xref: /rk3399_rockchip-uboot/README (revision 9453967e28c5e3abbf856f95735ea69bae1e77fa)
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_DS4510	* ds4510 I2C gpio commands
607		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
608		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
609		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
610		CONFIG_CMD_DTT		* Digital Therm and Thermostat
611		CONFIG_CMD_ECHO		  echo arguments
612		CONFIG_CMD_EEPROM	* EEPROM read/write support
613		CONFIG_CMD_ELF		* bootelf, bootvx
614		CONFIG_CMD_SAVEENV	  saveenv
615		CONFIG_CMD_FDC		* Floppy Disk Support
616		CONFIG_CMD_FAT		* FAT partition support
617		CONFIG_CMD_FDOS		* Dos diskette Support
618		CONFIG_CMD_FLASH	  flinfo, erase, protect
619		CONFIG_CMD_FPGA		  FPGA device initialization support
620		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
621		CONFIG_CMD_I2C		* I2C serial bus support
622		CONFIG_CMD_IDE		* IDE harddisk support
623		CONFIG_CMD_IMI		  iminfo
624		CONFIG_CMD_IMLS		  List all found images
625		CONFIG_CMD_IMMAP	* IMMR dump support
626		CONFIG_CMD_IRQ		* irqinfo
627		CONFIG_CMD_ITEST	  Integer/string test of 2 values
628		CONFIG_CMD_JFFS2	* JFFS2 Support
629		CONFIG_CMD_KGDB		* kgdb
630		CONFIG_CMD_LOADB	  loadb
631		CONFIG_CMD_LOADS	  loads
632		CONFIG_CMD_MD5SUM	  print md5 message digest
633					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
634		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
635					  loop, loopw, mtest
636		CONFIG_CMD_MISC		  Misc functions like sleep etc
637		CONFIG_CMD_MMC		* MMC memory mapped support
638		CONFIG_CMD_MII		* MII utility commands
639		CONFIG_CMD_MTDPARTS	* MTD partition support
640		CONFIG_CMD_NAND		* NAND support
641		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
642		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
643		CONFIG_CMD_PCA953X_INFO	* PCA953x I2C gpio info command
644		CONFIG_CMD_PCI		* pciinfo
645		CONFIG_CMD_PCMCIA		* PCMCIA support
646		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
647					  host
648		CONFIG_CMD_PORTIO	* Port I/O
649		CONFIG_CMD_REGINFO	* Register dump
650		CONFIG_CMD_RUN		  run command in env variable
651		CONFIG_CMD_SAVES	* save S record dump
652		CONFIG_CMD_SCSI		* SCSI Support
653		CONFIG_CMD_SDRAM	* print SDRAM configuration information
654					  (requires CONFIG_CMD_I2C)
655		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
656					  (4xx only)
657		CONFIG_CMD_SHA1		  print sha1 memory digest
658					  (requires CONFIG_CMD_MEMORY)
659		CONFIG_CMD_SOURCE	  "source" command Support
660		CONFIG_CMD_SPI		* SPI serial bus support
661		CONFIG_CMD_USB		* USB support
662		CONFIG_CMD_VFD		* VFD support (TRAB)
663		CONFIG_CMD_CDP		* Cisco Discover Protocol support
664		CONFIG_CMD_FSL		* Microblaze FSL support
665
666
667		EXAMPLE: If you want all functions except of network
668		support you can write:
669
670		#include "config_cmd_all.h"
671		#undef CONFIG_CMD_NET
672
673	Other Commands:
674		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
675
676	Note:	Don't enable the "icache" and "dcache" commands
677		(configuration option CONFIG_CMD_CACHE) unless you know
678		what you (and your U-Boot users) are doing. Data
679		cache cannot be enabled on systems like the 8xx or
680		8260 (where accesses to the IMMR region must be
681		uncached), and it cannot be disabled on all other
682		systems where we (mis-) use the data cache to hold an
683		initial stack and some data.
684
685
686		XXX - this list needs to get updated!
687
688- Watchdog:
689		CONFIG_WATCHDOG
690		If this variable is defined, it enables watchdog
691		support. There must be support in the platform specific
692		code for a watchdog. For the 8xx and 8260 CPUs, the
693		SIU Watchdog feature is enabled in the SYPCR
694		register.
695
696- U-Boot Version:
697		CONFIG_VERSION_VARIABLE
698		If this variable is defined, an environment variable
699		named "ver" is created by U-Boot showing the U-Boot
700		version as printed by the "version" command.
701		This variable is readonly.
702
703- Real-Time Clock:
704
705		When CONFIG_CMD_DATE is selected, the type of the RTC
706		has to be selected, too. Define exactly one of the
707		following options:
708
709		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
710		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
711		CONFIG_RTC_MC13783	- use MC13783 RTC
712		CONFIG_RTC_MC146818	- use MC146818 RTC
713		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
714		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
715		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
716		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
717		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
718		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
719		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
720
721		Note that if the RTC uses I2C, then the I2C interface
722		must also be configured. See I2C Support, below.
723
724- GPIO Support:
725		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
726		CONFIG_PCA953X_INFO	- enable pca953x info command
727
728		Note that if the GPIO device uses I2C, then the I2C interface
729		must also be configured. See I2C Support, below.
730
731- Timestamp Support:
732
733		When CONFIG_TIMESTAMP is selected, the timestamp
734		(date and time) of an image is printed by image
735		commands like bootm or iminfo. This option is
736		automatically enabled when you select CONFIG_CMD_DATE .
737
738- Partition Support:
739		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
740		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
741
742		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
743		CONFIG_CMD_SCSI) you must configure support for at
744		least one partition type as well.
745
746- IDE Reset method:
747		CONFIG_IDE_RESET_ROUTINE - this is defined in several
748		board configurations files but used nowhere!
749
750		CONFIG_IDE_RESET - is this is defined, IDE Reset will
751		be performed by calling the function
752			ide_set_reset(int reset)
753		which has to be defined in a board specific file
754
755- ATAPI Support:
756		CONFIG_ATAPI
757
758		Set this to enable ATAPI support.
759
760- LBA48 Support
761		CONFIG_LBA48
762
763		Set this to enable support for disks larger than 137GB
764		Also look at CONFIG_SYS_64BIT_LBA ,CONFIG_SYS_64BIT_VSPRINTF and CONFIG_SYS_64BIT_STRTOUL
765		Whithout these , LBA48 support uses 32bit variables and will 'only'
766		support disks up to 2.1TB.
767
768		CONFIG_SYS_64BIT_LBA:
769			When enabled, makes the IDE subsystem use 64bit sector addresses.
770			Default is 32bit.
771
772- SCSI Support:
773		At the moment only there is only support for the
774		SYM53C8XX SCSI controller; define
775		CONFIG_SCSI_SYM53C8XX to enable it.
776
777		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
778		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
779		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
780		maximum numbers of LUNs, SCSI ID's and target
781		devices.
782		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
783
784- NETWORK Support (PCI):
785		CONFIG_E1000
786		Support for Intel 8254x gigabit chips.
787
788		CONFIG_E1000_FALLBACK_MAC
789		default MAC for empty EEPROM after production.
790
791		CONFIG_EEPRO100
792		Support for Intel 82557/82559/82559ER chips.
793		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
794		write routine for first time initialisation.
795
796		CONFIG_TULIP
797		Support for Digital 2114x chips.
798		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
799		modem chip initialisation (KS8761/QS6611).
800
801		CONFIG_NATSEMI
802		Support for National dp83815 chips.
803
804		CONFIG_NS8382X
805		Support for National dp8382[01] gigabit chips.
806
807- NETWORK Support (other):
808
809		CONFIG_DRIVER_LAN91C96
810		Support for SMSC's LAN91C96 chips.
811
812			CONFIG_LAN91C96_BASE
813			Define this to hold the physical address
814			of the LAN91C96's I/O space
815
816			CONFIG_LAN91C96_USE_32_BIT
817			Define this to enable 32 bit addressing
818
819		CONFIG_DRIVER_SMC91111
820		Support for SMSC's LAN91C111 chip
821
822			CONFIG_SMC91111_BASE
823			Define this to hold the physical address
824			of the device (I/O space)
825
826			CONFIG_SMC_USE_32_BIT
827			Define this if data bus is 32 bits
828
829			CONFIG_SMC_USE_IOFUNCS
830			Define this to use i/o functions instead of macros
831			(some hardware wont work with macros)
832
833		CONFIG_DRIVER_SMC911X
834		Support for SMSC's LAN911x and LAN921x chips
835
836			CONFIG_DRIVER_SMC911X_BASE
837			Define this to hold the physical address
838			of the device (I/O space)
839
840			CONFIG_DRIVER_SMC911X_32_BIT
841			Define this if data bus is 32 bits
842
843			CONFIG_DRIVER_SMC911X_16_BIT
844			Define this if data bus is 16 bits. If your processor
845			automatically converts one 32 bit word to two 16 bit
846			words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
847
848- USB Support:
849		At the moment only the UHCI host controller is
850		supported (PIP405, MIP405, MPC5200); define
851		CONFIG_USB_UHCI to enable it.
852		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
853		and define CONFIG_USB_STORAGE to enable the USB
854		storage devices.
855		Note:
856		Supported are USB Keyboards and USB Floppy drives
857		(TEAC FD-05PUB).
858		MPC5200 USB requires additional defines:
859			CONFIG_USB_CLOCK
860				for 528 MHz Clock: 0x0001bbbb
861			CONFIG_PSC3_USB
862				for USB on PSC3
863			CONFIG_USB_CONFIG
864				for differential drivers: 0x00001000
865				for single ended drivers: 0x00005000
866				for differential drivers on PSC3: 0x00000100
867				for single ended drivers on PSC3: 0x00004100
868			CONFIG_SYS_USB_EVENT_POLL
869				May be defined to allow interrupt polling
870				instead of using asynchronous interrupts
871
872- USB Device:
873		Define the below if you wish to use the USB console.
874		Once firmware is rebuilt from a serial console issue the
875		command "setenv stdin usbtty; setenv stdout usbtty" and
876		attach your USB cable. The Unix command "dmesg" should print
877		it has found a new device. The environment variable usbtty
878		can be set to gserial or cdc_acm to enable your device to
879		appear to a USB host as a Linux gserial device or a
880		Common Device Class Abstract Control Model serial device.
881		If you select usbtty = gserial you should be able to enumerate
882		a Linux host by
883		# modprobe usbserial vendor=0xVendorID product=0xProductID
884		else if using cdc_acm, simply setting the environment
885		variable usbtty to be cdc_acm should suffice. The following
886		might be defined in YourBoardName.h
887
888			CONFIG_USB_DEVICE
889			Define this to build a UDC device
890
891			CONFIG_USB_TTY
892			Define this to have a tty type of device available to
893			talk to the UDC device
894
895			CONFIG_SYS_CONSOLE_IS_IN_ENV
896			Define this if you want stdin, stdout &/or stderr to
897			be set to usbtty.
898
899			mpc8xx:
900				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
901				Derive USB clock from external clock "blah"
902				- CONFIG_SYS_USB_EXTC_CLK 0x02
903
904				CONFIG_SYS_USB_BRG_CLK 0xBLAH
905				Derive USB clock from brgclk
906				- CONFIG_SYS_USB_BRG_CLK 0x04
907
908		If you have a USB-IF assigned VendorID then you may wish to
909		define your own vendor specific values either in BoardName.h
910		or directly in usbd_vendor_info.h. If you don't define
911		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
912		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
913		should pretend to be a Linux device to it's target host.
914
915			CONFIG_USBD_MANUFACTURER
916			Define this string as the name of your company for
917			- CONFIG_USBD_MANUFACTURER "my company"
918
919			CONFIG_USBD_PRODUCT_NAME
920			Define this string as the name of your product
921			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
922
923			CONFIG_USBD_VENDORID
924			Define this as your assigned Vendor ID from the USB
925			Implementors Forum. This *must* be a genuine Vendor ID
926			to avoid polluting the USB namespace.
927			- CONFIG_USBD_VENDORID 0xFFFF
928
929			CONFIG_USBD_PRODUCTID
930			Define this as the unique Product ID
931			for your device
932			- CONFIG_USBD_PRODUCTID 0xFFFF
933
934
935- MMC Support:
936		The MMC controller on the Intel PXA is supported. To
937		enable this define CONFIG_MMC. The MMC can be
938		accessed from the boot prompt by mapping the device
939		to physical memory similar to flash. Command line is
940		enabled with CONFIG_CMD_MMC. The MMC driver also works with
941		the FAT fs. This is enabled with CONFIG_CMD_FAT.
942
943- Journaling Flash filesystem support:
944		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
945		CONFIG_JFFS2_NAND_DEV
946		Define these for a default partition on a NAND device
947
948		CONFIG_SYS_JFFS2_FIRST_SECTOR,
949		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
950		Define these for a default partition on a NOR device
951
952		CONFIG_SYS_JFFS_CUSTOM_PART
953		Define this to create an own partition. You have to provide a
954		function struct part_info* jffs2_part_info(int part_num)
955
956		If you define only one JFFS2 partition you may also want to
957		#define CONFIG_SYS_JFFS_SINGLE_PART	1
958		to disable the command chpart. This is the default when you
959		have not defined a custom partition
960
961- Keyboard Support:
962		CONFIG_ISA_KEYBOARD
963
964		Define this to enable standard (PC-Style) keyboard
965		support
966
967		CONFIG_I8042_KBD
968		Standard PC keyboard driver with US (is default) and
969		GERMAN key layout (switch via environment 'keymap=de') support.
970		Export function i8042_kbd_init, i8042_tstc and i8042_getc
971		for cfb_console. Supports cursor blinking.
972
973- Video support:
974		CONFIG_VIDEO
975
976		Define this to enable video support (for output to
977		video).
978
979		CONFIG_VIDEO_CT69000
980
981		Enable Chips & Technologies 69000 Video chip
982
983		CONFIG_VIDEO_SMI_LYNXEM
984		Enable Silicon Motion SMI 712/710/810 Video chip. The
985		video output is selected via environment 'videoout'
986		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
987		assumed.
988
989		For the CT69000 and SMI_LYNXEM drivers, videomode is
990		selected via environment 'videomode'. Two different ways
991		are possible:
992		- "videomode=num"   'num' is a standard LiLo mode numbers.
993		Following standard modes are supported	(* is default):
994
995		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
996		-------------+---------------------------------------------
997		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
998		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
999		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1000		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1001		-------------+---------------------------------------------
1002		(i.e. setenv videomode 317; saveenv; reset;)
1003
1004		- "videomode=bootargs" all the video parameters are parsed
1005		from the bootargs. (See drivers/video/videomodes.c)
1006
1007
1008		CONFIG_VIDEO_SED13806
1009		Enable Epson SED13806 driver. This driver supports 8bpp
1010		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1011		or CONFIG_VIDEO_SED13806_16BPP
1012
1013- Keyboard Support:
1014		CONFIG_KEYBOARD
1015
1016		Define this to enable a custom keyboard support.
1017		This simply calls drv_keyboard_init() which must be
1018		defined in your board-specific files.
1019		The only board using this so far is RBC823.
1020
1021- LCD Support:	CONFIG_LCD
1022
1023		Define this to enable LCD support (for output to LCD
1024		display); also select one of the supported displays
1025		by defining one of these:
1026
1027		CONFIG_ATMEL_LCD:
1028
1029			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1030
1031		CONFIG_NEC_NL6448AC33:
1032
1033			NEC NL6448AC33-18. Active, color, single scan.
1034
1035		CONFIG_NEC_NL6448BC20
1036
1037			NEC NL6448BC20-08. 6.5", 640x480.
1038			Active, color, single scan.
1039
1040		CONFIG_NEC_NL6448BC33_54
1041
1042			NEC NL6448BC33-54. 10.4", 640x480.
1043			Active, color, single scan.
1044
1045		CONFIG_SHARP_16x9
1046
1047			Sharp 320x240. Active, color, single scan.
1048			It isn't 16x9, and I am not sure what it is.
1049
1050		CONFIG_SHARP_LQ64D341
1051
1052			Sharp LQ64D341 display, 640x480.
1053			Active, color, single scan.
1054
1055		CONFIG_HLD1045
1056
1057			HLD1045 display, 640x480.
1058			Active, color, single scan.
1059
1060		CONFIG_OPTREX_BW
1061
1062			Optrex	 CBL50840-2 NF-FW 99 22 M5
1063			or
1064			Hitachi	 LMG6912RPFC-00T
1065			or
1066			Hitachi	 SP14Q002
1067
1068			320x240. Black & white.
1069
1070		Normally display is black on white background; define
1071		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1072
1073- Splash Screen Support: CONFIG_SPLASH_SCREEN
1074
1075		If this option is set, the environment is checked for
1076		a variable "splashimage". If found, the usual display
1077		of logo, copyright and system information on the LCD
1078		is suppressed and the BMP image at the address
1079		specified in "splashimage" is loaded instead. The
1080		console is redirected to the "nulldev", too. This
1081		allows for a "silent" boot where a splash screen is
1082		loaded very quickly after power-on.
1083
1084		CONFIG_SPLASH_SCREEN_ALIGN
1085
1086		If this option is set the splash image can be freely positioned
1087		on the screen. Environment variable "splashpos" specifies the
1088		position as "x,y". If a positive number is given it is used as
1089		number of pixel from left/top. If a negative number is given it
1090		is used as number of pixel from right/bottom. You can also
1091		specify 'm' for centering the image.
1092
1093		Example:
1094		setenv splashpos m,m
1095			=> image at center of screen
1096
1097		setenv splashpos 30,20
1098			=> image at x = 30 and y = 20
1099
1100		setenv splashpos -10,m
1101			=> vertically centered image
1102			   at x = dspWidth - bmpWidth - 9
1103
1104- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1105
1106		If this option is set, additionally to standard BMP
1107		images, gzipped BMP images can be displayed via the
1108		splashscreen support or the bmp command.
1109
1110- Compression support:
1111		CONFIG_BZIP2
1112
1113		If this option is set, support for bzip2 compressed
1114		images is included. If not, only uncompressed and gzip
1115		compressed images are supported.
1116
1117		NOTE: the bzip2 algorithm requires a lot of RAM, so
1118		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1119		be at least 4MB.
1120
1121		CONFIG_LZMA
1122
1123		If this option is set, support for lzma compressed
1124		images is included.
1125
1126		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1127		requires an amount of dynamic memory that is given by the
1128		formula:
1129
1130			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1131
1132		Where lc and lp stand for, respectively, Literal context bits
1133		and Literal pos bits.
1134
1135		This value is upper-bounded by 14MB in the worst case. Anyway,
1136		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1137		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1138		a very small buffer.
1139
1140		Use the lzmainfo tool to determinate the lc and lp values and
1141		then calculate the amount of needed dynamic memory (ensuring
1142		the appropriate CONFIG_SYS_MALLOC_LEN value).
1143
1144- MII/PHY support:
1145		CONFIG_PHY_ADDR
1146
1147		The address of PHY on MII bus.
1148
1149		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1150
1151		The clock frequency of the MII bus
1152
1153		CONFIG_PHY_GIGE
1154
1155		If this option is set, support for speed/duplex
1156		detection of gigabit PHY is included.
1157
1158		CONFIG_PHY_RESET_DELAY
1159
1160		Some PHY like Intel LXT971A need extra delay after
1161		reset before any MII register access is possible.
1162		For such PHY, set this option to the usec delay
1163		required. (minimum 300usec for LXT971A)
1164
1165		CONFIG_PHY_CMD_DELAY (ppc4xx)
1166
1167		Some PHY like Intel LXT971A need extra delay after
1168		command issued before MII status register can be read
1169
1170- Ethernet address:
1171		CONFIG_ETHADDR
1172		CONFIG_ETH1ADDR
1173		CONFIG_ETH2ADDR
1174		CONFIG_ETH3ADDR
1175		CONFIG_ETH4ADDR
1176		CONFIG_ETH5ADDR
1177
1178		Define a default value for Ethernet address to use
1179		for the respective Ethernet interface, in case this
1180		is not determined automatically.
1181
1182- IP address:
1183		CONFIG_IPADDR
1184
1185		Define a default value for the IP address to use for
1186		the default Ethernet interface, in case this is not
1187		determined through e.g. bootp.
1188
1189- Server IP address:
1190		CONFIG_SERVERIP
1191
1192		Defines a default value for the IP address of a TFTP
1193		server to contact when using the "tftboot" command.
1194
1195		CONFIG_KEEP_SERVERADDR
1196
1197		Keeps the server's MAC address, in the env 'serveraddr'
1198		for passing to bootargs (like Linux's netconsole option)
1199
1200- Multicast TFTP Mode:
1201		CONFIG_MCAST_TFTP
1202
1203		Defines whether you want to support multicast TFTP as per
1204		rfc-2090; for example to work with atftp.  Lets lots of targets
1205		tftp down the same boot image concurrently.  Note: the Ethernet
1206		driver in use must provide a function: mcast() to join/leave a
1207		multicast group.
1208
1209		CONFIG_BOOTP_RANDOM_DELAY
1210- BOOTP Recovery Mode:
1211		CONFIG_BOOTP_RANDOM_DELAY
1212
1213		If you have many targets in a network that try to
1214		boot using BOOTP, you may want to avoid that all
1215		systems send out BOOTP requests at precisely the same
1216		moment (which would happen for instance at recovery
1217		from a power failure, when all systems will try to
1218		boot, thus flooding the BOOTP server. Defining
1219		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1220		inserted before sending out BOOTP requests. The
1221		following delays are inserted then:
1222
1223		1st BOOTP request:	delay 0 ... 1 sec
1224		2nd BOOTP request:	delay 0 ... 2 sec
1225		3rd BOOTP request:	delay 0 ... 4 sec
1226		4th and following
1227		BOOTP requests:		delay 0 ... 8 sec
1228
1229- DHCP Advanced Options:
1230		You can fine tune the DHCP functionality by defining
1231		CONFIG_BOOTP_* symbols:
1232
1233		CONFIG_BOOTP_SUBNETMASK
1234		CONFIG_BOOTP_GATEWAY
1235		CONFIG_BOOTP_HOSTNAME
1236		CONFIG_BOOTP_NISDOMAIN
1237		CONFIG_BOOTP_BOOTPATH
1238		CONFIG_BOOTP_BOOTFILESIZE
1239		CONFIG_BOOTP_DNS
1240		CONFIG_BOOTP_DNS2
1241		CONFIG_BOOTP_SEND_HOSTNAME
1242		CONFIG_BOOTP_NTPSERVER
1243		CONFIG_BOOTP_TIMEOFFSET
1244		CONFIG_BOOTP_VENDOREX
1245
1246		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1247		environment variable, not the BOOTP server.
1248
1249		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1250		serverip from a DHCP server, it is possible that more
1251		than one DNS serverip is offered to the client.
1252		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1253		serverip will be stored in the additional environment
1254		variable "dnsip2". The first DNS serverip is always
1255		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1256		is defined.
1257
1258		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1259		to do a dynamic update of a DNS server. To do this, they
1260		need the hostname of the DHCP requester.
1261		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1262		of the "hostname" environment variable is passed as
1263		option 12 to the DHCP server.
1264
1265		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1266
1267		A 32bit value in microseconds for a delay between
1268		receiving a "DHCP Offer" and sending the "DHCP Request".
1269		This fixes a problem with certain DHCP servers that don't
1270		respond 100% of the time to a "DHCP request". E.g. On an
1271		AT91RM9200 processor running at 180MHz, this delay needed
1272		to be *at least* 15,000 usec before a Windows Server 2003
1273		DHCP server would reply 100% of the time. I recommend at
1274		least 50,000 usec to be safe. The alternative is to hope
1275		that one of the retries will be successful but note that
1276		the DHCP timeout and retry process takes a longer than
1277		this delay.
1278
1279 - CDP Options:
1280		CONFIG_CDP_DEVICE_ID
1281
1282		The device id used in CDP trigger frames.
1283
1284		CONFIG_CDP_DEVICE_ID_PREFIX
1285
1286		A two character string which is prefixed to the MAC address
1287		of the device.
1288
1289		CONFIG_CDP_PORT_ID
1290
1291		A printf format string which contains the ascii name of
1292		the port. Normally is set to "eth%d" which sets
1293		eth0 for the first Ethernet, eth1 for the second etc.
1294
1295		CONFIG_CDP_CAPABILITIES
1296
1297		A 32bit integer which indicates the device capabilities;
1298		0x00000010 for a normal host which does not forwards.
1299
1300		CONFIG_CDP_VERSION
1301
1302		An ascii string containing the version of the software.
1303
1304		CONFIG_CDP_PLATFORM
1305
1306		An ascii string containing the name of the platform.
1307
1308		CONFIG_CDP_TRIGGER
1309
1310		A 32bit integer sent on the trigger.
1311
1312		CONFIG_CDP_POWER_CONSUMPTION
1313
1314		A 16bit integer containing the power consumption of the
1315		device in .1 of milliwatts.
1316
1317		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1318
1319		A byte containing the id of the VLAN.
1320
1321- Status LED:	CONFIG_STATUS_LED
1322
1323		Several configurations allow to display the current
1324		status using a LED. For instance, the LED will blink
1325		fast while running U-Boot code, stop blinking as
1326		soon as a reply to a BOOTP request was received, and
1327		start blinking slow once the Linux kernel is running
1328		(supported by a status LED driver in the Linux
1329		kernel). Defining CONFIG_STATUS_LED enables this
1330		feature in U-Boot.
1331
1332- CAN Support:	CONFIG_CAN_DRIVER
1333
1334		Defining CONFIG_CAN_DRIVER enables CAN driver support
1335		on those systems that support this (optional)
1336		feature, like the TQM8xxL modules.
1337
1338- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1339
1340		These enable I2C serial bus commands. Defining either of
1341		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1342		include the appropriate I2C driver for the selected CPU.
1343
1344		This will allow you to use i2c commands at the u-boot
1345		command line (as long as you set CONFIG_CMD_I2C in
1346		CONFIG_COMMANDS) and communicate with i2c based realtime
1347		clock chips. See common/cmd_i2c.c for a description of the
1348		command line interface.
1349
1350		CONFIG_HARD_I2C selects a hardware I2C controller.
1351
1352		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1353		bit-banging) driver instead of CPM or similar hardware
1354		support for I2C.
1355
1356		There are several other quantities that must also be
1357		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1358
1359		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1360		to be the frequency (in Hz) at which you wish your i2c bus
1361		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1362		the CPU's i2c node address).
1363
1364		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1365		sets the CPU up as a master node and so its address should
1366		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1367		p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
1368
1369		That's all that's required for CONFIG_HARD_I2C.
1370
1371		If you use the software i2c interface (CONFIG_SOFT_I2C)
1372		then the following macros need to be defined (examples are
1373		from include/configs/lwmon.h):
1374
1375		I2C_INIT
1376
1377		(Optional). Any commands necessary to enable the I2C
1378		controller or configure ports.
1379
1380		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1381
1382		I2C_PORT
1383
1384		(Only for MPC8260 CPU). The I/O port to use (the code
1385		assumes both bits are on the same port). Valid values
1386		are 0..3 for ports A..D.
1387
1388		I2C_ACTIVE
1389
1390		The code necessary to make the I2C data line active
1391		(driven).  If the data line is open collector, this
1392		define can be null.
1393
1394		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1395
1396		I2C_TRISTATE
1397
1398		The code necessary to make the I2C data line tri-stated
1399		(inactive).  If the data line is open collector, this
1400		define can be null.
1401
1402		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1403
1404		I2C_READ
1405
1406		Code that returns TRUE if the I2C data line is high,
1407		FALSE if it is low.
1408
1409		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1410
1411		I2C_SDA(bit)
1412
1413		If <bit> is TRUE, sets the I2C data line high. If it
1414		is FALSE, it clears it (low).
1415
1416		eg: #define I2C_SDA(bit) \
1417			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1418			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1419
1420		I2C_SCL(bit)
1421
1422		If <bit> is TRUE, sets the I2C clock line high. If it
1423		is FALSE, it clears it (low).
1424
1425		eg: #define I2C_SCL(bit) \
1426			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1427			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1428
1429		I2C_DELAY
1430
1431		This delay is invoked four times per clock cycle so this
1432		controls the rate of data transfer.  The data rate thus
1433		is 1 / (I2C_DELAY * 4). Often defined to be something
1434		like:
1435
1436		#define I2C_DELAY  udelay(2)
1437
1438		CONFIG_SYS_I2C_INIT_BOARD
1439
1440		When a board is reset during an i2c bus transfer
1441		chips might think that the current transfer is still
1442		in progress. On some boards it is possible to access
1443		the i2c SCLK line directly, either by using the
1444		processor pin as a GPIO or by having a second pin
1445		connected to the bus. If this option is defined a
1446		custom i2c_init_board() routine in boards/xxx/board.c
1447		is run early in the boot sequence.
1448
1449		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1450
1451		This option enables configuration of bi_iic_fast[] flags
1452		in u-boot bd_info structure based on u-boot environment
1453		variable "i2cfast". (see also i2cfast)
1454
1455		CONFIG_I2C_MULTI_BUS
1456
1457		This option allows the use of multiple I2C buses, each of which
1458		must have a controller.  At any point in time, only one bus is
1459		active.  To switch to a different bus, use the 'i2c dev' command.
1460		Note that bus numbering is zero-based.
1461
1462		CONFIG_SYS_I2C_NOPROBES
1463
1464		This option specifies a list of I2C devices that will be skipped
1465		when the 'i2c probe' command is issued.  If CONFIG_I2C_MULTI_BUS
1466		is set, specify a list of bus-device pairs.  Otherwise, specify
1467		a 1D array of device addresses
1468
1469		e.g.
1470			#undef	CONFIG_I2C_MULTI_BUS
1471			#define CONFIG_SYS_I2C_NOPROBES	{0x50,0x68}
1472
1473		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1474
1475			#define	CONFIG_I2C_MULTI_BUS
1476			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1477
1478		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1479
1480		CONFIG_SYS_SPD_BUS_NUM
1481
1482		If defined, then this indicates the I2C bus number for DDR SPD.
1483		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1484
1485		CONFIG_SYS_RTC_BUS_NUM
1486
1487		If defined, then this indicates the I2C bus number for the RTC.
1488		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1489
1490		CONFIG_SYS_DTT_BUS_NUM
1491
1492		If defined, then this indicates the I2C bus number for the DTT.
1493		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1494
1495		CONFIG_SYS_I2C_DTT_ADDR:
1496
1497		If defined, specifies the I2C address of the DTT device.
1498		If not defined, then U-Boot uses predefined value for
1499		specified DTT device.
1500
1501		CONFIG_FSL_I2C
1502
1503		Define this option if you want to use Freescale's I2C driver in
1504		drivers/i2c/fsl_i2c.c.
1505
1506		CONFIG_I2C_MUX
1507
1508		Define this option if you have I2C devices reached over 1 .. n
1509		I2C Muxes like the pca9544a. This option addes a new I2C
1510		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1511		new I2C Bus to the existing I2C Busses. If you select the
1512		new Bus with "i2c dev", u-bbot sends first the commandos for
1513		the muxes to activate this new "bus".
1514
1515		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1516		feature!
1517
1518		Example:
1519		Adding a new I2C Bus reached over 2 pca9544a muxes
1520			The First mux with address 70 and channel 6
1521			The Second mux with address 71 and channel 4
1522
1523		=> i2c bus pca9544a:70:6:pca9544a:71:4
1524
1525		Use the "i2c bus" command without parameter, to get a list
1526		of I2C Busses with muxes:
1527
1528		=> i2c bus
1529		Busses reached over muxes:
1530		Bus ID: 2
1531		  reached over Mux(es):
1532		    pca9544a@70 ch: 4
1533		Bus ID: 3
1534		  reached over Mux(es):
1535		    pca9544a@70 ch: 6
1536		    pca9544a@71 ch: 4
1537		=>
1538
1539		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1540		u-boot sends First the Commando to the mux@70 to enable
1541		channel 6, and then the Commando to the mux@71 to enable
1542		the channel 4.
1543
1544		After that, you can use the "normal" i2c commands as
1545		usual, to communicate with your I2C devices behind
1546		the 2 muxes.
1547
1548		This option is actually implemented for the bitbanging
1549		algorithm in common/soft_i2c.c and for the Hardware I2C
1550		Bus on the MPC8260. But it should be not so difficult
1551		to add this option to other architectures.
1552
1553		CONFIG_SOFT_I2C_READ_REPEATED_START
1554
1555		defining this will force the i2c_read() function in
1556		the soft_i2c driver to perform an I2C repeated start
1557		between writing the address pointer and reading the
1558		data.  If this define is omitted the default behaviour
1559		of doing a stop-start sequence will be used.  Most I2C
1560		devices can use either method, but some require one or
1561		the other.
1562
1563- SPI Support:	CONFIG_SPI
1564
1565		Enables SPI driver (so far only tested with
1566		SPI EEPROM, also an instance works with Crystal A/D and
1567		D/As on the SACSng board)
1568
1569		CONFIG_SPI_X
1570
1571		Enables extended (16-bit) SPI EEPROM addressing.
1572		(symmetrical to CONFIG_I2C_X)
1573
1574		CONFIG_SOFT_SPI
1575
1576		Enables a software (bit-bang) SPI driver rather than
1577		using hardware support. This is a general purpose
1578		driver that only requires three general I/O port pins
1579		(two outputs, one input) to function. If this is
1580		defined, the board configuration must define several
1581		SPI configuration items (port pins to use, etc). For
1582		an example, see include/configs/sacsng.h.
1583
1584		CONFIG_HARD_SPI
1585
1586		Enables a hardware SPI driver for general-purpose reads
1587		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1588		must define a list of chip-select function pointers.
1589		Currently supported on some MPC8xxx processors.  For an
1590		example, see include/configs/mpc8349emds.h.
1591
1592		CONFIG_MXC_SPI
1593
1594		Enables the driver for the SPI controllers on i.MX and MXC
1595		SoCs. Currently only i.MX31 is supported.
1596
1597- FPGA Support: CONFIG_FPGA
1598
1599		Enables FPGA subsystem.
1600
1601		CONFIG_FPGA_<vendor>
1602
1603		Enables support for specific chip vendors.
1604		(ALTERA, XILINX)
1605
1606		CONFIG_FPGA_<family>
1607
1608		Enables support for FPGA family.
1609		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1610
1611		CONFIG_FPGA_COUNT
1612
1613		Specify the number of FPGA devices to support.
1614
1615		CONFIG_SYS_FPGA_PROG_FEEDBACK
1616
1617		Enable printing of hash marks during FPGA configuration.
1618
1619		CONFIG_SYS_FPGA_CHECK_BUSY
1620
1621		Enable checks on FPGA configuration interface busy
1622		status by the configuration function. This option
1623		will require a board or device specific function to
1624		be written.
1625
1626		CONFIG_FPGA_DELAY
1627
1628		If defined, a function that provides delays in the FPGA
1629		configuration driver.
1630
1631		CONFIG_SYS_FPGA_CHECK_CTRLC
1632		Allow Control-C to interrupt FPGA configuration
1633
1634		CONFIG_SYS_FPGA_CHECK_ERROR
1635
1636		Check for configuration errors during FPGA bitfile
1637		loading. For example, abort during Virtex II
1638		configuration if the INIT_B line goes low (which
1639		indicated a CRC error).
1640
1641		CONFIG_SYS_FPGA_WAIT_INIT
1642
1643		Maximum time to wait for the INIT_B line to deassert
1644		after PROB_B has been deasserted during a Virtex II
1645		FPGA configuration sequence. The default time is 500
1646		ms.
1647
1648		CONFIG_SYS_FPGA_WAIT_BUSY
1649
1650		Maximum time to wait for BUSY to deassert during
1651		Virtex II FPGA configuration. The default is 5 ms.
1652
1653		CONFIG_SYS_FPGA_WAIT_CONFIG
1654
1655		Time to wait after FPGA configuration. The default is
1656		200 ms.
1657
1658- Configuration Management:
1659		CONFIG_IDENT_STRING
1660
1661		If defined, this string will be added to the U-Boot
1662		version information (U_BOOT_VERSION)
1663
1664- Vendor Parameter Protection:
1665
1666		U-Boot considers the values of the environment
1667		variables "serial#" (Board Serial Number) and
1668		"ethaddr" (Ethernet Address) to be parameters that
1669		are set once by the board vendor / manufacturer, and
1670		protects these variables from casual modification by
1671		the user. Once set, these variables are read-only,
1672		and write or delete attempts are rejected. You can
1673		change this behaviour:
1674
1675		If CONFIG_ENV_OVERWRITE is #defined in your config
1676		file, the write protection for vendor parameters is
1677		completely disabled. Anybody can change or delete
1678		these parameters.
1679
1680		Alternatively, if you #define _both_ CONFIG_ETHADDR
1681		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1682		Ethernet address is installed in the environment,
1683		which can be changed exactly ONCE by the user. [The
1684		serial# is unaffected by this, i. e. it remains
1685		read-only.]
1686
1687- Protected RAM:
1688		CONFIG_PRAM
1689
1690		Define this variable to enable the reservation of
1691		"protected RAM", i. e. RAM which is not overwritten
1692		by U-Boot. Define CONFIG_PRAM to hold the number of
1693		kB you want to reserve for pRAM. You can overwrite
1694		this default value by defining an environment
1695		variable "pram" to the number of kB you want to
1696		reserve. Note that the board info structure will
1697		still show the full amount of RAM. If pRAM is
1698		reserved, a new environment variable "mem" will
1699		automatically be defined to hold the amount of
1700		remaining RAM in a form that can be passed as boot
1701		argument to Linux, for instance like that:
1702
1703			setenv bootargs ... mem=\${mem}
1704			saveenv
1705
1706		This way you can tell Linux not to use this memory,
1707		either, which results in a memory region that will
1708		not be affected by reboots.
1709
1710		*WARNING* If your board configuration uses automatic
1711		detection of the RAM size, you must make sure that
1712		this memory test is non-destructive. So far, the
1713		following board configurations are known to be
1714		"pRAM-clean":
1715
1716			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1717			HERMES, IP860, RPXlite, LWMON, LANTEC,
1718			PCU_E, FLAGADM, TQM8260
1719
1720- Error Recovery:
1721		CONFIG_PANIC_HANG
1722
1723		Define this variable to stop the system in case of a
1724		fatal error, so that you have to reset it manually.
1725		This is probably NOT a good idea for an embedded
1726		system where you want the system to reboot
1727		automatically as fast as possible, but it may be
1728		useful during development since you can try to debug
1729		the conditions that lead to the situation.
1730
1731		CONFIG_NET_RETRY_COUNT
1732
1733		This variable defines the number of retries for
1734		network operations like ARP, RARP, TFTP, or BOOTP
1735		before giving up the operation. If not defined, a
1736		default value of 5 is used.
1737
1738		CONFIG_ARP_TIMEOUT
1739
1740		Timeout waiting for an ARP reply in milliseconds.
1741
1742- Command Interpreter:
1743		CONFIG_AUTO_COMPLETE
1744
1745		Enable auto completion of commands using TAB.
1746
1747		Note that this feature has NOT been implemented yet
1748		for the "hush" shell.
1749
1750
1751		CONFIG_SYS_HUSH_PARSER
1752
1753		Define this variable to enable the "hush" shell (from
1754		Busybox) as command line interpreter, thus enabling
1755		powerful command line syntax like
1756		if...then...else...fi conditionals or `&&' and '||'
1757		constructs ("shell scripts").
1758
1759		If undefined, you get the old, much simpler behaviour
1760		with a somewhat smaller memory footprint.
1761
1762
1763		CONFIG_SYS_PROMPT_HUSH_PS2
1764
1765		This defines the secondary prompt string, which is
1766		printed when the command interpreter needs more input
1767		to complete a command. Usually "> ".
1768
1769	Note:
1770
1771		In the current implementation, the local variables
1772		space and global environment variables space are
1773		separated. Local variables are those you define by
1774		simply typing `name=value'. To access a local
1775		variable later on, you have write `$name' or
1776		`${name}'; to execute the contents of a variable
1777		directly type `$name' at the command prompt.
1778
1779		Global environment variables are those you use
1780		setenv/printenv to work with. To run a command stored
1781		in such a variable, you need to use the run command,
1782		and you must not use the '$' sign to access them.
1783
1784		To store commands and special characters in a
1785		variable, please use double quotation marks
1786		surrounding the whole text of the variable, instead
1787		of the backslashes before semicolons and special
1788		symbols.
1789
1790- Commandline Editing and History:
1791		CONFIG_CMDLINE_EDITING
1792
1793		Enable editing and History functions for interactive
1794		commandline input operations
1795
1796- Default Environment:
1797		CONFIG_EXTRA_ENV_SETTINGS
1798
1799		Define this to contain any number of null terminated
1800		strings (variable = value pairs) that will be part of
1801		the default environment compiled into the boot image.
1802
1803		For example, place something like this in your
1804		board's config file:
1805
1806		#define CONFIG_EXTRA_ENV_SETTINGS \
1807			"myvar1=value1\0" \
1808			"myvar2=value2\0"
1809
1810		Warning: This method is based on knowledge about the
1811		internal format how the environment is stored by the
1812		U-Boot code. This is NOT an official, exported
1813		interface! Although it is unlikely that this format
1814		will change soon, there is no guarantee either.
1815		You better know what you are doing here.
1816
1817		Note: overly (ab)use of the default environment is
1818		discouraged. Make sure to check other ways to preset
1819		the environment like the "source" command or the
1820		boot command first.
1821
1822- DataFlash Support:
1823		CONFIG_HAS_DATAFLASH
1824
1825		Defining this option enables DataFlash features and
1826		allows to read/write in Dataflash via the standard
1827		commands cp, md...
1828
1829- SystemACE Support:
1830		CONFIG_SYSTEMACE
1831
1832		Adding this option adds support for Xilinx SystemACE
1833		chips attached via some sort of local bus. The address
1834		of the chip must also be defined in the
1835		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
1836
1837		#define CONFIG_SYSTEMACE
1838		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
1839
1840		When SystemACE support is added, the "ace" device type
1841		becomes available to the fat commands, i.e. fatls.
1842
1843- TFTP Fixed UDP Port:
1844		CONFIG_TFTP_PORT
1845
1846		If this is defined, the environment variable tftpsrcp
1847		is used to supply the TFTP UDP source port value.
1848		If tftpsrcp isn't defined, the normal pseudo-random port
1849		number generator is used.
1850
1851		Also, the environment variable tftpdstp is used to supply
1852		the TFTP UDP destination port value.  If tftpdstp isn't
1853		defined, the normal port 69 is used.
1854
1855		The purpose for tftpsrcp is to allow a TFTP server to
1856		blindly start the TFTP transfer using the pre-configured
1857		target IP address and UDP port. This has the effect of
1858		"punching through" the (Windows XP) firewall, allowing
1859		the remainder of the TFTP transfer to proceed normally.
1860		A better solution is to properly configure the firewall,
1861		but sometimes that is not allowed.
1862
1863- Show boot progress:
1864		CONFIG_SHOW_BOOT_PROGRESS
1865
1866		Defining this option allows to add some board-
1867		specific code (calling a user-provided function
1868		"show_boot_progress(int)") that enables you to show
1869		the system's boot progress on some display (for
1870		example, some LED's) on your board. At the moment,
1871		the following checkpoints are implemented:
1872
1873- Automatic software updates via TFTP server
1874		CONFIG_UPDATE_TFTP
1875		CONFIG_UPDATE_TFTP_CNT_MAX
1876		CONFIG_UPDATE_TFTP_MSEC_MAX
1877
1878		These options enable and control the auto-update feature;
1879		for a more detailed description refer to doc/README.update.
1880
1881- MTD Support (mtdparts command, UBI support)
1882		CONFIG_MTD_DEVICE
1883
1884		Adds the MTD device infrastructure from the Linux kernel.
1885		Needed for mtdparts command support.
1886
1887		CONFIG_MTD_PARTITIONS
1888
1889		Adds the MTD partitioning infrastructure from the Linux
1890		kernel. Needed for UBI support.
1891
1892Legacy uImage format:
1893
1894  Arg	Where			When
1895    1	common/cmd_bootm.c	before attempting to boot an image
1896   -1	common/cmd_bootm.c	Image header has bad	 magic number
1897    2	common/cmd_bootm.c	Image header has correct magic number
1898   -2	common/cmd_bootm.c	Image header has bad	 checksum
1899    3	common/cmd_bootm.c	Image header has correct checksum
1900   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1901    4	common/cmd_bootm.c	Image data   has correct checksum
1902   -4	common/cmd_bootm.c	Image is for unsupported architecture
1903    5	common/cmd_bootm.c	Architecture check OK
1904   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1905    6	common/cmd_bootm.c	Image Type check OK
1906   -6	common/cmd_bootm.c	gunzip uncompression error
1907   -7	common/cmd_bootm.c	Unimplemented compression type
1908    7	common/cmd_bootm.c	Uncompression OK
1909    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1910   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1911
1912    9	common/image.c		Start initial ramdisk verification
1913  -10	common/image.c		Ramdisk header has bad	   magic number
1914  -11	common/image.c		Ramdisk header has bad	   checksum
1915   10	common/image.c		Ramdisk header is OK
1916  -12	common/image.c		Ramdisk data   has bad	   checksum
1917   11	common/image.c		Ramdisk data   has correct checksum
1918   12	common/image.c		Ramdisk verification complete, start loading
1919  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
1920   13	common/image.c		Start multifile image verification
1921   14	common/image.c		No initial ramdisk, no multifile, continue.
1922
1923   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1924
1925  -30	lib_ppc/board.c		Fatal error, hang the system
1926  -31	post/post.c		POST test failed, detected by post_output_backlog()
1927  -32	post/post.c		POST test failed, detected by post_run_single()
1928
1929   34	common/cmd_doc.c	before loading a Image from a DOC device
1930  -35	common/cmd_doc.c	Bad usage of "doc" command
1931   35	common/cmd_doc.c	correct usage of "doc" command
1932  -36	common/cmd_doc.c	No boot device
1933   36	common/cmd_doc.c	correct boot device
1934  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1935   37	common/cmd_doc.c	correct chip ID found, device available
1936  -38	common/cmd_doc.c	Read Error on boot device
1937   38	common/cmd_doc.c	reading Image header from DOC device OK
1938  -39	common/cmd_doc.c	Image header has bad magic number
1939   39	common/cmd_doc.c	Image header has correct magic number
1940  -40	common/cmd_doc.c	Error reading Image from DOC device
1941   40	common/cmd_doc.c	Image header has correct magic number
1942   41	common/cmd_ide.c	before loading a Image from a IDE device
1943  -42	common/cmd_ide.c	Bad usage of "ide" command
1944   42	common/cmd_ide.c	correct usage of "ide" command
1945  -43	common/cmd_ide.c	No boot device
1946   43	common/cmd_ide.c	boot device found
1947  -44	common/cmd_ide.c	Device not available
1948   44	common/cmd_ide.c	Device available
1949  -45	common/cmd_ide.c	wrong partition selected
1950   45	common/cmd_ide.c	partition selected
1951  -46	common/cmd_ide.c	Unknown partition table
1952   46	common/cmd_ide.c	valid partition table found
1953  -47	common/cmd_ide.c	Invalid partition type
1954   47	common/cmd_ide.c	correct partition type
1955  -48	common/cmd_ide.c	Error reading Image Header on boot device
1956   48	common/cmd_ide.c	reading Image Header from IDE device OK
1957  -49	common/cmd_ide.c	Image header has bad magic number
1958   49	common/cmd_ide.c	Image header has correct magic number
1959  -50	common/cmd_ide.c	Image header has bad	 checksum
1960   50	common/cmd_ide.c	Image header has correct checksum
1961  -51	common/cmd_ide.c	Error reading Image from IDE device
1962   51	common/cmd_ide.c	reading Image from IDE device OK
1963   52	common/cmd_nand.c	before loading a Image from a NAND device
1964  -53	common/cmd_nand.c	Bad usage of "nand" command
1965   53	common/cmd_nand.c	correct usage of "nand" command
1966  -54	common/cmd_nand.c	No boot device
1967   54	common/cmd_nand.c	boot device found
1968  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1969   55	common/cmd_nand.c	correct chip ID found, device available
1970  -56	common/cmd_nand.c	Error reading Image Header on boot device
1971   56	common/cmd_nand.c	reading Image Header from NAND device OK
1972  -57	common/cmd_nand.c	Image header has bad magic number
1973   57	common/cmd_nand.c	Image header has correct magic number
1974  -58	common/cmd_nand.c	Error reading Image from NAND device
1975   58	common/cmd_nand.c	reading Image from NAND device OK
1976
1977  -60	common/env_common.c	Environment has a bad CRC, using default
1978
1979   64	net/eth.c		starting with Ethernet configuration.
1980  -64	net/eth.c		no Ethernet found.
1981   65	net/eth.c		Ethernet found.
1982
1983  -80	common/cmd_net.c	usage wrong
1984   80	common/cmd_net.c	before calling NetLoop()
1985  -81	common/cmd_net.c	some error in NetLoop() occurred
1986   81	common/cmd_net.c	NetLoop() back without error
1987  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1988   82	common/cmd_net.c	trying automatic boot
1989   83	common/cmd_net.c	running "source" command
1990  -83	common/cmd_net.c	some error in automatic boot or "source" command
1991   84	common/cmd_net.c	end without errors
1992
1993FIT uImage format:
1994
1995  Arg	Where			When
1996  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1997 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1998  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1999 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2000  102	common/cmd_bootm.c	Kernel unit name specified
2001 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2002  103	common/cmd_bootm.c	Found configuration node
2003  104	common/cmd_bootm.c	Got kernel subimage node offset
2004 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2005  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2006 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2007  106	common/cmd_bootm.c	Architecture check OK
2008 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2009  107	common/cmd_bootm.c	Kernel subimage type OK
2010 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2011  108	common/cmd_bootm.c	Got kernel subimage data/size
2012 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2013 -109	common/cmd_bootm.c	Can't get kernel subimage type
2014 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2015 -111	common/cmd_bootm.c	Can't get kernel subimage os
2016 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2017 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2018
2019  120	common/image.c		Start initial ramdisk verification
2020 -120	common/image.c		Ramdisk FIT image has incorrect format
2021  121	common/image.c		Ramdisk FIT image has correct format
2022  122	common/image.c		No ramdisk subimage unit name, using configuration
2023 -122	common/image.c		Can't get configuration for ramdisk subimage
2024  123	common/image.c		Ramdisk unit name specified
2025 -124	common/image.c		Can't get ramdisk subimage node offset
2026  125	common/image.c		Got ramdisk subimage node offset
2027 -125	common/image.c		Ramdisk subimage hash verification failed
2028  126	common/image.c		Ramdisk subimage hash verification OK
2029 -126	common/image.c		Ramdisk subimage for unsupported architecture
2030  127	common/image.c		Architecture check OK
2031 -127	common/image.c		Can't get ramdisk subimage data/size
2032  128	common/image.c		Got ramdisk subimage data/size
2033  129	common/image.c		Can't get ramdisk load address
2034 -129	common/image.c		Got ramdisk load address
2035
2036 -130	common/cmd_doc.c	Incorrect FIT image format
2037  131	common/cmd_doc.c	FIT image format OK
2038
2039 -140	common/cmd_ide.c	Incorrect FIT image format
2040  141	common/cmd_ide.c	FIT image format OK
2041
2042 -150	common/cmd_nand.c	Incorrect FIT image format
2043  151	common/cmd_nand.c	FIT image format OK
2044
2045
2046Modem Support:
2047--------------
2048
2049[so far only for SMDK2400 and TRAB boards]
2050
2051- Modem support enable:
2052		CONFIG_MODEM_SUPPORT
2053
2054- RTS/CTS Flow control enable:
2055		CONFIG_HWFLOW
2056
2057- Modem debug support:
2058		CONFIG_MODEM_SUPPORT_DEBUG
2059
2060		Enables debugging stuff (char screen[1024], dbg())
2061		for modem support. Useful only with BDI2000.
2062
2063- Interrupt support (PPC):
2064
2065		There are common interrupt_init() and timer_interrupt()
2066		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2067		for CPU specific initialization. interrupt_init_cpu()
2068		should set decrementer_count to appropriate value. If
2069		CPU resets decrementer automatically after interrupt
2070		(ppc4xx) it should set decrementer_count to zero.
2071		timer_interrupt() calls timer_interrupt_cpu() for CPU
2072		specific handling. If board has watchdog / status_led
2073		/ other_activity_monitor it works automatically from
2074		general timer_interrupt().
2075
2076- General:
2077
2078		In the target system modem support is enabled when a
2079		specific key (key combination) is pressed during
2080		power-on. Otherwise U-Boot will boot normally
2081		(autoboot). The key_pressed() function is called from
2082		board_init(). Currently key_pressed() is a dummy
2083		function, returning 1 and thus enabling modem
2084		initialization.
2085
2086		If there are no modem init strings in the
2087		environment, U-Boot proceed to autoboot; the
2088		previous output (banner, info printfs) will be
2089		suppressed, though.
2090
2091		See also: doc/README.Modem
2092
2093
2094Configuration Settings:
2095-----------------------
2096
2097- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2098		undefine this when you're short of memory.
2099
2100- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2101		width of the commands listed in the 'help' command output.
2102
2103- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2104		prompt for user input.
2105
2106- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2107
2108- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2109
2110- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2111
2112- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2113		the application (usually a Linux kernel) when it is
2114		booted
2115
2116- CONFIG_SYS_BAUDRATE_TABLE:
2117		List of legal baudrate settings for this board.
2118
2119- CONFIG_SYS_CONSOLE_INFO_QUIET
2120		Suppress display of console information at boot.
2121
2122- CONFIG_SYS_CONSOLE_IS_IN_ENV
2123		If the board specific function
2124			extern int overwrite_console (void);
2125		returns 1, the stdin, stderr and stdout are switched to the
2126		serial port, else the settings in the environment are used.
2127
2128- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2129		Enable the call to overwrite_console().
2130
2131- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2132		Enable overwrite of previous console environment settings.
2133
2134- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2135		Begin and End addresses of the area used by the
2136		simple memory test.
2137
2138- CONFIG_SYS_ALT_MEMTEST:
2139		Enable an alternate, more extensive memory test.
2140
2141- CONFIG_SYS_MEMTEST_SCRATCH:
2142		Scratch address used by the alternate memory test
2143		You only need to set this if address zero isn't writeable
2144
2145- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2146		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2147		this specified memory area will get subtracted from the top
2148		(end) of RAM and won't get "touched" at all by U-Boot. By
2149		fixing up gd->ram_size the Linux kernel should gets passed
2150		the now "corrected" memory size and won't touch it either.
2151		This should work for arch/ppc and arch/powerpc. Only Linux
2152		board ports in arch/powerpc with bootwrapper support that
2153		recalculate the memory size from the SDRAM controller setup
2154		will have to get fixed in Linux additionally.
2155
2156		This option can be used as a workaround for the 440EPx/GRx
2157		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2158		be touched.
2159
2160		WARNING: Please make sure that this value is a multiple of
2161		the Linux page size (normally 4k). If this is not the case,
2162		then the end address of the Linux memory will be located at a
2163		non page size aligned address and this could cause major
2164		problems.
2165
2166- CONFIG_SYS_TFTP_LOADADDR:
2167		Default load address for network file downloads
2168
2169- CONFIG_SYS_LOADS_BAUD_CHANGE:
2170		Enable temporary baudrate change while serial download
2171
2172- CONFIG_SYS_SDRAM_BASE:
2173		Physical start address of SDRAM. _Must_ be 0 here.
2174
2175- CONFIG_SYS_MBIO_BASE:
2176		Physical start address of Motherboard I/O (if using a
2177		Cogent motherboard)
2178
2179- CONFIG_SYS_FLASH_BASE:
2180		Physical start address of Flash memory.
2181
2182- CONFIG_SYS_MONITOR_BASE:
2183		Physical start address of boot monitor code (set by
2184		make config files to be same as the text base address
2185		(TEXT_BASE) used when linking) - same as
2186		CONFIG_SYS_FLASH_BASE when booting from flash.
2187
2188- CONFIG_SYS_MONITOR_LEN:
2189		Size of memory reserved for monitor code, used to
2190		determine _at_compile_time_ (!) if the environment is
2191		embedded within the U-Boot image, or in a separate
2192		flash sector.
2193
2194- CONFIG_SYS_MALLOC_LEN:
2195		Size of DRAM reserved for malloc() use.
2196
2197- CONFIG_SYS_BOOTM_LEN:
2198		Normally compressed uImages are limited to an
2199		uncompressed size of 8 MBytes. If this is not enough,
2200		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2201		to adjust this setting to your needs.
2202
2203- CONFIG_SYS_BOOTMAPSZ:
2204		Maximum size of memory mapped by the startup code of
2205		the Linux kernel; all data that must be processed by
2206		the Linux kernel (bd_info, boot arguments, FDT blob if
2207		used) must be put below this limit, unless "bootm_low"
2208		enviroment variable is defined and non-zero. In such case
2209		all data for the Linux kernel must be between "bootm_low"
2210		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
2211
2212- CONFIG_SYS_MAX_FLASH_BANKS:
2213		Max number of Flash memory banks
2214
2215- CONFIG_SYS_MAX_FLASH_SECT:
2216		Max number of sectors on a Flash chip
2217
2218- CONFIG_SYS_FLASH_ERASE_TOUT:
2219		Timeout for Flash erase operations (in ms)
2220
2221- CONFIG_SYS_FLASH_WRITE_TOUT:
2222		Timeout for Flash write operations (in ms)
2223
2224- CONFIG_SYS_FLASH_LOCK_TOUT
2225		Timeout for Flash set sector lock bit operation (in ms)
2226
2227- CONFIG_SYS_FLASH_UNLOCK_TOUT
2228		Timeout for Flash clear lock bits operation (in ms)
2229
2230- CONFIG_SYS_FLASH_PROTECTION
2231		If defined, hardware flash sectors protection is used
2232		instead of U-Boot software protection.
2233
2234- CONFIG_SYS_DIRECT_FLASH_TFTP:
2235
2236		Enable TFTP transfers directly to flash memory;
2237		without this option such a download has to be
2238		performed in two steps: (1) download to RAM, and (2)
2239		copy from RAM to flash.
2240
2241		The two-step approach is usually more reliable, since
2242		you can check if the download worked before you erase
2243		the flash, but in some situations (when system RAM is
2244		too limited to allow for a temporary copy of the
2245		downloaded image) this option may be very useful.
2246
2247- CONFIG_SYS_FLASH_CFI:
2248		Define if the flash driver uses extra elements in the
2249		common flash structure for storing flash geometry.
2250
2251- CONFIG_FLASH_CFI_DRIVER
2252		This option also enables the building of the cfi_flash driver
2253		in the drivers directory
2254
2255- CONFIG_FLASH_CFI_MTD
2256		This option enables the building of the cfi_mtd driver
2257		in the drivers directory. The driver exports CFI flash
2258		to the MTD layer.
2259
2260- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2261		Use buffered writes to flash.
2262
2263- CONFIG_FLASH_SPANSION_S29WS_N
2264		s29ws-n MirrorBit flash has non-standard addresses for buffered
2265		write commands.
2266
2267- CONFIG_SYS_FLASH_QUIET_TEST
2268		If this option is defined, the common CFI flash doesn't
2269		print it's warning upon not recognized FLASH banks. This
2270		is useful, if some of the configured banks are only
2271		optionally available.
2272
2273- CONFIG_FLASH_SHOW_PROGRESS
2274		If defined (must be an integer), print out countdown
2275		digits and dots.  Recommended value: 45 (9..1) for 80
2276		column displays, 15 (3..1) for 40 column displays.
2277
2278- CONFIG_SYS_RX_ETH_BUFFER:
2279		Defines the number of Ethernet receive buffers. On some
2280		Ethernet controllers it is recommended to set this value
2281		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2282		buffers can be full shortly after enabling the interface
2283		on high Ethernet traffic.
2284		Defaults to 4 if not defined.
2285
2286The following definitions that deal with the placement and management
2287of environment data (variable area); in general, we support the
2288following configurations:
2289
2290- CONFIG_ENV_IS_IN_FLASH:
2291
2292	Define this if the environment is in flash memory.
2293
2294	a) The environment occupies one whole flash sector, which is
2295	   "embedded" in the text segment with the U-Boot code. This
2296	   happens usually with "bottom boot sector" or "top boot
2297	   sector" type flash chips, which have several smaller
2298	   sectors at the start or the end. For instance, such a
2299	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2300	   such a case you would place the environment in one of the
2301	   4 kB sectors - with U-Boot code before and after it. With
2302	   "top boot sector" type flash chips, you would put the
2303	   environment in one of the last sectors, leaving a gap
2304	   between U-Boot and the environment.
2305
2306	- CONFIG_ENV_OFFSET:
2307
2308	   Offset of environment data (variable area) to the
2309	   beginning of flash memory; for instance, with bottom boot
2310	   type flash chips the second sector can be used: the offset
2311	   for this sector is given here.
2312
2313	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2314
2315	- CONFIG_ENV_ADDR:
2316
2317	   This is just another way to specify the start address of
2318	   the flash sector containing the environment (instead of
2319	   CONFIG_ENV_OFFSET).
2320
2321	- CONFIG_ENV_SECT_SIZE:
2322
2323	   Size of the sector containing the environment.
2324
2325
2326	b) Sometimes flash chips have few, equal sized, BIG sectors.
2327	   In such a case you don't want to spend a whole sector for
2328	   the environment.
2329
2330	- CONFIG_ENV_SIZE:
2331
2332	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2333	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2334	   of this flash sector for the environment. This saves
2335	   memory for the RAM copy of the environment.
2336
2337	   It may also save flash memory if you decide to use this
2338	   when your environment is "embedded" within U-Boot code,
2339	   since then the remainder of the flash sector could be used
2340	   for U-Boot code. It should be pointed out that this is
2341	   STRONGLY DISCOURAGED from a robustness point of view:
2342	   updating the environment in flash makes it always
2343	   necessary to erase the WHOLE sector. If something goes
2344	   wrong before the contents has been restored from a copy in
2345	   RAM, your target system will be dead.
2346
2347	- CONFIG_ENV_ADDR_REDUND
2348	  CONFIG_ENV_SIZE_REDUND
2349
2350	   These settings describe a second storage area used to hold
2351	   a redundant copy of the environment data, so that there is
2352	   a valid backup copy in case there is a power failure during
2353	   a "saveenv" operation.
2354
2355BE CAREFUL! Any changes to the flash layout, and some changes to the
2356source code will make it necessary to adapt <board>/u-boot.lds*
2357accordingly!
2358
2359
2360- CONFIG_ENV_IS_IN_NVRAM:
2361
2362	Define this if you have some non-volatile memory device
2363	(NVRAM, battery buffered SRAM) which you want to use for the
2364	environment.
2365
2366	- CONFIG_ENV_ADDR:
2367	- CONFIG_ENV_SIZE:
2368
2369	  These two #defines are used to determine the memory area you
2370	  want to use for environment. It is assumed that this memory
2371	  can just be read and written to, without any special
2372	  provision.
2373
2374BE CAREFUL! The first access to the environment happens quite early
2375in U-Boot initalization (when we try to get the setting of for the
2376console baudrate). You *MUST* have mapped your NVRAM area then, or
2377U-Boot will hang.
2378
2379Please note that even with NVRAM we still use a copy of the
2380environment in RAM: we could work on NVRAM directly, but we want to
2381keep settings there always unmodified except somebody uses "saveenv"
2382to save the current settings.
2383
2384
2385- CONFIG_ENV_IS_IN_EEPROM:
2386
2387	Use this if you have an EEPROM or similar serial access
2388	device and a driver for it.
2389
2390	- CONFIG_ENV_OFFSET:
2391	- CONFIG_ENV_SIZE:
2392
2393	  These two #defines specify the offset and size of the
2394	  environment area within the total memory of your EEPROM.
2395
2396	- CONFIG_SYS_I2C_EEPROM_ADDR:
2397	  If defined, specified the chip address of the EEPROM device.
2398	  The default address is zero.
2399
2400	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2401	  If defined, the number of bits used to address bytes in a
2402	  single page in the EEPROM device.  A 64 byte page, for example
2403	  would require six bits.
2404
2405	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2406	  If defined, the number of milliseconds to delay between
2407	  page writes.	The default is zero milliseconds.
2408
2409	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2410	  The length in bytes of the EEPROM memory array address.  Note
2411	  that this is NOT the chip address length!
2412
2413	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2414	  EEPROM chips that implement "address overflow" are ones
2415	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2416	  address and the extra bits end up in the "chip address" bit
2417	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2418	  byte chips.
2419
2420	  Note that we consider the length of the address field to
2421	  still be one byte because the extra address bits are hidden
2422	  in the chip address.
2423
2424	- CONFIG_SYS_EEPROM_SIZE:
2425	  The size in bytes of the EEPROM device.
2426
2427
2428- CONFIG_ENV_IS_IN_DATAFLASH:
2429
2430	Define this if you have a DataFlash memory device which you
2431	want to use for the environment.
2432
2433	- CONFIG_ENV_OFFSET:
2434	- CONFIG_ENV_ADDR:
2435	- CONFIG_ENV_SIZE:
2436
2437	  These three #defines specify the offset and size of the
2438	  environment area within the total memory of your DataFlash placed
2439	  at the specified address.
2440
2441- CONFIG_ENV_IS_IN_NAND:
2442
2443	Define this if you have a NAND device which you want to use
2444	for the environment.
2445
2446	- CONFIG_ENV_OFFSET:
2447	- CONFIG_ENV_SIZE:
2448
2449	  These two #defines specify the offset and size of the environment
2450	  area within the first NAND device.
2451
2452	- CONFIG_ENV_OFFSET_REDUND
2453
2454	  This setting describes a second storage area of CONFIG_ENV_SIZE
2455	  size used to hold a redundant copy of the environment data,
2456	  so that there is a valid backup copy in case there is a
2457	  power failure during a "saveenv" operation.
2458
2459	Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2460	to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2461	the NAND devices block size.
2462
2463- CONFIG_NAND_ENV_DST
2464
2465	Defines address in RAM to which the nand_spl code should copy the
2466	environment. If redundant environment is used, it will be copied to
2467	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2468
2469- CONFIG_SYS_SPI_INIT_OFFSET
2470
2471	Defines offset to the initial SPI buffer area in DPRAM. The
2472	area is used at an early stage (ROM part) if the environment
2473	is configured to reside in the SPI EEPROM: We need a 520 byte
2474	scratch DPRAM area. It is used between the two initialization
2475	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2476	to be a good choice since it makes it far enough from the
2477	start of the data area as well as from the stack pointer.
2478
2479Please note that the environment is read-only until the monitor
2480has been relocated to RAM and a RAM copy of the environment has been
2481created; also, when using EEPROM you will have to use getenv_r()
2482until then to read environment variables.
2483
2484The environment is protected by a CRC32 checksum. Before the monitor
2485is relocated into RAM, as a result of a bad CRC you will be working
2486with the compiled-in default environment - *silently*!!! [This is
2487necessary, because the first environment variable we need is the
2488"baudrate" setting for the console - if we have a bad CRC, we don't
2489have any device yet where we could complain.]
2490
2491Note: once the monitor has been relocated, then it will complain if
2492the default environment is used; a new CRC is computed as soon as you
2493use the "saveenv" command to store a valid environment.
2494
2495- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2496		Echo the inverted Ethernet link state to the fault LED.
2497
2498		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2499		      also needs to be defined.
2500
2501- CONFIG_SYS_FAULT_MII_ADDR:
2502		MII address of the PHY to check for the Ethernet link state.
2503
2504- CONFIG_SYS_64BIT_VSPRINTF:
2505		Makes vsprintf (and all *printf functions) support printing
2506		of 64bit values by using the L quantifier
2507
2508- CONFIG_SYS_64BIT_STRTOUL:
2509		Adds simple_strtoull that returns a 64bit value
2510
2511- CONFIG_NS16550_MIN_FUNCTIONS:
2512		Define this if you desire to only have use of the NS16550_init
2513		and NS16550_putc functions for the serial driver located at
2514		drivers/serial/ns16550.c.  This option is useful for saving
2515		space for already greatly restricted images, including but not
2516		limited to NAND_SPL configurations.
2517
2518Low Level (hardware related) configuration options:
2519---------------------------------------------------
2520
2521- CONFIG_SYS_CACHELINE_SIZE:
2522		Cache Line Size of the CPU.
2523
2524- CONFIG_SYS_DEFAULT_IMMR:
2525		Default address of the IMMR after system reset.
2526
2527		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2528		and RPXsuper) to be able to adjust the position of
2529		the IMMR register after a reset.
2530
2531- Floppy Disk Support:
2532		CONFIG_SYS_FDC_DRIVE_NUMBER
2533
2534		the default drive number (default value 0)
2535
2536		CONFIG_SYS_ISA_IO_STRIDE
2537
2538		defines the spacing between FDC chipset registers
2539		(default value 1)
2540
2541		CONFIG_SYS_ISA_IO_OFFSET
2542
2543		defines the offset of register from address. It
2544		depends on which part of the data bus is connected to
2545		the FDC chipset. (default value 0)
2546
2547		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2548		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2549		default value.
2550
2551		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2552		fdc_hw_init() is called at the beginning of the FDC
2553		setup. fdc_hw_init() must be provided by the board
2554		source code. It is used to make hardware dependant
2555		initializations.
2556
2557- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
2558		DO NOT CHANGE unless you know exactly what you're
2559		doing! (11-4) [MPC8xx/82xx systems only]
2560
2561- CONFIG_SYS_INIT_RAM_ADDR:
2562
2563		Start address of memory area that can be used for
2564		initial data and stack; please note that this must be
2565		writable memory that is working WITHOUT special
2566		initialization, i. e. you CANNOT use normal RAM which
2567		will become available only after programming the
2568		memory controller and running certain initialization
2569		sequences.
2570
2571		U-Boot uses the following memory types:
2572		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2573		- MPC824X: data cache
2574		- PPC4xx:  data cache
2575
2576- CONFIG_SYS_GBL_DATA_OFFSET:
2577
2578		Offset of the initial data structure in the memory
2579		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2580		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2581		data is located at the end of the available space
2582		(sometimes written as (CONFIG_SYS_INIT_RAM_END -
2583		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
2584		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2585		CONFIG_SYS_GBL_DATA_OFFSET) downward.
2586
2587	Note:
2588		On the MPC824X (or other systems that use the data
2589		cache for initial memory) the address chosen for
2590		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2591		point to an otherwise UNUSED address space between
2592		the top of RAM and the start of the PCI space.
2593
2594- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
2595
2596- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
2597
2598- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
2599
2600- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
2601
2602- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2603
2604- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
2605
2606- CONFIG_SYS_OR_TIMING_SDRAM:
2607		SDRAM timing
2608
2609- CONFIG_SYS_MAMR_PTA:
2610		periodic timer for refresh
2611
2612- CONFIG_SYS_DER:	Debug Event Register (37-47)
2613
2614- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2615  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2616  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2617  CONFIG_SYS_BR1_PRELIM:
2618		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2619
2620- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2621  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2622  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2623		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2624
2625- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
2626  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
2627		Machine Mode Register and Memory Periodic Timer
2628		Prescaler definitions (SDRAM timing)
2629
2630- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
2631		enable I2C microcode relocation patch (MPC8xx);
2632		define relocation offset in DPRAM [DSP2]
2633
2634- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
2635		enable SMC microcode relocation patch (MPC8xx);
2636		define relocation offset in DPRAM [SMC1]
2637
2638- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
2639		enable SPI microcode relocation patch (MPC8xx);
2640		define relocation offset in DPRAM [SCC4]
2641
2642- CONFIG_SYS_USE_OSCCLK:
2643		Use OSCM clock mode on MBX8xx board. Be careful,
2644		wrong setting might damage your board. Read
2645		doc/README.MBX before setting this variable!
2646
2647- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2648		Offset of the bootmode word in DPRAM used by post
2649		(Power On Self Tests). This definition overrides
2650		#define'd default value in commproc.h resp.
2651		cpm_8260.h.
2652
2653- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
2654  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
2655  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
2656  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
2657  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2658  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
2659  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
2660  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
2661		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2662
2663- CONFIG_PCI_DISABLE_PCIE:
2664		Disable PCI-Express on systems where it is supported but not
2665		required.
2666
2667- CONFIG_SPD_EEPROM
2668		Get DDR timing information from an I2C EEPROM. Common
2669		with pluggable memory modules such as SODIMMs
2670
2671  SPD_EEPROM_ADDRESS
2672		I2C address of the SPD EEPROM
2673
2674- CONFIG_SYS_SPD_BUS_NUM
2675		If SPD EEPROM is on an I2C bus other than the first
2676		one, specify here. Note that the value must resolve
2677		to something your driver can deal with.
2678
2679- CONFIG_SYS_83XX_DDR_USES_CS0
2680		Only for 83xx systems. If specified, then DDR should
2681		be configured using CS0 and CS1 instead of CS2 and CS3.
2682
2683- CONFIG_ETHER_ON_FEC[12]
2684		Define to enable FEC[12] on a 8xx series processor.
2685
2686- CONFIG_FEC[12]_PHY
2687		Define to the hardcoded PHY address which corresponds
2688		to the given FEC; i. e.
2689			#define CONFIG_FEC1_PHY 4
2690		means that the PHY with address 4 is connected to FEC1
2691
2692		When set to -1, means to probe for first available.
2693
2694- CONFIG_FEC[12]_PHY_NORXERR
2695		The PHY does not have a RXERR line (RMII only).
2696		(so program the FEC to ignore it).
2697
2698- CONFIG_RMII
2699		Enable RMII mode for all FECs.
2700		Note that this is a global option, we can't
2701		have one FEC in standard MII mode and another in RMII mode.
2702
2703- CONFIG_CRC32_VERIFY
2704		Add a verify option to the crc32 command.
2705		The syntax is:
2706
2707		=> crc32 -v <address> <count> <crc32>
2708
2709		Where address/count indicate a memory area
2710		and crc32 is the correct crc32 which the
2711		area should have.
2712
2713- CONFIG_LOOPW
2714		Add the "loopw" memory command. This only takes effect if
2715		the memory commands are activated globally (CONFIG_CMD_MEM).
2716
2717- CONFIG_MX_CYCLIC
2718		Add the "mdc" and "mwc" memory commands. These are cyclic
2719		"md/mw" commands.
2720		Examples:
2721
2722		=> mdc.b 10 4 500
2723		This command will print 4 bytes (10,11,12,13) each 500 ms.
2724
2725		=> mwc.l 100 12345678 10
2726		This command will write 12345678 to address 100 all 10 ms.
2727
2728		This only takes effect if the memory commands are activated
2729		globally (CONFIG_CMD_MEM).
2730
2731- CONFIG_SKIP_LOWLEVEL_INIT
2732- CONFIG_SKIP_RELOCATE_UBOOT
2733
2734		[ARM only] If these variables are defined, then
2735		certain low level initializations (like setting up
2736		the memory controller) are omitted and/or U-Boot does
2737		not relocate itself into RAM.
2738		Normally these variables MUST NOT be defined. The
2739		only exception is when U-Boot is loaded (to RAM) by
2740		some other boot loader or by a debugger which
2741		performs these initializations itself.
2742
2743- CONFIG_PRELOADER
2744
2745		Modifies the behaviour of start.S when compiling a loader
2746		that is executed before the actual U-Boot. E.g. when
2747		compiling a NAND SPL.
2748
2749Building the Software:
2750======================
2751
2752Building U-Boot has been tested in several native build environments
2753and in many different cross environments. Of course we cannot support
2754all possibly existing versions of cross development tools in all
2755(potentially obsolete) versions. In case of tool chain problems we
2756recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2757which is extensively used to build and test U-Boot.
2758
2759If you are not using a native environment, it is assumed that you
2760have GNU cross compiling tools available in your path. In this case,
2761you must set the environment variable CROSS_COMPILE in your shell.
2762Note that no changes to the Makefile or any other source files are
2763necessary. For example using the ELDK on a 4xx CPU, please enter:
2764
2765	$ CROSS_COMPILE=ppc_4xx-
2766	$ export CROSS_COMPILE
2767
2768Note: If you wish to generate Windows versions of the utilities in
2769      the tools directory you can use the MinGW toolchain
2770      (http://www.mingw.org).  Set your HOST tools to the MinGW
2771      toolchain and execute 'make tools'.  For example:
2772
2773       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
2774
2775      Binaries such as tools/mkimage.exe will be created which can
2776      be executed on computers running Windows.
2777
2778U-Boot is intended to be simple to build. After installing the
2779sources you must configure U-Boot for one specific board type. This
2780is done by typing:
2781
2782	make NAME_config
2783
2784where "NAME_config" is the name of one of the existing configu-
2785rations; see the main Makefile for supported names.
2786
2787Note: for some board special configuration names may exist; check if
2788      additional information is available from the board vendor; for
2789      instance, the TQM823L systems are available without (standard)
2790      or with LCD support. You can select such additional "features"
2791      when choosing the configuration, i. e.
2792
2793      make TQM823L_config
2794	- will configure for a plain TQM823L, i. e. no LCD support
2795
2796      make TQM823L_LCD_config
2797	- will configure for a TQM823L with U-Boot console on LCD
2798
2799      etc.
2800
2801
2802Finally, type "make all", and you should get some working U-Boot
2803images ready for download to / installation on your system:
2804
2805- "u-boot.bin" is a raw binary image
2806- "u-boot" is an image in ELF binary format
2807- "u-boot.srec" is in Motorola S-Record format
2808
2809By default the build is performed locally and the objects are saved
2810in the source directory. One of the two methods can be used to change
2811this behavior and build U-Boot to some external directory:
2812
28131. Add O= to the make command line invocations:
2814
2815	make O=/tmp/build distclean
2816	make O=/tmp/build NAME_config
2817	make O=/tmp/build all
2818
28192. Set environment variable BUILD_DIR to point to the desired location:
2820
2821	export BUILD_DIR=/tmp/build
2822	make distclean
2823	make NAME_config
2824	make all
2825
2826Note that the command line "O=" setting overrides the BUILD_DIR environment
2827variable.
2828
2829
2830Please be aware that the Makefiles assume you are using GNU make, so
2831for instance on NetBSD you might need to use "gmake" instead of
2832native "make".
2833
2834
2835If the system board that you have is not listed, then you will need
2836to port U-Boot to your hardware platform. To do this, follow these
2837steps:
2838
28391.  Add a new configuration option for your board to the toplevel
2840    "Makefile" and to the "MAKEALL" script, using the existing
2841    entries as examples. Note that here and at many other places
2842    boards and other names are listed in alphabetical sort order. Please
2843    keep this order.
28442.  Create a new directory to hold your board specific code. Add any
2845    files you need. In your board directory, you will need at least
2846    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
28473.  Create a new configuration file "include/configs/<board>.h" for
2848    your board
28493.  If you're porting U-Boot to a new CPU, then also create a new
2850    directory to hold your CPU specific code. Add any files you need.
28514.  Run "make <board>_config" with your new name.
28525.  Type "make", and you should get a working "u-boot.srec" file
2853    to be installed on your target system.
28546.  Debug and solve any problems that might arise.
2855    [Of course, this last step is much harder than it sounds.]
2856
2857
2858Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2859==============================================================
2860
2861If you have modified U-Boot sources (for instance added a new board
2862or support for new devices, a new CPU, etc.) you are expected to
2863provide feedback to the other developers. The feedback normally takes
2864the form of a "patch", i. e. a context diff against a certain (latest
2865official or latest in the git repository) version of U-Boot sources.
2866
2867But before you submit such a patch, please verify that your modifi-
2868cation did not break existing code. At least make sure that *ALL* of
2869the supported boards compile WITHOUT ANY compiler warnings. To do so,
2870just run the "MAKEALL" script, which will configure and build U-Boot
2871for ALL supported system. Be warned, this will take a while. You can
2872select which (cross) compiler to use by passing a `CROSS_COMPILE'
2873environment variable to the script, i. e. to use the ELDK cross tools
2874you can type
2875
2876	CROSS_COMPILE=ppc_8xx- MAKEALL
2877
2878or to build on a native PowerPC system you can type
2879
2880	CROSS_COMPILE=' ' MAKEALL
2881
2882When using the MAKEALL script, the default behaviour is to build
2883U-Boot in the source directory. This location can be changed by
2884setting the BUILD_DIR environment variable. Also, for each target
2885built, the MAKEALL script saves two log files (<target>.ERR and
2886<target>.MAKEALL) in the <source dir>/LOG directory. This default
2887location can be changed by setting the MAKEALL_LOGDIR environment
2888variable. For example:
2889
2890	export BUILD_DIR=/tmp/build
2891	export MAKEALL_LOGDIR=/tmp/log
2892	CROSS_COMPILE=ppc_8xx- MAKEALL
2893
2894With the above settings build objects are saved in the /tmp/build,
2895log files are saved in the /tmp/log and the source tree remains clean
2896during the whole build process.
2897
2898
2899See also "U-Boot Porting Guide" below.
2900
2901
2902Monitor Commands - Overview:
2903============================
2904
2905go	- start application at address 'addr'
2906run	- run commands in an environment variable
2907bootm	- boot application image from memory
2908bootp	- boot image via network using BootP/TFTP protocol
2909tftpboot- boot image via network using TFTP protocol
2910	       and env variables "ipaddr" and "serverip"
2911	       (and eventually "gatewayip")
2912rarpboot- boot image via network using RARP/TFTP protocol
2913diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2914loads	- load S-Record file over serial line
2915loadb	- load binary file over serial line (kermit mode)
2916md	- memory display
2917mm	- memory modify (auto-incrementing)
2918nm	- memory modify (constant address)
2919mw	- memory write (fill)
2920cp	- memory copy
2921cmp	- memory compare
2922crc32	- checksum calculation
2923i2c	- I2C sub-system
2924sspi	- SPI utility commands
2925base	- print or set address offset
2926printenv- print environment variables
2927setenv	- set environment variables
2928saveenv - save environment variables to persistent storage
2929protect - enable or disable FLASH write protection
2930erase	- erase FLASH memory
2931flinfo	- print FLASH memory information
2932bdinfo	- print Board Info structure
2933iminfo	- print header information for application image
2934coninfo - print console devices and informations
2935ide	- IDE sub-system
2936loop	- infinite loop on address range
2937loopw	- infinite write loop on address range
2938mtest	- simple RAM test
2939icache	- enable or disable instruction cache
2940dcache	- enable or disable data cache
2941reset	- Perform RESET of the CPU
2942echo	- echo args to console
2943version - print monitor version
2944help	- print online help
2945?	- alias for 'help'
2946
2947
2948Monitor Commands - Detailed Description:
2949========================================
2950
2951TODO.
2952
2953For now: just type "help <command>".
2954
2955
2956Environment Variables:
2957======================
2958
2959U-Boot supports user configuration using Environment Variables which
2960can be made persistent by saving to Flash memory.
2961
2962Environment Variables are set using "setenv", printed using
2963"printenv", and saved to Flash using "saveenv". Using "setenv"
2964without a value can be used to delete a variable from the
2965environment. As long as you don't save the environment you are
2966working with an in-memory copy. In case the Flash area containing the
2967environment is erased by accident, a default environment is provided.
2968
2969Some configuration options can be set using Environment Variables:
2970
2971  baudrate	- see CONFIG_BAUDRATE
2972
2973  bootdelay	- see CONFIG_BOOTDELAY
2974
2975  bootcmd	- see CONFIG_BOOTCOMMAND
2976
2977  bootargs	- Boot arguments when booting an RTOS image
2978
2979  bootfile	- Name of the image to load with TFTP
2980
2981  bootm_low	- Memory range available for image processing in the bootm
2982		  command can be restricted. This variable is given as
2983		  a hexadecimal number and defines lowest address allowed
2984		  for use by the bootm command. See also "bootm_size"
2985		  environment variable. Address defined by "bootm_low" is
2986		  also the base of the initial memory mapping for the Linux
2987		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
2988
2989  bootm_size	- Memory range available for image processing in the bootm
2990		  command can be restricted. This variable is given as
2991		  a hexadecimal number and defines the size of the region
2992		  allowed for use by the bootm command. See also "bootm_low"
2993		  environment variable.
2994
2995  updatefile	- Location of the software update file on a TFTP server, used
2996		  by the automatic software update feature. Please refer to
2997		  documentation in doc/README.update for more details.
2998
2999  autoload	- if set to "no" (any string beginning with 'n'),
3000		  "bootp" will just load perform a lookup of the
3001		  configuration from the BOOTP server, but not try to
3002		  load any image using TFTP
3003
3004  autoscript	- if set to "yes" commands like "loadb", "loady",
3005		  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
3006		  to automatically run script images (by internally
3007		  calling "source").
3008
3009  autoscript_uname - if script image is in a format (FIT) this
3010		     variable is used to get script subimage unit name.
3011
3012  autostart	- if set to "yes", an image loaded using the "bootp",
3013		  "rarpboot", "tftpboot" or "diskboot" commands will
3014		  be automatically started (by internally calling
3015		  "bootm")
3016
3017		  If set to "no", a standalone image passed to the
3018		  "bootm" command will be copied to the load address
3019		  (and eventually uncompressed), but NOT be started.
3020		  This can be used to load and uncompress arbitrary
3021		  data.
3022
3023  i2cfast	- (PPC405GP|PPC405EP only)
3024		  if set to 'y' configures Linux I2C driver for fast
3025		  mode (400kHZ). This environment variable is used in
3026		  initialization code. So, for changes to be effective
3027		  it must be saved and board must be reset.
3028
3029  initrd_high	- restrict positioning of initrd images:
3030		  If this variable is not set, initrd images will be
3031		  copied to the highest possible address in RAM; this
3032		  is usually what you want since it allows for
3033		  maximum initrd size. If for some reason you want to
3034		  make sure that the initrd image is loaded below the
3035		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3036		  variable to a value of "no" or "off" or "0".
3037		  Alternatively, you can set it to a maximum upper
3038		  address to use (U-Boot will still check that it
3039		  does not overwrite the U-Boot stack and data).
3040
3041		  For instance, when you have a system with 16 MB
3042		  RAM, and want to reserve 4 MB from use by Linux,
3043		  you can do this by adding "mem=12M" to the value of
3044		  the "bootargs" variable. However, now you must make
3045		  sure that the initrd image is placed in the first
3046		  12 MB as well - this can be done with
3047
3048		  setenv initrd_high 00c00000
3049
3050		  If you set initrd_high to 0xFFFFFFFF, this is an
3051		  indication to U-Boot that all addresses are legal
3052		  for the Linux kernel, including addresses in flash
3053		  memory. In this case U-Boot will NOT COPY the
3054		  ramdisk at all. This may be useful to reduce the
3055		  boot time on your system, but requires that this
3056		  feature is supported by your Linux kernel.
3057
3058  ipaddr	- IP address; needed for tftpboot command
3059
3060  loadaddr	- Default load address for commands like "bootp",
3061		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3062
3063  loads_echo	- see CONFIG_LOADS_ECHO
3064
3065  serverip	- TFTP server IP address; needed for tftpboot command
3066
3067  bootretry	- see CONFIG_BOOT_RETRY_TIME
3068
3069  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3070
3071  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3072
3073  ethprime	- When CONFIG_NET_MULTI is enabled controls which
3074		  interface is used first.
3075
3076  ethact	- When CONFIG_NET_MULTI is enabled controls which
3077		  interface is currently active. For example you
3078		  can do the following
3079
3080		  => setenv ethact FEC ETHERNET
3081		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
3082		  => setenv ethact SCC ETHERNET
3083		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
3084
3085  ethrotate	- When set to "no" U-Boot does not go through all
3086		  available network interfaces.
3087		  It just stays at the currently selected interface.
3088
3089   netretry	- When set to "no" each network operation will
3090		  either succeed or fail without retrying.
3091		  When set to "once" the network operation will
3092		  fail when all the available network interfaces
3093		  are tried once without success.
3094		  Useful on scripts which control the retry operation
3095		  themselves.
3096
3097  npe_ucode	- set load address for the NPE microcode
3098
3099  tftpsrcport	- If this is set, the value is used for TFTP's
3100		  UDP source port.
3101
3102  tftpdstport	- If this is set, the value is used for TFTP's UDP
3103		  destination port instead of the Well Know Port 69.
3104
3105   vlan		- When set to a value < 4095 the traffic over
3106		  Ethernet is encapsulated/received over 802.1q
3107		  VLAN tagged frames.
3108
3109The following environment variables may be used and automatically
3110updated by the network boot commands ("bootp" and "rarpboot"),
3111depending the information provided by your boot server:
3112
3113  bootfile	- see above
3114  dnsip		- IP address of your Domain Name Server
3115  dnsip2	- IP address of your secondary Domain Name Server
3116  gatewayip	- IP address of the Gateway (Router) to use
3117  hostname	- Target hostname
3118  ipaddr	- see above
3119  netmask	- Subnet Mask
3120  rootpath	- Pathname of the root filesystem on the NFS server
3121  serverip	- see above
3122
3123
3124There are two special Environment Variables:
3125
3126  serial#	- contains hardware identification information such
3127		  as type string and/or serial number
3128  ethaddr	- Ethernet address
3129
3130These variables can be set only once (usually during manufacturing of
3131the board). U-Boot refuses to delete or overwrite these variables
3132once they have been set once.
3133
3134
3135Further special Environment Variables:
3136
3137  ver		- Contains the U-Boot version string as printed
3138		  with the "version" command. This variable is
3139		  readonly (see CONFIG_VERSION_VARIABLE).
3140
3141
3142Please note that changes to some configuration parameters may take
3143only effect after the next boot (yes, that's just like Windoze :-).
3144
3145
3146Command Line Parsing:
3147=====================
3148
3149There are two different command line parsers available with U-Boot:
3150the old "simple" one, and the much more powerful "hush" shell:
3151
3152Old, simple command line parser:
3153--------------------------------
3154
3155- supports environment variables (through setenv / saveenv commands)
3156- several commands on one line, separated by ';'
3157- variable substitution using "... ${name} ..." syntax
3158- special characters ('$', ';') can be escaped by prefixing with '\',
3159  for example:
3160	setenv bootcmd bootm \${address}
3161- You can also escape text by enclosing in single apostrophes, for example:
3162	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3163
3164Hush shell:
3165-----------
3166
3167- similar to Bourne shell, with control structures like
3168  if...then...else...fi, for...do...done; while...do...done,
3169  until...do...done, ...
3170- supports environment ("global") variables (through setenv / saveenv
3171  commands) and local shell variables (through standard shell syntax
3172  "name=value"); only environment variables can be used with "run"
3173  command
3174
3175General rules:
3176--------------
3177
3178(1) If a command line (or an environment variable executed by a "run"
3179    command) contains several commands separated by semicolon, and
3180    one of these commands fails, then the remaining commands will be
3181    executed anyway.
3182
3183(2) If you execute several variables with one call to run (i. e.
3184    calling run with a list of variables as arguments), any failing
3185    command will cause "run" to terminate, i. e. the remaining
3186    variables are not executed.
3187
3188Note for Redundant Ethernet Interfaces:
3189=======================================
3190
3191Some boards come with redundant Ethernet interfaces; U-Boot supports
3192such configurations and is capable of automatic selection of a
3193"working" interface when needed. MAC assignment works as follows:
3194
3195Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3196MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3197"eth1addr" (=>eth1), "eth2addr", ...
3198
3199If the network interface stores some valid MAC address (for instance
3200in SROM), this is used as default address if there is NO correspon-
3201ding setting in the environment; if the corresponding environment
3202variable is set, this overrides the settings in the card; that means:
3203
3204o If the SROM has a valid MAC address, and there is no address in the
3205  environment, the SROM's address is used.
3206
3207o If there is no valid address in the SROM, and a definition in the
3208  environment exists, then the value from the environment variable is
3209  used.
3210
3211o If both the SROM and the environment contain a MAC address, and
3212  both addresses are the same, this MAC address is used.
3213
3214o If both the SROM and the environment contain a MAC address, and the
3215  addresses differ, the value from the environment is used and a
3216  warning is printed.
3217
3218o If neither SROM nor the environment contain a MAC address, an error
3219  is raised.
3220
3221
3222Image Formats:
3223==============
3224
3225U-Boot is capable of booting (and performing other auxiliary operations on)
3226images in two formats:
3227
3228New uImage format (FIT)
3229-----------------------
3230
3231Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3232to Flattened Device Tree). It allows the use of images with multiple
3233components (several kernels, ramdisks, etc.), with contents protected by
3234SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3235
3236
3237Old uImage format
3238-----------------
3239
3240Old image format is based on binary files which can be basically anything,
3241preceded by a special header; see the definitions in include/image.h for
3242details; basically, the header defines the following image properties:
3243
3244* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3245  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3246  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3247  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3248  INTEGRITY).
3249* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3250  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3251  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3252* Compression Type (uncompressed, gzip, bzip2)
3253* Load Address
3254* Entry Point
3255* Image Name
3256* Image Timestamp
3257
3258The header is marked by a special Magic Number, and both the header
3259and the data portions of the image are secured against corruption by
3260CRC32 checksums.
3261
3262
3263Linux Support:
3264==============
3265
3266Although U-Boot should support any OS or standalone application
3267easily, the main focus has always been on Linux during the design of
3268U-Boot.
3269
3270U-Boot includes many features that so far have been part of some
3271special "boot loader" code within the Linux kernel. Also, any
3272"initrd" images to be used are no longer part of one big Linux image;
3273instead, kernel and "initrd" are separate images. This implementation
3274serves several purposes:
3275
3276- the same features can be used for other OS or standalone
3277  applications (for instance: using compressed images to reduce the
3278  Flash memory footprint)
3279
3280- it becomes much easier to port new Linux kernel versions because
3281  lots of low-level, hardware dependent stuff are done by U-Boot
3282
3283- the same Linux kernel image can now be used with different "initrd"
3284  images; of course this also means that different kernel images can
3285  be run with the same "initrd". This makes testing easier (you don't
3286  have to build a new "zImage.initrd" Linux image when you just
3287  change a file in your "initrd"). Also, a field-upgrade of the
3288  software is easier now.
3289
3290
3291Linux HOWTO:
3292============
3293
3294Porting Linux to U-Boot based systems:
3295---------------------------------------
3296
3297U-Boot cannot save you from doing all the necessary modifications to
3298configure the Linux device drivers for use with your target hardware
3299(no, we don't intend to provide a full virtual machine interface to
3300Linux :-).
3301
3302But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3303
3304Just make sure your machine specific header file (for instance
3305include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3306Information structure as we define in include/asm-<arch>/u-boot.h,
3307and make sure that your definition of IMAP_ADDR uses the same value
3308as your U-Boot configuration in CONFIG_SYS_IMMR.
3309
3310
3311Configuring the Linux kernel:
3312-----------------------------
3313
3314No specific requirements for U-Boot. Make sure you have some root
3315device (initial ramdisk, NFS) for your target system.
3316
3317
3318Building a Linux Image:
3319-----------------------
3320
3321With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3322not used. If you use recent kernel source, a new build target
3323"uImage" will exist which automatically builds an image usable by
3324U-Boot. Most older kernels also have support for a "pImage" target,
3325which was introduced for our predecessor project PPCBoot and uses a
3326100% compatible format.
3327
3328Example:
3329
3330	make TQM850L_config
3331	make oldconfig
3332	make dep
3333	make uImage
3334
3335The "uImage" build target uses a special tool (in 'tools/mkimage') to
3336encapsulate a compressed Linux kernel image with header	 information,
3337CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3338
3339* build a standard "vmlinux" kernel image (in ELF binary format):
3340
3341* convert the kernel into a raw binary image:
3342
3343	${CROSS_COMPILE}-objcopy -O binary \
3344				 -R .note -R .comment \
3345				 -S vmlinux linux.bin
3346
3347* compress the binary image:
3348
3349	gzip -9 linux.bin
3350
3351* package compressed binary image for U-Boot:
3352
3353	mkimage -A ppc -O linux -T kernel -C gzip \
3354		-a 0 -e 0 -n "Linux Kernel Image" \
3355		-d linux.bin.gz uImage
3356
3357
3358The "mkimage" tool can also be used to create ramdisk images for use
3359with U-Boot, either separated from the Linux kernel image, or
3360combined into one file. "mkimage" encapsulates the images with a 64
3361byte header containing information about target architecture,
3362operating system, image type, compression method, entry points, time
3363stamp, CRC32 checksums, etc.
3364
3365"mkimage" can be called in two ways: to verify existing images and
3366print the header information, or to build new images.
3367
3368In the first form (with "-l" option) mkimage lists the information
3369contained in the header of an existing U-Boot image; this includes
3370checksum verification:
3371
3372	tools/mkimage -l image
3373	  -l ==> list image header information
3374
3375The second form (with "-d" option) is used to build a U-Boot image
3376from a "data file" which is used as image payload:
3377
3378	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3379		      -n name -d data_file image
3380	  -A ==> set architecture to 'arch'
3381	  -O ==> set operating system to 'os'
3382	  -T ==> set image type to 'type'
3383	  -C ==> set compression type 'comp'
3384	  -a ==> set load address to 'addr' (hex)
3385	  -e ==> set entry point to 'ep' (hex)
3386	  -n ==> set image name to 'name'
3387	  -d ==> use image data from 'datafile'
3388
3389Right now, all Linux kernels for PowerPC systems use the same load
3390address (0x00000000), but the entry point address depends on the
3391kernel version:
3392
3393- 2.2.x kernels have the entry point at 0x0000000C,
3394- 2.3.x and later kernels have the entry point at 0x00000000.
3395
3396So a typical call to build a U-Boot image would read:
3397
3398	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3399	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3400	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3401	> examples/uImage.TQM850L
3402	Image Name:   2.4.4 kernel for TQM850L
3403	Created:      Wed Jul 19 02:34:59 2000
3404	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3405	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3406	Load Address: 0x00000000
3407	Entry Point:  0x00000000
3408
3409To verify the contents of the image (or check for corruption):
3410
3411	-> tools/mkimage -l examples/uImage.TQM850L
3412	Image Name:   2.4.4 kernel for TQM850L
3413	Created:      Wed Jul 19 02:34:59 2000
3414	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3415	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3416	Load Address: 0x00000000
3417	Entry Point:  0x00000000
3418
3419NOTE: for embedded systems where boot time is critical you can trade
3420speed for memory and install an UNCOMPRESSED image instead: this
3421needs more space in Flash, but boots much faster since it does not
3422need to be uncompressed:
3423
3424	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3425	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3426	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3427	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3428	> examples/uImage.TQM850L-uncompressed
3429	Image Name:   2.4.4 kernel for TQM850L
3430	Created:      Wed Jul 19 02:34:59 2000
3431	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3432	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3433	Load Address: 0x00000000
3434	Entry Point:  0x00000000
3435
3436
3437Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3438when your kernel is intended to use an initial ramdisk:
3439
3440	-> tools/mkimage -n 'Simple Ramdisk Image' \
3441	> -A ppc -O linux -T ramdisk -C gzip \
3442	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3443	Image Name:   Simple Ramdisk Image
3444	Created:      Wed Jan 12 14:01:50 2000
3445	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3446	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3447	Load Address: 0x00000000
3448	Entry Point:  0x00000000
3449
3450
3451Installing a Linux Image:
3452-------------------------
3453
3454To downloading a U-Boot image over the serial (console) interface,
3455you must convert the image to S-Record format:
3456
3457	objcopy -I binary -O srec examples/image examples/image.srec
3458
3459The 'objcopy' does not understand the information in the U-Boot
3460image header, so the resulting S-Record file will be relative to
3461address 0x00000000. To load it to a given address, you need to
3462specify the target address as 'offset' parameter with the 'loads'
3463command.
3464
3465Example: install the image to address 0x40100000 (which on the
3466TQM8xxL is in the first Flash bank):
3467
3468	=> erase 40100000 401FFFFF
3469
3470	.......... done
3471	Erased 8 sectors
3472
3473	=> loads 40100000
3474	## Ready for S-Record download ...
3475	~>examples/image.srec
3476	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3477	...
3478	15989 15990 15991 15992
3479	[file transfer complete]
3480	[connected]
3481	## Start Addr = 0x00000000
3482
3483
3484You can check the success of the download using the 'iminfo' command;
3485this includes a checksum verification so you can be sure no data
3486corruption happened:
3487
3488	=> imi 40100000
3489
3490	## Checking Image at 40100000 ...
3491	   Image Name:	 2.2.13 for initrd on TQM850L
3492	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3493	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3494	   Load Address: 00000000
3495	   Entry Point:	 0000000c
3496	   Verifying Checksum ... OK
3497
3498
3499Boot Linux:
3500-----------
3501
3502The "bootm" command is used to boot an application that is stored in
3503memory (RAM or Flash). In case of a Linux kernel image, the contents
3504of the "bootargs" environment variable is passed to the kernel as
3505parameters. You can check and modify this variable using the
3506"printenv" and "setenv" commands:
3507
3508
3509	=> printenv bootargs
3510	bootargs=root=/dev/ram
3511
3512	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3513
3514	=> printenv bootargs
3515	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3516
3517	=> bootm 40020000
3518	## Booting Linux kernel at 40020000 ...
3519	   Image Name:	 2.2.13 for NFS on TQM850L
3520	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3521	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3522	   Load Address: 00000000
3523	   Entry Point:	 0000000c
3524	   Verifying Checksum ... OK
3525	   Uncompressing Kernel Image ... OK
3526	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
3527	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3528	time_init: decrementer frequency = 187500000/60
3529	Calibrating delay loop... 49.77 BogoMIPS
3530	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3531	...
3532
3533If you want to boot a Linux kernel with initial RAM disk, you pass
3534the memory addresses of both the kernel and the initrd image (PPBCOOT
3535format!) to the "bootm" command:
3536
3537	=> imi 40100000 40200000
3538
3539	## Checking Image at 40100000 ...
3540	   Image Name:	 2.2.13 for initrd on TQM850L
3541	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3542	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3543	   Load Address: 00000000
3544	   Entry Point:	 0000000c
3545	   Verifying Checksum ... OK
3546
3547	## Checking Image at 40200000 ...
3548	   Image Name:	 Simple Ramdisk Image
3549	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3550	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3551	   Load Address: 00000000
3552	   Entry Point:	 00000000
3553	   Verifying Checksum ... OK
3554
3555	=> bootm 40100000 40200000
3556	## Booting Linux kernel at 40100000 ...
3557	   Image Name:	 2.2.13 for initrd on TQM850L
3558	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3559	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3560	   Load Address: 00000000
3561	   Entry Point:	 0000000c
3562	   Verifying Checksum ... OK
3563	   Uncompressing Kernel Image ... OK
3564	## Loading RAMDisk Image at 40200000 ...
3565	   Image Name:	 Simple Ramdisk Image
3566	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3567	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3568	   Load Address: 00000000
3569	   Entry Point:	 00000000
3570	   Verifying Checksum ... OK
3571	   Loading Ramdisk ... OK
3572	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
3573	Boot arguments: root=/dev/ram
3574	time_init: decrementer frequency = 187500000/60
3575	Calibrating delay loop... 49.77 BogoMIPS
3576	...
3577	RAMDISK: Compressed image found at block 0
3578	VFS: Mounted root (ext2 filesystem).
3579
3580	bash#
3581
3582Boot Linux and pass a flat device tree:
3583-----------
3584
3585First, U-Boot must be compiled with the appropriate defines. See the section
3586titled "Linux Kernel Interface" above for a more in depth explanation. The
3587following is an example of how to start a kernel and pass an updated
3588flat device tree:
3589
3590=> print oftaddr
3591oftaddr=0x300000
3592=> print oft
3593oft=oftrees/mpc8540ads.dtb
3594=> tftp $oftaddr $oft
3595Speed: 1000, full duplex
3596Using TSEC0 device
3597TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3598Filename 'oftrees/mpc8540ads.dtb'.
3599Load address: 0x300000
3600Loading: #
3601done
3602Bytes transferred = 4106 (100a hex)
3603=> tftp $loadaddr $bootfile
3604Speed: 1000, full duplex
3605Using TSEC0 device
3606TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3607Filename 'uImage'.
3608Load address: 0x200000
3609Loading:############
3610done
3611Bytes transferred = 1029407 (fb51f hex)
3612=> print loadaddr
3613loadaddr=200000
3614=> print oftaddr
3615oftaddr=0x300000
3616=> bootm $loadaddr - $oftaddr
3617## Booting image at 00200000 ...
3618   Image Name:	 Linux-2.6.17-dirty
3619   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3620   Data Size:	 1029343 Bytes = 1005.2 kB
3621   Load Address: 00000000
3622   Entry Point:	 00000000
3623   Verifying Checksum ... OK
3624   Uncompressing Kernel Image ... OK
3625Booting using flat device tree at 0x300000
3626Using MPC85xx ADS machine description
3627Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3628[snip]
3629
3630
3631More About U-Boot Image Types:
3632------------------------------
3633
3634U-Boot supports the following image types:
3635
3636   "Standalone Programs" are directly runnable in the environment
3637	provided by U-Boot; it is expected that (if they behave
3638	well) you can continue to work in U-Boot after return from
3639	the Standalone Program.
3640   "OS Kernel Images" are usually images of some Embedded OS which
3641	will take over control completely. Usually these programs
3642	will install their own set of exception handlers, device
3643	drivers, set up the MMU, etc. - this means, that you cannot
3644	expect to re-enter U-Boot except by resetting the CPU.
3645   "RAMDisk Images" are more or less just data blocks, and their
3646	parameters (address, size) are passed to an OS kernel that is
3647	being started.
3648   "Multi-File Images" contain several images, typically an OS
3649	(Linux) kernel image and one or more data images like
3650	RAMDisks. This construct is useful for instance when you want
3651	to boot over the network using BOOTP etc., where the boot
3652	server provides just a single image file, but you want to get
3653	for instance an OS kernel and a RAMDisk image.
3654
3655	"Multi-File Images" start with a list of image sizes, each
3656	image size (in bytes) specified by an "uint32_t" in network
3657	byte order. This list is terminated by an "(uint32_t)0".
3658	Immediately after the terminating 0 follow the images, one by
3659	one, all aligned on "uint32_t" boundaries (size rounded up to
3660	a multiple of 4 bytes).
3661
3662   "Firmware Images" are binary images containing firmware (like
3663	U-Boot or FPGA images) which usually will be programmed to
3664	flash memory.
3665
3666   "Script files" are command sequences that will be executed by
3667	U-Boot's command interpreter; this feature is especially
3668	useful when you configure U-Boot to use a real shell (hush)
3669	as command interpreter.
3670
3671
3672Standalone HOWTO:
3673=================
3674
3675One of the features of U-Boot is that you can dynamically load and
3676run "standalone" applications, which can use some resources of
3677U-Boot like console I/O functions or interrupt services.
3678
3679Two simple examples are included with the sources:
3680
3681"Hello World" Demo:
3682-------------------
3683
3684'examples/hello_world.c' contains a small "Hello World" Demo
3685application; it is automatically compiled when you build U-Boot.
3686It's configured to run at address 0x00040004, so you can play with it
3687like that:
3688
3689	=> loads
3690	## Ready for S-Record download ...
3691	~>examples/hello_world.srec
3692	1 2 3 4 5 6 7 8 9 10 11 ...
3693	[file transfer complete]
3694	[connected]
3695	## Start Addr = 0x00040004
3696
3697	=> go 40004 Hello World! This is a test.
3698	## Starting application at 0x00040004 ...
3699	Hello World
3700	argc = 7
3701	argv[0] = "40004"
3702	argv[1] = "Hello"
3703	argv[2] = "World!"
3704	argv[3] = "This"
3705	argv[4] = "is"
3706	argv[5] = "a"
3707	argv[6] = "test."
3708	argv[7] = "<NULL>"
3709	Hit any key to exit ...
3710
3711	## Application terminated, rc = 0x0
3712
3713Another example, which demonstrates how to register a CPM interrupt
3714handler with the U-Boot code, can be found in 'examples/timer.c'.
3715Here, a CPM timer is set up to generate an interrupt every second.
3716The interrupt service routine is trivial, just printing a '.'
3717character, but this is just a demo program. The application can be
3718controlled by the following keys:
3719
3720	? - print current values og the CPM Timer registers
3721	b - enable interrupts and start timer
3722	e - stop timer and disable interrupts
3723	q - quit application
3724
3725	=> loads
3726	## Ready for S-Record download ...
3727	~>examples/timer.srec
3728	1 2 3 4 5 6 7 8 9 10 11 ...
3729	[file transfer complete]
3730	[connected]
3731	## Start Addr = 0x00040004
3732
3733	=> go 40004
3734	## Starting application at 0x00040004 ...
3735	TIMERS=0xfff00980
3736	Using timer 1
3737	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3738
3739Hit 'b':
3740	[q, b, e, ?] Set interval 1000000 us
3741	Enabling timer
3742Hit '?':
3743	[q, b, e, ?] ........
3744	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3745Hit '?':
3746	[q, b, e, ?] .
3747	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3748Hit '?':
3749	[q, b, e, ?] .
3750	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3751Hit '?':
3752	[q, b, e, ?] .
3753	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3754Hit 'e':
3755	[q, b, e, ?] ...Stopping timer
3756Hit 'q':
3757	[q, b, e, ?] ## Application terminated, rc = 0x0
3758
3759
3760Minicom warning:
3761================
3762
3763Over time, many people have reported problems when trying to use the
3764"minicom" terminal emulation program for serial download. I (wd)
3765consider minicom to be broken, and recommend not to use it. Under
3766Unix, I recommend to use C-Kermit for general purpose use (and
3767especially for kermit binary protocol download ("loadb" command), and
3768use "cu" for S-Record download ("loads" command).
3769
3770Nevertheless, if you absolutely want to use it try adding this
3771configuration to your "File transfer protocols" section:
3772
3773	   Name	   Program			Name U/D FullScr IO-Red. Multi
3774	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3775	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3776
3777
3778NetBSD Notes:
3779=============
3780
3781Starting at version 0.9.2, U-Boot supports NetBSD both as host
3782(build U-Boot) and target system (boots NetBSD/mpc8xx).
3783
3784Building requires a cross environment; it is known to work on
3785NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3786need gmake since the Makefiles are not compatible with BSD make).
3787Note that the cross-powerpc package does not install include files;
3788attempting to build U-Boot will fail because <machine/ansi.h> is
3789missing.  This file has to be installed and patched manually:
3790
3791	# cd /usr/pkg/cross/powerpc-netbsd/include
3792	# mkdir powerpc
3793	# ln -s powerpc machine
3794	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3795	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3796
3797Native builds *don't* work due to incompatibilities between native
3798and U-Boot include files.
3799
3800Booting assumes that (the first part of) the image booted is a
3801stage-2 loader which in turn loads and then invokes the kernel
3802proper. Loader sources will eventually appear in the NetBSD source
3803tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3804meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3805
3806
3807Implementation Internals:
3808=========================
3809
3810The following is not intended to be a complete description of every
3811implementation detail. However, it should help to understand the
3812inner workings of U-Boot and make it easier to port it to custom
3813hardware.
3814
3815
3816Initial Stack, Global Data:
3817---------------------------
3818
3819The implementation of U-Boot is complicated by the fact that U-Boot
3820starts running out of ROM (flash memory), usually without access to
3821system RAM (because the memory controller is not initialized yet).
3822This means that we don't have writable Data or BSS segments, and BSS
3823is not initialized as zero. To be able to get a C environment working
3824at all, we have to allocate at least a minimal stack. Implementation
3825options for this are defined and restricted by the CPU used: Some CPU
3826models provide on-chip memory (like the IMMR area on MPC8xx and
3827MPC826x processors), on others (parts of) the data cache can be
3828locked as (mis-) used as memory, etc.
3829
3830	Chris Hallinan posted a good summary of these issues to the
3831	U-Boot mailing list:
3832
3833	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3834	From: "Chris Hallinan" <clh@net1plus.com>
3835	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3836	...
3837
3838	Correct me if I'm wrong, folks, but the way I understand it
3839	is this: Using DCACHE as initial RAM for Stack, etc, does not
3840	require any physical RAM backing up the cache. The cleverness
3841	is that the cache is being used as a temporary supply of
3842	necessary storage before the SDRAM controller is setup. It's
3843	beyond the scope of this list to explain the details, but you
3844	can see how this works by studying the cache architecture and
3845	operation in the architecture and processor-specific manuals.
3846
3847	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3848	is another option for the system designer to use as an
3849	initial stack/RAM area prior to SDRAM being available. Either
3850	option should work for you. Using CS 4 should be fine if your
3851	board designers haven't used it for something that would
3852	cause you grief during the initial boot! It is frequently not
3853	used.
3854
3855	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3856	with your processor/board/system design. The default value
3857	you will find in any recent u-boot distribution in
3858	walnut.h should work for you. I'd set it to a value larger
3859	than your SDRAM module. If you have a 64MB SDRAM module, set
3860	it above 400_0000. Just make sure your board has no resources
3861	that are supposed to respond to that address! That code in
3862	start.S has been around a while and should work as is when
3863	you get the config right.
3864
3865	-Chris Hallinan
3866	DS4.COM, Inc.
3867
3868It is essential to remember this, since it has some impact on the C
3869code for the initialization procedures:
3870
3871* Initialized global data (data segment) is read-only. Do not attempt
3872  to write it.
3873
3874* Do not use any uninitialized global data (or implicitely initialized
3875  as zero data - BSS segment) at all - this is undefined, initiali-
3876  zation is performed later (when relocating to RAM).
3877
3878* Stack space is very limited. Avoid big data buffers or things like
3879  that.
3880
3881Having only the stack as writable memory limits means we cannot use
3882normal global data to share information beween the code. But it
3883turned out that the implementation of U-Boot can be greatly
3884simplified by making a global data structure (gd_t) available to all
3885functions. We could pass a pointer to this data as argument to _all_
3886functions, but this would bloat the code. Instead we use a feature of
3887the GCC compiler (Global Register Variables) to share the data: we
3888place a pointer (gd) to the global data into a register which we
3889reserve for this purpose.
3890
3891When choosing a register for such a purpose we are restricted by the
3892relevant  (E)ABI  specifications for the current architecture, and by
3893GCC's implementation.
3894
3895For PowerPC, the following registers have specific use:
3896	R1:	stack pointer
3897	R2:	reserved for system use
3898	R3-R4:	parameter passing and return values
3899	R5-R10: parameter passing
3900	R13:	small data area pointer
3901	R30:	GOT pointer
3902	R31:	frame pointer
3903
3904	(U-Boot also uses R14 as internal GOT pointer.)
3905
3906    ==> U-Boot will use R2 to hold a pointer to the global data
3907
3908    Note: on PPC, we could use a static initializer (since the
3909    address of the global data structure is known at compile time),
3910    but it turned out that reserving a register results in somewhat
3911    smaller code - although the code savings are not that big (on
3912    average for all boards 752 bytes for the whole U-Boot image,
3913    624 text + 127 data).
3914
3915On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3916	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3917
3918    ==> U-Boot will use P5 to hold a pointer to the global data
3919
3920On ARM, the following registers are used:
3921
3922	R0:	function argument word/integer result
3923	R1-R3:	function argument word
3924	R9:	GOT pointer
3925	R10:	stack limit (used only if stack checking if enabled)
3926	R11:	argument (frame) pointer
3927	R12:	temporary workspace
3928	R13:	stack pointer
3929	R14:	link register
3930	R15:	program counter
3931
3932    ==> U-Boot will use R8 to hold a pointer to the global data
3933
3934NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3935or current versions of GCC may "optimize" the code too much.
3936
3937Memory Management:
3938------------------
3939
3940U-Boot runs in system state and uses physical addresses, i.e. the
3941MMU is not used either for address mapping nor for memory protection.
3942
3943The available memory is mapped to fixed addresses using the memory
3944controller. In this process, a contiguous block is formed for each
3945memory type (Flash, SDRAM, SRAM), even when it consists of several
3946physical memory banks.
3947
3948U-Boot is installed in the first 128 kB of the first Flash bank (on
3949TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3950booting and sizing and initializing DRAM, the code relocates itself
3951to the upper end of DRAM. Immediately below the U-Boot code some
3952memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3953configuration setting]. Below that, a structure with global Board
3954Info data is placed, followed by the stack (growing downward).
3955
3956Additionally, some exception handler code is copied to the low 8 kB
3957of DRAM (0x00000000 ... 0x00001FFF).
3958
3959So a typical memory configuration with 16 MB of DRAM could look like
3960this:
3961
3962	0x0000 0000	Exception Vector code
3963	      :
3964	0x0000 1FFF
3965	0x0000 2000	Free for Application Use
3966	      :
3967	      :
3968
3969	      :
3970	      :
3971	0x00FB FF20	Monitor Stack (Growing downward)
3972	0x00FB FFAC	Board Info Data and permanent copy of global data
3973	0x00FC 0000	Malloc Arena
3974	      :
3975	0x00FD FFFF
3976	0x00FE 0000	RAM Copy of Monitor Code
3977	...		eventually: LCD or video framebuffer
3978	...		eventually: pRAM (Protected RAM - unchanged by reset)
3979	0x00FF FFFF	[End of RAM]
3980
3981
3982System Initialization:
3983----------------------
3984
3985In the reset configuration, U-Boot starts at the reset entry point
3986(on most PowerPC systems at address 0x00000100). Because of the reset
3987configuration for CS0# this is a mirror of the onboard Flash memory.
3988To be able to re-map memory U-Boot then jumps to its link address.
3989To be able to implement the initialization code in C, a (small!)
3990initial stack is set up in the internal Dual Ported RAM (in case CPUs
3991which provide such a feature like MPC8xx or MPC8260), or in a locked
3992part of the data cache. After that, U-Boot initializes the CPU core,
3993the caches and the SIU.
3994
3995Next, all (potentially) available memory banks are mapped using a
3996preliminary mapping. For example, we put them on 512 MB boundaries
3997(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3998on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3999programmed for SDRAM access. Using the temporary configuration, a
4000simple memory test is run that determines the size of the SDRAM
4001banks.
4002
4003When there is more than one SDRAM bank, and the banks are of
4004different size, the largest is mapped first. For equal size, the first
4005bank (CS2#) is mapped first. The first mapping is always for address
40060x00000000, with any additional banks following immediately to create
4007contiguous memory starting from 0.
4008
4009Then, the monitor installs itself at the upper end of the SDRAM area
4010and allocates memory for use by malloc() and for the global Board
4011Info data; also, the exception vector code is copied to the low RAM
4012pages, and the final stack is set up.
4013
4014Only after this relocation will you have a "normal" C environment;
4015until that you are restricted in several ways, mostly because you are
4016running from ROM, and because the code will have to be relocated to a
4017new address in RAM.
4018
4019
4020U-Boot Porting Guide:
4021----------------------
4022
4023[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4024list, October 2002]
4025
4026
4027int main(int argc, char *argv[])
4028{
4029	sighandler_t no_more_time;
4030
4031	signal(SIGALRM, no_more_time);
4032	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4033
4034	if (available_money > available_manpower) {
4035		Pay consultant to port U-Boot;
4036		return 0;
4037	}
4038
4039	Download latest U-Boot source;
4040
4041	Subscribe to u-boot mailing list;
4042
4043	if (clueless)
4044		email("Hi, I am new to U-Boot, how do I get started?");
4045
4046	while (learning) {
4047		Read the README file in the top level directory;
4048		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4049		Read applicable doc/*.README;
4050		Read the source, Luke;
4051		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4052	}
4053
4054	if (available_money > toLocalCurrency ($2500))
4055		Buy a BDI3000;
4056	else
4057		Add a lot of aggravation and time;
4058
4059	if (a similar board exists) {	/* hopefully... */
4060		cp -a board/<similar> board/<myboard>
4061		cp include/configs/<similar>.h include/configs/<myboard>.h
4062	} else {
4063		Create your own board support subdirectory;
4064		Create your own board include/configs/<myboard>.h file;
4065	}
4066	Edit new board/<myboard> files
4067	Edit new include/configs/<myboard>.h
4068
4069	while (!accepted) {
4070		while (!running) {
4071			do {
4072				Add / modify source code;
4073			} until (compiles);
4074			Debug;
4075			if (clueless)
4076				email("Hi, I am having problems...");
4077		}
4078		Send patch file to the U-Boot email list;
4079		if (reasonable critiques)
4080			Incorporate improvements from email list code review;
4081		else
4082			Defend code as written;
4083	}
4084
4085	return 0;
4086}
4087
4088void no_more_time (int sig)
4089{
4090      hire_a_guru();
4091}
4092
4093
4094Coding Standards:
4095-----------------
4096
4097All contributions to U-Boot should conform to the Linux kernel
4098coding style; see the file "Documentation/CodingStyle" and the script
4099"scripts/Lindent" in your Linux kernel source directory.  In sources
4100originating from U-Boot a style corresponding to "Lindent -pcs" (adding
4101spaces before parameters to function calls) is actually used.
4102
4103Source files originating from a different project (for example the
4104MTD subsystem) are generally exempt from these guidelines and are not
4105reformated to ease subsequent migration to newer versions of those
4106sources.
4107
4108Please note that U-Boot is implemented in C (and to some small parts in
4109Assembler); no C++ is used, so please do not use C++ style comments (//)
4110in your code.
4111
4112Please also stick to the following formatting rules:
4113- remove any trailing white space
4114- use TAB characters for indentation, not spaces
4115- make sure NOT to use DOS '\r\n' line feeds
4116- do not add more than 2 empty lines to source files
4117- do not add trailing empty lines to source files
4118
4119Submissions which do not conform to the standards may be returned
4120with a request to reformat the changes.
4121
4122
4123Submitting Patches:
4124-------------------
4125
4126Since the number of patches for U-Boot is growing, we need to
4127establish some rules. Submissions which do not conform to these rules
4128may be rejected, even when they contain important and valuable stuff.
4129
4130Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4131
4132Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4133see http://lists.denx.de/mailman/listinfo/u-boot
4134
4135When you send a patch, please include the following information with
4136it:
4137
4138* For bug fixes: a description of the bug and how your patch fixes
4139  this bug. Please try to include a way of demonstrating that the
4140  patch actually fixes something.
4141
4142* For new features: a description of the feature and your
4143  implementation.
4144
4145* A CHANGELOG entry as plaintext (separate from the patch)
4146
4147* For major contributions, your entry to the CREDITS file
4148
4149* When you add support for a new board, don't forget to add this
4150  board to the MAKEALL script, too.
4151
4152* If your patch adds new configuration options, don't forget to
4153  document these in the README file.
4154
4155* The patch itself. If you are using git (which is *strongly*
4156  recommended) you can easily generate the patch using the
4157  "git-format-patch". If you then use "git-send-email" to send it to
4158  the U-Boot mailing list, you will avoid most of the common problems
4159  with some other mail clients.
4160
4161  If you cannot use git, use "diff -purN OLD NEW". If your version of
4162  diff does not support these options, then get the latest version of
4163  GNU diff.
4164
4165  The current directory when running this command shall be the parent
4166  directory of the U-Boot source tree (i. e. please make sure that
4167  your patch includes sufficient directory information for the
4168  affected files).
4169
4170  We prefer patches as plain text. MIME attachments are discouraged,
4171  and compressed attachments must not be used.
4172
4173* If one logical set of modifications affects or creates several
4174  files, all these changes shall be submitted in a SINGLE patch file.
4175
4176* Changesets that contain different, unrelated modifications shall be
4177  submitted as SEPARATE patches, one patch per changeset.
4178
4179
4180Notes:
4181
4182* Before sending the patch, run the MAKEALL script on your patched
4183  source tree and make sure that no errors or warnings are reported
4184  for any of the boards.
4185
4186* Keep your modifications to the necessary minimum: A patch
4187  containing several unrelated changes or arbitrary reformats will be
4188  returned with a request to re-formatting / split it.
4189
4190* If you modify existing code, make sure that your new code does not
4191  add to the memory footprint of the code ;-) Small is beautiful!
4192  When adding new features, these should compile conditionally only
4193  (using #ifdef), and the resulting code with the new feature
4194  disabled must not need more memory than the old code without your
4195  modification.
4196
4197* Remember that there is a size limit of 100 kB per message on the
4198  u-boot mailing list. Bigger patches will be moderated. If they are
4199  reasonable and not too big, they will be acknowledged. But patches
4200  bigger than the size limit should be avoided.
4201