin.gz uImage
3142
3143
3144The "mkimage" tool can also be used to create ramdisk images for use
3145with U-Boot, either separated from the Linux kernel image, or
3146combined into one file. "mkimage" encapsulates the images with a 64
3147byte header containing information about target architecture,
3148operating system, image type, compression method, entry points, time
3149stamp, CRC32 checksums, etc.
3150
3151"mkimage" can be called in two ways: to verify existing images and
3152print the header information, or to build new images.
3153
3154In the first form (with "-l" option) mkimage lists the information
3155contained in the header of an existing U-Boot image; this includes
3156checksum verification:
3157
3158	tools/mkimage -l image
3159	  -l ==> list image header information
3160
3161The second form (with "-d" option) is used to build a U-Boot image
3162from a "data file" which is used as image payload:
3163
3164	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3165		      -n name -d data_file image
3166	  -A ==> set architecture to 'arch'
3167	  -O ==> set operating system to 'os'
3168	  -T ==> set image type to 'type'
3169	  -C ==> set compression type 'comp'
3170	  -a ==> set load address to 'addr' (hex)
3171	  -e ==> set entry point to 'ep' (hex)
3172	  -n ==> set image name to 'name'
3173	  -d ==> use image data from 'datafile'
3174
3175Right now, all Linux kernels for PowerPC systems use the same load
3176address (0x00000000), but the entry point address depends on the
3177kernel version:
3178
3179- 2.2.x kernels have the entry point at 0x0000000C,
3180- 2.3.x and later kernels have the entry point at 0x00000000.
3181
3182So a typical call to build a U-Boot image would read:
3183
3184	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3185	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3186	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3187	> examples/uImage.TQM850L
3188	Image Name:   2.4.4 kernel for TQM850L
3189	Created:      Wed Jul 19 02:34:59 2000
3190	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3191	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3192	Load Address: 0x00000000
3193	Entry Point:  0x00000000
3194
3195To verify the contents of the image (or check for corruption):
3196
3197	-> tools/mkimage -l examples/uImage.TQM850L
3198	Image Name:   2.4.4 kernel for TQM850L
3199	Created:      Wed Jul 19 02:34:59 2000
3200	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3201	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3202	Load Address: 0x00000000
3203	Entry Point:  0x00000000
3204
3205NOTE: for embedded systems where boot time is critical you can trade
3206speed for memory and install an UNCOMPRESSED image instead: this
3207needs more space in Flash, but boots much faster since it does not
3208need to be uncompressed:
3209
3210	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3211	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3212	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3213	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3214	> examples/uImage.TQM850L-uncompressed
3215	Image Name:   2.4.4 kernel for TQM850L
3216	Created:      Wed Jul 19 02:34:59 2000
3217	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3218	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3219	Load Address: 0x00000000
3220	Entry Point:  0x00000000
3221
3222
3223Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3224when your kernel is intended to use an initial ramdisk:
3225
3226	-> tools/mkimage -n 'Simple Ramdisk Image' \
3227	> -A ppc -O linux -T ramdisk -C gzip \
3228	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3229	Image Name:   Simple Ramdisk Image
3230	Created:      Wed Jan 12 14:01:50 2000
3231	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3232	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3233	Load Address: 0x00000000
3234	Entry Point:  0x00000000
3235
3236
3237Installing a Linux Image:
3238-------------------------
3239
3240To downloading a U-Boot image over the serial (console) interface,
3241you must convert the image to S-Record format:
3242
3243	objcopy -I binary -O srec examples/image examples/image.srec
3244
3245The 'objcopy' does not understand the information in the U-Boot
3246image header, so the resulting S-Record file will be relative to
3247address 0x00000000. To load it to a given address, you need to
3248specify the target address as 'offset' parameter with the 'loads'
3249command.
3250
3251Example: install the image to address 0x40100000 (which on the
3252TQM8xxL is in the first Flash bank):
3253
3254	=> erase 40100000 401FFFFF
3255
3256	.......... done
3257	Erased 8 sectors
3258
3259	=> loads 40100000
3260	## Ready for S-Record download ...
3261	~>examples/image.srec
3262	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3263	...
3264	15989 15990 15991 15992
3265	[file transfer complete]
3266	[connected]
3267	## Start Addr = 0x00000000
3268
3269
3270You can check the success of the download using the 'iminfo' command;
3271this includes a checksum verification so you can be sure no data
3272corruption happened:
3273
3274	=> imi 40100000
3275
3276	## Checking Image at 40100000 ...
3277	   Image Name:	 2.2.13 for initrd on TQM850L
3278	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3279	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3280	   Load Address: 00000000
3281	   Entry Point:	 0000000c
3282	   Verifying Checksum ... OK
3283
3284
3285Boot Linux:
3286-----------
3287
3288The "bootm" command is used to boot an application that is stored in
3289memory (RAM or Flash). In case of a Linux kernel image, the contents
3290of the "bootargs" environment variable is passed to the kernel as
3291parameters. You can check and modify this variable using the
3292"printenv" and "setenv" commands:
3293
3294
3295	=> printenv bootargs
3296	bootargs=root=/dev/ram
3297
3298	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3299
3300	=> printenv bootargs
3301	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3302
3303	=> bootm 40020000
3304	## Booting Linux kernel at 40020000 ...
3305	   Image Name:	 2.2.13 for NFS on TQM850L
3306	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3307	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3308	   Load Address: 00000000
3309	   Entry Point:	 0000000c
3310	   Verifying Checksum ... OK
3311	   Uncompressing Kernel Image ... OK
3312	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
3313	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3314	time_init: decrementer frequency = 187500000/60
3315	Calibrating delay loop... 49.77 BogoMIPS
3316	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3317	...
3318
3319If you want to boot a Linux kernel with initial RAM disk, you pass
3320the memory addresses of both the kernel and the initrd image (PPBCOOT
3321format!) to the "bootm" command:
3322
3323	=> imi 40100000 40200000
3324
3325	## Checking Image at 40100000 ...
3326	   Image Name:	 2.2.13 for initrd on TQM850L
3327	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3328	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3329	   Load Address: 00000000
3330	   Entry Point:	 0000000c
3331	   Verifying Checksum ... OK
3332
3333	## Checking Image at 40200000 ...
3334	   Image Name:	 Simple Ramdisk Image
3335	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3336	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3337	   Load Address: 00000000
3338	   Entry Point:	 00000000
3339	   Verifying Checksum ... OK
3340
3341	=> bootm 40100000 40200000
3342	## Booting Linux kernel at 40100000 ...
3343	   Image Name:	 2.2.13 for initrd on TQM850L
3344	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3345	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3346	   Load Address: 00000000
3347	   Entry Point:	 0000000c
3348	   Verifying Checksum ... OK
3349	   Uncompressing Kernel Image ... OK
3350	## Loading RAMDisk Image at 40200000 ...
3351	   Image Name:	 Simple Ramdisk Image
3352	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3353	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3354	   Load Address: 00000000
3355	   Entry Point:	 00000000
3356	   Verifying Checksum ... OK
3357	   Loading Ramdisk ... OK
3358	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
3359	Boot arguments: root=/dev/ram
3360	time_init: decrementer frequency = 187500000/60
3361	Calibrating delay loop... 49.77 BogoMIPS
3362	...
3363	RAMDISK: Compressed image found at block 0
3364	VFS: Mounted root (ext2 filesystem).
3365
3366	bash#
3367
3368Boot Linux and pass a flat device tree:
3369-----------
3370
3371First, U-Boot must be compiled with the appropriate defines. See the section
3372titled "Linux Kernel Interface" above for a more in depth explanation. The
3373following is an example of how to start a kernel and pass an updated
3374flat device tree:
3375
3376=> print oftaddr
3377oftaddr=0x300000
3378=> print oft
3379oft=oftrees/mpc8540ads.dtb
3380=> tftp $oftaddr $oft
3381Speed: 1000, full duplex
3382Using TSEC0 device
3383TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3384Filename 'oftrees/mpc8540ads.dtb'.
3385Load address: 0x300000
3386Loading: #
3387done
3388Bytes transferred = 4106 (100a hex)
3389=> tftp $loadaddr $bootfile
3390Speed: 1000, full duplex
3391Using TSEC0 device
3392TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3393Filename 'uImage'.
3394Load address: 0x200000
3395Loading:############
3396done
3397Bytes transferred = 1029407 (fb51f hex)
3398=> print loadaddr
3399loadaddr=200000
3400=> print oftaddr
3401oftaddr=0x300000
3402=> bootm $loadaddr - $oftaddr
3403## Booting image at 00200000 ...
3404   Image Name:	 Linux-2.6.17-dirty
3405   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3406   Data Size:	 1029343 Bytes = 1005.2 kB
3407   Load Address: 00000000
3408   Entry Point:	 00000000
3409   Verifying Checksum ... OK
3410   Uncompressing Kernel Image ... OK
3411Booting using flat device tree at 0x300000
3412Using MPC85xx ADS machine description
3413Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3414[snip]
3415
3416
3417More About U-Boot Image Types:
3418------------------------------
3419
3420U-Boot supports the following image types:
3421
3422   "Standalone Programs" are directly runnable in the environment
3423	provided by U-Boot; it is expected that (if they behave
3424	well) you can continue to work in U-Boot after return from
3425	the Standalone Program.
3426   "OS Kernel Images" are usually images of some Embedded OS which
3427	will take over control completely. Usually these programs
3428	will install their own set of exception handlers, device
3429	drivers, set up the MMU, etc. - this means, that you cannot
3430	expect to re-enter U-Boot except by resetting the CPU.
3431   "RAMDisk Images" are more or less just data blocks, and their
3432	parameters (address, size) are passed to an OS kernel that is
3433	being started.
3434   "Multi-File Images" contain several images, typically an OS
3435	(Linux) kernel image and one or more data images like
3436	RAMDisks. This construct is useful for instance when you want
3437	to boot over the network using BOOTP etc., where the boot
3438	server provides just a single image file, but you want to get
3439	for instance an OS kernel and a RAMDisk image.
3440
3441	"Multi-File Images" start with a list of image sizes, each
3442	image size (in bytes) specified by an "uint32_t" in network
3443	byte order. This list is terminated by an "(uint32_t)0".
3444	Immediately after the terminating 0 follow the images, one by
3445	one, all aligned on "uint32_t" boundaries (size rounded up to
3446	a multiple of 4 bytes).
3447
3448   "Firmware Images" are binary images containing firmware (like
3449	U-Boot or FPGA images) which usually will be programmed to
3450	flash memory.
3451
3452   "Script files" are command sequences that will be executed by
3453	U-Boot's command interpreter; this feature is especially
3454	useful when you configure U-Boot to use a real shell (hush)
3455	as command interpreter.
3456
3457
3458Standalone HOWTO:
3459=================
3460
3461One of the features of U-Boot is that you can dynamically load and
3462run "standalone" applications, which can use some resources of
3463U-Boot like console I/O functions or interrupt services.
3464
3465Two simple examples are included with the sources:
3466
3467"Hello World" Demo:
3468-------------------
3469
3470'examples/hello_world.c' contains a small "Hello World" Demo
3471application; it is automatically compiled when you build U-Boot.
3472It's configured to run at address 0x00040004, so you can play with it
3473like that:
3474
3475	=> loads
3476	## Ready for S-Record download ...
3477	~>examples/hello_world.srec
3478	1 2 3 4 5 6 7 8 9 10 11 ...
3479	[file transfer complete]
3480	[connected]
3481	## Start Addr = 0x00040004
3482
3483	=> go 40004 Hello World! This is a test.
3484	## Starting application at 0x00040004 ...
3485	Hello World
3486	argc = 7
3487	argv[0] = "40004"
3488	argv[1] = "Hello"
3489	argv[2] = "World!"
3490	argv[3] = "This"
3491	argv[4] = "is"
3492	argv[5] = "a"
3493	argv[6] = "test."
3494	argv[7] = "<NULL>"
3495	Hit any key to exit ...
3496
3497	## Application terminated, rc = 0x0
3498
3499Another example, which demonstrates how to register a CPM interrupt
3500handler with the U-Boot code, can be found in 'examples/timer.c'.
3501Here, a CPM timer is set up to generate an interrupt every second.
3502The interrupt service routine is trivial, just printing a '.'
3503character, but this is just a demo program. The application can be
3504controlled by the following keys:
3505
3506	? - print current values og the CPM Timer registers
3507	b - enable interrupts and start timer
3508	e - stop timer and disable interrupts
3509	q - quit application
3510
3511	=> loads
3512	## Ready for S-Record download ...
3513	~>examples/timer.srec
3514	1 2 3 4 5 6 7 8 9 10 11 ...
3515	[file transfer complete]
3516	[connected]
3517	## Start Addr = 0x00040004
3518
3519	=> go 40004
3520	## Starting application at 0x00040004 ...
3521	TIMERS=0xfff00980
3522	Using timer 1
3523	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3524
3525Hit 'b':
3526	[q, b, e, ?] Set interval 1000000 us
3527	Enabling timer
3528Hit '?':
3529	[q, b, e, ?] ........
3530	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3531Hit '?':
3532	[q, b, e, ?] .
3533	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3534Hit '?':
3535	[q, b, e, ?] .
3536	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3537Hit '?':
3538	[q, b, e, ?] .
3539	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3540Hit 'e':
3541	[q, b, e, ?] ...Stopping timer
3542Hit 'q':
3543	[q, b, e, ?] ## Application terminated, rc = 0x0
3544
3545
3546Minicom warning:
3547================
3548
3549Over time, many people have reported problems when trying to use the
3550"minicom" terminal emulation program for serial download. I (wd)
3551consider minicom to be broken, and recommend not to use it. Under
3552Unix, I recommend to use C-Kermit for general purpose use (and
3553especially for kermit binary protocol download ("loadb" command), and
3554use "cu" for S-Record download ("loads" command).
3555
3556Nevertheless, if you absolutely want to use it try adding this
3557configuration to your "File transfer protocols" section:
3558
3559	   Name	   Program			Name U/D FullScr IO-Red. Multi
3560	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3561	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3562
3563
3564NetBSD Notes:
3565=============
3566
3567Starting at version 0.9.2, U-Boot supports NetBSD both as host
3568(build U-Boot) and target system (boots NetBSD/mpc8xx).
3569
3570Building requires a cross environment; it is known to work on
3571NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3572need gmake since the Makefiles are not compatible with BSD make).
3573Note that the cross-powerpc package does not install include files;
3574attempting to build U-Boot will fail because <machine/ansi.h> is
3575missing.  This file has to be installed and patched manually:
3576
3577	# cd /usr/pkg/cross/powerpc-netbsd/include
3578	# mkdir powerpc
3579	# ln -s powerpc machine
3580	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3581	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3582
3583Native builds *don't* work due to incompatibilities between native
3584and U-Boot include files.
3585
3586Booting assumes that (the first part of) the image booted is a
3587stage-2 loader which in turn loads and then invokes the kernel
3588proper. Loader sources will eventually appear in the NetBSD source
3589tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3590meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3591
3592
3593Implementation Internals:
3594=========================
3595
3596The following is not intended to be a complete description of every
3597implementation detail. However, it should help to understand the
3598inner workings of U-Boot and make it easier to port it to custom
3599hardware.
3600
3601
3602Initial Stack, Global Data:
3603---------------------------
3604
3605The implementation of U-Boot is complicated by the fact that U-Boot
3606starts running out of ROM (flash memory), usually without access to
3607system RAM (because the memory controller is not initialized yet).
3608This means that we don't have writable Data or BSS segments, and BSS
3609is not initialized as zero. To be able to get a C environment working
3610at all, we have to allocate at least a minimal stack. Implementation
3611options for this are defined and restricted by the CPU used: Some CPU
3612models provide on-chip memory (like the IMMR area on MPC8xx and
3613MPC826x processors), on others (parts of) the data cache can be
3614locked as (mis-) used as memory, etc.
3615
3616	Chris Hallinan posted a good summary of these issues to the
3617	u-boot-users mailing list:
3618
3619	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3620	From: "Chris Hallinan" <clh@net1plus.com>
3621	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3622	...
3623
3624	Correct me if I'm wrong, folks, but the way I understand it
3625	is this: Using DCACHE as initial RAM for Stack, etc, does not
3626	require any physical RAM backing up the cache. The cleverness
3627	is that the cache is being used as a temporary supply of
3628	necessary storage before the SDRAM controller is setup. It's
3629	beyond the scope of this list to explain the details, but you
3630	can see how this works by studying the cache architecture and
3631	operation in the architecture and processor-specific manuals.
3632
3633	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3634	is another option for the system designer to use as an
3635	initial stack/RAM area prior to SDRAM being available. Either
3636	option should work for you. Using CS 4 should be fine if your
3637	board designers haven't used it for something that would
3638	cause you grief during the initial boot! It is frequently not
3639	used.
3640
3641	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3642	with your processor/board/system design. The default value
3643	you will find in any recent u-boot distribution in
3644	walnut.h should work for you. I'd set it to a value larger
3645	than your SDRAM module. If you have a 64MB SDRAM module, set
3646	it above 400_0000. Just make sure your board has no resources
3647	that are supposed to respond to that address! That code in
3648	start.S has been around a while and should work as is when
3649	you get the config right.
3650
3651	-Chris Hallinan
3652	DS4.COM, Inc.
3653
3654It is essential to remember this, since it has some impact on the C
3655code for the initialization procedures:
3656
3657* Initialized global data (data segment) is read-only. Do not attempt
3658  to write it.
3659
3660* Do not use any uninitialized global data (or implicitely initialized
3661  as zero data - BSS segment) at all - this is undefined, initiali-
3662  zation is performed later (when relocating to RAM).
3663
3664* Stack space is very limited. Avoid big data buffers or things like
3665  that.
3666
3667Having only the stack as writable memory limits means we cannot use
3668normal global data to share information beween the code. But it
3669turned out that the implementation of U-Boot can be greatly
3670simplified by making a global data structure (gd_t) available to all
3671functions. We could pass a pointer to this data as argument to _all_
3672functions, but this would bloat the code. Instead we use a feature of
3673the GCC compiler (Global Register Variables) to share the data: we
3674place a pointer (gd) to the global data into a register which we
3675reserve for this purpose.
3676
3677When choosing a register for such a purpose we are restricted by the
3678relevant  (E)ABI  specifications for the current architecture, and by
3679GCC's implementation.
3680
3681For PowerPC, the following registers have specific use:
3682	R1:	stack pointer
3683	R2:	reserved for system use
3684	R3-R4:	parameter passing and return values
3685	R5-R10: parameter passing
3686	R13:	small data area pointer
3687	R30:	GOT pointer
3688	R31:	frame pointer
3689
3690	(U-Boot also uses R14 as internal GOT pointer.)
3691
3692    ==> U-Boot will use R2 to hold a pointer to the global data
3693
3694    Note: on PPC, we could use a static initializer (since the
3695    address of the global data structure is known at compile time),
3696    but it turned out that reserving a register results in somewhat
3697    smaller code - although the code savings are not that big (on
3698    average for all boards 752 bytes for the whole U-Boot image,
3699    624 text + 127 data).
3700
3701On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3702	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3703
3704    ==> U-Boot will use P5 to hold a pointer to the global data
3705
3706On ARM, the following registers are used:
3707
3708	R0:	function argument word/integer result
3709	R1-R3:	function argument word
3710	R9:	GOT pointer
3711	R10:	stack limit (used only if stack checking if enabled)
3712	R11:	argument (frame) pointer
3713	R12:	temporary workspace
3714	R13:	stack pointer
3715	R14:	link register
3716	R15:	program counter
3717
3718    ==> U-Boot will use R8 to hold a pointer to the global data
3719
3720NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3721or current versions of GCC may "optimize" the code too much.
3722
3723Memory Management:
3724------------------
3725
3726U-Boot runs in system state and uses physical addresses, i.e. the
3727MMU is not used either for address mapping nor for memory protection.
3728
3729The available memory is mapped to fixed addresses using the memory
3730controller. In this process, a contiguous block is formed for each
3731memory type (Flash, SDRAM, SRAM), even when it consists of several
3732physical memory banks.
3733
3734U-Boot is installed in the first 128 kB of the first Flash bank (on
3735TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3736booting and sizing and initializing DRAM, the code relocates itself
3737to the upper end of DRAM. Immediately below the U-Boot code some
3738memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3739configuration setting]. Below that, a structure with global Board
3740Info data is placed, followed by the stack (growing downward).
3741
3742Additionally, some exception handler code is copied to the low 8 kB
3743of DRAM (0x00000000 ... 0x00001FFF).
3744
3745So a typical memory configuration with 16 MB of DRAM could look like
3746this:
3747
3748	0x0000 0000	Exception Vector code
3749	      :
3750	0x0000 1FFF
3751	0x0000 2000	Free for Application Use
3752	      :
3753	      :
3754
3755	      :
3756	      :
3757	0x00FB FF20	Monitor Stack (Growing downward)
3758	0x00FB FFAC	Board Info Data and permanent copy of global data
3759	0x00FC 0000	Malloc Arena
3760	      :
3761	0x00FD FFFF
3762	0x00FE 0000	RAM Copy of Monitor Code
3763	...		eventually: LCD or video framebuffer
3764	...		eventually: pRAM (Protected RAM - unchanged by reset)
3765	0x00FF FFFF	[End of RAM]
3766
3767
3768System Initialization:
3769----------------------
3770
3771In the reset configuration, U-Boot starts at the reset entry point
3772(on most PowerPC systems at address 0x00000100). Because of the reset
3773configuration for CS0# this is a mirror of the onboard Flash memory.
3774To be able to re-map memory U-Boot then jumps to its link address.
3775To be able to implement the initialization code in C, a (small!)
3776initial stack is set up in the internal Dual Ported RAM (in case CPUs
3777which provide such a feature like MPC8xx or MPC8260), or in a locked
3778part of the data cache. After that, U-Boot initializes the CPU core,
3779the caches and the SIU.
3780
3781Next, all (potentially) available memory banks are mapped using a
3782preliminary mapping. For example, we put them on 512 MB boundaries
3783(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3784on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3785programmed for SDRAM access. Using the temporary configuration, a
3786simple memory test is run that determines the size of the SDRAM
3787banks.
3788
3789When there is more than one SDRAM bank, and the banks are of
3790different size, the largest is mapped first. For equal size, the first
3791bank (CS2#) is mapped first. The first mapping is always for address
37920x00000000, with any additional banks following immediately to create
3793contiguous memory starting from 0.
3794
3795Then, the monitor installs itself at the upper end of the SDRAM area
3796and allocates memory for use by malloc() and for the global Board
3797Info data; also, the exception vector code is copied to the low RAM
3798pages, and the final stack is set up.
3799
3800Only after this relocation will you have a "normal" C environment;
3801until that you are restricted in several ways, mostly because you are
3802running from ROM, and because the code will have to be relocated to a
3803new address in RAM.
3804
3805
3806U-Boot Porting Guide:
3807----------------------
3808
3809[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3810list, October 2002]
3811
3812
3813int main (int argc, char *argv[])
3814{
3815	sighandler_t no_more_time;
3816
3817	signal (SIGALRM, no_more_time);
3818	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3819
3820	if (available_money > available_manpower) {
3821		pay consultant to port U-Boot;
3822		return 0;
3823	}
3824
3825	Download latest U-Boot source;
3826
3827	Subscribe to u-boot-users mailing list;
3828
3829	if (clueless) {
3830		email ("Hi, I am new to U-Boot, how do I get started?");
3831	}
3832
3833	while (learning) {
3834		Read the README file in the top level directory;
3835		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3836		Read the source, Luke;
3837	}
3838
3839	if (available_money > toLocalCurrency ($2500)) {
3840		Buy a BDI2000;
3841	} else {
3842		Add a lot of aggravation and time;
3843	}
3844
3845	Create your own board support subdirectory;
3846
3847	Create your own board config file;
3848
3849	while (!running) {
3850		do {
3851			Add / modify source code;
3852		} until (compiles);
3853		Debug;
3854		if (clueless)
3855			email ("Hi, I am having problems...");
3856	}
3857	Send patch file to Wolfgang;
3858
3859	return 0;
3860}
3861
3862void no_more_time (int sig)
3863{
3864      hire_a_guru();
3865}
3866
3867
3868Coding Standards:
3869-----------------
3870
3871All contributions to U-Boot should conform to the Linux kernel
3872coding style; see the file "Documentation/CodingStyle" and the script
3873"scripts/Lindent" in your Linux kernel source directory.  In sources
3874originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3875spaces before parameters to function calls) is actually used.
3876
3877Source files originating from a different project (for example the
3878MTD subsystem) are generally exempt from these guidelines and are not
3879reformated to ease subsequent migration to newer versions of those
3880sources.
3881
3882Please note that U-Boot is implemented in C (and to some small parts in
3883Assembler); no C++ is used, so please do not use C++ style comments (//)
3884in your code.
3885
3886Please also stick to the following formatting rules:
3887- remove any trailing white space
3888- use TAB characters for indentation, not spaces
3889- make sure NOT to use DOS '\r\n' line feeds
3890- do not add more than 2 empty lines to source files
3891- do not add trailing empty lines to source files
3892
3893Submissions which do not conform to the standards may be returned
3894with a request to reformat the changes.
3895
3896
3897Submitting Patches:
3898-------------------
3899
3900Since the number of patches for U-Boot is growing, we need to
3901establish some rules. Submissions which do not conform to these rules
3902may be rejected, even when they contain important and valuable stuff.
3903
3904Patches shall be sent to the u-boot-users mailing list.
3905
3906Please see http://www.denx.de/wiki/UBoot/Patches for details.
3907
3908When you send a patch, please include the following information with
3909it:
3910
3911* For bug fixes: a description of the bug and how your patch fixes
3912  this bug. Please try to include a way of demonstrating that the
3913  patch actually fixes something.
3914
3915* For new features: a description of the feature and your
3916  implementation.
3917
3918* A CHANGELOG entry as plaintext (separate from the patch)
3919
3920* For major contributions, your entry to the CREDITS file
3921
3922* When you add support for a new board, don't forget to add this
3923  board to the MAKEALL script, too.
3924
3925* If your patch adds new configuration options, don't forget to
3926  document these in the README file.
3927
3928* The patch itself. If you are using git (which is *strongly*
3929  recommended) you can easily generate the patch using the
3930  "git-format-patch". If you then use "git-send-email" to send it to
3931  the U-Boot mailing list, you will avoid most of the common problems
3932  with some other mail clients.
3933
3934  If you cannot use git, use "diff -purN OLD NEW". If your version of
3935  diff does not support these options, then get the latest version of
3936  GNU diff.
3937
3938  The current directory when running this command shall be the parent
3939  directory of the U-Boot source tree (i. e. please make sure that
3940  your patch includes sufficient directory information for the
3941  affected files).
3942
3943  We prefer patches as plain text. MIME attachments are discouraged,
3944  and compressed attachments must not be used.
3945
3946* If one logical set of modifications affects or creates several
3947  files, all these changes shall be submitted in a SINGLE patch file.
3948
3949* Changesets that contain different, unrelated modifications shall be
3950  submitted as SEPARATE patches, one patch per changeset.
3951
3952
3953Notes:
3954
3955* Before sending the patch, run the MAKEALL script on your patched
3956  source tree and make sure that no errors or warnings are reported
3957  for any of the boards.
3958
3959* Keep your modifications to the necessary minimum: A patch
3960  containing several unrelated changes or arbitrary reformats will be
3961  returned with a request to re-formatting / split it.
3962
3963* If you modify existing code, make sure that your new code does not
3964  add to the memory footprint of the code ;-) Small is beautiful!
3965  When adding new features, these should compile conditionally only
3966  (using #ifdef), and the resulting code with the new feature
3967  disabled must not need more memory than the old code without your
3968  modification.
3969
3970* Remember that there is a size limit of 40 kB per message on the
3971  u-boot-users mailing list. Bigger patches will be moderated. If
3972  they are reasonable and not bigger than 100 kB, they will be
3973  acknowledged. Even bigger patches should be avoided.
3974