xref: /openbmc/u-boot/README (revision bf9a5215)
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@lists.denx.de>. There is also an archive of previous traffic
64on the mailing list - please search the archive before asking FAQ's.
65Please see http://lists.denx.de/pipermail/u-boot and
66http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
67
68
69Where to get source code:
70=========================
71
72The U-Boot source code is maintained in the git repository at
73git://www.denx.de/git/u-boot.git ; you can browse it online at
74http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
75
76The "snapshot" links on this page allow you to download tarballs of
77any version you might be interested in. Official releases are also
78available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
79directory.
80
81Pre-built (and tested) images are available from
82ftp://ftp.denx.de/pub/u-boot/images/
83
84
85Where we come from:
86===================
87
88- start from 8xxrom sources
89- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
90- clean up code
91- make it easier to add custom boards
92- make it possible to add other [PowerPC] CPUs
93- extend functions, especially:
94  * Provide extended interface to Linux boot loader
95  * S-Record download
96  * network boot
97  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98- create ARMBoot project (http://sourceforge.net/projects/armboot)
99- add other CPU families (starting with ARM)
100- create U-Boot project (http://sourceforge.net/projects/u-boot)
101- current project page: see http://www.denx.de/wiki/U-Boot
102
103
104Names and Spelling:
105===================
106
107The "official" name of this project is "Das U-Boot". The spelling
108"U-Boot" shall be used in all written text (documentation, comments
109in source files etc.). Example:
110
111	This is the README file for the U-Boot project.
112
113File names etc. shall be based on the string "u-boot". Examples:
114
115	include/asm-ppc/u-boot.h
116
117	#include <asm/u-boot.h>
118
119Variable names, preprocessor constants etc. shall be either based on
120the string "u_boot" or on "U_BOOT". Example:
121
122	U_BOOT_VERSION		u_boot_logo
123	IH_OS_U_BOOT		u_boot_hush_start
124
125
126Versioning:
127===========
128
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  - blackfin	Files specific to Analog Devices Blackfin CPUs
155  - i386	Files specific to i386 CPUs
156  - ixp		Files specific to Intel XScale IXP CPUs
157  - leon2	Files specific to Gaisler LEON2 SPARC CPU
158  - leon3	Files specific to Gaisler LEON3 SPARC CPU
159  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
160  - mcf5227x	Files specific to Freescale ColdFire MCF5227x CPUs
161  - mcf532x	Files specific to Freescale ColdFire MCF5329 CPUs
162  - mcf5445x	Files specific to Freescale ColdFire MCF5445x CPUs
163  - mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
164  - mips	Files specific to MIPS CPUs
165  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
166  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
167  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
168  - mpc8220	Files specific to Freescale MPC8220 CPUs
169  - mpc824x	Files specific to Freescale MPC824x CPUs
170  - mpc8260	Files specific to Freescale MPC8260 CPUs
171  - mpc85xx	Files specific to Freescale MPC85xx CPUs
172  - nios	Files specific to Altera NIOS CPUs
173  - nios2	Files specific to Altera Nios-II CPUs
174  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
175  - pxa		Files specific to Intel XScale PXA CPUs
176  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
177  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
178- disk		Code for disk drive partition handling
179- doc		Documentation (don't expect too much)
180- drivers	Commonly used device drivers
181- dtt		Digital Thermometer and Thermostat drivers
182- examples	Example code for standalone applications, etc.
183- include	Header Files
184- lib_arm	Files generic to ARM	 architecture
185- lib_avr32	Files generic to AVR32	 architecture
186- lib_blackfin	Files generic to Blackfin architecture
187- lib_generic	Files generic to all	 architectures
188- lib_i386	Files generic to i386	 architecture
189- lib_m68k	Files generic to m68k	 architecture
190- lib_mips	Files generic to MIPS	 architecture
191- lib_nios	Files generic to NIOS	 architecture
192- lib_ppc	Files generic to PowerPC architecture
193- lib_sparc	Files generic to SPARC	 architecture
194- libfdt	Library files to support flattened device trees
195- net		Networking code
196- post		Power On Self Test
197- rtc		Real Time Clock drivers
198- tools		Tools to build S-Record or U-Boot images, etc.
199
200Software Configuration:
201=======================
202
203Configuration is usually done using C preprocessor defines; the
204rationale behind that is to avoid dead code whenever possible.
205
206There are two classes of configuration variables:
207
208* Configuration _OPTIONS_:
209  These are selectable by the user and have names beginning with
210  "CONFIG_".
211
212* Configuration _SETTINGS_:
213  These depend on the hardware etc. and should not be meddled with if
214  you don't know what you're doing; they have names beginning with
215  "CONFIG_SYS_".
216
217Later we will add a configuration tool - probably similar to or even
218identical to what's used for the Linux kernel. Right now, we have to
219do the configuration by hand, which means creating some symbolic
220links and editing some configuration files. We use the TQM8xxL boards
221as an example here.
222
223
224Selection of Processor Architecture and Board Type:
225---------------------------------------------------
226
227For all supported boards there are ready-to-use default
228configurations available; just type "make <board_name>_config".
229
230Example: For a TQM823L module type:
231
232	cd u-boot
233	make TQM823L_config
234
235For the Cogent platform, you need to specify the CPU type as well;
236e.g. "make cogent_mpc8xx_config". And also configure the cogent
237directory according to the instructions in cogent/README.
238
239
240Configuration Options:
241----------------------
242
243Configuration depends on the combination of board and CPU type; all
244such information is kept in a configuration file
245"include/configs/<board_name>.h".
246
247Example: For a TQM823L module, all configuration settings are in
248"include/configs/TQM823L.h".
249
250
251Many of the options are named exactly as the corresponding Linux
252kernel configuration options. The intention is to make it easier to
253build a config tool - later.
254
255
256The following options need to be configured:
257
258- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
259
260- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
261
262- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
263		Define exactly one, e.g. CONFIG_ATSTK1002
264
265- CPU Module Type: (if CONFIG_COGENT is defined)
266		Define exactly one of
267		CONFIG_CMA286_60_OLD
268--- FIXME --- not tested yet:
269		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
270		CONFIG_CMA287_23, CONFIG_CMA287_50
271
272- Motherboard Type: (if CONFIG_COGENT is defined)
273		Define exactly one of
274		CONFIG_CMA101, CONFIG_CMA102
275
276- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
277		Define one or more of
278		CONFIG_CMA302
279
280- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
281		Define one or more of
282		CONFIG_LCD_HEARTBEAT	- update a character position on
283					  the LCD display every second with
284					  a "rotator" |\-/|\-/
285
286- Board flavour: (if CONFIG_MPC8260ADS is defined)
287		CONFIG_ADSTYPE
288		Possible values are:
289			CONFIG_SYS_8260ADS	- original MPC8260ADS
290			CONFIG_SYS_8266ADS	- MPC8266ADS
291			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
292			CONFIG_SYS_8272ADS	- MPC8272ADS
293
294- MPC824X Family Member (if CONFIG_MPC824X is defined)
295		Define exactly one of
296		CONFIG_MPC8240, CONFIG_MPC8245
297
298- 8xx CPU Options: (if using an MPC8xx CPU)
299		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
300					  get_gclk_freq() cannot work
301					  e.g. if there is no 32KHz
302					  reference PIT/RTC clock
303		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
304					  or XTAL/EXTAL)
305
306- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
307		CONFIG_SYS_8xx_CPUCLK_MIN
308		CONFIG_SYS_8xx_CPUCLK_MAX
309		CONFIG_8xx_CPUCLK_DEFAULT
310			See doc/README.MPC866
311
312		CONFIG_SYS_MEASURE_CPUCLK
313
314		Define this to measure the actual CPU clock instead
315		of relying on the correctness of the configured
316		values. Mostly useful for board bringup to make sure
317		the PLL is locked at the intended frequency. Note
318		that this requires a (stable) reference clock (32 kHz
319		RTC clock or CONFIG_SYS_8XX_XIN)
320
321		CONFIG_SYS_DELAYED_ICACHE
322
323		Define this option if you want to enable the
324		ICache only when Code runs from RAM.
325
326- Intel Monahans options:
327		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
328
329		Defines the Monahans run mode to oscillator
330		ratio. Valid values are 8, 16, 24, 31. The core
331		frequency is this value multiplied by 13 MHz.
332
333		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
334
335		Defines the Monahans turbo mode to oscillator
336		ratio. Valid values are 1 (default if undefined) and
337		2. The core frequency as calculated above is multiplied
338		by this value.
339
340- Linux Kernel Interface:
341		CONFIG_CLOCKS_IN_MHZ
342
343		U-Boot stores all clock information in Hz
344		internally. For binary compatibility with older Linux
345		kernels (which expect the clocks passed in the
346		bd_info data to be in MHz) the environment variable
347		"clocks_in_mhz" can be defined so that U-Boot
348		converts clock data to MHZ before passing it to the
349		Linux kernel.
350		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
351		"clocks_in_mhz=1" is automatically included in the
352		default environment.
353
354		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
355
356		When transferring memsize parameter to linux, some versions
357		expect it to be in bytes, others in MB.
358		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
359
360		CONFIG_OF_LIBFDT
361
362		New kernel versions are expecting firmware settings to be
363		passed using flattened device trees (based on open firmware
364		concepts).
365
366		CONFIG_OF_LIBFDT
367		 * New libfdt-based support
368		 * Adds the "fdt" command
369		 * The bootm command automatically updates the fdt
370
371		OF_CPU - The proper name of the cpus node.
372		OF_SOC - The proper name of the soc node.
373		OF_TBCLK - The timebase frequency.
374		OF_STDOUT_PATH - The path to the console device
375
376		boards with QUICC Engines require OF_QE to set UCC MAC
377		addresses
378
379		CONFIG_OF_BOARD_SETUP
380
381		Board code has addition modification that it wants to make
382		to the flat device tree before handing it off to the kernel
383
384		CONFIG_OF_BOOT_CPU
385
386		This define fills in the correct boot CPU in the boot
387		param header, the default value is zero if undefined.
388
389- vxWorks boot parameters:
390
391		bootvx constructs a valid bootline using the following
392		environments variables: bootfile, ipaddr, serverip, hostname.
393		It loads the vxWorks image pointed bootfile.
394
395		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
396		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
397		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
398		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
399
400		CONFIG_SYS_VXWORKS_ADD_PARAMS
401
402		Add it at the end of the bootline. E.g "u=username pw=secret"
403
404		Note: If a "bootargs" environment is defined, it will overwride
405		the defaults discussed just above.
406
407- Serial Ports:
408		CONFIG_PL010_SERIAL
409
410		Define this if you want support for Amba PrimeCell PL010 UARTs.
411
412		CONFIG_PL011_SERIAL
413
414		Define this if you want support for Amba PrimeCell PL011 UARTs.
415
416		CONFIG_PL011_CLOCK
417
418		If you have Amba PrimeCell PL011 UARTs, set this variable to
419		the clock speed of the UARTs.
420
421		CONFIG_PL01x_PORTS
422
423		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
424		define this to a list of base addresses for each (supported)
425		port. See e.g. include/configs/versatile.h
426
427
428- Console Interface:
429		Depending on board, define exactly one serial port
430		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
431		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
432		console by defining CONFIG_8xx_CONS_NONE
433
434		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
435		port routines must be defined elsewhere
436		(i.e. serial_init(), serial_getc(), ...)
437
438		CONFIG_CFB_CONSOLE
439		Enables console device for a color framebuffer. Needs following
440		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
441			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
442						(default big endian)
443			VIDEO_HW_RECTFILL	graphic chip supports
444						rectangle fill
445						(cf. smiLynxEM)
446			VIDEO_HW_BITBLT		graphic chip supports
447						bit-blit (cf. smiLynxEM)
448			VIDEO_VISIBLE_COLS	visible pixel columns
449						(cols=pitch)
450			VIDEO_VISIBLE_ROWS	visible pixel rows
451			VIDEO_PIXEL_SIZE	bytes per pixel
452			VIDEO_DATA_FORMAT	graphic data format
453						(0-5, cf. cfb_console.c)
454			VIDEO_FB_ADRS		framebuffer address
455			VIDEO_KBD_INIT_FCT	keyboard int fct
456						(i.e. i8042_kbd_init())
457			VIDEO_TSTC_FCT		test char fct
458						(i.e. i8042_tstc)
459			VIDEO_GETC_FCT		get char fct
460						(i.e. i8042_getc)
461			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
462						(requires blink timer
463						cf. i8042.c)
464			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
465			CONFIG_CONSOLE_TIME	display time/date info in
466						upper right corner
467						(requires CONFIG_CMD_DATE)
468			CONFIG_VIDEO_LOGO	display Linux logo in
469						upper left corner
470			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
471						linux_logo.h for logo.
472						Requires CONFIG_VIDEO_LOGO
473			CONFIG_CONSOLE_EXTRA_INFO
474						additional board info beside
475						the logo
476
477		When CONFIG_CFB_CONSOLE is defined, video console is
478		default i/o. Serial console can be forced with
479		environment 'console=serial'.
480
481		When CONFIG_SILENT_CONSOLE is defined, all console
482		messages (by U-Boot and Linux!) can be silenced with
483		the "silent" environment variable. See
484		doc/README.silent for more information.
485
486- Console Baudrate:
487		CONFIG_BAUDRATE - in bps
488		Select one of the baudrates listed in
489		CONFIG_SYS_BAUDRATE_TABLE, see below.
490		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
491
492- Console Rx buffer length
493		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
494		the maximum receive buffer length for the SMC.
495		This option is actual only for 82xx and 8xx possible.
496		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
497		must be defined, to setup the maximum idle timeout for
498		the SMC.
499
500- Interrupt driven serial port input:
501		CONFIG_SERIAL_SOFTWARE_FIFO
502
503		PPC405GP only.
504		Use an interrupt handler for receiving data on the
505		serial port. It also enables using hardware handshake
506		(RTS/CTS) and UART's built-in FIFO. Set the number of
507		bytes the interrupt driven input buffer should have.
508
509		Leave undefined to disable this feature, including
510		disable the buffer and hardware handshake.
511
512- Console UART Number:
513		CONFIG_UART1_CONSOLE
514
515		AMCC PPC4xx only.
516		If defined internal UART1 (and not UART0) is used
517		as default U-Boot console.
518
519- Boot Delay:	CONFIG_BOOTDELAY - in seconds
520		Delay before automatically booting the default image;
521		set to -1 to disable autoboot.
522
523		See doc/README.autoboot for these options that
524		work with CONFIG_BOOTDELAY. None are required.
525		CONFIG_BOOT_RETRY_TIME
526		CONFIG_BOOT_RETRY_MIN
527		CONFIG_AUTOBOOT_KEYED
528		CONFIG_AUTOBOOT_PROMPT
529		CONFIG_AUTOBOOT_DELAY_STR
530		CONFIG_AUTOBOOT_STOP_STR
531		CONFIG_AUTOBOOT_DELAY_STR2
532		CONFIG_AUTOBOOT_STOP_STR2
533		CONFIG_ZERO_BOOTDELAY_CHECK
534		CONFIG_RESET_TO_RETRY
535
536- Autoboot Command:
537		CONFIG_BOOTCOMMAND
538		Only needed when CONFIG_BOOTDELAY is enabled;
539		define a command string that is automatically executed
540		when no character is read on the console interface
541		within "Boot Delay" after reset.
542
543		CONFIG_BOOTARGS
544		This can be used to pass arguments to the bootm
545		command. The value of CONFIG_BOOTARGS goes into the
546		environment value "bootargs".
547
548		CONFIG_RAMBOOT and CONFIG_NFSBOOT
549		The value of these goes into the environment as
550		"ramboot" and "nfsboot" respectively, and can be used
551		as a convenience, when switching between booting from
552		RAM and NFS.
553
554- Pre-Boot Commands:
555		CONFIG_PREBOOT
556
557		When this option is #defined, the existence of the
558		environment variable "preboot" will be checked
559		immediately before starting the CONFIG_BOOTDELAY
560		countdown and/or running the auto-boot command resp.
561		entering interactive mode.
562
563		This feature is especially useful when "preboot" is
564		automatically generated or modified. For an example
565		see the LWMON board specific code: here "preboot" is
566		modified when the user holds down a certain
567		combination of keys on the (special) keyboard when
568		booting the systems
569
570- Serial Download Echo Mode:
571		CONFIG_LOADS_ECHO
572		If defined to 1, all characters received during a
573		serial download (using the "loads" command) are
574		echoed back. This might be needed by some terminal
575		emulations (like "cu"), but may as well just take
576		time on others. This setting #define's the initial
577		value of the "loads_echo" environment variable.
578
579- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
580		CONFIG_KGDB_BAUDRATE
581		Select one of the baudrates listed in
582		CONFIG_SYS_BAUDRATE_TABLE, see below.
583
584- Monitor Functions:
585		Monitor commands can be included or excluded
586		from the build by using the #include files
587		"config_cmd_all.h" and #undef'ing unwanted
588		commands, or using "config_cmd_default.h"
589		and augmenting with additional #define's
590		for wanted commands.
591
592		The default command configuration includes all commands
593		except those marked below with a "*".
594
595		CONFIG_CMD_ASKENV	* ask for env variable
596		CONFIG_CMD_BDI		  bdinfo
597		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
598		CONFIG_CMD_BMP		* BMP support
599		CONFIG_CMD_BSP		* Board specific commands
600		CONFIG_CMD_BOOTD	  bootd
601		CONFIG_CMD_CACHE	* icache, dcache
602		CONFIG_CMD_CONSOLE	  coninfo
603		CONFIG_CMD_DATE		* support for RTC, date/time...
604		CONFIG_CMD_DHCP		* DHCP support
605		CONFIG_CMD_DIAG		* Diagnostics
606		CONFIG_CMD_DOC		* Disk-On-Chip Support
607		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
608		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
609		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
610		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
611		CONFIG_CMD_DTT		* Digital Therm and Thermostat
612		CONFIG_CMD_ECHO		  echo arguments
613		CONFIG_CMD_EEPROM	* EEPROM read/write support
614		CONFIG_CMD_ELF		* bootelf, bootvx
615		CONFIG_CMD_SAVEENV	  saveenv
616		CONFIG_CMD_FDC		* Floppy Disk Support
617		CONFIG_CMD_FAT		* FAT partition support
618		CONFIG_CMD_FDOS		* Dos diskette Support
619		CONFIG_CMD_FLASH	  flinfo, erase, protect
620		CONFIG_CMD_FPGA		  FPGA device initialization support
621		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
622		CONFIG_CMD_I2C		* I2C serial bus support
623		CONFIG_CMD_IDE		* IDE harddisk support
624		CONFIG_CMD_IMI		  iminfo
625		CONFIG_CMD_IMLS		  List all found images
626		CONFIG_CMD_IMMAP	* IMMR dump support
627		CONFIG_CMD_IRQ		* irqinfo
628		CONFIG_CMD_ITEST	  Integer/string test of 2 values
629		CONFIG_CMD_JFFS2	* JFFS2 Support
630		CONFIG_CMD_KGDB		* kgdb
631		CONFIG_CMD_LOADB	  loadb
632		CONFIG_CMD_LOADS	  loads
633		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
634					  loop, loopw, mtest
635		CONFIG_CMD_MISC		  Misc functions like sleep etc
636		CONFIG_CMD_MMC		* MMC memory mapped support
637		CONFIG_CMD_MII		* MII utility commands
638		CONFIG_CMD_MTDPARTS	* MTD partition support
639		CONFIG_CMD_NAND		* NAND support
640		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
641		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
642		CONFIG_CMD_PCA953X_INFO	* PCA953x I2C gpio info command
643		CONFIG_CMD_PCI		* pciinfo
644		CONFIG_CMD_PCMCIA		* PCMCIA support
645		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
646					  host
647		CONFIG_CMD_PORTIO	* Port I/O
648		CONFIG_CMD_REGINFO	* Register dump
649		CONFIG_CMD_RUN		  run command in env variable
650		CONFIG_CMD_SAVES	* save S record dump
651		CONFIG_CMD_SCSI		* SCSI Support
652		CONFIG_CMD_SDRAM	* print SDRAM configuration information
653					  (requires CONFIG_CMD_I2C)
654		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
655					  (4xx only)
656		CONFIG_CMD_SOURCE	  "source" command Support
657		CONFIG_CMD_SPI		* SPI serial bus support
658		CONFIG_CMD_USB		* USB support
659		CONFIG_CMD_VFD		* VFD support (TRAB)
660		CONFIG_CMD_CDP		* Cisco Discover Protocol support
661		CONFIG_CMD_FSL		* Microblaze FSL support
662
663
664		EXAMPLE: If you want all functions except of network
665		support you can write:
666
667		#include "config_cmd_all.h"
668		#undef CONFIG_CMD_NET
669
670	Other Commands:
671		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
672
673	Note:	Don't enable the "icache" and "dcache" commands
674		(configuration option CONFIG_CMD_CACHE) unless you know
675		what you (and your U-Boot users) are doing. Data
676		cache cannot be enabled on systems like the 8xx or
677		8260 (where accesses to the IMMR region must be
678		uncached), and it cannot be disabled on all other
679		systems where we (mis-) use the data cache to hold an
680		initial stack and some data.
681
682
683		XXX - this list needs to get updated!
684
685- Watchdog:
686		CONFIG_WATCHDOG
687		If this variable is defined, it enables watchdog
688		support. There must be support in the platform specific
689		code for a watchdog. For the 8xx and 8260 CPUs, the
690		SIU Watchdog feature is enabled in the SYPCR
691		register.
692
693- U-Boot Version:
694		CONFIG_VERSION_VARIABLE
695		If this variable is defined, an environment variable
696		named "ver" is created by U-Boot showing the U-Boot
697		version as printed by the "version" command.
698		This variable is readonly.
699
700- Real-Time Clock:
701
702		When CONFIG_CMD_DATE is selected, the type of the RTC
703		has to be selected, too. Define exactly one of the
704		following options:
705
706		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
707		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
708		CONFIG_RTC_MC13783	- use MC13783 RTC
709		CONFIG_RTC_MC146818	- use MC146818 RTC
710		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
711		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
712		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
713		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
714		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
715		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
716		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
717
718		Note that if the RTC uses I2C, then the I2C interface
719		must also be configured. See I2C Support, below.
720
721- GPIO Support:
722		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
723		CONFIG_PCA953X_INFO	- enable pca953x info command
724
725		Note that if the GPIO device uses I2C, then the I2C interface
726		must also be configured. See I2C Support, below.
727
728- Timestamp Support:
729
730		When CONFIG_TIMESTAMP is selected, the timestamp
731		(date and time) of an image is printed by image
732		commands like bootm or iminfo. This option is
733		automatically enabled when you select CONFIG_CMD_DATE .
734
735- Partition Support:
736		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
737		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
738
739		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
740		CONFIG_CMD_SCSI) you must configure support for at
741		least one partition type as well.
742
743- IDE Reset method:
744		CONFIG_IDE_RESET_ROUTINE - this is defined in several
745		board configurations files but used nowhere!
746
747		CONFIG_IDE_RESET - is this is defined, IDE Reset will
748		be performed by calling the function
749			ide_set_reset(int reset)
750		which has to be defined in a board specific file
751
752- ATAPI Support:
753		CONFIG_ATAPI
754
755		Set this to enable ATAPI support.
756
757- LBA48 Support
758		CONFIG_LBA48
759
760		Set this to enable support for disks larger than 137GB
761		Also look at CONFIG_SYS_64BIT_LBA ,CONFIG_SYS_64BIT_VSPRINTF and CONFIG_SYS_64BIT_STRTOUL
762		Whithout these , LBA48 support uses 32bit variables and will 'only'
763		support disks up to 2.1TB.
764
765		CONFIG_SYS_64BIT_LBA:
766			When enabled, makes the IDE subsystem use 64bit sector addresses.
767			Default is 32bit.
768
769- SCSI Support:
770		At the moment only there is only support for the
771		SYM53C8XX SCSI controller; define
772		CONFIG_SCSI_SYM53C8XX to enable it.
773
774		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
775		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
776		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
777		maximum numbers of LUNs, SCSI ID's and target
778		devices.
779		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
780
781- NETWORK Support (PCI):
782		CONFIG_E1000
783		Support for Intel 8254x gigabit chips.
784
785		CONFIG_E1000_FALLBACK_MAC
786		default MAC for empty EEPROM after production.
787
788		CONFIG_EEPRO100
789		Support for Intel 82557/82559/82559ER chips.
790		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
791		write routine for first time initialisation.
792
793		CONFIG_TULIP
794		Support for Digital 2114x chips.
795		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
796		modem chip initialisation (KS8761/QS6611).
797
798		CONFIG_NATSEMI
799		Support for National dp83815 chips.
800
801		CONFIG_NS8382X
802		Support for National dp8382[01] gigabit chips.
803
804- NETWORK Support (other):
805
806		CONFIG_DRIVER_LAN91C96
807		Support for SMSC's LAN91C96 chips.
808
809			CONFIG_LAN91C96_BASE
810			Define this to hold the physical address
811			of the LAN91C96's I/O space
812
813			CONFIG_LAN91C96_USE_32_BIT
814			Define this to enable 32 bit addressing
815
816		CONFIG_DRIVER_SMC91111
817		Support for SMSC's LAN91C111 chip
818
819			CONFIG_SMC91111_BASE
820			Define this to hold the physical address
821			of the device (I/O space)
822
823			CONFIG_SMC_USE_32_BIT
824			Define this if data bus is 32 bits
825
826			CONFIG_SMC_USE_IOFUNCS
827			Define this to use i/o functions instead of macros
828			(some hardware wont work with macros)
829
830		CONFIG_DRIVER_SMC911X
831		Support for SMSC's LAN911x and LAN921x chips
832
833			CONFIG_DRIVER_SMC911X_BASE
834			Define this to hold the physical address
835			of the device (I/O space)
836
837			CONFIG_DRIVER_SMC911X_32_BIT
838			Define this if data bus is 32 bits
839
840			CONFIG_DRIVER_SMC911X_16_BIT
841			Define this if data bus is 16 bits. If your processor
842			automatically converts one 32 bit word to two 16 bit
843			words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
844
845- USB Support:
846		At the moment only the UHCI host controller is
847		supported (PIP405, MIP405, MPC5200); define
848		CONFIG_USB_UHCI to enable it.
849		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
850		and define CONFIG_USB_STORAGE to enable the USB
851		storage devices.
852		Note:
853		Supported are USB Keyboards and USB Floppy drives
854		(TEAC FD-05PUB).
855		MPC5200 USB requires additional defines:
856			CONFIG_USB_CLOCK
857				for 528 MHz Clock: 0x0001bbbb
858			CONFIG_USB_CONFIG
859				for differential drivers: 0x00001000
860				for single ended drivers: 0x00005000
861			CONFIG_SYS_USB_EVENT_POLL
862				May be defined to allow interrupt polling
863				instead of using asynchronous interrupts
864
865- USB Device:
866		Define the below if you wish to use the USB console.
867		Once firmware is rebuilt from a serial console issue the
868		command "setenv stdin usbtty; setenv stdout usbtty" and
869		attach your USB cable. The Unix command "dmesg" should print
870		it has found a new device. The environment variable usbtty
871		can be set to gserial or cdc_acm to enable your device to
872		appear to a USB host as a Linux gserial device or a
873		Common Device Class Abstract Control Model serial device.
874		If you select usbtty = gserial you should be able to enumerate
875		a Linux host by
876		# modprobe usbserial vendor=0xVendorID product=0xProductID
877		else if using cdc_acm, simply setting the environment
878		variable usbtty to be cdc_acm should suffice. The following
879		might be defined in YourBoardName.h
880
881			CONFIG_USB_DEVICE
882			Define this to build a UDC device
883
884			CONFIG_USB_TTY
885			Define this to have a tty type of device available to
886			talk to the UDC device
887
888			CONFIG_SYS_CONSOLE_IS_IN_ENV
889			Define this if you want stdin, stdout &/or stderr to
890			be set to usbtty.
891
892			mpc8xx:
893				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
894				Derive USB clock from external clock "blah"
895				- CONFIG_SYS_USB_EXTC_CLK 0x02
896
897				CONFIG_SYS_USB_BRG_CLK 0xBLAH
898				Derive USB clock from brgclk
899				- CONFIG_SYS_USB_BRG_CLK 0x04
900
901		If you have a USB-IF assigned VendorID then you may wish to
902		define your own vendor specific values either in BoardName.h
903		or directly in usbd_vendor_info.h. If you don't define
904		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
905		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
906		should pretend to be a Linux device to it's target host.
907
908			CONFIG_USBD_MANUFACTURER
909			Define this string as the name of your company for
910			- CONFIG_USBD_MANUFACTURER "my company"
911
912			CONFIG_USBD_PRODUCT_NAME
913			Define this string as the name of your product
914			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
915
916			CONFIG_USBD_VENDORID
917			Define this as your assigned Vendor ID from the USB
918			Implementors Forum. This *must* be a genuine Vendor ID
919			to avoid polluting the USB namespace.
920			- CONFIG_USBD_VENDORID 0xFFFF
921
922			CONFIG_USBD_PRODUCTID
923			Define this as the unique Product ID
924			for your device
925			- CONFIG_USBD_PRODUCTID 0xFFFF
926
927
928- MMC Support:
929		The MMC controller on the Intel PXA is supported. To
930		enable this define CONFIG_MMC. The MMC can be
931		accessed from the boot prompt by mapping the device
932		to physical memory similar to flash. Command line is
933		enabled with CONFIG_CMD_MMC. The MMC driver also works with
934		the FAT fs. This is enabled with CONFIG_CMD_FAT.
935
936- Journaling Flash filesystem support:
937		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
938		CONFIG_JFFS2_NAND_DEV
939		Define these for a default partition on a NAND device
940
941		CONFIG_SYS_JFFS2_FIRST_SECTOR,
942		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
943		Define these for a default partition on a NOR device
944
945		CONFIG_SYS_JFFS_CUSTOM_PART
946		Define this to create an own partition. You have to provide a
947		function struct part_info* jffs2_part_info(int part_num)
948
949		If you define only one JFFS2 partition you may also want to
950		#define CONFIG_SYS_JFFS_SINGLE_PART	1
951		to disable the command chpart. This is the default when you
952		have not defined a custom partition
953
954- Keyboard Support:
955		CONFIG_ISA_KEYBOARD
956
957		Define this to enable standard (PC-Style) keyboard
958		support
959
960		CONFIG_I8042_KBD
961		Standard PC keyboard driver with US (is default) and
962		GERMAN key layout (switch via environment 'keymap=de') support.
963		Export function i8042_kbd_init, i8042_tstc and i8042_getc
964		for cfb_console. Supports cursor blinking.
965
966- Video support:
967		CONFIG_VIDEO
968
969		Define this to enable video support (for output to
970		video).
971
972		CONFIG_VIDEO_CT69000
973
974		Enable Chips & Technologies 69000 Video chip
975
976		CONFIG_VIDEO_SMI_LYNXEM
977		Enable Silicon Motion SMI 712/710/810 Video chip. The
978		video output is selected via environment 'videoout'
979		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
980		assumed.
981
982		For the CT69000 and SMI_LYNXEM drivers, videomode is
983		selected via environment 'videomode'. Two different ways
984		are possible:
985		- "videomode=num"   'num' is a standard LiLo mode numbers.
986		Following standard modes are supported	(* is default):
987
988		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
989		-------------+---------------------------------------------
990		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
991		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
992		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
993		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
994		-------------+---------------------------------------------
995		(i.e. setenv videomode 317; saveenv; reset;)
996
997		- "videomode=bootargs" all the video parameters are parsed
998		from the bootargs. (See drivers/video/videomodes.c)
999
1000
1001		CONFIG_VIDEO_SED13806
1002		Enable Epson SED13806 driver. This driver supports 8bpp
1003		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1004		or CONFIG_VIDEO_SED13806_16BPP
1005
1006- Keyboard Support:
1007		CONFIG_KEYBOARD
1008
1009		Define this to enable a custom keyboard support.
1010		This simply calls drv_keyboard_init() which must be
1011		defined in your board-specific files.
1012		The only board using this so far is RBC823.
1013
1014- LCD Support:	CONFIG_LCD
1015
1016		Define this to enable LCD support (for output to LCD
1017		display); also select one of the supported displays
1018		by defining one of these:
1019
1020		CONFIG_ATMEL_LCD:
1021
1022			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1023
1024		CONFIG_NEC_NL6448AC33:
1025
1026			NEC NL6448AC33-18. Active, color, single scan.
1027
1028		CONFIG_NEC_NL6448BC20
1029
1030			NEC NL6448BC20-08. 6.5", 640x480.
1031			Active, color, single scan.
1032
1033		CONFIG_NEC_NL6448BC33_54
1034
1035			NEC NL6448BC33-54. 10.4", 640x480.
1036			Active, color, single scan.
1037
1038		CONFIG_SHARP_16x9
1039
1040			Sharp 320x240. Active, color, single scan.
1041			It isn't 16x9, and I am not sure what it is.
1042
1043		CONFIG_SHARP_LQ64D341
1044
1045			Sharp LQ64D341 display, 640x480.
1046			Active, color, single scan.
1047
1048		CONFIG_HLD1045
1049
1050			HLD1045 display, 640x480.
1051			Active, color, single scan.
1052
1053		CONFIG_OPTREX_BW
1054
1055			Optrex	 CBL50840-2 NF-FW 99 22 M5
1056			or
1057			Hitachi	 LMG6912RPFC-00T
1058			or
1059			Hitachi	 SP14Q002
1060
1061			320x240. Black & white.
1062
1063		Normally display is black on white background; define
1064		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1065
1066- Splash Screen Support: CONFIG_SPLASH_SCREEN
1067
1068		If this option is set, the environment is checked for
1069		a variable "splashimage". If found, the usual display
1070		of logo, copyright and system information on the LCD
1071		is suppressed and the BMP image at the address
1072		specified in "splashimage" is loaded instead. The
1073		console is redirected to the "nulldev", too. This
1074		allows for a "silent" boot where a splash screen is
1075		loaded very quickly after power-on.
1076
1077- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1078
1079		If this option is set, additionally to standard BMP
1080		images, gzipped BMP images can be displayed via the
1081		splashscreen support or the bmp command.
1082
1083- Compression support:
1084		CONFIG_BZIP2
1085
1086		If this option is set, support for bzip2 compressed
1087		images is included. If not, only uncompressed and gzip
1088		compressed images are supported.
1089
1090		NOTE: the bzip2 algorithm requires a lot of RAM, so
1091		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1092		be at least 4MB.
1093
1094		CONFIG_LZMA
1095
1096		If this option is set, support for lzma compressed
1097		images is included.
1098
1099		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1100		requires an amount of dynamic memory that is given by the
1101		formula:
1102
1103			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1104
1105		Where lc and lp stand for, respectively, Literal context bits
1106		and Literal pos bits.
1107
1108		This value is upper-bounded by 14MB in the worst case. Anyway,
1109		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1110		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1111		a very small buffer.
1112
1113		Use the lzmainfo tool to determinate the lc and lp values and
1114		then calculate the amount of needed dynamic memory (ensuring
1115		the appropriate CONFIG_SYS_MALLOC_LEN value).
1116
1117- MII/PHY support:
1118		CONFIG_PHY_ADDR
1119
1120		The address of PHY on MII bus.
1121
1122		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1123
1124		The clock frequency of the MII bus
1125
1126		CONFIG_PHY_GIGE
1127
1128		If this option is set, support for speed/duplex
1129		detection of gigabit PHY is included.
1130
1131		CONFIG_PHY_RESET_DELAY
1132
1133		Some PHY like Intel LXT971A need extra delay after
1134		reset before any MII register access is possible.
1135		For such PHY, set this option to the usec delay
1136		required. (minimum 300usec for LXT971A)
1137
1138		CONFIG_PHY_CMD_DELAY (ppc4xx)
1139
1140		Some PHY like Intel LXT971A need extra delay after
1141		command issued before MII status register can be read
1142
1143- Ethernet address:
1144		CONFIG_ETHADDR
1145		CONFIG_ETH1ADDR
1146		CONFIG_ETH2ADDR
1147		CONFIG_ETH3ADDR
1148		CONFIG_ETH4ADDR
1149		CONFIG_ETH5ADDR
1150
1151		Define a default value for Ethernet address to use
1152		for the respective Ethernet interface, in case this
1153		is not determined automatically.
1154
1155- IP address:
1156		CONFIG_IPADDR
1157
1158		Define a default value for the IP address to use for
1159		the default Ethernet interface, in case this is not
1160		determined through e.g. bootp.
1161
1162- Server IP address:
1163		CONFIG_SERVERIP
1164
1165		Defines a default value for the IP address of a TFTP
1166		server to contact when using the "tftboot" command.
1167
1168- Multicast TFTP Mode:
1169		CONFIG_MCAST_TFTP
1170
1171		Defines whether you want to support multicast TFTP as per
1172		rfc-2090; for example to work with atftp.  Lets lots of targets
1173		tftp down the same boot image concurrently.  Note: the Ethernet
1174		driver in use must provide a function: mcast() to join/leave a
1175		multicast group.
1176
1177		CONFIG_BOOTP_RANDOM_DELAY
1178- BOOTP Recovery Mode:
1179		CONFIG_BOOTP_RANDOM_DELAY
1180
1181		If you have many targets in a network that try to
1182		boot using BOOTP, you may want to avoid that all
1183		systems send out BOOTP requests at precisely the same
1184		moment (which would happen for instance at recovery
1185		from a power failure, when all systems will try to
1186		boot, thus flooding the BOOTP server. Defining
1187		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1188		inserted before sending out BOOTP requests. The
1189		following delays are inserted then:
1190
1191		1st BOOTP request:	delay 0 ... 1 sec
1192		2nd BOOTP request:	delay 0 ... 2 sec
1193		3rd BOOTP request:	delay 0 ... 4 sec
1194		4th and following
1195		BOOTP requests:		delay 0 ... 8 sec
1196
1197- DHCP Advanced Options:
1198		You can fine tune the DHCP functionality by defining
1199		CONFIG_BOOTP_* symbols:
1200
1201		CONFIG_BOOTP_SUBNETMASK
1202		CONFIG_BOOTP_GATEWAY
1203		CONFIG_BOOTP_HOSTNAME
1204		CONFIG_BOOTP_NISDOMAIN
1205		CONFIG_BOOTP_BOOTPATH
1206		CONFIG_BOOTP_BOOTFILESIZE
1207		CONFIG_BOOTP_DNS
1208		CONFIG_BOOTP_DNS2
1209		CONFIG_BOOTP_SEND_HOSTNAME
1210		CONFIG_BOOTP_NTPSERVER
1211		CONFIG_BOOTP_TIMEOFFSET
1212		CONFIG_BOOTP_VENDOREX
1213
1214		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1215		environment variable, not the BOOTP server.
1216
1217		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1218		serverip from a DHCP server, it is possible that more
1219		than one DNS serverip is offered to the client.
1220		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1221		serverip will be stored in the additional environment
1222		variable "dnsip2". The first DNS serverip is always
1223		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1224		is defined.
1225
1226		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1227		to do a dynamic update of a DNS server. To do this, they
1228		need the hostname of the DHCP requester.
1229		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1230		of the "hostname" environment variable is passed as
1231		option 12 to the DHCP server.
1232
1233		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1234
1235		A 32bit value in microseconds for a delay between
1236		receiving a "DHCP Offer" and sending the "DHCP Request".
1237		This fixes a problem with certain DHCP servers that don't
1238		respond 100% of the time to a "DHCP request". E.g. On an
1239		AT91RM9200 processor running at 180MHz, this delay needed
1240		to be *at least* 15,000 usec before a Windows Server 2003
1241		DHCP server would reply 100% of the time. I recommend at
1242		least 50,000 usec to be safe. The alternative is to hope
1243		that one of the retries will be successful but note that
1244		the DHCP timeout and retry process takes a longer than
1245		this delay.
1246
1247 - CDP Options:
1248		CONFIG_CDP_DEVICE_ID
1249
1250		The device id used in CDP trigger frames.
1251
1252		CONFIG_CDP_DEVICE_ID_PREFIX
1253
1254		A two character string which is prefixed to the MAC address
1255		of the device.
1256
1257		CONFIG_CDP_PORT_ID
1258
1259		A printf format string which contains the ascii name of
1260		the port. Normally is set to "eth%d" which sets
1261		eth0 for the first Ethernet, eth1 for the second etc.
1262
1263		CONFIG_CDP_CAPABILITIES
1264
1265		A 32bit integer which indicates the device capabilities;
1266		0x00000010 for a normal host which does not forwards.
1267
1268		CONFIG_CDP_VERSION
1269
1270		An ascii string containing the version of the software.
1271
1272		CONFIG_CDP_PLATFORM
1273
1274		An ascii string containing the name of the platform.
1275
1276		CONFIG_CDP_TRIGGER
1277
1278		A 32bit integer sent on the trigger.
1279
1280		CONFIG_CDP_POWER_CONSUMPTION
1281
1282		A 16bit integer containing the power consumption of the
1283		device in .1 of milliwatts.
1284
1285		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1286
1287		A byte containing the id of the VLAN.
1288
1289- Status LED:	CONFIG_STATUS_LED
1290
1291		Several configurations allow to display the current
1292		status using a LED. For instance, the LED will blink
1293		fast while running U-Boot code, stop blinking as
1294		soon as a reply to a BOOTP request was received, and
1295		start blinking slow once the Linux kernel is running
1296		(supported by a status LED driver in the Linux
1297		kernel). Defining CONFIG_STATUS_LED enables this
1298		feature in U-Boot.
1299
1300- CAN Support:	CONFIG_CAN_DRIVER
1301
1302		Defining CONFIG_CAN_DRIVER enables CAN driver support
1303		on those systems that support this (optional)
1304		feature, like the TQM8xxL modules.
1305
1306- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1307
1308		These enable I2C serial bus commands. Defining either of
1309		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1310		include the appropriate I2C driver for the selected CPU.
1311
1312		This will allow you to use i2c commands at the u-boot
1313		command line (as long as you set CONFIG_CMD_I2C in
1314		CONFIG_COMMANDS) and communicate with i2c based realtime
1315		clock chips. See common/cmd_i2c.c for a description of the
1316		command line interface.
1317
1318		CONFIG_HARD_I2C selects a hardware I2C controller.
1319
1320		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1321		bit-banging) driver instead of CPM or similar hardware
1322		support for I2C.
1323
1324		There are several other quantities that must also be
1325		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1326
1327		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1328		to be the frequency (in Hz) at which you wish your i2c bus
1329		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1330		the CPU's i2c node address).
1331
1332		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1333		sets the CPU up as a master node and so its address should
1334		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1335		p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
1336
1337		That's all that's required for CONFIG_HARD_I2C.
1338
1339		If you use the software i2c interface (CONFIG_SOFT_I2C)
1340		then the following macros need to be defined (examples are
1341		from include/configs/lwmon.h):
1342
1343		I2C_INIT
1344
1345		(Optional). Any commands necessary to enable the I2C
1346		controller or configure ports.
1347
1348		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1349
1350		I2C_PORT
1351
1352		(Only for MPC8260 CPU). The I/O port to use (the code
1353		assumes both bits are on the same port). Valid values
1354		are 0..3 for ports A..D.
1355
1356		I2C_ACTIVE
1357
1358		The code necessary to make the I2C data line active
1359		(driven).  If the data line is open collector, this
1360		define can be null.
1361
1362		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1363
1364		I2C_TRISTATE
1365
1366		The code necessary to make the I2C data line tri-stated
1367		(inactive).  If the data line is open collector, this
1368		define can be null.
1369
1370		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1371
1372		I2C_READ
1373
1374		Code that returns TRUE if the I2C data line is high,
1375		FALSE if it is low.
1376
1377		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1378
1379		I2C_SDA(bit)
1380
1381		If <bit> is TRUE, sets the I2C data line high. If it
1382		is FALSE, it clears it (low).
1383
1384		eg: #define I2C_SDA(bit) \
1385			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1386			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1387
1388		I2C_SCL(bit)
1389
1390		If <bit> is TRUE, sets the I2C clock line high. If it
1391		is FALSE, it clears it (low).
1392
1393		eg: #define I2C_SCL(bit) \
1394			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1395			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1396
1397		I2C_DELAY
1398
1399		This delay is invoked four times per clock cycle so this
1400		controls the rate of data transfer.  The data rate thus
1401		is 1 / (I2C_DELAY * 4). Often defined to be something
1402		like:
1403
1404		#define I2C_DELAY  udelay(2)
1405
1406		CONFIG_SYS_I2C_INIT_BOARD
1407
1408		When a board is reset during an i2c bus transfer
1409		chips might think that the current transfer is still
1410		in progress. On some boards it is possible to access
1411		the i2c SCLK line directly, either by using the
1412		processor pin as a GPIO or by having a second pin
1413		connected to the bus. If this option is defined a
1414		custom i2c_init_board() routine in boards/xxx/board.c
1415		is run early in the boot sequence.
1416
1417		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1418
1419		This option enables configuration of bi_iic_fast[] flags
1420		in u-boot bd_info structure based on u-boot environment
1421		variable "i2cfast". (see also i2cfast)
1422
1423		CONFIG_I2C_MULTI_BUS
1424
1425		This option allows the use of multiple I2C buses, each of which
1426		must have a controller.  At any point in time, only one bus is
1427		active.  To switch to a different bus, use the 'i2c dev' command.
1428		Note that bus numbering is zero-based.
1429
1430		CONFIG_SYS_I2C_NOPROBES
1431
1432		This option specifies a list of I2C devices that will be skipped
1433		when the 'i2c probe' command is issued.  If CONFIG_I2C_MULTI_BUS
1434		is set, specify a list of bus-device pairs.  Otherwise, specify
1435		a 1D array of device addresses
1436
1437		e.g.
1438			#undef	CONFIG_I2C_MULTI_BUS
1439			#define CONFIG_SYS_I2C_NOPROBES	{0x50,0x68}
1440
1441		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1442
1443			#define	CONFIG_I2C_MULTI_BUS
1444			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1445
1446		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1447
1448		CONFIG_SYS_SPD_BUS_NUM
1449
1450		If defined, then this indicates the I2C bus number for DDR SPD.
1451		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1452
1453		CONFIG_SYS_RTC_BUS_NUM
1454
1455		If defined, then this indicates the I2C bus number for the RTC.
1456		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1457
1458		CONFIG_SYS_DTT_BUS_NUM
1459
1460		If defined, then this indicates the I2C bus number for the DTT.
1461		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1462
1463		CONFIG_SYS_I2C_DTT_ADDR:
1464
1465		If defined, specifies the I2C address of the DTT device.
1466		If not defined, then U-Boot uses predefined value for
1467		specified DTT device.
1468
1469		CONFIG_FSL_I2C
1470
1471		Define this option if you want to use Freescale's I2C driver in
1472		drivers/i2c/fsl_i2c.c.
1473
1474		CONFIG_I2C_MUX
1475
1476		Define this option if you have I2C devices reached over 1 .. n
1477		I2C Muxes like the pca9544a. This option addes a new I2C
1478		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1479		new I2C Bus to the existing I2C Busses. If you select the
1480		new Bus with "i2c dev", u-bbot sends first the commandos for
1481		the muxes to activate this new "bus".
1482
1483		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1484		feature!
1485
1486		Example:
1487		Adding a new I2C Bus reached over 2 pca9544a muxes
1488			The First mux with address 70 and channel 6
1489			The Second mux with address 71 and channel 4
1490
1491		=> i2c bus pca9544a:70:6:pca9544a:71:4
1492
1493		Use the "i2c bus" command without parameter, to get a list
1494		of I2C Busses with muxes:
1495
1496		=> i2c bus
1497		Busses reached over muxes:
1498		Bus ID: 2
1499		  reached over Mux(es):
1500		    pca9544a@70 ch: 4
1501		Bus ID: 3
1502		  reached over Mux(es):
1503		    pca9544a@70 ch: 6
1504		    pca9544a@71 ch: 4
1505		=>
1506
1507		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1508		u-boot sends First the Commando to the mux@70 to enable
1509		channel 6, and then the Commando to the mux@71 to enable
1510		the channel 4.
1511
1512		After that, you can use the "normal" i2c commands as
1513		usual, to communicate with your I2C devices behind
1514		the 2 muxes.
1515
1516		This option is actually implemented for the bitbanging
1517		algorithm in common/soft_i2c.c and for the Hardware I2C
1518		Bus on the MPC8260. But it should be not so difficult
1519		to add this option to other architectures.
1520
1521		CONFIG_SOFT_I2C_READ_REPEATED_START
1522
1523		defining this will force the i2c_read() function in
1524		the soft_i2c driver to perform an I2C repeated start
1525		between writing the address pointer and reading the
1526		data.  If this define is omitted the default behaviour
1527		of doing a stop-start sequence will be used.  Most I2C
1528		devices can use either method, but some require one or
1529		the other.
1530
1531- SPI Support:	CONFIG_SPI
1532
1533		Enables SPI driver (so far only tested with
1534		SPI EEPROM, also an instance works with Crystal A/D and
1535		D/As on the SACSng board)
1536
1537		CONFIG_SPI_X
1538
1539		Enables extended (16-bit) SPI EEPROM addressing.
1540		(symmetrical to CONFIG_I2C_X)
1541
1542		CONFIG_SOFT_SPI
1543
1544		Enables a software (bit-bang) SPI driver rather than
1545		using hardware support. This is a general purpose
1546		driver that only requires three general I/O port pins
1547		(two outputs, one input) to function. If this is
1548		defined, the board configuration must define several
1549		SPI configuration items (port pins to use, etc). For
1550		an example, see include/configs/sacsng.h.
1551
1552		CONFIG_HARD_SPI
1553
1554		Enables a hardware SPI driver for general-purpose reads
1555		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1556		must define a list of chip-select function pointers.
1557		Currently supported on some MPC8xxx processors.  For an
1558		example, see include/configs/mpc8349emds.h.
1559
1560		CONFIG_MXC_SPI
1561
1562		Enables the driver for the SPI controllers on i.MX and MXC
1563		SoCs. Currently only i.MX31 is supported.
1564
1565- FPGA Support: CONFIG_FPGA
1566
1567		Enables FPGA subsystem.
1568
1569		CONFIG_FPGA_<vendor>
1570
1571		Enables support for specific chip vendors.
1572		(ALTERA, XILINX)
1573
1574		CONFIG_FPGA_<family>
1575
1576		Enables support for FPGA family.
1577		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1578
1579		CONFIG_FPGA_COUNT
1580
1581		Specify the number of FPGA devices to support.
1582
1583		CONFIG_SYS_FPGA_PROG_FEEDBACK
1584
1585		Enable printing of hash marks during FPGA configuration.
1586
1587		CONFIG_SYS_FPGA_CHECK_BUSY
1588
1589		Enable checks on FPGA configuration interface busy
1590		status by the configuration function. This option
1591		will require a board or device specific function to
1592		be written.
1593
1594		CONFIG_FPGA_DELAY
1595
1596		If defined, a function that provides delays in the FPGA
1597		configuration driver.
1598
1599		CONFIG_SYS_FPGA_CHECK_CTRLC
1600		Allow Control-C to interrupt FPGA configuration
1601
1602		CONFIG_SYS_FPGA_CHECK_ERROR
1603
1604		Check for configuration errors during FPGA bitfile
1605		loading. For example, abort during Virtex II
1606		configuration if the INIT_B line goes low (which
1607		indicated a CRC error).
1608
1609		CONFIG_SYS_FPGA_WAIT_INIT
1610
1611		Maximum time to wait for the INIT_B line to deassert
1612		after PROB_B has been deasserted during a Virtex II
1613		FPGA configuration sequence. The default time is 500
1614		ms.
1615
1616		CONFIG_SYS_FPGA_WAIT_BUSY
1617
1618		Maximum time to wait for BUSY to deassert during
1619		Virtex II FPGA configuration. The default is 5 ms.
1620
1621		CONFIG_SYS_FPGA_WAIT_CONFIG
1622
1623		Time to wait after FPGA configuration. The default is
1624		200 ms.
1625
1626- Configuration Management:
1627		CONFIG_IDENT_STRING
1628
1629		If defined, this string will be added to the U-Boot
1630		version information (U_BOOT_VERSION)
1631
1632- Vendor Parameter Protection:
1633
1634		U-Boot considers the values of the environment
1635		variables "serial#" (Board Serial Number) and
1636		"ethaddr" (Ethernet Address) to be parameters that
1637		are set once by the board vendor / manufacturer, and
1638		protects these variables from casual modification by
1639		the user. Once set, these variables are read-only,
1640		and write or delete attempts are rejected. You can
1641		change this behaviour:
1642
1643		If CONFIG_ENV_OVERWRITE is #defined in your config
1644		file, the write protection for vendor parameters is
1645		completely disabled. Anybody can change or delete
1646		these parameters.
1647
1648		Alternatively, if you #define _both_ CONFIG_ETHADDR
1649		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1650		Ethernet address is installed in the environment,
1651		which can be changed exactly ONCE by the user. [The
1652		serial# is unaffected by this, i. e. it remains
1653		read-only.]
1654
1655- Protected RAM:
1656		CONFIG_PRAM
1657
1658		Define this variable to enable the reservation of
1659		"protected RAM", i. e. RAM which is not overwritten
1660		by U-Boot. Define CONFIG_PRAM to hold the number of
1661		kB you want to reserve for pRAM. You can overwrite
1662		this default value by defining an environment
1663		variable "pram" to the number of kB you want to
1664		reserve. Note that the board info structure will
1665		still show the full amount of RAM. If pRAM is
1666		reserved, a new environment variable "mem" will
1667		automatically be defined to hold the amount of
1668		remaining RAM in a form that can be passed as boot
1669		argument to Linux, for instance like that:
1670
1671			setenv bootargs ... mem=\${mem}
1672			saveenv
1673
1674		This way you can tell Linux not to use this memory,
1675		either, which results in a memory region that will
1676		not be affected by reboots.
1677
1678		*WARNING* If your board configuration uses automatic
1679		detection of the RAM size, you must make sure that
1680		this memory test is non-destructive. So far, the
1681		following board configurations are known to be
1682		"pRAM-clean":
1683
1684			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1685			HERMES, IP860, RPXlite, LWMON, LANTEC,
1686			PCU_E, FLAGADM, TQM8260
1687
1688- Error Recovery:
1689		CONFIG_PANIC_HANG
1690
1691		Define this variable to stop the system in case of a
1692		fatal error, so that you have to reset it manually.
1693		This is probably NOT a good idea for an embedded
1694		system where you want the system to reboot
1695		automatically as fast as possible, but it may be
1696		useful during development since you can try to debug
1697		the conditions that lead to the situation.
1698
1699		CONFIG_NET_RETRY_COUNT
1700
1701		This variable defines the number of retries for
1702		network operations like ARP, RARP, TFTP, or BOOTP
1703		before giving up the operation. If not defined, a
1704		default value of 5 is used.
1705
1706		CONFIG_ARP_TIMEOUT
1707
1708		Timeout waiting for an ARP reply in milliseconds.
1709
1710- Command Interpreter:
1711		CONFIG_AUTO_COMPLETE
1712
1713		Enable auto completion of commands using TAB.
1714
1715		Note that this feature has NOT been implemented yet
1716		for the "hush" shell.
1717
1718
1719		CONFIG_SYS_HUSH_PARSER
1720
1721		Define this variable to enable the "hush" shell (from
1722		Busybox) as command line interpreter, thus enabling
1723		powerful command line syntax like
1724		if...then...else...fi conditionals or `&&' and '||'
1725		constructs ("shell scripts").
1726
1727		If undefined, you get the old, much simpler behaviour
1728		with a somewhat smaller memory footprint.
1729
1730
1731		CONFIG_SYS_PROMPT_HUSH_PS2
1732
1733		This defines the secondary prompt string, which is
1734		printed when the command interpreter needs more input
1735		to complete a command. Usually "> ".
1736
1737	Note:
1738
1739		In the current implementation, the local variables
1740		space and global environment variables space are
1741		separated. Local variables are those you define by
1742		simply typing `name=value'. To access a local
1743		variable later on, you have write `$name' or
1744		`${name}'; to execute the contents of a variable
1745		directly type `$name' at the command prompt.
1746
1747		Global environment variables are those you use
1748		setenv/printenv to work with. To run a command stored
1749		in such a variable, you need to use the run command,
1750		and you must not use the '$' sign to access them.
1751
1752		To store commands and special characters in a
1753		variable, please use double quotation marks
1754		surrounding the whole text of the variable, instead
1755		of the backslashes before semicolons and special
1756		symbols.
1757
1758- Commandline Editing and History:
1759		CONFIG_CMDLINE_EDITING
1760
1761		Enable editing and History functions for interactive
1762		commandline input operations
1763
1764- Default Environment:
1765		CONFIG_EXTRA_ENV_SETTINGS
1766
1767		Define this to contain any number of null terminated
1768		strings (variable = value pairs) that will be part of
1769		the default environment compiled into the boot image.
1770
1771		For example, place something like this in your
1772		board's config file:
1773
1774		#define CONFIG_EXTRA_ENV_SETTINGS \
1775			"myvar1=value1\0" \
1776			"myvar2=value2\0"
1777
1778		Warning: This method is based on knowledge about the
1779		internal format how the environment is stored by the
1780		U-Boot code. This is NOT an official, exported
1781		interface! Although it is unlikely that this format
1782		will change soon, there is no guarantee either.
1783		You better know what you are doing here.
1784
1785		Note: overly (ab)use of the default environment is
1786		discouraged. Make sure to check other ways to preset
1787		the environment like the "source" command or the
1788		boot command first.
1789
1790- DataFlash Support:
1791		CONFIG_HAS_DATAFLASH
1792
1793		Defining this option enables DataFlash features and
1794		allows to read/write in Dataflash via the standard
1795		commands cp, md...
1796
1797- SystemACE Support:
1798		CONFIG_SYSTEMACE
1799
1800		Adding this option adds support for Xilinx SystemACE
1801		chips attached via some sort of local bus. The address
1802		of the chip must also be defined in the
1803		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
1804
1805		#define CONFIG_SYSTEMACE
1806		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
1807
1808		When SystemACE support is added, the "ace" device type
1809		becomes available to the fat commands, i.e. fatls.
1810
1811- TFTP Fixed UDP Port:
1812		CONFIG_TFTP_PORT
1813
1814		If this is defined, the environment variable tftpsrcp
1815		is used to supply the TFTP UDP source port value.
1816		If tftpsrcp isn't defined, the normal pseudo-random port
1817		number generator is used.
1818
1819		Also, the environment variable tftpdstp is used to supply
1820		the TFTP UDP destination port value.  If tftpdstp isn't
1821		defined, the normal port 69 is used.
1822
1823		The purpose for tftpsrcp is to allow a TFTP server to
1824		blindly start the TFTP transfer using the pre-configured
1825		target IP address and UDP port. This has the effect of
1826		"punching through" the (Windows XP) firewall, allowing
1827		the remainder of the TFTP transfer to proceed normally.
1828		A better solution is to properly configure the firewall,
1829		but sometimes that is not allowed.
1830
1831- Show boot progress:
1832		CONFIG_SHOW_BOOT_PROGRESS
1833
1834		Defining this option allows to add some board-
1835		specific code (calling a user-provided function
1836		"show_boot_progress(int)") that enables you to show
1837		the system's boot progress on some display (for
1838		example, some LED's) on your board. At the moment,
1839		the following checkpoints are implemented:
1840
1841- Automatic software updates via TFTP server
1842		CONFIG_UPDATE_TFTP
1843		CONFIG_UPDATE_TFTP_CNT_MAX
1844		CONFIG_UPDATE_TFTP_MSEC_MAX
1845
1846		These options enable and control the auto-update feature;
1847		for a more detailed description refer to doc/README.update.
1848
1849- MTD Support (mtdparts command, UBI support)
1850		CONFIG_MTD_DEVICE
1851
1852		Adds the MTD device infrastructure from the Linux kernel.
1853		Needed for mtdparts command support.
1854
1855		CONFIG_MTD_PARTITIONS
1856
1857		Adds the MTD partitioning infrastructure from the Linux
1858		kernel. Needed for UBI support.
1859
1860Legacy uImage format:
1861
1862  Arg	Where			When
1863    1	common/cmd_bootm.c	before attempting to boot an image
1864   -1	common/cmd_bootm.c	Image header has bad	 magic number
1865    2	common/cmd_bootm.c	Image header has correct magic number
1866   -2	common/cmd_bootm.c	Image header has bad	 checksum
1867    3	common/cmd_bootm.c	Image header has correct checksum
1868   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1869    4	common/cmd_bootm.c	Image data   has correct checksum
1870   -4	common/cmd_bootm.c	Image is for unsupported architecture
1871    5	common/cmd_bootm.c	Architecture check OK
1872   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1873    6	common/cmd_bootm.c	Image Type check OK
1874   -6	common/cmd_bootm.c	gunzip uncompression error
1875   -7	common/cmd_bootm.c	Unimplemented compression type
1876    7	common/cmd_bootm.c	Uncompression OK
1877    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1878   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1879
1880    9	common/image.c		Start initial ramdisk verification
1881  -10	common/image.c		Ramdisk header has bad	   magic number
1882  -11	common/image.c		Ramdisk header has bad	   checksum
1883   10	common/image.c		Ramdisk header is OK
1884  -12	common/image.c		Ramdisk data   has bad	   checksum
1885   11	common/image.c		Ramdisk data   has correct checksum
1886   12	common/image.c		Ramdisk verification complete, start loading
1887  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
1888   13	common/image.c		Start multifile image verification
1889   14	common/image.c		No initial ramdisk, no multifile, continue.
1890
1891   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1892
1893  -30	lib_ppc/board.c		Fatal error, hang the system
1894  -31	post/post.c		POST test failed, detected by post_output_backlog()
1895  -32	post/post.c		POST test failed, detected by post_run_single()
1896
1897   34	common/cmd_doc.c	before loading a Image from a DOC device
1898  -35	common/cmd_doc.c	Bad usage of "doc" command
1899   35	common/cmd_doc.c	correct usage of "doc" command
1900  -36	common/cmd_doc.c	No boot device
1901   36	common/cmd_doc.c	correct boot device
1902  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1903   37	common/cmd_doc.c	correct chip ID found, device available
1904  -38	common/cmd_doc.c	Read Error on boot device
1905   38	common/cmd_doc.c	reading Image header from DOC device OK
1906  -39	common/cmd_doc.c	Image header has bad magic number
1907   39	common/cmd_doc.c	Image header has correct magic number
1908  -40	common/cmd_doc.c	Error reading Image from DOC device
1909   40	common/cmd_doc.c	Image header has correct magic number
1910   41	common/cmd_ide.c	before loading a Image from a IDE device
1911  -42	common/cmd_ide.c	Bad usage of "ide" command
1912   42	common/cmd_ide.c	correct usage of "ide" command
1913  -43	common/cmd_ide.c	No boot device
1914   43	common/cmd_ide.c	boot device found
1915  -44	common/cmd_ide.c	Device not available
1916   44	common/cmd_ide.c	Device available
1917  -45	common/cmd_ide.c	wrong partition selected
1918   45	common/cmd_ide.c	partition selected
1919  -46	common/cmd_ide.c	Unknown partition table
1920   46	common/cmd_ide.c	valid partition table found
1921  -47	common/cmd_ide.c	Invalid partition type
1922   47	common/cmd_ide.c	correct partition type
1923  -48	common/cmd_ide.c	Error reading Image Header on boot device
1924   48	common/cmd_ide.c	reading Image Header from IDE device OK
1925  -49	common/cmd_ide.c	Image header has bad magic number
1926   49	common/cmd_ide.c	Image header has correct magic number
1927  -50	common/cmd_ide.c	Image header has bad	 checksum
1928   50	common/cmd_ide.c	Image header has correct checksum
1929  -51	common/cmd_ide.c	Error reading Image from IDE device
1930   51	common/cmd_ide.c	reading Image from IDE device OK
1931   52	common/cmd_nand.c	before loading a Image from a NAND device
1932  -53	common/cmd_nand.c	Bad usage of "nand" command
1933   53	common/cmd_nand.c	correct usage of "nand" command
1934  -54	common/cmd_nand.c	No boot device
1935   54	common/cmd_nand.c	boot device found
1936  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1937   55	common/cmd_nand.c	correct chip ID found, device available
1938  -56	common/cmd_nand.c	Error reading Image Header on boot device
1939   56	common/cmd_nand.c	reading Image Header from NAND device OK
1940  -57	common/cmd_nand.c	Image header has bad magic number
1941   57	common/cmd_nand.c	Image header has correct magic number
1942  -58	common/cmd_nand.c	Error reading Image from NAND device
1943   58	common/cmd_nand.c	reading Image from NAND device OK
1944
1945  -60	common/env_common.c	Environment has a bad CRC, using default
1946
1947   64	net/eth.c		starting with Ethernet configuration.
1948  -64	net/eth.c		no Ethernet found.
1949   65	net/eth.c		Ethernet found.
1950
1951  -80	common/cmd_net.c	usage wrong
1952   80	common/cmd_net.c	before calling NetLoop()
1953  -81	common/cmd_net.c	some error in NetLoop() occurred
1954   81	common/cmd_net.c	NetLoop() back without error
1955  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1956   82	common/cmd_net.c	trying automatic boot
1957   83	common/cmd_net.c	running "source" command
1958  -83	common/cmd_net.c	some error in automatic boot or "source" command
1959   84	common/cmd_net.c	end without errors
1960
1961FIT uImage format:
1962
1963  Arg	Where			When
1964  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1965 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1966  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1967 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
1968  102	common/cmd_bootm.c	Kernel unit name specified
1969 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
1970  103	common/cmd_bootm.c	Found configuration node
1971  104	common/cmd_bootm.c	Got kernel subimage node offset
1972 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
1973  105	common/cmd_bootm.c	Kernel subimage hash verification OK
1974 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
1975  106	common/cmd_bootm.c	Architecture check OK
1976 -106	common/cmd_bootm.c	Kernel subimage has wrong type
1977  107	common/cmd_bootm.c	Kernel subimage type OK
1978 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
1979  108	common/cmd_bootm.c	Got kernel subimage data/size
1980 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
1981 -109	common/cmd_bootm.c	Can't get kernel subimage type
1982 -110	common/cmd_bootm.c	Can't get kernel subimage comp
1983 -111	common/cmd_bootm.c	Can't get kernel subimage os
1984 -112	common/cmd_bootm.c	Can't get kernel subimage load address
1985 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
1986
1987  120	common/image.c		Start initial ramdisk verification
1988 -120	common/image.c		Ramdisk FIT image has incorrect format
1989  121	common/image.c		Ramdisk FIT image has correct format
1990  122	common/image.c		No ramdisk subimage unit name, using configuration
1991 -122	common/image.c		Can't get configuration for ramdisk subimage
1992  123	common/image.c		Ramdisk unit name specified
1993 -124	common/image.c		Can't get ramdisk subimage node offset
1994  125	common/image.c		Got ramdisk subimage node offset
1995 -125	common/image.c		Ramdisk subimage hash verification failed
1996  126	common/image.c		Ramdisk subimage hash verification OK
1997 -126	common/image.c		Ramdisk subimage for unsupported architecture
1998  127	common/image.c		Architecture check OK
1999 -127	common/image.c		Can't get ramdisk subimage data/size
2000  128	common/image.c		Got ramdisk subimage data/size
2001  129	common/image.c		Can't get ramdisk load address
2002 -129	common/image.c		Got ramdisk load address
2003
2004 -130	common/cmd_doc.c	Incorrect FIT image format
2005  131	common/cmd_doc.c	FIT image format OK
2006
2007 -140	common/cmd_ide.c	Incorrect FIT image format
2008  141	common/cmd_ide.c	FIT image format OK
2009
2010 -150	common/cmd_nand.c	Incorrect FIT image format
2011  151	common/cmd_nand.c	FIT image format OK
2012
2013
2014Modem Support:
2015--------------
2016
2017[so far only for SMDK2400 and TRAB boards]
2018
2019- Modem support enable:
2020		CONFIG_MODEM_SUPPORT
2021
2022- RTS/CTS Flow control enable:
2023		CONFIG_HWFLOW
2024
2025- Modem debug support:
2026		CONFIG_MODEM_SUPPORT_DEBUG
2027
2028		Enables debugging stuff (char screen[1024], dbg())
2029		for modem support. Useful only with BDI2000.
2030
2031- Interrupt support (PPC):
2032
2033		There are common interrupt_init() and timer_interrupt()
2034		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2035		for CPU specific initialization. interrupt_init_cpu()
2036		should set decrementer_count to appropriate value. If
2037		CPU resets decrementer automatically after interrupt
2038		(ppc4xx) it should set decrementer_count to zero.
2039		timer_interrupt() calls timer_interrupt_cpu() for CPU
2040		specific handling. If board has watchdog / status_led
2041		/ other_activity_monitor it works automatically from
2042		general timer_interrupt().
2043
2044- General:
2045
2046		In the target system modem support is enabled when a
2047		specific key (key combination) is pressed during
2048		power-on. Otherwise U-Boot will boot normally
2049		(autoboot). The key_pressed() function is called from
2050		board_init(). Currently key_pressed() is a dummy
2051		function, returning 1 and thus enabling modem
2052		initialization.
2053
2054		If there are no modem init strings in the
2055		environment, U-Boot proceed to autoboot; the
2056		previous output (banner, info printfs) will be
2057		suppressed, though.
2058
2059		See also: doc/README.Modem
2060
2061
2062Configuration Settings:
2063-----------------------
2064
2065- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2066		undefine this when you're short of memory.
2067
2068- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2069		width of the commands listed in the 'help' command output.
2070
2071- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2072		prompt for user input.
2073
2074- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2075
2076- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2077
2078- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2079
2080- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2081		the application (usually a Linux kernel) when it is
2082		booted
2083
2084- CONFIG_SYS_BAUDRATE_TABLE:
2085		List of legal baudrate settings for this board.
2086
2087- CONFIG_SYS_CONSOLE_INFO_QUIET
2088		Suppress display of console information at boot.
2089
2090- CONFIG_SYS_CONSOLE_IS_IN_ENV
2091		If the board specific function
2092			extern int overwrite_console (void);
2093		returns 1, the stdin, stderr and stdout are switched to the
2094		serial port, else the settings in the environment are used.
2095
2096- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2097		Enable the call to overwrite_console().
2098
2099- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2100		Enable overwrite of previous console environment settings.
2101
2102- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2103		Begin and End addresses of the area used by the
2104		simple memory test.
2105
2106- CONFIG_SYS_ALT_MEMTEST:
2107		Enable an alternate, more extensive memory test.
2108
2109- CONFIG_SYS_MEMTEST_SCRATCH:
2110		Scratch address used by the alternate memory test
2111		You only need to set this if address zero isn't writeable
2112
2113- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2114		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2115		this specified memory area will get subtracted from the top
2116		(end) of RAM and won't get "touched" at all by U-Boot. By
2117		fixing up gd->ram_size the Linux kernel should gets passed
2118		the now "corrected" memory size and won't touch it either.
2119		This should work for arch/ppc and arch/powerpc. Only Linux
2120		board ports in arch/powerpc with bootwrapper support that
2121		recalculate the memory size from the SDRAM controller setup
2122		will have to get fixed in Linux additionally.
2123
2124		This option can be used as a workaround for the 440EPx/GRx
2125		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2126		be touched.
2127
2128		WARNING: Please make sure that this value is a multiple of
2129		the Linux page size (normally 4k). If this is not the case,
2130		then the end address of the Linux memory will be located at a
2131		non page size aligned address and this could cause major
2132		problems.
2133
2134- CONFIG_SYS_TFTP_LOADADDR:
2135		Default load address for network file downloads
2136
2137- CONFIG_SYS_LOADS_BAUD_CHANGE:
2138		Enable temporary baudrate change while serial download
2139
2140- CONFIG_SYS_SDRAM_BASE:
2141		Physical start address of SDRAM. _Must_ be 0 here.
2142
2143- CONFIG_SYS_MBIO_BASE:
2144		Physical start address of Motherboard I/O (if using a
2145		Cogent motherboard)
2146
2147- CONFIG_SYS_FLASH_BASE:
2148		Physical start address of Flash memory.
2149
2150- CONFIG_SYS_MONITOR_BASE:
2151		Physical start address of boot monitor code (set by
2152		make config files to be same as the text base address
2153		(TEXT_BASE) used when linking) - same as
2154		CONFIG_SYS_FLASH_BASE when booting from flash.
2155
2156- CONFIG_SYS_MONITOR_LEN:
2157		Size of memory reserved for monitor code, used to
2158		determine _at_compile_time_ (!) if the environment is
2159		embedded within the U-Boot image, or in a separate
2160		flash sector.
2161
2162- CONFIG_SYS_MALLOC_LEN:
2163		Size of DRAM reserved for malloc() use.
2164
2165- CONFIG_SYS_BOOTM_LEN:
2166		Normally compressed uImages are limited to an
2167		uncompressed size of 8 MBytes. If this is not enough,
2168		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2169		to adjust this setting to your needs.
2170
2171- CONFIG_SYS_BOOTMAPSZ:
2172		Maximum size of memory mapped by the startup code of
2173		the Linux kernel; all data that must be processed by
2174		the Linux kernel (bd_info, boot arguments, FDT blob if
2175		used) must be put below this limit, unless "bootm_low"
2176		enviroment variable is defined and non-zero. In such case
2177		all data for the Linux kernel must be between "bootm_low"
2178		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
2179
2180- CONFIG_SYS_MAX_FLASH_BANKS:
2181		Max number of Flash memory banks
2182
2183- CONFIG_SYS_MAX_FLASH_SECT:
2184		Max number of sectors on a Flash chip
2185
2186- CONFIG_SYS_FLASH_ERASE_TOUT:
2187		Timeout for Flash erase operations (in ms)
2188
2189- CONFIG_SYS_FLASH_WRITE_TOUT:
2190		Timeout for Flash write operations (in ms)
2191
2192- CONFIG_SYS_FLASH_LOCK_TOUT
2193		Timeout for Flash set sector lock bit operation (in ms)
2194
2195- CONFIG_SYS_FLASH_UNLOCK_TOUT
2196		Timeout for Flash clear lock bits operation (in ms)
2197
2198- CONFIG_SYS_FLASH_PROTECTION
2199		If defined, hardware flash sectors protection is used
2200		instead of U-Boot software protection.
2201
2202- CONFIG_SYS_DIRECT_FLASH_TFTP:
2203
2204		Enable TFTP transfers directly to flash memory;
2205		without this option such a download has to be
2206		performed in two steps: (1) download to RAM, and (2)
2207		copy from RAM to flash.
2208
2209		The two-step approach is usually more reliable, since
2210		you can check if the download worked before you erase
2211		the flash, but in some situations (when system RAM is
2212		too limited to allow for a temporary copy of the
2213		downloaded image) this option may be very useful.
2214
2215- CONFIG_SYS_FLASH_CFI:
2216		Define if the flash driver uses extra elements in the
2217		common flash structure for storing flash geometry.
2218
2219- CONFIG_FLASH_CFI_DRIVER
2220		This option also enables the building of the cfi_flash driver
2221		in the drivers directory
2222
2223- CONFIG_FLASH_CFI_MTD
2224		This option enables the building of the cfi_mtd driver
2225		in the drivers directory. The driver exports CFI flash
2226		to the MTD layer.
2227
2228- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2229		Use buffered writes to flash.
2230
2231- CONFIG_FLASH_SPANSION_S29WS_N
2232		s29ws-n MirrorBit flash has non-standard addresses for buffered
2233		write commands.
2234
2235- CONFIG_SYS_FLASH_QUIET_TEST
2236		If this option is defined, the common CFI flash doesn't
2237		print it's warning upon not recognized FLASH banks. This
2238		is useful, if some of the configured banks are only
2239		optionally available.
2240
2241- CONFIG_FLASH_SHOW_PROGRESS
2242		If defined (must be an integer), print out countdown
2243		digits and dots.  Recommended value: 45 (9..1) for 80
2244		column displays, 15 (3..1) for 40 column displays.
2245
2246- CONFIG_SYS_RX_ETH_BUFFER:
2247		Defines the number of Ethernet receive buffers. On some
2248		Ethernet controllers it is recommended to set this value
2249		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2250		buffers can be full shortly after enabling the interface
2251		on high Ethernet traffic.
2252		Defaults to 4 if not defined.
2253
2254The following definitions that deal with the placement and management
2255of environment data (variable area); in general, we support the
2256following configurations:
2257
2258- CONFIG_ENV_IS_IN_FLASH:
2259
2260	Define this if the environment is in flash memory.
2261
2262	a) The environment occupies one whole flash sector, which is
2263	   "embedded" in the text segment with the U-Boot code. This
2264	   happens usually with "bottom boot sector" or "top boot
2265	   sector" type flash chips, which have several smaller
2266	   sectors at the start or the end. For instance, such a
2267	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2268	   such a case you would place the environment in one of the
2269	   4 kB sectors - with U-Boot code before and after it. With
2270	   "top boot sector" type flash chips, you would put the
2271	   environment in one of the last sectors, leaving a gap
2272	   between U-Boot and the environment.
2273
2274	- CONFIG_ENV_OFFSET:
2275
2276	   Offset of environment data (variable area) to the
2277	   beginning of flash memory; for instance, with bottom boot
2278	   type flash chips the second sector can be used: the offset
2279	   for this sector is given here.
2280
2281	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2282
2283	- CONFIG_ENV_ADDR:
2284
2285	   This is just another way to specify the start address of
2286	   the flash sector containing the environment (instead of
2287	   CONFIG_ENV_OFFSET).
2288
2289	- CONFIG_ENV_SECT_SIZE:
2290
2291	   Size of the sector containing the environment.
2292
2293
2294	b) Sometimes flash chips have few, equal sized, BIG sectors.
2295	   In such a case you don't want to spend a whole sector for
2296	   the environment.
2297
2298	- CONFIG_ENV_SIZE:
2299
2300	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2301	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2302	   of this flash sector for the environment. This saves
2303	   memory for the RAM copy of the environment.
2304
2305	   It may also save flash memory if you decide to use this
2306	   when your environment is "embedded" within U-Boot code,
2307	   since then the remainder of the flash sector could be used
2308	   for U-Boot code. It should be pointed out that this is
2309	   STRONGLY DISCOURAGED from a robustness point of view:
2310	   updating the environment in flash makes it always
2311	   necessary to erase the WHOLE sector. If something goes
2312	   wrong before the contents has been restored from a copy in
2313	   RAM, your target system will be dead.
2314
2315	- CONFIG_ENV_ADDR_REDUND
2316	  CONFIG_ENV_SIZE_REDUND
2317
2318	   These settings describe a second storage area used to hold
2319	   a redundant copy of the environment data, so that there is
2320	   a valid backup copy in case there is a power failure during
2321	   a "saveenv" operation.
2322
2323BE CAREFUL! Any changes to the flash layout, and some changes to the
2324source code will make it necessary to adapt <board>/u-boot.lds*
2325accordingly!
2326
2327
2328- CONFIG_ENV_IS_IN_NVRAM:
2329
2330	Define this if you have some non-volatile memory device
2331	(NVRAM, battery buffered SRAM) which you want to use for the
2332	environment.
2333
2334	- CONFIG_ENV_ADDR:
2335	- CONFIG_ENV_SIZE:
2336
2337	  These two #defines are used to determine the memory area you
2338	  want to use for environment. It is assumed that this memory
2339	  can just be read and written to, without any special
2340	  provision.
2341
2342BE CAREFUL! The first access to the environment happens quite early
2343in U-Boot initalization (when we try to get the setting of for the
2344console baudrate). You *MUST* have mapped your NVRAM area then, or
2345U-Boot will hang.
2346
2347Please note that even with NVRAM we still use a copy of the
2348environment in RAM: we could work on NVRAM directly, but we want to
2349keep settings there always unmodified except somebody uses "saveenv"
2350to save the current settings.
2351
2352
2353- CONFIG_ENV_IS_IN_EEPROM:
2354
2355	Use this if you have an EEPROM or similar serial access
2356	device and a driver for it.
2357
2358	- CONFIG_ENV_OFFSET:
2359	- CONFIG_ENV_SIZE:
2360
2361	  These two #defines specify the offset and size of the
2362	  environment area within the total memory of your EEPROM.
2363
2364	- CONFIG_SYS_I2C_EEPROM_ADDR:
2365	  If defined, specified the chip address of the EEPROM device.
2366	  The default address is zero.
2367
2368	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2369	  If defined, the number of bits used to address bytes in a
2370	  single page in the EEPROM device.  A 64 byte page, for example
2371	  would require six bits.
2372
2373	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2374	  If defined, the number of milliseconds to delay between
2375	  page writes.	The default is zero milliseconds.
2376
2377	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2378	  The length in bytes of the EEPROM memory array address.  Note
2379	  that this is NOT the chip address length!
2380
2381	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2382	  EEPROM chips that implement "address overflow" are ones
2383	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2384	  address and the extra bits end up in the "chip address" bit
2385	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2386	  byte chips.
2387
2388	  Note that we consider the length of the address field to
2389	  still be one byte because the extra address bits are hidden
2390	  in the chip address.
2391
2392	- CONFIG_SYS_EEPROM_SIZE:
2393	  The size in bytes of the EEPROM device.
2394
2395
2396- CONFIG_ENV_IS_IN_DATAFLASH:
2397
2398	Define this if you have a DataFlash memory device which you
2399	want to use for the environment.
2400
2401	- CONFIG_ENV_OFFSET:
2402	- CONFIG_ENV_ADDR:
2403	- CONFIG_ENV_SIZE:
2404
2405	  These three #defines specify the offset and size of the
2406	  environment area within the total memory of your DataFlash placed
2407	  at the specified address.
2408
2409- CONFIG_ENV_IS_IN_NAND:
2410
2411	Define this if you have a NAND device which you want to use
2412	for the environment.
2413
2414	- CONFIG_ENV_OFFSET:
2415	- CONFIG_ENV_SIZE:
2416
2417	  These two #defines specify the offset and size of the environment
2418	  area within the first NAND device.
2419
2420	- CONFIG_ENV_OFFSET_REDUND
2421
2422	  This setting describes a second storage area of CONFIG_ENV_SIZE
2423	  size used to hold a redundant copy of the environment data,
2424	  so that there is a valid backup copy in case there is a
2425	  power failure during a "saveenv" operation.
2426
2427	Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2428	to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2429	the NAND devices block size.
2430
2431- CONFIG_NAND_ENV_DST
2432
2433	Defines address in RAM to which the nand_spl code should copy the
2434	environment. If redundant environment is used, it will be copied to
2435	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2436
2437- CONFIG_SYS_SPI_INIT_OFFSET
2438
2439	Defines offset to the initial SPI buffer area in DPRAM. The
2440	area is used at an early stage (ROM part) if the environment
2441	is configured to reside in the SPI EEPROM: We need a 520 byte
2442	scratch DPRAM area. It is used between the two initialization
2443	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2444	to be a good choice since it makes it far enough from the
2445	start of the data area as well as from the stack pointer.
2446
2447Please note that the environment is read-only until the monitor
2448has been relocated to RAM and a RAM copy of the environment has been
2449created; also, when using EEPROM you will have to use getenv_r()
2450until then to read environment variables.
2451
2452The environment is protected by a CRC32 checksum. Before the monitor
2453is relocated into RAM, as a result of a bad CRC you will be working
2454with the compiled-in default environment - *silently*!!! [This is
2455necessary, because the first environment variable we need is the
2456"baudrate" setting for the console - if we have a bad CRC, we don't
2457have any device yet where we could complain.]
2458
2459Note: once the monitor has been relocated, then it will complain if
2460the default environment is used; a new CRC is computed as soon as you
2461use the "saveenv" command to store a valid environment.
2462
2463- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2464		Echo the inverted Ethernet link state to the fault LED.
2465
2466		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2467		      also needs to be defined.
2468
2469- CONFIG_SYS_FAULT_MII_ADDR:
2470		MII address of the PHY to check for the Ethernet link state.
2471
2472- CONFIG_SYS_64BIT_VSPRINTF:
2473		Makes vsprintf (and all *printf functions) support printing
2474		of 64bit values by using the L quantifier
2475
2476- CONFIG_SYS_64BIT_STRTOUL:
2477		Adds simple_strtoull that returns a 64bit value
2478
2479- CONFIG_NS16550_MIN_FUNCTIONS:
2480		Define this if you desire to only have use of the NS16550_init
2481		and NS16550_putc functions for the serial driver located at
2482		drivers/serial/ns16550.c.  This option is useful for saving
2483		space for already greatly restricted images, including but not
2484		limited to NAND_SPL configurations.
2485
2486Low Level (hardware related) configuration options:
2487---------------------------------------------------
2488
2489- CONFIG_SYS_CACHELINE_SIZE:
2490		Cache Line Size of the CPU.
2491
2492- CONFIG_SYS_DEFAULT_IMMR:
2493		Default address of the IMMR after system reset.
2494
2495		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2496		and RPXsuper) to be able to adjust the position of
2497		the IMMR register after a reset.
2498
2499- Floppy Disk Support:
2500		CONFIG_SYS_FDC_DRIVE_NUMBER
2501
2502		the default drive number (default value 0)
2503
2504		CONFIG_SYS_ISA_IO_STRIDE
2505
2506		defines the spacing between FDC chipset registers
2507		(default value 1)
2508
2509		CONFIG_SYS_ISA_IO_OFFSET
2510
2511		defines the offset of register from address. It
2512		depends on which part of the data bus is connected to
2513		the FDC chipset. (default value 0)
2514
2515		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2516		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2517		default value.
2518
2519		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2520		fdc_hw_init() is called at the beginning of the FDC
2521		setup. fdc_hw_init() must be provided by the board
2522		source code. It is used to make hardware dependant
2523		initializations.
2524
2525- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
2526		DO NOT CHANGE unless you know exactly what you're
2527		doing! (11-4) [MPC8xx/82xx systems only]
2528
2529- CONFIG_SYS_INIT_RAM_ADDR:
2530
2531		Start address of memory area that can be used for
2532		initial data and stack; please note that this must be
2533		writable memory that is working WITHOUT special
2534		initialization, i. e. you CANNOT use normal RAM which
2535		will become available only after programming the
2536		memory controller and running certain initialization
2537		sequences.
2538
2539		U-Boot uses the following memory types:
2540		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2541		- MPC824X: data cache
2542		- PPC4xx:  data cache
2543
2544- CONFIG_SYS_GBL_DATA_OFFSET:
2545
2546		Offset of the initial data structure in the memory
2547		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2548		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2549		data is located at the end of the available space
2550		(sometimes written as (CONFIG_SYS_INIT_RAM_END -
2551		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
2552		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2553		CONFIG_SYS_GBL_DATA_OFFSET) downward.
2554
2555	Note:
2556		On the MPC824X (or other systems that use the data
2557		cache for initial memory) the address chosen for
2558		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2559		point to an otherwise UNUSED address space between
2560		the top of RAM and the start of the PCI space.
2561
2562- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
2563
2564- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
2565
2566- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
2567
2568- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
2569
2570- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2571
2572- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
2573
2574- CONFIG_SYS_OR_TIMING_SDRAM:
2575		SDRAM timing
2576
2577- CONFIG_SYS_MAMR_PTA:
2578		periodic timer for refresh
2579
2580- CONFIG_SYS_DER:	Debug Event Register (37-47)
2581
2582- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2583  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2584  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2585  CONFIG_SYS_BR1_PRELIM:
2586		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2587
2588- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2589  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2590  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2591		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2592
2593- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
2594  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
2595		Machine Mode Register and Memory Periodic Timer
2596		Prescaler definitions (SDRAM timing)
2597
2598- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
2599		enable I2C microcode relocation patch (MPC8xx);
2600		define relocation offset in DPRAM [DSP2]
2601
2602- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
2603		enable SMC microcode relocation patch (MPC8xx);
2604		define relocation offset in DPRAM [SMC1]
2605
2606- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
2607		enable SPI microcode relocation patch (MPC8xx);
2608		define relocation offset in DPRAM [SCC4]
2609
2610- CONFIG_SYS_USE_OSCCLK:
2611		Use OSCM clock mode on MBX8xx board. Be careful,
2612		wrong setting might damage your board. Read
2613		doc/README.MBX before setting this variable!
2614
2615- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2616		Offset of the bootmode word in DPRAM used by post
2617		(Power On Self Tests). This definition overrides
2618		#define'd default value in commproc.h resp.
2619		cpm_8260.h.
2620
2621- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
2622  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
2623  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
2624  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
2625  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2626  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
2627  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
2628  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
2629		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2630
2631- CONFIG_PCI_DISABLE_PCIE:
2632		Disable PCI-Express on systems where it is supported but not
2633		required.
2634
2635- CONFIG_SPD_EEPROM
2636		Get DDR timing information from an I2C EEPROM. Common
2637		with pluggable memory modules such as SODIMMs
2638
2639  SPD_EEPROM_ADDRESS
2640		I2C address of the SPD EEPROM
2641
2642- CONFIG_SYS_SPD_BUS_NUM
2643		If SPD EEPROM is on an I2C bus other than the first
2644		one, specify here. Note that the value must resolve
2645		to something your driver can deal with.
2646
2647- CONFIG_SYS_83XX_DDR_USES_CS0
2648		Only for 83xx systems. If specified, then DDR should
2649		be configured using CS0 and CS1 instead of CS2 and CS3.
2650
2651- CONFIG_ETHER_ON_FEC[12]
2652		Define to enable FEC[12] on a 8xx series processor.
2653
2654- CONFIG_FEC[12]_PHY
2655		Define to the hardcoded PHY address which corresponds
2656		to the given FEC; i. e.
2657			#define CONFIG_FEC1_PHY 4
2658		means that the PHY with address 4 is connected to FEC1
2659
2660		When set to -1, means to probe for first available.
2661
2662- CONFIG_FEC[12]_PHY_NORXERR
2663		The PHY does not have a RXERR line (RMII only).
2664		(so program the FEC to ignore it).
2665
2666- CONFIG_RMII
2667		Enable RMII mode for all FECs.
2668		Note that this is a global option, we can't
2669		have one FEC in standard MII mode and another in RMII mode.
2670
2671- CONFIG_CRC32_VERIFY
2672		Add a verify option to the crc32 command.
2673		The syntax is:
2674
2675		=> crc32 -v <address> <count> <crc32>
2676
2677		Where address/count indicate a memory area
2678		and crc32 is the correct crc32 which the
2679		area should have.
2680
2681- CONFIG_LOOPW
2682		Add the "loopw" memory command. This only takes effect if
2683		the memory commands are activated globally (CONFIG_CMD_MEM).
2684
2685- CONFIG_MX_CYCLIC
2686		Add the "mdc" and "mwc" memory commands. These are cyclic
2687		"md/mw" commands.
2688		Examples:
2689
2690		=> mdc.b 10 4 500
2691		This command will print 4 bytes (10,11,12,13) each 500 ms.
2692
2693		=> mwc.l 100 12345678 10
2694		This command will write 12345678 to address 100 all 10 ms.
2695
2696		This only takes effect if the memory commands are activated
2697		globally (CONFIG_CMD_MEM).
2698
2699- CONFIG_SKIP_LOWLEVEL_INIT
2700- CONFIG_SKIP_RELOCATE_UBOOT
2701
2702		[ARM only] If these variables are defined, then
2703		certain low level initializations (like setting up
2704		the memory controller) are omitted and/or U-Boot does
2705		not relocate itself into RAM.
2706		Normally these variables MUST NOT be defined. The
2707		only exception is when U-Boot is loaded (to RAM) by
2708		some other boot loader or by a debugger which
2709		performs these initializations itself.
2710
2711- CONFIG_PRELOADER
2712
2713		Modifies the behaviour of start.S when compiling a loader
2714		that is executed before the actual U-Boot. E.g. when
2715		compiling a NAND SPL.
2716
2717Building the Software:
2718======================
2719
2720Building U-Boot has been tested in several native build environments
2721and in many different cross environments. Of course we cannot support
2722all possibly existing versions of cross development tools in all
2723(potentially obsolete) versions. In case of tool chain problems we
2724recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2725which is extensively used to build and test U-Boot.
2726
2727If you are not using a native environment, it is assumed that you
2728have GNU cross compiling tools available in your path. In this case,
2729you must set the environment variable CROSS_COMPILE in your shell.
2730Note that no changes to the Makefile or any other source files are
2731necessary. For example using the ELDK on a 4xx CPU, please enter:
2732
2733	$ CROSS_COMPILE=ppc_4xx-
2734	$ export CROSS_COMPILE
2735
2736Note: If you wish to generate Windows versions of the utilities in
2737      the tools directory you can use the MinGW toolchain
2738      (http://www.mingw.org).  Set your HOST tools to the MinGW
2739      toolchain and execute 'make tools'.  For example:
2740
2741       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
2742
2743      Binaries such as tools/mkimage.exe will be created which can
2744      be executed on computers running Windows.
2745
2746U-Boot is intended to be simple to build. After installing the
2747sources you must configure U-Boot for one specific board type. This
2748is done by typing:
2749
2750	make NAME_config
2751
2752where "NAME_config" is the name of one of the existing configu-
2753rations; see the main Makefile for supported names.
2754
2755Note: for some board special configuration names may exist; check if
2756      additional information is available from the board vendor; for
2757      instance, the TQM823L systems are available without (standard)
2758      or with LCD support. You can select such additional "features"
2759      when choosing the configuration, i. e.
2760
2761      make TQM823L_config
2762	- will configure for a plain TQM823L, i. e. no LCD support
2763
2764      make TQM823L_LCD_config
2765	- will configure for a TQM823L with U-Boot console on LCD
2766
2767      etc.
2768
2769
2770Finally, type "make all", and you should get some working U-Boot
2771images ready for download to / installation on your system:
2772
2773- "u-boot.bin" is a raw binary image
2774- "u-boot" is an image in ELF binary format
2775- "u-boot.srec" is in Motorola S-Record format
2776
2777By default the build is performed locally and the objects are saved
2778in the source directory. One of the two methods can be used to change
2779this behavior and build U-Boot to some external directory:
2780
27811. Add O= to the make command line invocations:
2782
2783	make O=/tmp/build distclean
2784	make O=/tmp/build NAME_config
2785	make O=/tmp/build all
2786
27872. Set environment variable BUILD_DIR to point to the desired location:
2788
2789	export BUILD_DIR=/tmp/build
2790	make distclean
2791	make NAME_config
2792	make all
2793
2794Note that the command line "O=" setting overrides the BUILD_DIR environment
2795variable.
2796
2797
2798Please be aware that the Makefiles assume you are using GNU make, so
2799for instance on NetBSD you might need to use "gmake" instead of
2800native "make".
2801
2802
2803If the system board that you have is not listed, then you will need
2804to port U-Boot to your hardware platform. To do this, follow these
2805steps:
2806
28071.  Add a new configuration option for your board to the toplevel
2808    "Makefile" and to the "MAKEALL" script, using the existing
2809    entries as examples. Note that here and at many other places
2810    boards and other names are listed in alphabetical sort order. Please
2811    keep this order.
28122.  Create a new directory to hold your board specific code. Add any
2813    files you need. In your board directory, you will need at least
2814    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
28153.  Create a new configuration file "include/configs/<board>.h" for
2816    your board
28173.  If you're porting U-Boot to a new CPU, then also create a new
2818    directory to hold your CPU specific code. Add any files you need.
28194.  Run "make <board>_config" with your new name.
28205.  Type "make", and you should get a working "u-boot.srec" file
2821    to be installed on your target system.
28226.  Debug and solve any problems that might arise.
2823    [Of course, this last step is much harder than it sounds.]
2824
2825
2826Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2827==============================================================
2828
2829If you have modified U-Boot sources (for instance added a new board
2830or support for new devices, a new CPU, etc.) you are expected to
2831provide feedback to the other developers. The feedback normally takes
2832the form of a "patch", i. e. a context diff against a certain (latest
2833official or latest in the git repository) version of U-Boot sources.
2834
2835But before you submit such a patch, please verify that your modifi-
2836cation did not break existing code. At least make sure that *ALL* of
2837the supported boards compile WITHOUT ANY compiler warnings. To do so,
2838just run the "MAKEALL" script, which will configure and build U-Boot
2839for ALL supported system. Be warned, this will take a while. You can
2840select which (cross) compiler to use by passing a `CROSS_COMPILE'
2841environment variable to the script, i. e. to use the ELDK cross tools
2842you can type
2843
2844	CROSS_COMPILE=ppc_8xx- MAKEALL
2845
2846or to build on a native PowerPC system you can type
2847
2848	CROSS_COMPILE=' ' MAKEALL
2849
2850When using the MAKEALL script, the default behaviour is to build
2851U-Boot in the source directory. This location can be changed by
2852setting the BUILD_DIR environment variable. Also, for each target
2853built, the MAKEALL script saves two log files (<target>.ERR and
2854<target>.MAKEALL) in the <source dir>/LOG directory. This default
2855location can be changed by setting the MAKEALL_LOGDIR environment
2856variable. For example:
2857
2858	export BUILD_DIR=/tmp/build
2859	export MAKEALL_LOGDIR=/tmp/log
2860	CROSS_COMPILE=ppc_8xx- MAKEALL
2861
2862With the above settings build objects are saved in the /tmp/build,
2863log files are saved in the /tmp/log and the source tree remains clean
2864during the whole build process.
2865
2866
2867See also "U-Boot Porting Guide" below.
2868
2869
2870Monitor Commands - Overview:
2871============================
2872
2873go	- start application at address 'addr'
2874run	- run commands in an environment variable
2875bootm	- boot application image from memory
2876bootp	- boot image via network using BootP/TFTP protocol
2877tftpboot- boot image via network using TFTP protocol
2878	       and env variables "ipaddr" and "serverip"
2879	       (and eventually "gatewayip")
2880rarpboot- boot image via network using RARP/TFTP protocol
2881diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2882loads	- load S-Record file over serial line
2883loadb	- load binary file over serial line (kermit mode)
2884md	- memory display
2885mm	- memory modify (auto-incrementing)
2886nm	- memory modify (constant address)
2887mw	- memory write (fill)
2888cp	- memory copy
2889cmp	- memory compare
2890crc32	- checksum calculation
2891i2c	- I2C sub-system
2892sspi	- SPI utility commands
2893base	- print or set address offset
2894printenv- print environment variables
2895setenv	- set environment variables
2896saveenv - save environment variables to persistent storage
2897protect - enable or disable FLASH write protection
2898erase	- erase FLASH memory
2899flinfo	- print FLASH memory information
2900bdinfo	- print Board Info structure
2901iminfo	- print header information for application image
2902coninfo - print console devices and informations
2903ide	- IDE sub-system
2904loop	- infinite loop on address range
2905loopw	- infinite write loop on address range
2906mtest	- simple RAM test
2907icache	- enable or disable instruction cache
2908dcache	- enable or disable data cache
2909reset	- Perform RESET of the CPU
2910echo	- echo args to console
2911version - print monitor version
2912help	- print online help
2913?	- alias for 'help'
2914
2915
2916Monitor Commands - Detailed Description:
2917========================================
2918
2919TODO.
2920
2921For now: just type "help <command>".
2922
2923
2924Environment Variables:
2925======================
2926
2927U-Boot supports user configuration using Environment Variables which
2928can be made persistent by saving to Flash memory.
2929
2930Environment Variables are set using "setenv", printed using
2931"printenv", and saved to Flash using "saveenv". Using "setenv"
2932without a value can be used to delete a variable from the
2933environment. As long as you don't save the environment you are
2934working with an in-memory copy. In case the Flash area containing the
2935environment is erased by accident, a default environment is provided.
2936
2937Some configuration options can be set using Environment Variables:
2938
2939  baudrate	- see CONFIG_BAUDRATE
2940
2941  bootdelay	- see CONFIG_BOOTDELAY
2942
2943  bootcmd	- see CONFIG_BOOTCOMMAND
2944
2945  bootargs	- Boot arguments when booting an RTOS image
2946
2947  bootfile	- Name of the image to load with TFTP
2948
2949  bootm_low	- Memory range available for image processing in the bootm
2950		  command can be restricted. This variable is given as
2951		  a hexadecimal number and defines lowest address allowed
2952		  for use by the bootm command. See also "bootm_size"
2953		  environment variable. Address defined by "bootm_low" is
2954		  also the base of the initial memory mapping for the Linux
2955		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
2956
2957  bootm_size	- Memory range available for image processing in the bootm
2958		  command can be restricted. This variable is given as
2959		  a hexadecimal number and defines the size of the region
2960		  allowed for use by the bootm command. See also "bootm_low"
2961		  environment variable.
2962
2963  updatefile	- Location of the software update file on a TFTP server, used
2964		  by the automatic software update feature. Please refer to
2965		  documentation in doc/README.update for more details.
2966
2967  autoload	- if set to "no" (any string beginning with 'n'),
2968		  "bootp" will just load perform a lookup of the
2969		  configuration from the BOOTP server, but not try to
2970		  load any image using TFTP
2971
2972  autoscript	- if set to "yes" commands like "loadb", "loady",
2973		  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2974		  to automatically run script images (by internally
2975		  calling "source").
2976
2977  autoscript_uname - if script image is in a format (FIT) this
2978		     variable is used to get script subimage unit name.
2979
2980  autostart	- if set to "yes", an image loaded using the "bootp",
2981		  "rarpboot", "tftpboot" or "diskboot" commands will
2982		  be automatically started (by internally calling
2983		  "bootm")
2984
2985		  If set to "no", a standalone image passed to the
2986		  "bootm" command will be copied to the load address
2987		  (and eventually uncompressed), but NOT be started.
2988		  This can be used to load and uncompress arbitrary
2989		  data.
2990
2991  i2cfast	- (PPC405GP|PPC405EP only)
2992		  if set to 'y' configures Linux I2C driver for fast
2993		  mode (400kHZ). This environment variable is used in
2994		  initialization code. So, for changes to be effective
2995		  it must be saved and board must be reset.
2996
2997  initrd_high	- restrict positioning of initrd images:
2998		  If this variable is not set, initrd images will be
2999		  copied to the highest possible address in RAM; this
3000		  is usually what you want since it allows for
3001		  maximum initrd size. If for some reason you want to
3002		  make sure that the initrd image is loaded below the
3003		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3004		  variable to a value of "no" or "off" or "0".
3005		  Alternatively, you can set it to a maximum upper
3006		  address to use (U-Boot will still check that it
3007		  does not overwrite the U-Boot stack and data).
3008
3009		  For instance, when you have a system with 16 MB
3010		  RAM, and want to reserve 4 MB from use by Linux,
3011		  you can do this by adding "mem=12M" to the value of
3012		  the "bootargs" variable. However, now you must make
3013		  sure that the initrd image is placed in the first
3014		  12 MB as well - this can be done with
3015
3016		  setenv initrd_high 00c00000
3017
3018		  If you set initrd_high to 0xFFFFFFFF, this is an
3019		  indication to U-Boot that all addresses are legal
3020		  for the Linux kernel, including addresses in flash
3021		  memory. In this case U-Boot will NOT COPY the
3022		  ramdisk at all. This may be useful to reduce the
3023		  boot time on your system, but requires that this
3024		  feature is supported by your Linux kernel.
3025
3026  ipaddr	- IP address; needed for tftpboot command
3027
3028  loadaddr	- Default load address for commands like "bootp",
3029		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3030
3031  loads_echo	- see CONFIG_LOADS_ECHO
3032
3033  serverip	- TFTP server IP address; needed for tftpboot command
3034
3035  bootretry	- see CONFIG_BOOT_RETRY_TIME
3036
3037  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3038
3039  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3040
3041  ethprime	- When CONFIG_NET_MULTI is enabled controls which
3042		  interface is used first.
3043
3044  ethact	- When CONFIG_NET_MULTI is enabled controls which
3045		  interface is currently active. For example you
3046		  can do the following
3047
3048		  => setenv ethact FEC ETHERNET
3049		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
3050		  => setenv ethact SCC ETHERNET
3051		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
3052
3053  ethrotate	- When set to "no" U-Boot does not go through all
3054		  available network interfaces.
3055		  It just stays at the currently selected interface.
3056
3057   netretry	- When set to "no" each network operation will
3058		  either succeed or fail without retrying.
3059		  When set to "once" the network operation will
3060		  fail when all the available network interfaces
3061		  are tried once without success.
3062		  Useful on scripts which control the retry operation
3063		  themselves.
3064
3065  npe_ucode	- set load address for the NPE microcode
3066
3067  tftpsrcport	- If this is set, the value is used for TFTP's
3068		  UDP source port.
3069
3070  tftpdstport	- If this is set, the value is used for TFTP's UDP
3071		  destination port instead of the Well Know Port 69.
3072
3073   vlan		- When set to a value < 4095 the traffic over
3074		  Ethernet is encapsulated/received over 802.1q
3075		  VLAN tagged frames.
3076
3077The following environment variables may be used and automatically
3078updated by the network boot commands ("bootp" and "rarpboot"),
3079depending the information provided by your boot server:
3080
3081  bootfile	- see above
3082  dnsip		- IP address of your Domain Name Server
3083  dnsip2	- IP address of your secondary Domain Name Server
3084  gatewayip	- IP address of the Gateway (Router) to use
3085  hostname	- Target hostname
3086  ipaddr	- see above
3087  netmask	- Subnet Mask
3088  rootpath	- Pathname of the root filesystem on the NFS server
3089  serverip	- see above
3090
3091
3092There are two special Environment Variables:
3093
3094  serial#	- contains hardware identification information such
3095		  as type string and/or serial number
3096  ethaddr	- Ethernet address
3097
3098These variables can be set only once (usually during manufacturing of
3099the board). U-Boot refuses to delete or overwrite these variables
3100once they have been set once.
3101
3102
3103Further special Environment Variables:
3104
3105  ver		- Contains the U-Boot version string as printed
3106		  with the "version" command. This variable is
3107		  readonly (see CONFIG_VERSION_VARIABLE).
3108
3109
3110Please note that changes to some configuration parameters may take
3111only effect after the next boot (yes, that's just like Windoze :-).
3112
3113
3114Command Line Parsing:
3115=====================
3116
3117There are two different command line parsers available with U-Boot:
3118the old "simple" one, and the much more powerful "hush" shell:
3119
3120Old, simple command line parser:
3121--------------------------------
3122
3123- supports environment variables (through setenv / saveenv commands)
3124- several commands on one line, separated by ';'
3125- variable substitution using "... ${name} ..." syntax
3126- special characters ('$', ';') can be escaped by prefixing with '\',
3127  for example:
3128	setenv bootcmd bootm \${address}
3129- You can also escape text by enclosing in single apostrophes, for example:
3130	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3131
3132Hush shell:
3133-----------
3134
3135- similar to Bourne shell, with control structures like
3136  if...then...else...fi, for...do...done; while...do...done,
3137  until...do...done, ...
3138- supports environment ("global") variables (through setenv / saveenv
3139  commands) and local shell variables (through standard shell syntax
3140  "name=value"); only environment variables can be used with "run"
3141  command
3142
3143General rules:
3144--------------
3145
3146(1) If a command line (or an environment variable executed by a "run"
3147    command) contains several commands separated by semicolon, and
3148    one of these commands fails, then the remaining commands will be
3149    executed anyway.
3150
3151(2) If you execute several variables with one call to run (i. e.
3152    calling run with a list of variables as arguments), any failing
3153    command will cause "run" to terminate, i. e. the remaining
3154    variables are not executed.
3155
3156Note for Redundant Ethernet Interfaces:
3157=======================================
3158
3159Some boards come with redundant Ethernet interfaces; U-Boot supports
3160such configurations and is capable of automatic selection of a
3161"working" interface when needed. MAC assignment works as follows:
3162
3163Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3164MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3165"eth1addr" (=>eth1), "eth2addr", ...
3166
3167If the network interface stores some valid MAC address (for instance
3168in SROM), this is used as default address if there is NO correspon-
3169ding setting in the environment; if the corresponding environment
3170variable is set, this overrides the settings in the card; that means:
3171
3172o If the SROM has a valid MAC address, and there is no address in the
3173  environment, the SROM's address is used.
3174
3175o If there is no valid address in the SROM, and a definition in the
3176  environment exists, then the value from the environment variable is
3177  used.
3178
3179o If both the SROM and the environment contain a MAC address, and
3180  both addresses are the same, this MAC address is used.
3181
3182o If both the SROM and the environment contain a MAC address, and the
3183  addresses differ, the value from the environment is used and a
3184  warning is printed.
3185
3186o If neither SROM nor the environment contain a MAC address, an error
3187  is raised.
3188
3189
3190Image Formats:
3191==============
3192
3193U-Boot is capable of booting (and performing other auxiliary operations on)
3194images in two formats:
3195
3196New uImage format (FIT)
3197-----------------------
3198
3199Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3200to Flattened Device Tree). It allows the use of images with multiple
3201components (several kernels, ramdisks, etc.), with contents protected by
3202SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3203
3204
3205Old uImage format
3206-----------------
3207
3208Old image format is based on binary files which can be basically anything,
3209preceded by a special header; see the definitions in include/image.h for
3210details; basically, the header defines the following image properties:
3211
3212* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3213  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3214  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3215  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3216  INTEGRITY).
3217* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3218  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3219  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3220* Compression Type (uncompressed, gzip, bzip2)
3221* Load Address
3222* Entry Point
3223* Image Name
3224* Image Timestamp
3225
3226The header is marked by a special Magic Number, and both the header
3227and the data portions of the image are secured against corruption by
3228CRC32 checksums.
3229
3230
3231Linux Support:
3232==============
3233
3234Although U-Boot should support any OS or standalone application
3235easily, the main focus has always been on Linux during the design of
3236U-Boot.
3237
3238U-Boot includes many features that so far have been part of some
3239special "boot loader" code within the Linux kernel. Also, any
3240"initrd" images to be used are no longer part of one big Linux image;
3241instead, kernel and "initrd" are separate images. This implementation
3242serves several purposes:
3243
3244- the same features can be used for other OS or standalone
3245  applications (for instance: using compressed images to reduce the
3246  Flash memory footprint)
3247
3248- it becomes much easier to port new Linux kernel versions because
3249  lots of low-level, hardware dependent stuff are done by U-Boot
3250
3251- the same Linux kernel image can now be used with different "initrd"
3252  images; of course this also means that different kernel images can
3253  be run with the same "initrd". This makes testing easier (you don't
3254  have to build a new "zImage.initrd" Linux image when you just
3255  change a file in your "initrd"). Also, a field-upgrade of the
3256  software is easier now.
3257
3258
3259Linux HOWTO:
3260============
3261
3262Porting Linux to U-Boot based systems:
3263---------------------------------------
3264
3265U-Boot cannot save you from doing all the necessary modifications to
3266configure the Linux device drivers for use with your target hardware
3267(no, we don't intend to provide a full virtual machine interface to
3268Linux :-).
3269
3270But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3271
3272Just make sure your machine specific header file (for instance
3273include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3274Information structure as we define in include/asm-<arch>/u-boot.h,
3275and make sure that your definition of IMAP_ADDR uses the same value
3276as your U-Boot configuration in CONFIG_SYS_IMMR.
3277
3278
3279Configuring the Linux kernel:
3280-----------------------------
3281
3282No specific requirements for U-Boot. Make sure you have some root
3283device (initial ramdisk, NFS) for your target system.
3284
3285
3286Building a Linux Image:
3287-----------------------
3288
3289With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3290not used. If you use recent kernel source, a new build target
3291"uImage" will exist which automatically builds an image usable by
3292U-Boot. Most older kernels also have support for a "pImage" target,
3293which was introduced for our predecessor project PPCBoot and uses a
3294100% compatible format.
3295
3296Example:
3297
3298	make TQM850L_config
3299	make oldconfig
3300	make dep
3301	make uImage
3302
3303The "uImage" build target uses a special tool (in 'tools/mkimage') to
3304encapsulate a compressed Linux kernel image with header	 information,
3305CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3306
3307* build a standard "vmlinux" kernel image (in ELF binary format):
3308
3309* convert the kernel into a raw binary image:
3310
3311	${CROSS_COMPILE}-objcopy -O binary \
3312				 -R .note -R .comment \
3313				 -S vmlinux linux.bin
3314
3315* compress the binary image:
3316
3317	gzip -9 linux.bin
3318
3319* package compressed binary image for U-Boot:
3320
3321	mkimage -A ppc -O linux -T kernel -C gzip \
3322		-a 0 -e 0 -n "Linux Kernel Image" \
3323		-d linux.bin.gz uImage
3324
3325
3326The "mkimage" tool can also be used to create ramdisk images for use
3327with U-Boot, either separated from the Linux kernel image, or
3328combined into one file. "mkimage" encapsulates the images with a 64
3329byte header containing information about target architecture,
3330operating system, image type, compression method, entry points, time
3331stamp, CRC32 checksums, etc.
3332
3333"mkimage" can be called in two ways: to verify existing images and
3334print the header information, or to build new images.
3335
3336In the first form (with "-l" option) mkimage lists the information
3337contained in the header of an existing U-Boot image; this includes
3338checksum verification:
3339
3340	tools/mkimage -l image
3341	  -l ==> list image header information
3342
3343The second form (with "-d" option) is used to build a U-Boot image
3344from a "data file" which is used as image payload:
3345
3346	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3347		      -n name -d data_file image
3348	  -A ==> set architecture to 'arch'
3349	  -O ==> set operating system to 'os'
3350	  -T ==> set image type to 'type'
3351	  -C ==> set compression type 'comp'
3352	  -a ==> set load address to 'addr' (hex)
3353	  -e ==> set entry point to 'ep' (hex)
3354	  -n ==> set image name to 'name'
3355	  -d ==> use image data from 'datafile'
3356
3357Right now, all Linux kernels for PowerPC systems use the same load
3358address (0x00000000), but the entry point address depends on the
3359kernel version:
3360
3361- 2.2.x kernels have the entry point at 0x0000000C,
3362- 2.3.x and later kernels have the entry point at 0x00000000.
3363
3364So a typical call to build a U-Boot image would read:
3365
3366	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3367	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3368	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3369	> examples/uImage.TQM850L
3370	Image Name:   2.4.4 kernel for TQM850L
3371	Created:      Wed Jul 19 02:34:59 2000
3372	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3373	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3374	Load Address: 0x00000000
3375	Entry Point:  0x00000000
3376
3377To verify the contents of the image (or check for corruption):
3378
3379	-> tools/mkimage -l examples/uImage.TQM850L
3380	Image Name:   2.4.4 kernel for TQM850L
3381	Created:      Wed Jul 19 02:34:59 2000
3382	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3383	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3384	Load Address: 0x00000000
3385	Entry Point:  0x00000000
3386
3387NOTE: for embedded systems where boot time is critical you can trade
3388speed for memory and install an UNCOMPRESSED image instead: this
3389needs more space in Flash, but boots much faster since it does not
3390need to be uncompressed:
3391
3392	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3393	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3394	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3395	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3396	> examples/uImage.TQM850L-uncompressed
3397	Image Name:   2.4.4 kernel for TQM850L
3398	Created:      Wed Jul 19 02:34:59 2000
3399	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3400	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3401	Load Address: 0x00000000
3402	Entry Point:  0x00000000
3403
3404
3405Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3406when your kernel is intended to use an initial ramdisk:
3407
3408	-> tools/mkimage -n 'Simple Ramdisk Image' \
3409	> -A ppc -O linux -T ramdisk -C gzip \
3410	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3411	Image Name:   Simple Ramdisk Image
3412	Created:      Wed Jan 12 14:01:50 2000
3413	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3414	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3415	Load Address: 0x00000000
3416	Entry Point:  0x00000000
3417
3418
3419Installing a Linux Image:
3420-------------------------
3421
3422To downloading a U-Boot image over the serial (console) interface,
3423you must convert the image to S-Record format:
3424
3425	objcopy -I binary -O srec examples/image examples/image.srec
3426
3427The 'objcopy' does not understand the information in the U-Boot
3428image header, so the resulting S-Record file will be relative to
3429address 0x00000000. To load it to a given address, you need to
3430specify the target address as 'offset' parameter with the 'loads'
3431command.
3432
3433Example: install the image to address 0x40100000 (which on the
3434TQM8xxL is in the first Flash bank):
3435
3436	=> erase 40100000 401FFFFF
3437
3438	.......... done
3439	Erased 8 sectors
3440
3441	=> loads 40100000
3442	## Ready for S-Record download ...
3443	~>examples/image.srec
3444	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3445	...
3446	15989 15990 15991 15992
3447	[file transfer complete]
3448	[connected]
3449	## Start Addr = 0x00000000
3450
3451
3452You can check the success of the download using the 'iminfo' command;
3453this includes a checksum verification so you can be sure no data
3454corruption happened:
3455
3456	=> imi 40100000
3457
3458	## Checking Image at 40100000 ...
3459	   Image Name:	 2.2.13 for initrd on TQM850L
3460	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3461	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3462	   Load Address: 00000000
3463	   Entry Point:	 0000000c
3464	   Verifying Checksum ... OK
3465
3466
3467Boot Linux:
3468-----------
3469
3470The "bootm" command is used to boot an application that is stored in
3471memory (RAM or Flash). In case of a Linux kernel image, the contents
3472of the "bootargs" environment variable is passed to the kernel as
3473parameters. You can check and modify this variable using the
3474"printenv" and "setenv" commands:
3475
3476
3477	=> printenv bootargs
3478	bootargs=root=/dev/ram
3479
3480	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3481
3482	=> printenv bootargs
3483	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3484
3485	=> bootm 40020000
3486	## Booting Linux kernel at 40020000 ...
3487	   Image Name:	 2.2.13 for NFS on TQM850L
3488	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3489	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3490	   Load Address: 00000000
3491	   Entry Point:	 0000000c
3492	   Verifying Checksum ... OK
3493	   Uncompressing Kernel Image ... OK
3494	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
3495	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3496	time_init: decrementer frequency = 187500000/60
3497	Calibrating delay loop... 49.77 BogoMIPS
3498	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3499	...
3500
3501If you want to boot a Linux kernel with initial RAM disk, you pass
3502the memory addresses of both the kernel and the initrd image (PPBCOOT
3503format!) to the "bootm" command:
3504
3505	=> imi 40100000 40200000
3506
3507	## Checking Image at 40100000 ...
3508	   Image Name:	 2.2.13 for initrd on TQM850L
3509	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3510	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3511	   Load Address: 00000000
3512	   Entry Point:	 0000000c
3513	   Verifying Checksum ... OK
3514
3515	## Checking Image at 40200000 ...
3516	   Image Name:	 Simple Ramdisk Image
3517	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3518	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3519	   Load Address: 00000000
3520	   Entry Point:	 00000000
3521	   Verifying Checksum ... OK
3522
3523	=> bootm 40100000 40200000
3524	## Booting Linux kernel at 40100000 ...
3525	   Image Name:	 2.2.13 for initrd on TQM850L
3526	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3527	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3528	   Load Address: 00000000
3529	   Entry Point:	 0000000c
3530	   Verifying Checksum ... OK
3531	   Uncompressing Kernel Image ... OK
3532	## Loading RAMDisk Image at 40200000 ...
3533	   Image Name:	 Simple Ramdisk Image
3534	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3535	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3536	   Load Address: 00000000
3537	   Entry Point:	 00000000
3538	   Verifying Checksum ... OK
3539	   Loading Ramdisk ... OK
3540	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
3541	Boot arguments: root=/dev/ram
3542	time_init: decrementer frequency = 187500000/60
3543	Calibrating delay loop... 49.77 BogoMIPS
3544	...
3545	RAMDISK: Compressed image found at block 0
3546	VFS: Mounted root (ext2 filesystem).
3547
3548	bash#
3549
3550Boot Linux and pass a flat device tree:
3551-----------
3552
3553First, U-Boot must be compiled with the appropriate defines. See the section
3554titled "Linux Kernel Interface" above for a more in depth explanation. The
3555following is an example of how to start a kernel and pass an updated
3556flat device tree:
3557
3558=> print oftaddr
3559oftaddr=0x300000
3560=> print oft
3561oft=oftrees/mpc8540ads.dtb
3562=> tftp $oftaddr $oft
3563Speed: 1000, full duplex
3564Using TSEC0 device
3565TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3566Filename 'oftrees/mpc8540ads.dtb'.
3567Load address: 0x300000
3568Loading: #
3569done
3570Bytes transferred = 4106 (100a hex)
3571=> tftp $loadaddr $bootfile
3572Speed: 1000, full duplex
3573Using TSEC0 device
3574TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3575Filename 'uImage'.
3576Load address: 0x200000
3577Loading:############
3578done
3579Bytes transferred = 1029407 (fb51f hex)
3580=> print loadaddr
3581loadaddr=200000
3582=> print oftaddr
3583oftaddr=0x300000
3584=> bootm $loadaddr - $oftaddr
3585## Booting image at 00200000 ...
3586   Image Name:	 Linux-2.6.17-dirty
3587   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3588   Data Size:	 1029343 Bytes = 1005.2 kB
3589   Load Address: 00000000
3590   Entry Point:	 00000000
3591   Verifying Checksum ... OK
3592   Uncompressing Kernel Image ... OK
3593Booting using flat device tree at 0x300000
3594Using MPC85xx ADS machine description
3595Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3596[snip]
3597
3598
3599More About U-Boot Image Types:
3600------------------------------
3601
3602U-Boot supports the following image types:
3603
3604   "Standalone Programs" are directly runnable in the environment
3605	provided by U-Boot; it is expected that (if they behave
3606	well) you can continue to work in U-Boot after return from
3607	the Standalone Program.
3608   "OS Kernel Images" are usually images of some Embedded OS which
3609	will take over control completely. Usually these programs
3610	will install their own set of exception handlers, device
3611	drivers, set up the MMU, etc. - this means, that you cannot
3612	expect to re-enter U-Boot except by resetting the CPU.
3613   "RAMDisk Images" are more or less just data blocks, and their
3614	parameters (address, size) are passed to an OS kernel that is
3615	being started.
3616   "Multi-File Images" contain several images, typically an OS
3617	(Linux) kernel image and one or more data images like
3618	RAMDisks. This construct is useful for instance when you want
3619	to boot over the network using BOOTP etc., where the boot
3620	server provides just a single image file, but you want to get
3621	for instance an OS kernel and a RAMDisk image.
3622
3623	"Multi-File Images" start with a list of image sizes, each
3624	image size (in bytes) specified by an "uint32_t" in network
3625	byte order. This list is terminated by an "(uint32_t)0".
3626	Immediately after the terminating 0 follow the images, one by
3627	one, all aligned on "uint32_t" boundaries (size rounded up to
3628	a multiple of 4 bytes).
3629
3630   "Firmware Images" are binary images containing firmware (like
3631	U-Boot or FPGA images) which usually will be programmed to
3632	flash memory.
3633
3634   "Script files" are command sequences that will be executed by
3635	U-Boot's command interpreter; this feature is especially
3636	useful when you configure U-Boot to use a real shell (hush)
3637	as command interpreter.
3638
3639
3640Standalone HOWTO:
3641=================
3642
3643One of the features of U-Boot is that you can dynamically load and
3644run "standalone" applications, which can use some resources of
3645U-Boot like console I/O functions or interrupt services.
3646
3647Two simple examples are included with the sources:
3648
3649"Hello World" Demo:
3650-------------------
3651
3652'examples/hello_world.c' contains a small "Hello World" Demo
3653application; it is automatically compiled when you build U-Boot.
3654It's configured to run at address 0x00040004, so you can play with it
3655like that:
3656
3657	=> loads
3658	## Ready for S-Record download ...
3659	~>examples/hello_world.srec
3660	1 2 3 4 5 6 7 8 9 10 11 ...
3661	[file transfer complete]
3662	[connected]
3663	## Start Addr = 0x00040004
3664
3665	=> go 40004 Hello World! This is a test.
3666	## Starting application at 0x00040004 ...
3667	Hello World
3668	argc = 7
3669	argv[0] = "40004"
3670	argv[1] = "Hello"
3671	argv[2] = "World!"
3672	argv[3] = "This"
3673	argv[4] = "is"
3674	argv[5] = "a"
3675	argv[6] = "test."
3676	argv[7] = "<NULL>"
3677	Hit any key to exit ...
3678
3679	## Application terminated, rc = 0x0
3680
3681Another example, which demonstrates how to register a CPM interrupt
3682handler with the U-Boot code, can be found in 'examples/timer.c'.
3683Here, a CPM timer is set up to generate an interrupt every second.
3684The interrupt service routine is trivial, just printing a '.'
3685character, but this is just a demo program. The application can be
3686controlled by the following keys:
3687
3688	? - print current values og the CPM Timer registers
3689	b - enable interrupts and start timer
3690	e - stop timer and disable interrupts
3691	q - quit application
3692
3693	=> loads
3694	## Ready for S-Record download ...
3695	~>examples/timer.srec
3696	1 2 3 4 5 6 7 8 9 10 11 ...
3697	[file transfer complete]
3698	[connected]
3699	## Start Addr = 0x00040004
3700
3701	=> go 40004
3702	## Starting application at 0x00040004 ...
3703	TIMERS=0xfff00980
3704	Using timer 1
3705	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3706
3707Hit 'b':
3708	[q, b, e, ?] Set interval 1000000 us
3709	Enabling timer
3710Hit '?':
3711	[q, b, e, ?] ........
3712	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3713Hit '?':
3714	[q, b, e, ?] .
3715	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3716Hit '?':
3717	[q, b, e, ?] .
3718	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3719Hit '?':
3720	[q, b, e, ?] .
3721	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3722Hit 'e':
3723	[q, b, e, ?] ...Stopping timer
3724Hit 'q':
3725	[q, b, e, ?] ## Application terminated, rc = 0x0
3726
3727
3728Minicom warning:
3729================
3730
3731Over time, many people have reported problems when trying to use the
3732"minicom" terminal emulation program for serial download. I (wd)
3733consider minicom to be broken, and recommend not to use it. Under
3734Unix, I recommend to use C-Kermit for general purpose use (and
3735especially for kermit binary protocol download ("loadb" command), and
3736use "cu" for S-Record download ("loads" command).
3737
3738Nevertheless, if you absolutely want to use it try adding this
3739configuration to your "File transfer protocols" section:
3740
3741	   Name	   Program			Name U/D FullScr IO-Red. Multi
3742	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3743	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3744
3745
3746NetBSD Notes:
3747=============
3748
3749Starting at version 0.9.2, U-Boot supports NetBSD both as host
3750(build U-Boot) and target system (boots NetBSD/mpc8xx).
3751
3752Building requires a cross environment; it is known to work on
3753NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3754need gmake since the Makefiles are not compatible with BSD make).
3755Note that the cross-powerpc package does not install include files;
3756attempting to build U-Boot will fail because <machine/ansi.h> is
3757missing.  This file has to be installed and patched manually:
3758
3759	# cd /usr/pkg/cross/powerpc-netbsd/include
3760	# mkdir powerpc
3761	# ln -s powerpc machine
3762	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3763	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3764
3765Native builds *don't* work due to incompatibilities between native
3766and U-Boot include files.
3767
3768Booting assumes that (the first part of) the image booted is a
3769stage-2 loader which in turn loads and then invokes the kernel
3770proper. Loader sources will eventually appear in the NetBSD source
3771tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3772meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3773
3774
3775Implementation Internals:
3776=========================
3777
3778The following is not intended to be a complete description of every
3779implementation detail. However, it should help to understand the
3780inner workings of U-Boot and make it easier to port it to custom
3781hardware.
3782
3783
3784Initial Stack, Global Data:
3785---------------------------
3786
3787The implementation of U-Boot is complicated by the fact that U-Boot
3788starts running out of ROM (flash memory), usually without access to
3789system RAM (because the memory controller is not initialized yet).
3790This means that we don't have writable Data or BSS segments, and BSS
3791is not initialized as zero. To be able to get a C environment working
3792at all, we have to allocate at least a minimal stack. Implementation
3793options for this are defined and restricted by the CPU used: Some CPU
3794models provide on-chip memory (like the IMMR area on MPC8xx and
3795MPC826x processors), on others (parts of) the data cache can be
3796locked as (mis-) used as memory, etc.
3797
3798	Chris Hallinan posted a good summary of these issues to the
3799	U-Boot mailing list:
3800
3801	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3802	From: "Chris Hallinan" <clh@net1plus.com>
3803	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3804	...
3805
3806	Correct me if I'm wrong, folks, but the way I understand it
3807	is this: Using DCACHE as initial RAM for Stack, etc, does not
3808	require any physical RAM backing up the cache. The cleverness
3809	is that the cache is being used as a temporary supply of
3810	necessary storage before the SDRAM controller is setup. It's
3811	beyond the scope of this list to explain the details, but you
3812	can see how this works by studying the cache architecture and
3813	operation in the architecture and processor-specific manuals.
3814
3815	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3816	is another option for the system designer to use as an
3817	initial stack/RAM area prior to SDRAM being available. Either
3818	option should work for you. Using CS 4 should be fine if your
3819	board designers haven't used it for something that would
3820	cause you grief during the initial boot! It is frequently not
3821	used.
3822
3823	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3824	with your processor/board/system design. The default value
3825	you will find in any recent u-boot distribution in
3826	walnut.h should work for you. I'd set it to a value larger
3827	than your SDRAM module. If you have a 64MB SDRAM module, set
3828	it above 400_0000. Just make sure your board has no resources
3829	that are supposed to respond to that address! That code in
3830	start.S has been around a while and should work as is when
3831	you get the config right.
3832
3833	-Chris Hallinan
3834	DS4.COM, Inc.
3835
3836It is essential to remember this, since it has some impact on the C
3837code for the initialization procedures:
3838
3839* Initialized global data (data segment) is read-only. Do not attempt
3840  to write it.
3841
3842* Do not use any uninitialized global data (or implicitely initialized
3843  as zero data - BSS segment) at all - this is undefined, initiali-
3844  zation is performed later (when relocating to RAM).
3845
3846* Stack space is very limited. Avoid big data buffers or things like
3847  that.
3848
3849Having only the stack as writable memory limits means we cannot use
3850normal global data to share information beween the code. But it
3851turned out that the implementation of U-Boot can be greatly
3852simplified by making a global data structure (gd_t) available to all
3853functions. We could pass a pointer to this data as argument to _all_
3854functions, but this would bloat the code. Instead we use a feature of
3855the GCC compiler (Global Register Variables) to share the data: we
3856place a pointer (gd) to the global data into a register which we
3857reserve for this purpose.
3858
3859When choosing a register for such a purpose we are restricted by the
3860relevant  (E)ABI  specifications for the current architecture, and by
3861GCC's implementation.
3862
3863For PowerPC, the following registers have specific use:
3864	R1:	stack pointer
3865	R2:	reserved for system use
3866	R3-R4:	parameter passing and return values
3867	R5-R10: parameter passing
3868	R13:	small data area pointer
3869	R30:	GOT pointer
3870	R31:	frame pointer
3871
3872	(U-Boot also uses R14 as internal GOT pointer.)
3873
3874    ==> U-Boot will use R2 to hold a pointer to the global data
3875
3876    Note: on PPC, we could use a static initializer (since the
3877    address of the global data structure is known at compile time),
3878    but it turned out that reserving a register results in somewhat
3879    smaller code - although the code savings are not that big (on
3880    average for all boards 752 bytes for the whole U-Boot image,
3881    624 text + 127 data).
3882
3883On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3884	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3885
3886    ==> U-Boot will use P5 to hold a pointer to the global data
3887
3888On ARM, the following registers are used:
3889
3890	R0:	function argument word/integer result
3891	R1-R3:	function argument word
3892	R9:	GOT pointer
3893	R10:	stack limit (used only if stack checking if enabled)
3894	R11:	argument (frame) pointer
3895	R12:	temporary workspace
3896	R13:	stack pointer
3897	R14:	link register
3898	R15:	program counter
3899
3900    ==> U-Boot will use R8 to hold a pointer to the global data
3901
3902NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3903or current versions of GCC may "optimize" the code too much.
3904
3905Memory Management:
3906------------------
3907
3908U-Boot runs in system state and uses physical addresses, i.e. the
3909MMU is not used either for address mapping nor for memory protection.
3910
3911The available memory is mapped to fixed addresses using the memory
3912controller. In this process, a contiguous block is formed for each
3913memory type (Flash, SDRAM, SRAM), even when it consists of several
3914physical memory banks.
3915
3916U-Boot is installed in the first 128 kB of the first Flash bank (on
3917TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3918booting and sizing and initializing DRAM, the code relocates itself
3919to the upper end of DRAM. Immediately below the U-Boot code some
3920memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3921configuration setting]. Below that, a structure with global Board
3922Info data is placed, followed by the stack (growing downward).
3923
3924Additionally, some exception handler code is copied to the low 8 kB
3925of DRAM (0x00000000 ... 0x00001FFF).
3926
3927So a typical memory configuration with 16 MB of DRAM could look like
3928this:
3929
3930	0x0000 0000	Exception Vector code
3931	      :
3932	0x0000 1FFF
3933	0x0000 2000	Free for Application Use
3934	      :
3935	      :
3936
3937	      :
3938	      :
3939	0x00FB FF20	Monitor Stack (Growing downward)
3940	0x00FB FFAC	Board Info Data and permanent copy of global data
3941	0x00FC 0000	Malloc Arena
3942	      :
3943	0x00FD FFFF
3944	0x00FE 0000	RAM Copy of Monitor Code
3945	...		eventually: LCD or video framebuffer
3946	...		eventually: pRAM (Protected RAM - unchanged by reset)
3947	0x00FF FFFF	[End of RAM]
3948
3949
3950System Initialization:
3951----------------------
3952
3953In the reset configuration, U-Boot starts at the reset entry point
3954(on most PowerPC systems at address 0x00000100). Because of the reset
3955configuration for CS0# this is a mirror of the onboard Flash memory.
3956To be able to re-map memory U-Boot then jumps to its link address.
3957To be able to implement the initialization code in C, a (small!)
3958initial stack is set up in the internal Dual Ported RAM (in case CPUs
3959which provide such a feature like MPC8xx or MPC8260), or in a locked
3960part of the data cache. After that, U-Boot initializes the CPU core,
3961the caches and the SIU.
3962
3963Next, all (potentially) available memory banks are mapped using a
3964preliminary mapping. For example, we put them on 512 MB boundaries
3965(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3966on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3967programmed for SDRAM access. Using the temporary configuration, a
3968simple memory test is run that determines the size of the SDRAM
3969banks.
3970
3971When there is more than one SDRAM bank, and the banks are of
3972different size, the largest is mapped first. For equal size, the first
3973bank (CS2#) is mapped first. The first mapping is always for address
39740x00000000, with any additional banks following immediately to create
3975contiguous memory starting from 0.
3976
3977Then, the monitor installs itself at the upper end of the SDRAM area
3978and allocates memory for use by malloc() and for the global Board
3979Info data; also, the exception vector code is copied to the low RAM
3980pages, and the final stack is set up.
3981
3982Only after this relocation will you have a "normal" C environment;
3983until that you are restricted in several ways, mostly because you are
3984running from ROM, and because the code will have to be relocated to a
3985new address in RAM.
3986
3987
3988U-Boot Porting Guide:
3989----------------------
3990
3991[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3992list, October 2002]
3993
3994
3995int main (int argc, char *argv[])
3996{
3997	sighandler_t no_more_time;
3998
3999	signal (SIGALRM, no_more_time);
4000	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
4001
4002	if (available_money > available_manpower) {
4003		pay consultant to port U-Boot;
4004		return 0;
4005	}
4006
4007	Download latest U-Boot source;
4008
4009	Subscribe to u-boot mailing list;
4010
4011	if (clueless) {
4012		email ("Hi, I am new to U-Boot, how do I get started?");
4013	}
4014
4015	while (learning) {
4016		Read the README file in the top level directory;
4017		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
4018		Read the source, Luke;
4019	}
4020
4021	if (available_money > toLocalCurrency ($2500)) {
4022		Buy a BDI2000;
4023	} else {
4024		Add a lot of aggravation and time;
4025	}
4026
4027	Create your own board support subdirectory;
4028
4029	Create your own board config file;
4030
4031	while (!running) {
4032		do {
4033			Add / modify source code;
4034		} until (compiles);
4035		Debug;
4036		if (clueless)
4037			email ("Hi, I am having problems...");
4038	}
4039	Send patch file to Wolfgang;
4040
4041	return 0;
4042}
4043
4044void no_more_time (int sig)
4045{
4046      hire_a_guru();
4047}
4048
4049
4050Coding Standards:
4051-----------------
4052
4053All contributions to U-Boot should conform to the Linux kernel
4054coding style; see the file "Documentation/CodingStyle" and the script
4055"scripts/Lindent" in your Linux kernel source directory.  In sources
4056originating from U-Boot a style corresponding to "Lindent -pcs" (adding
4057spaces before parameters to function calls) is actually used.
4058
4059Source files originating from a different project (for example the
4060MTD subsystem) are generally exempt from these guidelines and are not
4061reformated to ease subsequent migration to newer versions of those
4062sources.
4063
4064Please note that U-Boot is implemented in C (and to some small parts in
4065Assembler); no C++ is used, so please do not use C++ style comments (//)
4066in your code.
4067
4068Please also stick to the following formatting rules:
4069- remove any trailing white space
4070- use TAB characters for indentation, not spaces
4071- make sure NOT to use DOS '\r\n' line feeds
4072- do not add more than 2 empty lines to source files
4073- do not add trailing empty lines to source files
4074
4075Submissions which do not conform to the standards may be returned
4076with a request to reformat the changes.
4077
4078
4079Submitting Patches:
4080-------------------
4081
4082Since the number of patches for U-Boot is growing, we need to
4083establish some rules. Submissions which do not conform to these rules
4084may be rejected, even when they contain important and valuable stuff.
4085
4086Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4087
4088Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4089see http://lists.denx.de/mailman/listinfo/u-boot
4090
4091When you send a patch, please include the following information with
4092it:
4093
4094* For bug fixes: a description of the bug and how your patch fixes
4095  this bug. Please try to include a way of demonstrating that the
4096  patch actually fixes something.
4097
4098* For new features: a description of the feature and your
4099  implementation.
4100
4101* A CHANGELOG entry as plaintext (separate from the patch)
4102
4103* For major contributions, your entry to the CREDITS file
4104
4105* When you add support for a new board, don't forget to add this
4106  board to the MAKEALL script, too.
4107
4108* If your patch adds new configuration options, don't forget to
4109  document these in the README file.
4110
4111* The patch itself. If you are using git (which is *strongly*
4112  recommended) you can easily generate the patch using the
4113  "git-format-patch". If you then use "git-send-email" to send it to
4114  the U-Boot mailing list, you will avoid most of the common problems
4115  with some other mail clients.
4116
4117  If you cannot use git, use "diff -purN OLD NEW". If your version of
4118  diff does not support these options, then get the latest version of
4119  GNU diff.
4120
4121  The current directory when running this command shall be the parent
4122  directory of the U-Boot source tree (i. e. please make sure that
4123  your patch includes sufficient directory information for the
4124  affected files).
4125
4126  We prefer patches as plain text. MIME attachments are discouraged,
4127  and compressed attachments must not be used.
4128
4129* If one logical set of modifications affects or creates several
4130  files, all these changes shall be submitted in a SINGLE patch file.
4131
4132* Changesets that contain different, unrelated modifications shall be
4133  submitted as SEPARATE patches, one patch per changeset.
4134
4135
4136Notes:
4137
4138* Before sending the patch, run the MAKEALL script on your patched
4139  source tree and make sure that no errors or warnings are reported
4140  for any of the boards.
4141
4142* Keep your modifications to the necessary minimum: A patch
4143  containing several unrelated changes or arbitrary reformats will be
4144  returned with a request to re-formatting / split it.
4145
4146* If you modify existing code, make sure that your new code does not
4147  add to the memory footprint of the code ;-) Small is beautiful!
4148  When adding new features, these should compile conditionally only
4149  (using #ifdef), and the resulting code with the new feature
4150  disabled must not need more memory than the old code without your
4151  modification.
4152
4153* Remember that there is a size limit of 100 kB per message on the
4154  u-boot mailing list. Bigger patches will be moderated. If they are
4155  reasonable and not too big, they will be acknowledged. But patches
4156  bigger than the size limit should be avoided.
4157