2 # (C) Copyright 2000 - 2005
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # See file CREDITS for list of people who contributed to this
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.
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.
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,
27 This directory contains the source code for U-Boot, a boot loader for
28 Embedded boards based on PowerPC, ARM, MIPS and several other
29 processors, which can be installed in a boot ROM and used to
30 initialize and test the hardware or to download and run application
33 The development of U-Boot is closely related to Linux: some parts of
34 the source code originate in the Linux source tree, we have some
35 header files in common, and special provision has been made to
36 support booting of Linux images.
38 Some attention has been paid to make this software easily
39 configurable and extendable. For instance, all monitor commands are
40 implemented with the same call interface, so that it's very easy to
41 add new commands. Also, instead of permanently adding rarely used
42 code (for instance hardware test utilities) to the monitor, you can
43 load and run it dynamically.
49 In general, all boards for which a configuration option exists in the
50 Makefile have been tested to some extent and can be considered
51 "working". In fact, many of them are used in production systems.
53 In case of problems see the CHANGELOG and CREDITS files to find out
54 who contributed the specific port.
60 In case you have questions about, problems with or contributions for
61 U-Boot you should send a message to the U-Boot mailing list at
62 <u-boot-users@lists.sourceforge.net>. There is also an archive of
63 previous traffic on the mailing list - please search the archive
64 before asking FAQ's. Please see
65 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
71 - start from 8xxrom sources
72 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
74 - make it easier to add custom boards
75 - make it possible to add other [PowerPC] CPUs
76 - extend functions, especially:
77 * Provide extended interface to Linux boot loader
80 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
81 - create ARMBoot project (http://sourceforge.net/projects/armboot)
82 - add other CPU families (starting with ARM)
83 - create U-Boot project (http://sourceforge.net/projects/u-boot)
89 The "official" name of this project is "Das U-Boot". The spelling
90 "U-Boot" shall be used in all written text (documentation, comments
91 in source files etc.). Example:
93 This is the README file for the U-Boot project.
95 File names etc. shall be based on the string "u-boot". Examples:
97 include/asm-ppc/u-boot.h
99 #include <asm/u-boot.h>
101 Variable names, preprocessor constants etc. shall be either based on
102 the string "u_boot" or on "U_BOOT". Example:
104 U_BOOT_VERSION u_boot_logo
105 IH_OS_U_BOOT u_boot_hush_start
111 U-Boot uses a 3 level version number containing a version, a
112 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
113 sub-version "34", and patchlevel "4".
115 The patchlevel is used to indicate certain stages of development
116 between released versions, i. e. officially released versions of
117 U-Boot will always have a patchlevel of "0".
123 - board Board dependent files
124 - common Misc architecture independent functions
125 - cpu CPU specific files
126 - 74xx_7xx Files specific to Freescale MPC74xx and 7xx CPUs
127 - arm720t Files specific to ARM 720 CPUs
128 - arm920t Files specific to ARM 920 CPUs
129 - at91rm9200 Files specific to Atmel AT91RM9200 CPU
130 - imx Files specific to Freescale MC9328 i.MX CPUs
131 - s3c24x0 Files specific to Samsung S3C24X0 CPUs
132 - arm925t Files specific to ARM 925 CPUs
133 - arm926ejs Files specific to ARM 926 CPUs
134 - arm1136 Files specific to ARM 1136 CPUs
135 - at32ap Files specific to Atmel AVR32 AP CPUs
136 - i386 Files specific to i386 CPUs
137 - ixp Files specific to Intel XScale IXP CPUs
138 - mcf52x2 Files specific to Freescale ColdFire MCF52x2 CPUs
139 - mcf532x Files specific to Freescale ColdFire MCF5329 CPUs
140 - mips Files specific to MIPS CPUs
141 - mpc5xx Files specific to Freescale MPC5xx CPUs
142 - mpc5xxx Files specific to Freescale MPC5xxx CPUs
143 - mpc8xx Files specific to Freescale MPC8xx CPUs
144 - mpc8220 Files specific to Freescale MPC8220 CPUs
145 - mpc824x Files specific to Freescale MPC824x CPUs
146 - mpc8260 Files specific to Freescale MPC8260 CPUs
147 - mpc85xx Files specific to Freescale MPC85xx CPUs
148 - nios Files specific to Altera NIOS CPUs
149 - nios2 Files specific to Altera Nios-II CPUs
150 - ppc4xx Files specific to AMCC PowerPC 4xx CPUs
151 - pxa Files specific to Intel XScale PXA CPUs
152 - s3c44b0 Files specific to Samsung S3C44B0 CPUs
153 - sa1100 Files specific to Intel StrongARM SA1100 CPUs
154 - disk Code for disk drive partition handling
155 - doc Documentation (don't expect too much)
156 - drivers Commonly used device drivers
157 - dtt Digital Thermometer and Thermostat drivers
158 - examples Example code for standalone applications, etc.
159 - include Header Files
160 - lib_arm Files generic to ARM architecture
161 - lib_avr32 Files generic to AVR32 architecture
162 - lib_generic Files generic to all architectures
163 - lib_i386 Files generic to i386 architecture
164 - lib_m68k Files generic to m68k architecture
165 - lib_mips Files generic to MIPS architecture
166 - lib_nios Files generic to NIOS architecture
167 - lib_ppc Files generic to PowerPC architecture
168 - libfdt Library files to support flattened device trees
169 - net Networking code
170 - post Power On Self Test
171 - rtc Real Time Clock drivers
172 - tools Tools to build S-Record or U-Boot images, etc.
174 Software Configuration:
175 =======================
177 Configuration is usually done using C preprocessor defines; the
178 rationale behind that is to avoid dead code whenever possible.
180 There are two classes of configuration variables:
182 * Configuration _OPTIONS_:
183 These are selectable by the user and have names beginning with
186 * Configuration _SETTINGS_:
187 These depend on the hardware etc. and should not be meddled with if
188 you don't know what you're doing; they have names beginning with
191 Later we will add a configuration tool - probably similar to or even
192 identical to what's used for the Linux kernel. Right now, we have to
193 do the configuration by hand, which means creating some symbolic
194 links and editing some configuration files. We use the TQM8xxL boards
198 Selection of Processor Architecture and Board Type:
199 ---------------------------------------------------
201 For all supported boards there are ready-to-use default
202 configurations available; just type "make <board_name>_config".
204 Example: For a TQM823L module type:
209 For the Cogent platform, you need to specify the cpu type as well;
210 e.g. "make cogent_mpc8xx_config". And also configure the cogent
211 directory according to the instructions in cogent/README.
214 Configuration Options:
215 ----------------------
217 Configuration depends on the combination of board and CPU type; all
218 such information is kept in a configuration file
219 "include/configs/<board_name>.h".
221 Example: For a TQM823L module, all configuration settings are in
222 "include/configs/TQM823L.h".
225 Many of the options are named exactly as the corresponding Linux
226 kernel configuration options. The intention is to make it easier to
227 build a config tool - later.
230 The following options need to be configured:
232 - CPU Type: Define exactly one of
236 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
239 or CONFIG_MPC824X, CONFIG_MPC8260
259 MicroBlaze based CPUs:
260 ----------------------
264 ----------------------
268 ----------------------
271 - Board Type: Define exactly one of
273 PowerPC based boards:
274 ---------------------
276 CONFIG_ADCIOP CONFIG_FPS860L CONFIG_OXC
277 CONFIG_ADS860 CONFIG_GEN860T CONFIG_PCI405
278 CONFIG_AMX860 CONFIG_GENIETV CONFIG_PCIPPC2
279 CONFIG_AP1000 CONFIG_GTH CONFIG_PCIPPC6
280 CONFIG_AR405 CONFIG_gw8260 CONFIG_pcu_e
281 CONFIG_BAB7xx CONFIG_hermes CONFIG_PIP405
282 CONFIG_BC3450 CONFIG_hymod CONFIG_PM826
283 CONFIG_c2mon CONFIG_IAD210 CONFIG_ppmc8260
284 CONFIG_CANBT CONFIG_ICU862 CONFIG_QS823
285 CONFIG_CCM CONFIG_IP860 CONFIG_QS850
286 CONFIG_CMI CONFIG_IPHASE4539 CONFIG_QS860T
287 CONFIG_cogent_mpc8260 CONFIG_IVML24 CONFIG_RBC823
288 CONFIG_cogent_mpc8xx CONFIG_IVML24_128 CONFIG_RPXClassic
289 CONFIG_CPCI405 CONFIG_IVML24_256 CONFIG_RPXlite
290 CONFIG_CPCI4052 CONFIG_IVMS8 CONFIG_RPXsuper
291 CONFIG_CPCIISER4 CONFIG_IVMS8_128 CONFIG_rsdproto
292 CONFIG_CPU86 CONFIG_IVMS8_256 CONFIG_sacsng
293 CONFIG_CRAYL1 CONFIG_JSE CONFIG_Sandpoint8240
294 CONFIG_CSB272 CONFIG_LANTEC CONFIG_Sandpoint8245
295 CONFIG_CU824 CONFIG_LITE5200B CONFIG_sbc8260
296 CONFIG_DASA_SIM CONFIG_lwmon CONFIG_sbc8560
297 CONFIG_DB64360 CONFIG_MBX CONFIG_SM850
298 CONFIG_DB64460 CONFIG_MBX860T CONFIG_SPD823TS
299 CONFIG_DU405 CONFIG_MHPC CONFIG_STXGP3
300 CONFIG_DUET_ADS CONFIG_MIP405 CONFIG_SXNI855T
301 CONFIG_EBONY CONFIG_MOUSSE CONFIG_TQM823L
302 CONFIG_ELPPC CONFIG_MPC8260ADS CONFIG_TQM8260
303 CONFIG_ELPT860 CONFIG_MPC8540ADS CONFIG_TQM850L
304 CONFIG_ep8260 CONFIG_MPC8540EVAL CONFIG_TQM855L
305 CONFIG_ERIC CONFIG_MPC8560ADS CONFIG_TQM860L
306 CONFIG_ESTEEM192E CONFIG_MUSENKI CONFIG_TTTech
307 CONFIG_ETX094 CONFIG_MVS1 CONFIG_UTX8245
308 CONFIG_EVB64260 CONFIG_NETPHONE CONFIG_V37
309 CONFIG_FADS823 CONFIG_NETTA CONFIG_W7OLMC
310 CONFIG_FADS850SAR CONFIG_NETVIA CONFIG_W7OLMG
311 CONFIG_FADS860T CONFIG_NX823 CONFIG_WALNUT
312 CONFIG_FLAGADM CONFIG_OCRTC CONFIG_ZPC1900
313 CONFIG_FPS850L CONFIG_ORSG CONFIG_ZUMA
318 CONFIG_ARMADILLO, CONFIG_AT91RM9200DK, CONFIG_CERF250,
319 CONFIG_CSB637, CONFIG_DELTA, CONFIG_DNP1110,
320 CONFIG_EP7312, CONFIG_H2_OMAP1610, CONFIG_HHP_CRADLE,
321 CONFIG_IMPA7, CONFIG_INNOVATOROMAP1510, CONFIG_INNOVATOROMAP1610,
322 CONFIG_KB9202, CONFIG_LART, CONFIG_LPD7A400,
323 CONFIG_LUBBOCK, CONFIG_OSK_OMAP5912, CONFIG_OMAP2420H4,
324 CONFIG_PLEB2, CONFIG_SHANNON, CONFIG_P2_OMAP730,
325 CONFIG_SMDK2400, CONFIG_SMDK2410, CONFIG_TRAB,
328 MicroBlaze based boards:
329 ------------------------
334 ------------------------
336 CONFIG_PCI5441 CONFIG_PK1C20
337 CONFIG_EP1C20 CONFIG_EP1S10 CONFIG_EP1S40
344 - CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
345 Define exactly one of
349 - CPU Module Type: (if CONFIG_COGENT is defined)
350 Define exactly one of
352 --- FIXME --- not tested yet:
353 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
354 CONFIG_CMA287_23, CONFIG_CMA287_50
356 - Motherboard Type: (if CONFIG_COGENT is defined)
357 Define exactly one of
358 CONFIG_CMA101, CONFIG_CMA102
360 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
361 Define one or more of
364 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
365 Define one or more of
366 CONFIG_LCD_HEARTBEAT - update a character position on
367 the lcd display every second with
370 - Board flavour: (if CONFIG_MPC8260ADS is defined)
373 CFG_8260ADS - original MPC8260ADS
374 CFG_8266ADS - MPC8266ADS
375 CFG_PQ2FADS - PQ2FADS-ZU or PQ2FADS-VR
376 CFG_8272ADS - MPC8272ADS
378 - MPC824X Family Member (if CONFIG_MPC824X is defined)
379 Define exactly one of
380 CONFIG_MPC8240, CONFIG_MPC8245
382 - 8xx CPU Options: (if using an MPC8xx cpu)
383 CONFIG_8xx_GCLK_FREQ - deprecated: CPU clock if
384 get_gclk_freq() cannot work
385 e.g. if there is no 32KHz
386 reference PIT/RTC clock
387 CONFIG_8xx_OSCLK - PLL input clock (either EXTCLK
390 - 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
393 CONFIG_8xx_CPUCLK_DEFAULT
394 See doc/README.MPC866
398 Define this to measure the actual CPU clock instead
399 of relying on the correctness of the configured
400 values. Mostly useful for board bringup to make sure
401 the PLL is locked at the intended frequency. Note
402 that this requires a (stable) reference clock (32 kHz
403 RTC clock or CFG_8XX_XIN)
405 - Intel Monahans options:
406 CFG_MONAHANS_RUN_MODE_OSC_RATIO
408 Defines the Monahans run mode to oscillator
409 ratio. Valid values are 8, 16, 24, 31. The core
410 frequency is this value multiplied by 13 MHz.
412 CFG_MONAHANS_TURBO_RUN_MODE_RATIO
414 Defines the Monahans turbo mode to oscillator
415 ratio. Valid values are 1 (default if undefined) and
416 2. The core frequency as calculated above is multiplied
419 - Linux Kernel Interface:
422 U-Boot stores all clock information in Hz
423 internally. For binary compatibility with older Linux
424 kernels (which expect the clocks passed in the
425 bd_info data to be in MHz) the environment variable
426 "clocks_in_mhz" can be defined so that U-Boot
427 converts clock data to MHZ before passing it to the
429 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
430 "clocks_in_mhz=1" is automatically included in the
433 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
435 When transfering memsize parameter to linux, some versions
436 expect it to be in bytes, others in MB.
437 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
439 CONFIG_OF_LIBFDT / CONFIG_OF_FLAT_TREE
441 New kernel versions are expecting firmware settings to be
442 passed using flattened device trees (based on open firmware
446 * New libfdt-based support
447 * Adds the "fdt" command
448 * The bootm command does _not_ modify the fdt
451 * Deprecated, see CONFIG_OF_LIBFDT
452 * Original ft_build.c-based support
453 * Automatically modifies the dft as part of the bootm command
454 * The environment variable "disable_of", when set,
455 disables this functionality.
457 CONFIG_OF_FLAT_TREE_MAX_SIZE
459 The maximum size of the constructed OF tree.
461 OF_CPU - The proper name of the cpus node.
462 OF_SOC - The proper name of the soc node.
463 OF_TBCLK - The timebase frequency.
464 OF_STDOUT_PATH - The path to the console device
468 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
469 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
470 will have a copy of the bd_t. Space should be
471 pre-allocated in the dts for the bd_t.
473 CONFIG_OF_HAS_UBOOT_ENV
475 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
476 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
477 will have a copy of u-boot's environment variables
479 CONFIG_OF_BOARD_SETUP
481 Board code has addition modification that it wants to make
482 to the flat device tree before handing it off to the kernel
486 This define fills in the correct boot cpu in the boot
487 param header, the default value is zero if undefined.
492 Define this if you want support for Amba PrimeCell PL010 UARTs.
496 Define this if you want support for Amba PrimeCell PL011 UARTs.
500 If you have Amba PrimeCell PL011 UARTs, set this variable to
501 the clock speed of the UARTs.
505 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
506 define this to a list of base addresses for each (supported)
507 port. See e.g. include/configs/versatile.h
511 Depending on board, define exactly one serial port
512 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
513 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
514 console by defining CONFIG_8xx_CONS_NONE
516 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
517 port routines must be defined elsewhere
518 (i.e. serial_init(), serial_getc(), ...)
521 Enables console device for a color framebuffer. Needs following
522 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
523 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
525 VIDEO_HW_RECTFILL graphic chip supports
528 VIDEO_HW_BITBLT graphic chip supports
529 bit-blit (cf. smiLynxEM)
530 VIDEO_VISIBLE_COLS visible pixel columns
532 VIDEO_VISIBLE_ROWS visible pixel rows
533 VIDEO_PIXEL_SIZE bytes per pixel
534 VIDEO_DATA_FORMAT graphic data format
535 (0-5, cf. cfb_console.c)
536 VIDEO_FB_ADRS framebuffer address
537 VIDEO_KBD_INIT_FCT keyboard int fct
538 (i.e. i8042_kbd_init())
539 VIDEO_TSTC_FCT test char fct
541 VIDEO_GETC_FCT get char fct
543 CONFIG_CONSOLE_CURSOR cursor drawing on/off
544 (requires blink timer
546 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
547 CONFIG_CONSOLE_TIME display time/date info in
549 (requires CFG_CMD_DATE)
550 CONFIG_VIDEO_LOGO display Linux logo in
552 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
553 linux_logo.h for logo.
554 Requires CONFIG_VIDEO_LOGO
555 CONFIG_CONSOLE_EXTRA_INFO
556 addional board info beside
559 When CONFIG_CFB_CONSOLE is defined, video console is
560 default i/o. Serial console can be forced with
561 environment 'console=serial'.
563 When CONFIG_SILENT_CONSOLE is defined, all console
564 messages (by U-Boot and Linux!) can be silenced with
565 the "silent" environment variable. See
566 doc/README.silent for more information.
569 CONFIG_BAUDRATE - in bps
570 Select one of the baudrates listed in
571 CFG_BAUDRATE_TABLE, see below.
572 CFG_BRGCLK_PRESCALE, baudrate prescale
574 - Interrupt driven serial port input:
575 CONFIG_SERIAL_SOFTWARE_FIFO
578 Use an interrupt handler for receiving data on the
579 serial port. It also enables using hardware handshake
580 (RTS/CTS) and UART's built-in FIFO. Set the number of
581 bytes the interrupt driven input buffer should have.
583 Leave undefined to disable this feature, including
584 disable the buffer and hardware handshake.
586 - Console UART Number:
590 If defined internal UART1 (and not UART0) is used
591 as default U-Boot console.
593 - Boot Delay: CONFIG_BOOTDELAY - in seconds
594 Delay before automatically booting the default image;
595 set to -1 to disable autoboot.
597 See doc/README.autoboot for these options that
598 work with CONFIG_BOOTDELAY. None are required.
599 CONFIG_BOOT_RETRY_TIME
600 CONFIG_BOOT_RETRY_MIN
601 CONFIG_AUTOBOOT_KEYED
602 CONFIG_AUTOBOOT_PROMPT
603 CONFIG_AUTOBOOT_DELAY_STR
604 CONFIG_AUTOBOOT_STOP_STR
605 CONFIG_AUTOBOOT_DELAY_STR2
606 CONFIG_AUTOBOOT_STOP_STR2
607 CONFIG_ZERO_BOOTDELAY_CHECK
608 CONFIG_RESET_TO_RETRY
612 Only needed when CONFIG_BOOTDELAY is enabled;
613 define a command string that is automatically executed
614 when no character is read on the console interface
615 within "Boot Delay" after reset.
618 This can be used to pass arguments to the bootm
619 command. The value of CONFIG_BOOTARGS goes into the
620 environment value "bootargs".
622 CONFIG_RAMBOOT and CONFIG_NFSBOOT
623 The value of these goes into the environment as
624 "ramboot" and "nfsboot" respectively, and can be used
625 as a convenience, when switching between booting from
631 When this option is #defined, the existence of the
632 environment variable "preboot" will be checked
633 immediately before starting the CONFIG_BOOTDELAY
634 countdown and/or running the auto-boot command resp.
635 entering interactive mode.
637 This feature is especially useful when "preboot" is
638 automatically generated or modified. For an example
639 see the LWMON board specific code: here "preboot" is
640 modified when the user holds down a certain
641 combination of keys on the (special) keyboard when
644 - Serial Download Echo Mode:
646 If defined to 1, all characters received during a
647 serial download (using the "loads" command) are
648 echoed back. This might be needed by some terminal
649 emulations (like "cu"), but may as well just take
650 time on others. This setting #define's the initial
651 value of the "loads_echo" environment variable.
653 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
655 Select one of the baudrates listed in
656 CFG_BAUDRATE_TABLE, see below.
660 Most monitor functions can be selected (or
661 de-selected) by adjusting the definition of
662 CONFIG_COMMANDS; to select individual functions,
663 #define CONFIG_COMMANDS by "OR"ing any of the
666 #define enables commands:
667 -------------------------
668 CFG_CMD_ASKENV * ask for env variable
669 CFG_CMD_AUTOSCRIPT Autoscript Support
671 CFG_CMD_BEDBUG * Include BedBug Debugger
672 CFG_CMD_BMP * BMP support
673 CFG_CMD_BSP * Board specific commands
675 CFG_CMD_CACHE * icache, dcache
676 CFG_CMD_CONSOLE coninfo
677 CFG_CMD_DATE * support for RTC, date/time...
678 CFG_CMD_DHCP * DHCP support
679 CFG_CMD_DIAG * Diagnostics
680 CFG_CMD_DOC * Disk-On-Chip Support
681 CFG_CMD_DTT * Digital Therm and Thermostat
682 CFG_CMD_ECHO echo arguments
683 CFG_CMD_EEPROM * EEPROM read/write support
684 CFG_CMD_ELF * bootelf, bootvx
686 CFG_CMD_FDC * Floppy Disk Support
687 CFG_CMD_FAT * FAT partition support
688 CFG_CMD_FDOS * Dos diskette Support
689 CFG_CMD_FLASH flinfo, erase, protect
690 CFG_CMD_FPGA FPGA device initialization support
691 CFG_CMD_HWFLOW * RTS/CTS hw flow control
692 CFG_CMD_I2C * I2C serial bus support
693 CFG_CMD_IDE * IDE harddisk support
695 CFG_CMD_IMLS List all found images
696 CFG_CMD_IMMAP * IMMR dump support
697 CFG_CMD_IRQ * irqinfo
698 CFG_CMD_ITEST Integer/string test of 2 values
699 CFG_CMD_JFFS2 * JFFS2 Support
703 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
705 CFG_CMD_MISC Misc functions like sleep etc
706 CFG_CMD_MMC * MMC memory mapped support
707 CFG_CMD_MII * MII utility commands
708 CFG_CMD_NAND * NAND support
709 CFG_CMD_NET bootp, tftpboot, rarpboot
710 CFG_CMD_PCI * pciinfo
711 CFG_CMD_PCMCIA * PCMCIA support
712 CFG_CMD_PING * send ICMP ECHO_REQUEST to network host
713 CFG_CMD_PORTIO * Port I/O
714 CFG_CMD_REGINFO * Register dump
715 CFG_CMD_RUN run command in env variable
716 CFG_CMD_SAVES * save S record dump
717 CFG_CMD_SCSI * SCSI Support
718 CFG_CMD_SDRAM * print SDRAM configuration information
719 (requires CFG_CMD_I2C)
720 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
721 CFG_CMD_SPI * SPI serial bus support
722 CFG_CMD_USB * USB support
723 CFG_CMD_VFD * VFD support (TRAB)
724 CFG_CMD_BSP * Board SPecific functions
725 CFG_CMD_CDP * Cisco Discover Protocol support
726 CFG_CMD_FSL * Microblaze FSL support
727 -----------------------------------------------
730 CONFIG_CMD_DFL Default configuration; at the moment
731 this is includes all commands, except
732 the ones marked with "*" in the list
735 If you don't define CONFIG_COMMANDS it defaults to
736 CONFIG_CMD_DFL in include/cmd_confdefs.h. A board can
737 override the default settings in the respective
740 EXAMPLE: If you want all functions except of network
741 support you can write:
743 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
746 fdt (flattened device tree) command: CONFIG_OF_LIBFDT
748 Note: Don't enable the "icache" and "dcache" commands
749 (configuration option CFG_CMD_CACHE) unless you know
750 what you (and your U-Boot users) are doing. Data
751 cache cannot be enabled on systems like the 8xx or
752 8260 (where accesses to the IMMR region must be
753 uncached), and it cannot be disabled on all other
754 systems where we (mis-) use the data cache to hold an
755 initial stack and some data.
758 XXX - this list needs to get updated!
762 If this variable is defined, it enables watchdog
763 support. There must be support in the platform specific
764 code for a watchdog. For the 8xx and 8260 CPUs, the
765 SIU Watchdog feature is enabled in the SYPCR
769 CONFIG_VERSION_VARIABLE
770 If this variable is defined, an environment variable
771 named "ver" is created by U-Boot showing the U-Boot
772 version as printed by the "version" command.
773 This variable is readonly.
777 When CFG_CMD_DATE is selected, the type of the RTC
778 has to be selected, too. Define exactly one of the
781 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
782 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
783 CONFIG_RTC_MC146818 - use MC146818 RTC
784 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
785 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
786 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
787 CONFIG_RTC_DS164x - use Dallas DS164x RTC
788 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
790 Note that if the RTC uses I2C, then the I2C interface
791 must also be configured. See I2C Support, below.
795 When CONFIG_TIMESTAMP is selected, the timestamp
796 (date and time) of an image is printed by image
797 commands like bootm or iminfo. This option is
798 automatically enabled when you select CFG_CMD_DATE .
801 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
802 and/or CONFIG_ISO_PARTITION
804 If IDE or SCSI support is enabled (CFG_CMD_IDE or
805 CFG_CMD_SCSI) you must configure support for at least
806 one partition type as well.
809 CONFIG_IDE_RESET_ROUTINE - this is defined in several
810 board configurations files but used nowhere!
812 CONFIG_IDE_RESET - is this is defined, IDE Reset will
813 be performed by calling the function
814 ide_set_reset(int reset)
815 which has to be defined in a board specific file
820 Set this to enable ATAPI support.
825 Set this to enable support for disks larger than 137GB
826 Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
827 Whithout these , LBA48 support uses 32bit variables and will 'only'
828 support disks up to 2.1TB.
831 When enabled, makes the IDE subsystem use 64bit sector addresses.
835 At the moment only there is only support for the
836 SYM53C8XX SCSI controller; define
837 CONFIG_SCSI_SYM53C8XX to enable it.
839 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
840 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
841 CFG_SCSI_MAX_LUN] can be adjusted to define the
842 maximum numbers of LUNs, SCSI ID's and target
844 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
846 - NETWORK Support (PCI):
848 Support for Intel 8254x gigabit chips.
851 Support for Intel 82557/82559/82559ER chips.
852 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
853 write routine for first time initialisation.
856 Support for Digital 2114x chips.
857 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
858 modem chip initialisation (KS8761/QS6611).
861 Support for National dp83815 chips.
864 Support for National dp8382[01] gigabit chips.
866 - NETWORK Support (other):
868 CONFIG_DRIVER_LAN91C96
869 Support for SMSC's LAN91C96 chips.
872 Define this to hold the physical address
873 of the LAN91C96's I/O space
875 CONFIG_LAN91C96_USE_32_BIT
876 Define this to enable 32 bit addressing
878 CONFIG_DRIVER_SMC91111
879 Support for SMSC's LAN91C111 chip
882 Define this to hold the physical address
883 of the device (I/O space)
885 CONFIG_SMC_USE_32_BIT
886 Define this if data bus is 32 bits
888 CONFIG_SMC_USE_IOFUNCS
889 Define this to use i/o functions instead of macros
890 (some hardware wont work with macros)
893 At the moment only the UHCI host controller is
894 supported (PIP405, MIP405, MPC5200); define
895 CONFIG_USB_UHCI to enable it.
896 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
897 and define CONFIG_USB_STORAGE to enable the USB
900 Supported are USB Keyboards and USB Floppy drives
902 MPC5200 USB requires additional defines:
904 for 528 MHz Clock: 0x0001bbbb
906 for differential drivers: 0x00001000
907 for single ended drivers: 0x00005000
911 The MMC controller on the Intel PXA is supported. To
912 enable this define CONFIG_MMC. The MMC can be
913 accessed from the boot prompt by mapping the device
914 to physical memory similar to flash. Command line is
915 enabled with CFG_CMD_MMC. The MMC driver also works with
916 the FAT fs. This is enabled with CFG_CMD_FAT.
918 - Journaling Flash filesystem support:
919 CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
920 CONFIG_JFFS2_NAND_DEV
921 Define these for a default partition on a NAND device
923 CFG_JFFS2_FIRST_SECTOR,
924 CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
925 Define these for a default partition on a NOR device
928 Define this to create an own partition. You have to provide a
929 function struct part_info* jffs2_part_info(int part_num)
931 If you define only one JFFS2 partition you may also want to
932 #define CFG_JFFS_SINGLE_PART 1
933 to disable the command chpart. This is the default when you
934 have not defined a custom partition
939 Define this to enable standard (PC-Style) keyboard
943 Standard PC keyboard driver with US (is default) and
944 GERMAN key layout (switch via environment 'keymap=de') support.
945 Export function i8042_kbd_init, i8042_tstc and i8042_getc
946 for cfb_console. Supports cursor blinking.
951 Define this to enable video support (for output to
956 Enable Chips & Technologies 69000 Video chip
958 CONFIG_VIDEO_SMI_LYNXEM
959 Enable Silicon Motion SMI 712/710/810 Video chip. The
960 video output is selected via environment 'videoout'
961 (1 = LCD and 2 = CRT). If videoout is undefined, CRT is
964 For the CT69000 and SMI_LYNXEM drivers, videomode is
965 selected via environment 'videomode'. Two diferent ways
967 - "videomode=num" 'num' is a standard LiLo mode numbers.
968 Following standard modes are supported (* is default):
970 Colors 640x480 800x600 1024x768 1152x864 1280x1024
971 -------------+---------------------------------------------
972 8 bits | 0x301* 0x303 0x305 0x161 0x307
973 15 bits | 0x310 0x313 0x316 0x162 0x319
974 16 bits | 0x311 0x314 0x317 0x163 0x31A
975 24 bits | 0x312 0x315 0x318 ? 0x31B
976 -------------+---------------------------------------------
977 (i.e. setenv videomode 317; saveenv; reset;)
979 - "videomode=bootargs" all the video parameters are parsed
980 from the bootargs. (See drivers/videomodes.c)
983 CONFIG_VIDEO_SED13806
984 Enable Epson SED13806 driver. This driver supports 8bpp
985 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
986 or CONFIG_VIDEO_SED13806_16BPP
991 Define this to enable a custom keyboard support.
992 This simply calls drv_keyboard_init() which must be
993 defined in your board-specific files.
994 The only board using this so far is RBC823.
996 - LCD Support: CONFIG_LCD
998 Define this to enable LCD support (for output to LCD
999 display); also select one of the supported displays
1000 by defining one of these:
1002 CONFIG_NEC_NL6448AC33:
1004 NEC NL6448AC33-18. Active, color, single scan.
1006 CONFIG_NEC_NL6448BC20
1008 NEC NL6448BC20-08. 6.5", 640x480.
1009 Active, color, single scan.
1011 CONFIG_NEC_NL6448BC33_54
1013 NEC NL6448BC33-54. 10.4", 640x480.
1014 Active, color, single scan.
1018 Sharp 320x240. Active, color, single scan.
1019 It isn't 16x9, and I am not sure what it is.
1021 CONFIG_SHARP_LQ64D341
1023 Sharp LQ64D341 display, 640x480.
1024 Active, color, single scan.
1028 HLD1045 display, 640x480.
1029 Active, color, single scan.
1033 Optrex CBL50840-2 NF-FW 99 22 M5
1035 Hitachi LMG6912RPFC-00T
1039 320x240. Black & white.
1041 Normally display is black on white background; define
1042 CFG_WHITE_ON_BLACK to get it inverted.
1044 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1046 If this option is set, the environment is checked for
1047 a variable "splashimage". If found, the usual display
1048 of logo, copyright and system information on the LCD
1049 is suppressed and the BMP image at the address
1050 specified in "splashimage" is loaded instead. The
1051 console is redirected to the "nulldev", too. This
1052 allows for a "silent" boot where a splash screen is
1053 loaded very quickly after power-on.
1055 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1057 If this option is set, additionally to standard BMP
1058 images, gzipped BMP images can be displayed via the
1059 splashscreen support or the bmp command.
1061 - Compression support:
1064 If this option is set, support for bzip2 compressed
1065 images is included. If not, only uncompressed and gzip
1066 compressed images are supported.
1068 NOTE: the bzip2 algorithm requires a lot of RAM, so
1069 the malloc area (as defined by CFG_MALLOC_LEN) should
1075 The address of PHY on MII bus.
1077 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1079 The clock frequency of the MII bus
1083 If this option is set, support for speed/duplex
1084 detection of Gigabit PHY is included.
1086 CONFIG_PHY_RESET_DELAY
1088 Some PHY like Intel LXT971A need extra delay after
1089 reset before any MII register access is possible.
1090 For such PHY, set this option to the usec delay
1091 required. (minimum 300usec for LXT971A)
1093 CONFIG_PHY_CMD_DELAY (ppc4xx)
1095 Some PHY like Intel LXT971A need extra delay after
1096 command issued before MII status register can be read
1103 Define a default value for ethernet address to use
1104 for the respective ethernet interface, in case this
1105 is not determined automatically.
1110 Define a default value for the IP address to use for
1111 the default ethernet interface, in case this is not
1112 determined through e.g. bootp.
1114 - Server IP address:
1117 Defines a default value for theIP address of a TFTP
1118 server to contact when using the "tftboot" command.
1120 - BOOTP Recovery Mode:
1121 CONFIG_BOOTP_RANDOM_DELAY
1123 If you have many targets in a network that try to
1124 boot using BOOTP, you may want to avoid that all
1125 systems send out BOOTP requests at precisely the same
1126 moment (which would happen for instance at recovery
1127 from a power failure, when all systems will try to
1128 boot, thus flooding the BOOTP server. Defining
1129 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1130 inserted before sending out BOOTP requests. The
1131 following delays are insterted then:
1133 1st BOOTP request: delay 0 ... 1 sec
1134 2nd BOOTP request: delay 0 ... 2 sec
1135 3rd BOOTP request: delay 0 ... 4 sec
1137 BOOTP requests: delay 0 ... 8 sec
1139 - DHCP Advanced Options:
1142 You can fine tune the DHCP functionality by adding
1143 these flags to the CONFIG_BOOTP_MASK define:
1145 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1146 serverip from a DHCP server, it is possible that more
1147 than one DNS serverip is offered to the client.
1148 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1149 serverip will be stored in the additional environment
1150 variable "dnsip2". The first DNS serverip is always
1151 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1152 is added to the CONFIG_BOOTP_MASK.
1154 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1155 to do a dynamic update of a DNS server. To do this, they
1156 need the hostname of the DHCP requester.
1157 If CONFIG_BOOP_SEND_HOSTNAME is added to the
1158 CONFIG_BOOTP_MASK, the content of the "hostname"
1159 environment variable is passed as option 12 to
1163 CONFIG_CDP_DEVICE_ID
1165 The device id used in CDP trigger frames.
1167 CONFIG_CDP_DEVICE_ID_PREFIX
1169 A two character string which is prefixed to the MAC address
1174 A printf format string which contains the ascii name of
1175 the port. Normally is set to "eth%d" which sets
1176 eth0 for the first ethernet, eth1 for the second etc.
1178 CONFIG_CDP_CAPABILITIES
1180 A 32bit integer which indicates the device capabilities;
1181 0x00000010 for a normal host which does not forwards.
1185 An ascii string containing the version of the software.
1189 An ascii string containing the name of the platform.
1193 A 32bit integer sent on the trigger.
1195 CONFIG_CDP_POWER_CONSUMPTION
1197 A 16bit integer containing the power consumption of the
1198 device in .1 of milliwatts.
1200 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1202 A byte containing the id of the VLAN.
1204 - Status LED: CONFIG_STATUS_LED
1206 Several configurations allow to display the current
1207 status using a LED. For instance, the LED will blink
1208 fast while running U-Boot code, stop blinking as
1209 soon as a reply to a BOOTP request was received, and
1210 start blinking slow once the Linux kernel is running
1211 (supported by a status LED driver in the Linux
1212 kernel). Defining CONFIG_STATUS_LED enables this
1215 - CAN Support: CONFIG_CAN_DRIVER
1217 Defining CONFIG_CAN_DRIVER enables CAN driver support
1218 on those systems that support this (optional)
1219 feature, like the TQM8xxL modules.
1221 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1223 These enable I2C serial bus commands. Defining either of
1224 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1225 include the appropriate I2C driver for the selected cpu.
1227 This will allow you to use i2c commands at the u-boot
1228 command line (as long as you set CFG_CMD_I2C in
1229 CONFIG_COMMANDS) and communicate with i2c based realtime
1230 clock chips. See common/cmd_i2c.c for a description of the
1231 command line interface.
1233 CONFIG_I2C_CMD_TREE is a recommended option that places
1234 all I2C commands under a single 'i2c' root command. The
1235 older 'imm', 'imd', 'iprobe' etc. commands are considered
1236 deprecated and may disappear in the future.
1238 CONFIG_HARD_I2C selects a hardware I2C controller.
1240 CONFIG_SOFT_I2C configures u-boot to use a software (aka
1241 bit-banging) driver instead of CPM or similar hardware
1244 There are several other quantities that must also be
1245 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1247 In both cases you will need to define CFG_I2C_SPEED
1248 to be the frequency (in Hz) at which you wish your i2c bus
1249 to run and CFG_I2C_SLAVE to be the address of this node (ie
1250 the cpu's i2c node address).
1252 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1253 sets the cpu up as a master node and so its address should
1254 therefore be cleared to 0 (See, eg, MPC823e User's Manual
1255 p.16-473). So, set CFG_I2C_SLAVE to 0.
1257 That's all that's required for CONFIG_HARD_I2C.
1259 If you use the software i2c interface (CONFIG_SOFT_I2C)
1260 then the following macros need to be defined (examples are
1261 from include/configs/lwmon.h):
1265 (Optional). Any commands necessary to enable the I2C
1266 controller or configure ports.
1268 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1272 (Only for MPC8260 CPU). The I/O port to use (the code
1273 assumes both bits are on the same port). Valid values
1274 are 0..3 for ports A..D.
1278 The code necessary to make the I2C data line active
1279 (driven). If the data line is open collector, this
1282 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1286 The code necessary to make the I2C data line tri-stated
1287 (inactive). If the data line is open collector, this
1290 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1294 Code that returns TRUE if the I2C data line is high,
1297 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1301 If <bit> is TRUE, sets the I2C data line high. If it
1302 is FALSE, it clears it (low).
1304 eg: #define I2C_SDA(bit) \
1305 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1306 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1310 If <bit> is TRUE, sets the I2C clock line high. If it
1311 is FALSE, it clears it (low).
1313 eg: #define I2C_SCL(bit) \
1314 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1315 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1319 This delay is invoked four times per clock cycle so this
1320 controls the rate of data transfer. The data rate thus
1321 is 1 / (I2C_DELAY * 4). Often defined to be something
1324 #define I2C_DELAY udelay(2)
1328 When a board is reset during an i2c bus transfer
1329 chips might think that the current transfer is still
1330 in progress. On some boards it is possible to access
1331 the i2c SCLK line directly, either by using the
1332 processor pin as a GPIO or by having a second pin
1333 connected to the bus. If this option is defined a
1334 custom i2c_init_board() routine in boards/xxx/board.c
1335 is run early in the boot sequence.
1337 CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1339 This option enables configuration of bi_iic_fast[] flags
1340 in u-boot bd_info structure based on u-boot environment
1341 variable "i2cfast". (see also i2cfast)
1343 CONFIG_I2C_MULTI_BUS
1345 This option allows the use of multiple I2C buses, each of which
1346 must have a controller. At any point in time, only one bus is
1347 active. To switch to a different bus, use the 'i2c dev' command.
1348 Note that bus numbering is zero-based.
1352 This option specifies a list of I2C devices that will be skipped
1353 when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1354 command). If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1355 pairs. Otherwise, specify a 1D array of device addresses
1358 #undef CONFIG_I2C_MULTI_BUS
1359 #define CFG_I2C_NOPROBES {0x50,0x68}
1361 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1363 #define CONFIG_I2C_MULTI_BUS
1364 #define CFG_I2C_MULTI_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1366 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1370 If defined, then this indicates the I2C bus number for DDR SPD.
1371 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1375 If defined, then this indicates the I2C bus number for the RTC.
1376 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1380 If defined, then this indicates the I2C bus number for the DTT.
1381 If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1385 Define this option if you want to use Freescale's I2C driver in
1389 - SPI Support: CONFIG_SPI
1391 Enables SPI driver (so far only tested with
1392 SPI EEPROM, also an instance works with Crystal A/D and
1393 D/As on the SACSng board)
1397 Enables extended (16-bit) SPI EEPROM addressing.
1398 (symmetrical to CONFIG_I2C_X)
1402 Enables a software (bit-bang) SPI driver rather than
1403 using hardware support. This is a general purpose
1404 driver that only requires three general I/O port pins
1405 (two outputs, one input) to function. If this is
1406 defined, the board configuration must define several
1407 SPI configuration items (port pins to use, etc). For
1408 an example, see include/configs/sacsng.h.
1410 - FPGA Support: CONFIG_FPGA_COUNT
1412 Specify the number of FPGA devices to support.
1416 Used to specify the types of FPGA devices. For example,
1417 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1419 CFG_FPGA_PROG_FEEDBACK
1421 Enable printing of hash marks during FPGA configuration.
1425 Enable checks on FPGA configuration interface busy
1426 status by the configuration function. This option
1427 will require a board or device specific function to
1432 If defined, a function that provides delays in the FPGA
1433 configuration driver.
1435 CFG_FPGA_CHECK_CTRLC
1436 Allow Control-C to interrupt FPGA configuration
1438 CFG_FPGA_CHECK_ERROR
1440 Check for configuration errors during FPGA bitfile
1441 loading. For example, abort during Virtex II
1442 configuration if the INIT_B line goes low (which
1443 indicated a CRC error).
1447 Maximum time to wait for the INIT_B line to deassert
1448 after PROB_B has been deasserted during a Virtex II
1449 FPGA configuration sequence. The default time is 500
1454 Maximum time to wait for BUSY to deassert during
1455 Virtex II FPGA configuration. The default is 5 mS.
1457 CFG_FPGA_WAIT_CONFIG
1459 Time to wait after FPGA configuration. The default is
1462 - Configuration Management:
1465 If defined, this string will be added to the U-Boot
1466 version information (U_BOOT_VERSION)
1468 - Vendor Parameter Protection:
1470 U-Boot considers the values of the environment
1471 variables "serial#" (Board Serial Number) and
1472 "ethaddr" (Ethernet Address) to be parameters that
1473 are set once by the board vendor / manufacturer, and
1474 protects these variables from casual modification by
1475 the user. Once set, these variables are read-only,
1476 and write or delete attempts are rejected. You can
1477 change this behviour:
1479 If CONFIG_ENV_OVERWRITE is #defined in your config
1480 file, the write protection for vendor parameters is
1481 completely disabled. Anybody can change or delete
1484 Alternatively, if you #define _both_ CONFIG_ETHADDR
1485 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1486 ethernet address is installed in the environment,
1487 which can be changed exactly ONCE by the user. [The
1488 serial# is unaffected by this, i. e. it remains
1494 Define this variable to enable the reservation of
1495 "protected RAM", i. e. RAM which is not overwritten
1496 by U-Boot. Define CONFIG_PRAM to hold the number of
1497 kB you want to reserve for pRAM. You can overwrite
1498 this default value by defining an environment
1499 variable "pram" to the number of kB you want to
1500 reserve. Note that the board info structure will
1501 still show the full amount of RAM. If pRAM is
1502 reserved, a new environment variable "mem" will
1503 automatically be defined to hold the amount of
1504 remaining RAM in a form that can be passed as boot
1505 argument to Linux, for instance like that:
1507 setenv bootargs ... mem=\${mem}
1510 This way you can tell Linux not to use this memory,
1511 either, which results in a memory region that will
1512 not be affected by reboots.
1514 *WARNING* If your board configuration uses automatic
1515 detection of the RAM size, you must make sure that
1516 this memory test is non-destructive. So far, the
1517 following board configurations are known to be
1520 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1521 HERMES, IP860, RPXlite, LWMON, LANTEC,
1522 PCU_E, FLAGADM, TQM8260
1527 Define this variable to stop the system in case of a
1528 fatal error, so that you have to reset it manually.
1529 This is probably NOT a good idea for an embedded
1530 system where you want to system to reboot
1531 automatically as fast as possible, but it may be
1532 useful during development since you can try to debug
1533 the conditions that lead to the situation.
1535 CONFIG_NET_RETRY_COUNT
1537 This variable defines the number of retries for
1538 network operations like ARP, RARP, TFTP, or BOOTP
1539 before giving up the operation. If not defined, a
1540 default value of 5 is used.
1542 - Command Interpreter:
1543 CONFIG_AUTO_COMPLETE
1545 Enable auto completion of commands using TAB.
1547 Note that this feature has NOT been implemented yet
1548 for the "hush" shell.
1553 Define this variable to enable the "hush" shell (from
1554 Busybox) as command line interpreter, thus enabling
1555 powerful command line syntax like
1556 if...then...else...fi conditionals or `&&' and '||'
1557 constructs ("shell scripts").
1559 If undefined, you get the old, much simpler behaviour
1560 with a somewhat smaller memory footprint.
1565 This defines the secondary prompt string, which is
1566 printed when the command interpreter needs more input
1567 to complete a command. Usually "> ".
1571 In the current implementation, the local variables
1572 space and global environment variables space are
1573 separated. Local variables are those you define by
1574 simply typing `name=value'. To access a local
1575 variable later on, you have write `$name' or
1576 `${name}'; to execute the contents of a variable
1577 directly type `$name' at the command prompt.
1579 Global environment variables are those you use
1580 setenv/printenv to work with. To run a command stored
1581 in such a variable, you need to use the run command,
1582 and you must not use the '$' sign to access them.
1584 To store commands and special characters in a
1585 variable, please use double quotation marks
1586 surrounding the whole text of the variable, instead
1587 of the backslashes before semicolons and special
1590 - Commandline Editing and History:
1591 CONFIG_CMDLINE_EDITING
1593 Enable editiong and History functions for interactive
1594 commandline input operations
1596 - Default Environment:
1597 CONFIG_EXTRA_ENV_SETTINGS
1599 Define this to contain any number of null terminated
1600 strings (variable = value pairs) that will be part of
1601 the default environment compiled into the boot image.
1603 For example, place something like this in your
1604 board's config file:
1606 #define CONFIG_EXTRA_ENV_SETTINGS \
1610 Warning: This method is based on knowledge about the
1611 internal format how the environment is stored by the
1612 U-Boot code. This is NOT an official, exported
1613 interface! Although it is unlikely that this format
1614 will change soon, there is no guarantee either.
1615 You better know what you are doing here.
1617 Note: overly (ab)use of the default environment is
1618 discouraged. Make sure to check other ways to preset
1619 the environment like the autoscript function or the
1622 - DataFlash Support:
1623 CONFIG_HAS_DATAFLASH
1625 Defining this option enables DataFlash features and
1626 allows to read/write in Dataflash via the standard
1629 - SystemACE Support:
1632 Adding this option adds support for Xilinx SystemACE
1633 chips attached via some sort of local bus. The address
1634 of the chip must alsh be defined in the
1635 CFG_SYSTEMACE_BASE macro. For example:
1637 #define CONFIG_SYSTEMACE
1638 #define CFG_SYSTEMACE_BASE 0xf0000000
1640 When SystemACE support is added, the "ace" device type
1641 becomes available to the fat commands, i.e. fatls.
1643 - TFTP Fixed UDP Port:
1646 If this is defined, the environment variable tftpsrcp
1647 is used to supply the TFTP UDP source port value.
1648 If tftpsrcp isn't defined, the normal pseudo-random port
1649 number generator is used.
1651 Also, the environment variable tftpdstp is used to supply
1652 the TFTP UDP destination port value. If tftpdstp isn't
1653 defined, the normal port 69 is used.
1655 The purpose for tftpsrcp is to allow a TFTP server to
1656 blindly start the TFTP transfer using the pre-configured
1657 target IP address and UDP port. This has the effect of
1658 "punching through" the (Windows XP) firewall, allowing
1659 the remainder of the TFTP transfer to proceed normally.
1660 A better solution is to properly configure the firewall,
1661 but sometimes that is not allowed.
1663 - Show boot progress:
1664 CONFIG_SHOW_BOOT_PROGRESS
1666 Defining this option allows to add some board-
1667 specific code (calling a user-provided function
1668 "show_boot_progress(int)") that enables you to show
1669 the system's boot progress on some display (for
1670 example, some LED's) on your board. At the moment,
1671 the following checkpoints are implemented:
1674 1 common/cmd_bootm.c before attempting to boot an image
1675 -1 common/cmd_bootm.c Image header has bad magic number
1676 2 common/cmd_bootm.c Image header has correct magic number
1677 -2 common/cmd_bootm.c Image header has bad checksum
1678 3 common/cmd_bootm.c Image header has correct checksum
1679 -3 common/cmd_bootm.c Image data has bad checksum
1680 4 common/cmd_bootm.c Image data has correct checksum
1681 -4 common/cmd_bootm.c Image is for unsupported architecture
1682 5 common/cmd_bootm.c Architecture check OK
1683 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1684 6 common/cmd_bootm.c Image Type check OK
1685 -6 common/cmd_bootm.c gunzip uncompression error
1686 -7 common/cmd_bootm.c Unimplemented compression type
1687 7 common/cmd_bootm.c Uncompression OK
1688 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1689 8 common/cmd_bootm.c Image Type check OK
1690 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1691 9 common/cmd_bootm.c Start initial ramdisk verification
1692 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1693 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1694 10 common/cmd_bootm.c Ramdisk header is OK
1695 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1696 11 common/cmd_bootm.c Ramdisk data has correct checksum
1697 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1698 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1699 13 common/cmd_bootm.c Start multifile image verification
1700 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1701 15 common/cmd_bootm.c All preparation done, transferring control to OS
1703 -30 lib_ppc/board.c Fatal error, hang the system
1704 -31 post/post.c POST test failed, detected by post_output_backlog()
1705 -32 post/post.c POST test failed, detected by post_run_single()
1707 -1 common/cmd_doc.c Bad usage of "doc" command
1708 -1 common/cmd_doc.c No boot device
1709 -1 common/cmd_doc.c Unknown Chip ID on boot device
1710 -1 common/cmd_doc.c Read Error on boot device
1711 -1 common/cmd_doc.c Image header has bad magic number
1713 -1 common/cmd_ide.c Bad usage of "ide" command
1714 -1 common/cmd_ide.c No boot device
1715 -1 common/cmd_ide.c Unknown boot device
1716 -1 common/cmd_ide.c Unknown partition table
1717 -1 common/cmd_ide.c Invalid partition type
1718 -1 common/cmd_ide.c Read Error on boot device
1719 -1 common/cmd_ide.c Image header has bad magic number
1721 -1 common/cmd_nand.c Bad usage of "nand" command
1722 -1 common/cmd_nand.c No boot device
1723 -1 common/cmd_nand.c Unknown Chip ID on boot device
1724 -1 common/cmd_nand.c Read Error on boot device
1725 -1 common/cmd_nand.c Image header has bad magic number
1727 -1 common/env_common.c Environment has a bad CRC, using default
1733 [so far only for SMDK2400 and TRAB boards]
1735 - Modem support endable:
1736 CONFIG_MODEM_SUPPORT
1738 - RTS/CTS Flow control enable:
1741 - Modem debug support:
1742 CONFIG_MODEM_SUPPORT_DEBUG
1744 Enables debugging stuff (char screen[1024], dbg())
1745 for modem support. Useful only with BDI2000.
1747 - Interrupt support (PPC):
1749 There are common interrupt_init() and timer_interrupt()
1750 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1751 for cpu specific initialization. interrupt_init_cpu()
1752 should set decrementer_count to appropriate value. If
1753 cpu resets decrementer automatically after interrupt
1754 (ppc4xx) it should set decrementer_count to zero.
1755 timer_interrupt() calls timer_interrupt_cpu() for cpu
1756 specific handling. If board has watchdog / status_led
1757 / other_activity_monitor it works automatically from
1758 general timer_interrupt().
1762 In the target system modem support is enabled when a
1763 specific key (key combination) is pressed during
1764 power-on. Otherwise U-Boot will boot normally
1765 (autoboot). The key_pressed() fuction is called from
1766 board_init(). Currently key_pressed() is a dummy
1767 function, returning 1 and thus enabling modem
1770 If there are no modem init strings in the
1771 environment, U-Boot proceed to autoboot; the
1772 previous output (banner, info printfs) will be
1775 See also: doc/README.Modem
1778 Configuration Settings:
1779 -----------------------
1781 - CFG_LONGHELP: Defined when you want long help messages included;
1782 undefine this when you're short of memory.
1784 - CFG_PROMPT: This is what U-Boot prints on the console to
1785 prompt for user input.
1787 - CFG_CBSIZE: Buffer size for input from the Console
1789 - CFG_PBSIZE: Buffer size for Console output
1791 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1793 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1794 the application (usually a Linux kernel) when it is
1797 - CFG_BAUDRATE_TABLE:
1798 List of legal baudrate settings for this board.
1800 - CFG_CONSOLE_INFO_QUIET
1801 Suppress display of console information at boot.
1803 - CFG_CONSOLE_IS_IN_ENV
1804 If the board specific function
1805 extern int overwrite_console (void);
1806 returns 1, the stdin, stderr and stdout are switched to the
1807 serial port, else the settings in the environment are used.
1809 - CFG_CONSOLE_OVERWRITE_ROUTINE
1810 Enable the call to overwrite_console().
1812 - CFG_CONSOLE_ENV_OVERWRITE
1813 Enable overwrite of previous console environment settings.
1815 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1816 Begin and End addresses of the area used by the
1820 Enable an alternate, more extensive memory test.
1822 - CFG_MEMTEST_SCRATCH:
1823 Scratch address used by the alternate memory test
1824 You only need to set this if address zero isn't writeable
1826 - CFG_TFTP_LOADADDR:
1827 Default load address for network file downloads
1829 - CFG_LOADS_BAUD_CHANGE:
1830 Enable temporary baudrate change while serial download
1833 Physical start address of SDRAM. _Must_ be 0 here.
1836 Physical start address of Motherboard I/O (if using a
1840 Physical start address of Flash memory.
1843 Physical start address of boot monitor code (set by
1844 make config files to be same as the text base address
1845 (TEXT_BASE) used when linking) - same as
1846 CFG_FLASH_BASE when booting from flash.
1849 Size of memory reserved for monitor code, used to
1850 determine _at_compile_time_ (!) if the environment is
1851 embedded within the U-Boot image, or in a separate
1855 Size of DRAM reserved for malloc() use.
1858 Normally compressed uImages are limited to an
1859 uncompressed size of 8 MBytes. If this is not enough,
1860 you can define CFG_BOOTM_LEN in your board config file
1861 to adjust this setting to your needs.
1864 Maximum size of memory mapped by the startup code of
1865 the Linux kernel; all data that must be processed by
1866 the Linux kernel (bd_info, boot arguments, eventually
1867 initrd image) must be put below this limit.
1869 - CFG_MAX_FLASH_BANKS:
1870 Max number of Flash memory banks
1872 - CFG_MAX_FLASH_SECT:
1873 Max number of sectors on a Flash chip
1875 - CFG_FLASH_ERASE_TOUT:
1876 Timeout for Flash erase operations (in ms)
1878 - CFG_FLASH_WRITE_TOUT:
1879 Timeout for Flash write operations (in ms)
1881 - CFG_FLASH_LOCK_TOUT
1882 Timeout for Flash set sector lock bit operation (in ms)
1884 - CFG_FLASH_UNLOCK_TOUT
1885 Timeout for Flash clear lock bits operation (in ms)
1887 - CFG_FLASH_PROTECTION
1888 If defined, hardware flash sectors protection is used
1889 instead of U-Boot software protection.
1891 - CFG_DIRECT_FLASH_TFTP:
1893 Enable TFTP transfers directly to flash memory;
1894 without this option such a download has to be
1895 performed in two steps: (1) download to RAM, and (2)
1896 copy from RAM to flash.
1898 The two-step approach is usually more reliable, since
1899 you can check if the download worked before you erase
1900 the flash, but in some situations (when sytem RAM is
1901 too limited to allow for a tempory copy of the
1902 downloaded image) this option may be very useful.
1905 Define if the flash driver uses extra elements in the
1906 common flash structure for storing flash geometry.
1908 - CFG_FLASH_CFI_DRIVER
1909 This option also enables the building of the cfi_flash driver
1910 in the drivers directory
1912 - CFG_FLASH_QUIET_TEST
1913 If this option is defined, the common CFI flash doesn't
1914 print it's warning upon not recognized FLASH banks. This
1915 is useful, if some of the configured banks are only
1916 optionally available.
1918 - CFG_RX_ETH_BUFFER:
1919 Defines the number of ethernet receive buffers. On some
1920 ethernet controllers it is recommended to set this value
1921 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1922 buffers can be full shortly after enabling the interface
1923 on high ethernet traffic.
1924 Defaults to 4 if not defined.
1926 The following definitions that deal with the placement and management
1927 of environment data (variable area); in general, we support the
1928 following configurations:
1930 - CFG_ENV_IS_IN_FLASH:
1932 Define this if the environment is in flash memory.
1934 a) The environment occupies one whole flash sector, which is
1935 "embedded" in the text segment with the U-Boot code. This
1936 happens usually with "bottom boot sector" or "top boot
1937 sector" type flash chips, which have several smaller
1938 sectors at the start or the end. For instance, such a
1939 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1940 such a case you would place the environment in one of the
1941 4 kB sectors - with U-Boot code before and after it. With
1942 "top boot sector" type flash chips, you would put the
1943 environment in one of the last sectors, leaving a gap
1944 between U-Boot and the environment.
1948 Offset of environment data (variable area) to the
1949 beginning of flash memory; for instance, with bottom boot
1950 type flash chips the second sector can be used: the offset
1951 for this sector is given here.
1953 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1957 This is just another way to specify the start address of
1958 the flash sector containing the environment (instead of
1961 - CFG_ENV_SECT_SIZE:
1963 Size of the sector containing the environment.
1966 b) Sometimes flash chips have few, equal sized, BIG sectors.
1967 In such a case you don't want to spend a whole sector for
1972 If you use this in combination with CFG_ENV_IS_IN_FLASH
1973 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1974 of this flash sector for the environment. This saves
1975 memory for the RAM copy of the environment.
1977 It may also save flash memory if you decide to use this
1978 when your environment is "embedded" within U-Boot code,
1979 since then the remainder of the flash sector could be used
1980 for U-Boot code. It should be pointed out that this is
1981 STRONGLY DISCOURAGED from a robustness point of view:
1982 updating the environment in flash makes it always
1983 necessary to erase the WHOLE sector. If something goes
1984 wrong before the contents has been restored from a copy in
1985 RAM, your target system will be dead.
1987 - CFG_ENV_ADDR_REDUND
1990 These settings describe a second storage area used to hold
1991 a redundand copy of the environment data, so that there is
1992 a valid backup copy in case there is a power failure during
1993 a "saveenv" operation.
1995 BE CAREFUL! Any changes to the flash layout, and some changes to the
1996 source code will make it necessary to adapt <board>/u-boot.lds*
2000 - CFG_ENV_IS_IN_NVRAM:
2002 Define this if you have some non-volatile memory device
2003 (NVRAM, battery buffered SRAM) which you want to use for the
2009 These two #defines are used to determin the memory area you
2010 want to use for environment. It is assumed that this memory
2011 can just be read and written to, without any special
2014 BE CAREFUL! The first access to the environment happens quite early
2015 in U-Boot initalization (when we try to get the setting of for the
2016 console baudrate). You *MUST* have mappend your NVRAM area then, or
2019 Please note that even with NVRAM we still use a copy of the
2020 environment in RAM: we could work on NVRAM directly, but we want to
2021 keep settings there always unmodified except somebody uses "saveenv"
2022 to save the current settings.
2025 - CFG_ENV_IS_IN_EEPROM:
2027 Use this if you have an EEPROM or similar serial access
2028 device and a driver for it.
2033 These two #defines specify the offset and size of the
2034 environment area within the total memory of your EEPROM.
2036 - CFG_I2C_EEPROM_ADDR:
2037 If defined, specified the chip address of the EEPROM device.
2038 The default address is zero.
2040 - CFG_EEPROM_PAGE_WRITE_BITS:
2041 If defined, the number of bits used to address bytes in a
2042 single page in the EEPROM device. A 64 byte page, for example
2043 would require six bits.
2045 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2046 If defined, the number of milliseconds to delay between
2047 page writes. The default is zero milliseconds.
2049 - CFG_I2C_EEPROM_ADDR_LEN:
2050 The length in bytes of the EEPROM memory array address. Note
2051 that this is NOT the chip address length!
2053 - CFG_I2C_EEPROM_ADDR_OVERFLOW:
2054 EEPROM chips that implement "address overflow" are ones
2055 like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2056 address and the extra bits end up in the "chip address" bit
2057 slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2060 Note that we consider the length of the address field to
2061 still be one byte because the extra address bits are hidden
2062 in the chip address.
2065 The size in bytes of the EEPROM device.
2068 - CFG_ENV_IS_IN_DATAFLASH:
2070 Define this if you have a DataFlash memory device which you
2071 want to use for the environment.
2077 These three #defines specify the offset and size of the
2078 environment area within the total memory of your DataFlash placed
2079 at the specified address.
2081 - CFG_ENV_IS_IN_NAND:
2083 Define this if you have a NAND device which you want to use
2084 for the environment.
2089 These two #defines specify the offset and size of the environment
2090 area within the first NAND device.
2092 - CFG_ENV_OFFSET_REDUND
2094 This setting describes a second storage area of CFG_ENV_SIZE
2095 size used to hold a redundant copy of the environment data,
2096 so that there is a valid backup copy in case there is a
2097 power failure during a "saveenv" operation.
2099 Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2100 to a block boundary, and CFG_ENV_SIZE must be a multiple of
2101 the NAND devices block size.
2103 - CFG_SPI_INIT_OFFSET
2105 Defines offset to the initial SPI buffer area in DPRAM. The
2106 area is used at an early stage (ROM part) if the environment
2107 is configured to reside in the SPI EEPROM: We need a 520 byte
2108 scratch DPRAM area. It is used between the two initialization
2109 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2110 to be a good choice since it makes it far enough from the
2111 start of the data area as well as from the stack pointer.
2113 Please note that the environment is read-only as long as the monitor
2114 has been relocated to RAM and a RAM copy of the environment has been
2115 created; also, when using EEPROM you will have to use getenv_r()
2116 until then to read environment variables.
2118 The environment is protected by a CRC32 checksum. Before the monitor
2119 is relocated into RAM, as a result of a bad CRC you will be working
2120 with the compiled-in default environment - *silently*!!! [This is
2121 necessary, because the first environment variable we need is the
2122 "baudrate" setting for the console - if we have a bad CRC, we don't
2123 have any device yet where we could complain.]
2125 Note: once the monitor has been relocated, then it will complain if
2126 the default environment is used; a new CRC is computed as soon as you
2127 use the "saveenv" command to store a valid environment.
2129 - CFG_FAULT_ECHO_LINK_DOWN:
2130 Echo the inverted Ethernet link state to the fault LED.
2132 Note: If this option is active, then CFG_FAULT_MII_ADDR
2133 also needs to be defined.
2135 - CFG_FAULT_MII_ADDR:
2136 MII address of the PHY to check for the Ethernet link state.
2138 - CFG_64BIT_VSPRINTF:
2139 Makes vsprintf (and all *printf functions) support printing
2140 of 64bit values by using the L quantifier
2142 - CFG_64BIT_STRTOUL:
2143 Adds simple_strtoull that returns a 64bit value
2145 Low Level (hardware related) configuration options:
2146 ---------------------------------------------------
2148 - CFG_CACHELINE_SIZE:
2149 Cache Line Size of the CPU.
2152 Default address of the IMMR after system reset.
2154 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2155 and RPXsuper) to be able to adjust the position of
2156 the IMMR register after a reset.
2158 - Floppy Disk Support:
2159 CFG_FDC_DRIVE_NUMBER
2161 the default drive number (default value 0)
2165 defines the spacing between fdc chipset registers
2170 defines the offset of register from address. It
2171 depends on which part of the data bus is connected to
2172 the fdc chipset. (default value 0)
2174 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2175 CFG_FDC_DRIVE_NUMBER are undefined, they take their
2178 if CFG_FDC_HW_INIT is defined, then the function
2179 fdc_hw_init() is called at the beginning of the FDC
2180 setup. fdc_hw_init() must be provided by the board
2181 source code. It is used to make hardware dependant
2184 - CFG_IMMR: Physical address of the Internal Memory.
2185 DO NOT CHANGE unless you know exactly what you're
2186 doing! (11-4) [MPC8xx/82xx systems only]
2188 - CFG_INIT_RAM_ADDR:
2190 Start address of memory area that can be used for
2191 initial data and stack; please note that this must be
2192 writable memory that is working WITHOUT special
2193 initialization, i. e. you CANNOT use normal RAM which
2194 will become available only after programming the
2195 memory controller and running certain initialization
2198 U-Boot uses the following memory types:
2199 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2200 - MPC824X: data cache
2201 - PPC4xx: data cache
2203 - CFG_GBL_DATA_OFFSET:
2205 Offset of the initial data structure in the memory
2206 area defined by CFG_INIT_RAM_ADDR. Usually
2207 CFG_GBL_DATA_OFFSET is chosen such that the initial
2208 data is located at the end of the available space
2209 (sometimes written as (CFG_INIT_RAM_END -
2210 CFG_INIT_DATA_SIZE), and the initial stack is just
2211 below that area (growing from (CFG_INIT_RAM_ADDR +
2212 CFG_GBL_DATA_OFFSET) downward.
2215 On the MPC824X (or other systems that use the data
2216 cache for initial memory) the address chosen for
2217 CFG_INIT_RAM_ADDR is basically arbitrary - it must
2218 point to an otherwise UNUSED address space between
2219 the top of RAM and the start of the PCI space.
2221 - CFG_SIUMCR: SIU Module Configuration (11-6)
2223 - CFG_SYPCR: System Protection Control (11-9)
2225 - CFG_TBSCR: Time Base Status and Control (11-26)
2227 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
2229 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
2231 - CFG_SCCR: System Clock and reset Control Register (15-27)
2233 - CFG_OR_TIMING_SDRAM:
2237 periodic timer for refresh
2239 - CFG_DER: Debug Event Register (37-47)
2241 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2242 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2243 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2245 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2247 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2248 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2249 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2250 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2252 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2253 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2254 Machine Mode Register and Memory Periodic Timer
2255 Prescaler definitions (SDRAM timing)
2257 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2258 enable I2C microcode relocation patch (MPC8xx);
2259 define relocation offset in DPRAM [DSP2]
2261 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2262 enable SPI microcode relocation patch (MPC8xx);
2263 define relocation offset in DPRAM [SCC4]
2266 Use OSCM clock mode on MBX8xx board. Be careful,
2267 wrong setting might damage your board. Read
2268 doc/README.MBX before setting this variable!
2270 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2271 Offset of the bootmode word in DPRAM used by post
2272 (Power On Self Tests). This definition overrides
2273 #define'd default value in commproc.h resp.
2276 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2277 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2278 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2279 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2280 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2281 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2282 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2283 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2284 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2287 Get DDR timing information from an I2C EEPROM. Common with pluggable
2288 memory modules such as SODIMMs
2290 I2C address of the SPD EEPROM
2293 If SPD EEPROM is on an I2C bus other than the first one, specify here.
2294 Note that the value must resolve to something your driver can deal with.
2296 - CFG_83XX_DDR_USES_CS0
2297 Only for 83xx systems. If specified, then DDR should be configured
2298 using CS0 and CS1 instead of CS2 and CS3.
2300 - CFG_83XX_DDR_USES_CS0
2301 Only for 83xx systems. If specified, then DDR should be configured
2302 using CS0 and CS1 instead of CS2 and CS3.
2304 - CONFIG_ETHER_ON_FEC[12]
2305 Define to enable FEC[12] on a 8xx series processor.
2307 - CONFIG_FEC[12]_PHY
2308 Define to the hardcoded PHY address which corresponds
2309 to the given FEC; i. e.
2310 #define CONFIG_FEC1_PHY 4
2311 means that the PHY with address 4 is connected to FEC1
2313 When set to -1, means to probe for first available.
2315 - CONFIG_FEC[12]_PHY_NORXERR
2316 The PHY does not have a RXERR line (RMII only).
2317 (so program the FEC to ignore it).
2320 Enable RMII mode for all FECs.
2321 Note that this is a global option, we can't
2322 have one FEC in standard MII mode and another in RMII mode.
2324 - CONFIG_CRC32_VERIFY
2325 Add a verify option to the crc32 command.
2328 => crc32 -v <address> <count> <crc32>
2330 Where address/count indicate a memory area
2331 and crc32 is the correct crc32 which the
2335 Add the "loopw" memory command. This only takes effect if
2336 the memory commands are activated globally (CFG_CMD_MEM).
2339 Add the "mdc" and "mwc" memory commands. These are cyclic
2344 This command will print 4 bytes (10,11,12,13) each 500 ms.
2346 => mwc.l 100 12345678 10
2347 This command will write 12345678 to address 100 all 10 ms.
2349 This only takes effect if the memory commands are activated
2350 globally (CFG_CMD_MEM).
2352 - CONFIG_SKIP_LOWLEVEL_INIT
2353 - CONFIG_SKIP_RELOCATE_UBOOT
2355 [ARM only] If these variables are defined, then
2356 certain low level initializations (like setting up
2357 the memory controller) are omitted and/or U-Boot does
2358 not relocate itself into RAM.
2359 Normally these variables MUST NOT be defined. The
2360 only exception is when U-Boot is loaded (to RAM) by
2361 some other boot loader or by a debugger which
2362 performs these intializations itself.
2365 Building the Software:
2366 ======================
2368 Building U-Boot has been tested in native PPC environments (on a
2369 PowerBook G3 running LinuxPPC 2000) and in cross environments
2370 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2373 If you are not using a native PPC environment, it is assumed that you
2374 have the GNU cross compiling tools available in your path and named
2375 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2376 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2377 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2380 CROSS_COMPILE = ppc_4xx-
2383 U-Boot is intended to be simple to build. After installing the
2384 sources you must configure U-Boot for one specific board type. This
2389 where "NAME_config" is the name of one of the existing
2390 configurations; the following names are supported:
2392 ADCIOP_config FPS860L_config omap730p2_config
2393 ADS860_config GEN860T_config pcu_e_config
2395 AR405_config GENIETV_config PIP405_config
2396 at91rm9200dk_config GTH_config QS823_config
2397 CANBT_config hermes_config QS850_config
2398 cmi_mpc5xx_config hymod_config QS860T_config
2399 cogent_common_config IP860_config RPXlite_config
2400 cogent_mpc8260_config IVML24_config RPXlite_DW_config
2401 cogent_mpc8xx_config IVMS8_config RPXsuper_config
2402 CPCI405_config JSE_config rsdproto_config
2403 CPCIISER4_config LANTEC_config Sandpoint8240_config
2404 csb272_config lwmon_config sbc8260_config
2405 CU824_config MBX860T_config sbc8560_33_config
2406 DUET_ADS_config MBX_config sbc8560_66_config
2407 EBONY_config mpc7448hpc2_config SM850_config
2408 ELPT860_config MPC8260ADS_config SPD823TS_config
2409 ESTEEM192E_config MPC8540ADS_config stxgp3_config
2410 ETX094_config MPC8540EVAL_config SXNI855T_config
2411 FADS823_config NMPC8560ADS_config TQM823L_config
2412 FADS850SAR_config NETVIA_config TQM850L_config
2413 FADS860T_config omap1510inn_config TQM855L_config
2414 FPS850L_config omap1610h2_config TQM860L_config
2415 omap1610inn_config walnut_config
2416 omap5912osk_config Yukon8220_config
2417 omap2420h4_config ZPC1900_config
2419 Note: for some board special configuration names may exist; check if
2420 additional information is available from the board vendor; for
2421 instance, the TQM823L systems are available without (standard)
2422 or with LCD support. You can select such additional "features"
2423 when chosing the configuration, i. e.
2426 - will configure for a plain TQM823L, i. e. no LCD support
2428 make TQM823L_LCD_config
2429 - will configure for a TQM823L with U-Boot console on LCD
2434 Finally, type "make all", and you should get some working U-Boot
2435 images ready for download to / installation on your system:
2437 - "u-boot.bin" is a raw binary image
2438 - "u-boot" is an image in ELF binary format
2439 - "u-boot.srec" is in Motorola S-Record format
2441 By default the build is performed locally and the objects are saved
2442 in the source directory. One of the two methods can be used to change
2443 this behavior and build U-Boot to some external directory:
2445 1. Add O= to the make command line invocations:
2447 make O=/tmp/build distclean
2448 make O=/tmp/build NAME_config
2449 make O=/tmp/build all
2451 2. Set environment variable BUILD_DIR to point to the desired location:
2453 export BUILD_DIR=/tmp/build
2458 Note that the command line "O=" setting overrides the BUILD_DIR environment
2462 Please be aware that the Makefiles assume you are using GNU make, so
2463 for instance on NetBSD you might need to use "gmake" instead of
2467 If the system board that you have is not listed, then you will need
2468 to port U-Boot to your hardware platform. To do this, follow these
2471 1. Add a new configuration option for your board to the toplevel
2472 "Makefile" and to the "MAKEALL" script, using the existing
2473 entries as examples. Note that here and at many other places
2474 boards and other names are listed in alphabetical sort order. Please
2476 2. Create a new directory to hold your board specific code. Add any
2477 files you need. In your board directory, you will need at least
2478 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
2479 3. Create a new configuration file "include/configs/<board>.h" for
2481 3. If you're porting U-Boot to a new CPU, then also create a new
2482 directory to hold your CPU specific code. Add any files you need.
2483 4. Run "make <board>_config" with your new name.
2484 5. Type "make", and you should get a working "u-boot.srec" file
2485 to be installed on your target system.
2486 6. Debug and solve any problems that might arise.
2487 [Of course, this last step is much harder than it sounds.]
2490 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2491 ==============================================================
2493 If you have modified U-Boot sources (for instance added a new board
2494 or support for new devices, a new CPU, etc.) you are expected to
2495 provide feedback to the other developers. The feedback normally takes
2496 the form of a "patch", i. e. a context diff against a certain (latest
2497 official or latest in CVS) version of U-Boot sources.
2499 But before you submit such a patch, please verify that your modifi-
2500 cation did not break existing code. At least make sure that *ALL* of
2501 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2502 just run the "MAKEALL" script, which will configure and build U-Boot
2503 for ALL supported system. Be warned, this will take a while. You can
2504 select which (cross) compiler to use by passing a `CROSS_COMPILE'
2505 environment variable to the script, i. e. to use the cross tools from
2506 MontaVista's Hard Hat Linux you can type
2508 CROSS_COMPILE=ppc_8xx- MAKEALL
2510 or to build on a native PowerPC system you can type
2512 CROSS_COMPILE=' ' MAKEALL
2514 When using the MAKEALL script, the default behaviour is to build U-Boot
2515 in the source directory. This location can be changed by setting the
2516 BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2517 script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2518 <source dir>/LOG directory. This default location can be changed by
2519 setting the MAKEALL_LOGDIR environment variable. For example:
2521 export BUILD_DIR=/tmp/build
2522 export MAKEALL_LOGDIR=/tmp/log
2523 CROSS_COMPILE=ppc_8xx- MAKEALL
2525 With the above settings build objects are saved in the /tmp/build, log
2526 files are saved in the /tmp/log and the source tree remains clean during
2527 the whole build process.
2530 See also "U-Boot Porting Guide" below.
2533 Monitor Commands - Overview:
2534 ============================
2536 go - start application at address 'addr'
2537 run - run commands in an environment variable
2538 bootm - boot application image from memory
2539 bootp - boot image via network using BootP/TFTP protocol
2540 tftpboot- boot image via network using TFTP protocol
2541 and env variables "ipaddr" and "serverip"
2542 (and eventually "gatewayip")
2543 rarpboot- boot image via network using RARP/TFTP protocol
2544 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2545 loads - load S-Record file over serial line
2546 loadb - load binary file over serial line (kermit mode)
2548 mm - memory modify (auto-incrementing)
2549 nm - memory modify (constant address)
2550 mw - memory write (fill)
2552 cmp - memory compare
2553 crc32 - checksum calculation
2554 imd - i2c memory display
2555 imm - i2c memory modify (auto-incrementing)
2556 inm - i2c memory modify (constant address)
2557 imw - i2c memory write (fill)
2558 icrc32 - i2c checksum calculation
2559 iprobe - probe to discover valid I2C chip addresses
2560 iloop - infinite loop on address range
2561 isdram - print SDRAM configuration information
2562 sspi - SPI utility commands
2563 base - print or set address offset
2564 printenv- print environment variables
2565 setenv - set environment variables
2566 saveenv - save environment variables to persistent storage
2567 protect - enable or disable FLASH write protection
2568 erase - erase FLASH memory
2569 flinfo - print FLASH memory information
2570 bdinfo - print Board Info structure
2571 iminfo - print header information for application image
2572 coninfo - print console devices and informations
2573 ide - IDE sub-system
2574 loop - infinite loop on address range
2575 loopw - infinite write loop on address range
2576 mtest - simple RAM test
2577 icache - enable or disable instruction cache
2578 dcache - enable or disable data cache
2579 reset - Perform RESET of the CPU
2580 echo - echo args to console
2581 version - print monitor version
2582 help - print online help
2583 ? - alias for 'help'
2586 Monitor Commands - Detailed Description:
2587 ========================================
2591 For now: just type "help <command>".
2594 Environment Variables:
2595 ======================
2597 U-Boot supports user configuration using Environment Variables which
2598 can be made persistent by saving to Flash memory.
2600 Environment Variables are set using "setenv", printed using
2601 "printenv", and saved to Flash using "saveenv". Using "setenv"
2602 without a value can be used to delete a variable from the
2603 environment. As long as you don't save the environment you are
2604 working with an in-memory copy. In case the Flash area containing the
2605 environment is erased by accident, a default environment is provided.
2607 Some configuration options can be set using Environment Variables:
2609 baudrate - see CONFIG_BAUDRATE
2611 bootdelay - see CONFIG_BOOTDELAY
2613 bootcmd - see CONFIG_BOOTCOMMAND
2615 bootargs - Boot arguments when booting an RTOS image
2617 bootfile - Name of the image to load with TFTP
2619 autoload - if set to "no" (any string beginning with 'n'),
2620 "bootp" will just load perform a lookup of the
2621 configuration from the BOOTP server, but not try to
2622 load any image using TFTP
2624 autostart - if set to "yes", an image loaded using the "bootp",
2625 "rarpboot", "tftpboot" or "diskboot" commands will
2626 be automatically started (by internally calling
2629 If set to "no", a standalone image passed to the
2630 "bootm" command will be copied to the load address
2631 (and eventually uncompressed), but NOT be started.
2632 This can be used to load and uncompress arbitrary
2635 i2cfast - (PPC405GP|PPC405EP only)
2636 if set to 'y' configures Linux I2C driver for fast
2637 mode (400kHZ). This environment variable is used in
2638 initialization code. So, for changes to be effective
2639 it must be saved and board must be reset.
2641 initrd_high - restrict positioning of initrd images:
2642 If this variable is not set, initrd images will be
2643 copied to the highest possible address in RAM; this
2644 is usually what you want since it allows for
2645 maximum initrd size. If for some reason you want to
2646 make sure that the initrd image is loaded below the
2647 CFG_BOOTMAPSZ limit, you can set this environment
2648 variable to a value of "no" or "off" or "0".
2649 Alternatively, you can set it to a maximum upper
2650 address to use (U-Boot will still check that it
2651 does not overwrite the U-Boot stack and data).
2653 For instance, when you have a system with 16 MB
2654 RAM, and want to reserve 4 MB from use by Linux,
2655 you can do this by adding "mem=12M" to the value of
2656 the "bootargs" variable. However, now you must make
2657 sure that the initrd image is placed in the first
2658 12 MB as well - this can be done with
2660 setenv initrd_high 00c00000
2662 If you set initrd_high to 0xFFFFFFFF, this is an
2663 indication to U-Boot that all addresses are legal
2664 for the Linux kernel, including addresses in flash
2665 memory. In this case U-Boot will NOT COPY the
2666 ramdisk at all. This may be useful to reduce the
2667 boot time on your system, but requires that this
2668 feature is supported by your Linux kernel.
2670 ipaddr - IP address; needed for tftpboot command
2672 loadaddr - Default load address for commands like "bootp",
2673 "rarpboot", "tftpboot", "loadb" or "diskboot"
2675 loads_echo - see CONFIG_LOADS_ECHO
2677 serverip - TFTP server IP address; needed for tftpboot command
2679 bootretry - see CONFIG_BOOT_RETRY_TIME
2681 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2683 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2685 ethprime - When CONFIG_NET_MULTI is enabled controls which
2686 interface is used first.
2688 ethact - When CONFIG_NET_MULTI is enabled controls which
2689 interface is currently active. For example you
2690 can do the following
2692 => setenv ethact FEC ETHERNET
2693 => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2694 => setenv ethact SCC ETHERNET
2695 => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2697 netretry - When set to "no" each network operation will
2698 either succeed or fail without retrying.
2699 When set to "once" the network operation will
2700 fail when all the available network interfaces
2701 are tried once without success.
2702 Useful on scripts which control the retry operation
2705 tftpsrcport - If this is set, the value is used for TFTP's
2708 tftpdstport - If this is set, the value is used for TFTP's UDP
2709 destination port instead of the Well Know Port 69.
2711 vlan - When set to a value < 4095 the traffic over
2712 ethernet is encapsulated/received over 802.1q
2715 The following environment variables may be used and automatically
2716 updated by the network boot commands ("bootp" and "rarpboot"),
2717 depending the information provided by your boot server:
2719 bootfile - see above
2720 dnsip - IP address of your Domain Name Server
2721 dnsip2 - IP address of your secondary Domain Name Server
2722 gatewayip - IP address of the Gateway (Router) to use
2723 hostname - Target hostname
2725 netmask - Subnet Mask
2726 rootpath - Pathname of the root filesystem on the NFS server
2727 serverip - see above
2730 There are two special Environment Variables:
2732 serial# - contains hardware identification information such
2733 as type string and/or serial number
2734 ethaddr - Ethernet address
2736 These variables can be set only once (usually during manufacturing of
2737 the board). U-Boot refuses to delete or overwrite these variables
2738 once they have been set once.
2741 Further special Environment Variables:
2743 ver - Contains the U-Boot version string as printed
2744 with the "version" command. This variable is
2745 readonly (see CONFIG_VERSION_VARIABLE).
2748 Please note that changes to some configuration parameters may take
2749 only effect after the next boot (yes, that's just like Windoze :-).
2752 Command Line Parsing:
2753 =====================
2755 There are two different command line parsers available with U-Boot:
2756 the old "simple" one, and the much more powerful "hush" shell:
2758 Old, simple command line parser:
2759 --------------------------------
2761 - supports environment variables (through setenv / saveenv commands)
2762 - several commands on one line, separated by ';'
2763 - variable substitution using "... ${name} ..." syntax
2764 - special characters ('$', ';') can be escaped by prefixing with '\',
2766 setenv bootcmd bootm \${address}
2767 - You can also escape text by enclosing in single apostrophes, for example:
2768 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2773 - similar to Bourne shell, with control structures like
2774 if...then...else...fi, for...do...done; while...do...done,
2775 until...do...done, ...
2776 - supports environment ("global") variables (through setenv / saveenv
2777 commands) and local shell variables (through standard shell syntax
2778 "name=value"); only environment variables can be used with "run"
2784 (1) If a command line (or an environment variable executed by a "run"
2785 command) contains several commands separated by semicolon, and
2786 one of these commands fails, then the remaining commands will be
2789 (2) If you execute several variables with one call to run (i. e.
2790 calling run with a list af variables as arguments), any failing
2791 command will cause "run" to terminate, i. e. the remaining
2792 variables are not executed.
2794 Note for Redundant Ethernet Interfaces:
2795 =======================================
2797 Some boards come with redundant ethernet interfaces; U-Boot supports
2798 such configurations and is capable of automatic selection of a
2799 "working" interface when needed. MAC assignment works as follows:
2801 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2802 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2803 "eth1addr" (=>eth1), "eth2addr", ...
2805 If the network interface stores some valid MAC address (for instance
2806 in SROM), this is used as default address if there is NO correspon-
2807 ding setting in the environment; if the corresponding environment
2808 variable is set, this overrides the settings in the card; that means:
2810 o If the SROM has a valid MAC address, and there is no address in the
2811 environment, the SROM's address is used.
2813 o If there is no valid address in the SROM, and a definition in the
2814 environment exists, then the value from the environment variable is
2817 o If both the SROM and the environment contain a MAC address, and
2818 both addresses are the same, this MAC address is used.
2820 o If both the SROM and the environment contain a MAC address, and the
2821 addresses differ, the value from the environment is used and a
2824 o If neither SROM nor the environment contain a MAC address, an error
2831 The "boot" commands of this monitor operate on "image" files which
2832 can be basicly anything, preceeded by a special header; see the
2833 definitions in include/image.h for details; basicly, the header
2834 defines the following image properties:
2836 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2837 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2838 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2839 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2840 * Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2841 IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2842 Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2843 * Compression Type (uncompressed, gzip, bzip2)
2849 The header is marked by a special Magic Number, and both the header
2850 and the data portions of the image are secured against corruption by
2857 Although U-Boot should support any OS or standalone application
2858 easily, the main focus has always been on Linux during the design of
2861 U-Boot includes many features that so far have been part of some
2862 special "boot loader" code within the Linux kernel. Also, any
2863 "initrd" images to be used are no longer part of one big Linux image;
2864 instead, kernel and "initrd" are separate images. This implementation
2865 serves several purposes:
2867 - the same features can be used for other OS or standalone
2868 applications (for instance: using compressed images to reduce the
2869 Flash memory footprint)
2871 - it becomes much easier to port new Linux kernel versions because
2872 lots of low-level, hardware dependent stuff are done by U-Boot
2874 - the same Linux kernel image can now be used with different "initrd"
2875 images; of course this also means that different kernel images can
2876 be run with the same "initrd". This makes testing easier (you don't
2877 have to build a new "zImage.initrd" Linux image when you just
2878 change a file in your "initrd"). Also, a field-upgrade of the
2879 software is easier now.
2885 Porting Linux to U-Boot based systems:
2886 ---------------------------------------
2888 U-Boot cannot save you from doing all the necessary modifications to
2889 configure the Linux device drivers for use with your target hardware
2890 (no, we don't intend to provide a full virtual machine interface to
2893 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2895 Just make sure your machine specific header file (for instance
2896 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2897 Information structure as we define in include/u-boot.h, and make
2898 sure that your definition of IMAP_ADDR uses the same value as your
2899 U-Boot configuration in CFG_IMMR.
2902 Configuring the Linux kernel:
2903 -----------------------------
2905 No specific requirements for U-Boot. Make sure you have some root
2906 device (initial ramdisk, NFS) for your target system.
2909 Building a Linux Image:
2910 -----------------------
2912 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2913 not used. If you use recent kernel source, a new build target
2914 "uImage" will exist which automatically builds an image usable by
2915 U-Boot. Most older kernels also have support for a "pImage" target,
2916 which was introduced for our predecessor project PPCBoot and uses a
2917 100% compatible format.
2926 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2927 encapsulate a compressed Linux kernel image with header information,
2928 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2930 * build a standard "vmlinux" kernel image (in ELF binary format):
2932 * convert the kernel into a raw binary image:
2934 ${CROSS_COMPILE}-objcopy -O binary \
2935 -R .note -R .comment \
2936 -S vmlinux linux.bin
2938 * compress the binary image:
2942 * package compressed binary image for U-Boot:
2944 mkimage -A ppc -O linux -T kernel -C gzip \
2945 -a 0 -e 0 -n "Linux Kernel Image" \
2946 -d linux.bin.gz uImage
2949 The "mkimage" tool can also be used to create ramdisk images for use
2950 with U-Boot, either separated from the Linux kernel image, or
2951 combined into one file. "mkimage" encapsulates the images with a 64
2952 byte header containing information about target architecture,
2953 operating system, image type, compression method, entry points, time
2954 stamp, CRC32 checksums, etc.
2956 "mkimage" can be called in two ways: to verify existing images and
2957 print the header information, or to build new images.
2959 In the first form (with "-l" option) mkimage lists the information
2960 contained in the header of an existing U-Boot image; this includes
2961 checksum verification:
2963 tools/mkimage -l image
2964 -l ==> list image header information
2966 The second form (with "-d" option) is used to build a U-Boot image
2967 from a "data file" which is used as image payload:
2969 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2970 -n name -d data_file image
2971 -A ==> set architecture to 'arch'
2972 -O ==> set operating system to 'os'
2973 -T ==> set image type to 'type'
2974 -C ==> set compression type 'comp'
2975 -a ==> set load address to 'addr' (hex)
2976 -e ==> set entry point to 'ep' (hex)
2977 -n ==> set image name to 'name'
2978 -d ==> use image data from 'datafile'
2980 Right now, all Linux kernels for PowerPC systems use the same load
2981 address (0x00000000), but the entry point address depends on the
2984 - 2.2.x kernels have the entry point at 0x0000000C,
2985 - 2.3.x and later kernels have the entry point at 0x00000000.
2987 So a typical call to build a U-Boot image would read:
2989 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2990 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2991 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2992 > examples/uImage.TQM850L
2993 Image Name: 2.4.4 kernel for TQM850L
2994 Created: Wed Jul 19 02:34:59 2000
2995 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2996 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2997 Load Address: 0x00000000
2998 Entry Point: 0x00000000
3000 To verify the contents of the image (or check for corruption):
3002 -> tools/mkimage -l examples/uImage.TQM850L
3003 Image Name: 2.4.4 kernel for TQM850L
3004 Created: Wed Jul 19 02:34:59 2000
3005 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3006 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3007 Load Address: 0x00000000
3008 Entry Point: 0x00000000
3010 NOTE: for embedded systems where boot time is critical you can trade
3011 speed for memory and install an UNCOMPRESSED image instead: this
3012 needs more space in Flash, but boots much faster since it does not
3013 need to be uncompressed:
3015 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3016 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3017 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3018 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3019 > examples/uImage.TQM850L-uncompressed
3020 Image Name: 2.4.4 kernel for TQM850L
3021 Created: Wed Jul 19 02:34:59 2000
3022 Image Type: PowerPC Linux Kernel Image (uncompressed)
3023 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3024 Load Address: 0x00000000
3025 Entry Point: 0x00000000
3028 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3029 when your kernel is intended to use an initial ramdisk:
3031 -> tools/mkimage -n 'Simple Ramdisk Image' \
3032 > -A ppc -O linux -T ramdisk -C gzip \
3033 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3034 Image Name: Simple Ramdisk Image
3035 Created: Wed Jan 12 14:01:50 2000
3036 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3037 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3038 Load Address: 0x00000000
3039 Entry Point: 0x00000000
3042 Installing a Linux Image:
3043 -------------------------
3045 To downloading a U-Boot image over the serial (console) interface,
3046 you must convert the image to S-Record format:
3048 objcopy -I binary -O srec examples/image examples/image.srec
3050 The 'objcopy' does not understand the information in the U-Boot
3051 image header, so the resulting S-Record file will be relative to
3052 address 0x00000000. To load it to a given address, you need to
3053 specify the target address as 'offset' parameter with the 'loads'
3056 Example: install the image to address 0x40100000 (which on the
3057 TQM8xxL is in the first Flash bank):
3059 => erase 40100000 401FFFFF
3065 ## Ready for S-Record download ...
3066 ~>examples/image.srec
3067 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3069 15989 15990 15991 15992
3070 [file transfer complete]
3072 ## Start Addr = 0x00000000
3075 You can check the success of the download using the 'iminfo' command;
3076 this includes a checksum verification so you can be sure no data
3077 corruption happened:
3081 ## Checking Image at 40100000 ...
3082 Image Name: 2.2.13 for initrd on TQM850L
3083 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3084 Data Size: 335725 Bytes = 327 kB = 0 MB
3085 Load Address: 00000000
3086 Entry Point: 0000000c
3087 Verifying Checksum ... OK
3093 The "bootm" command is used to boot an application that is stored in
3094 memory (RAM or Flash). In case of a Linux kernel image, the contents
3095 of the "bootargs" environment variable is passed to the kernel as
3096 parameters. You can check and modify this variable using the
3097 "printenv" and "setenv" commands:
3100 => printenv bootargs
3101 bootargs=root=/dev/ram
3103 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3105 => printenv bootargs
3106 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3109 ## Booting Linux kernel at 40020000 ...
3110 Image Name: 2.2.13 for NFS on TQM850L
3111 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3112 Data Size: 381681 Bytes = 372 kB = 0 MB
3113 Load Address: 00000000
3114 Entry Point: 0000000c
3115 Verifying Checksum ... OK
3116 Uncompressing Kernel Image ... OK
3117 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
3118 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3119 time_init: decrementer frequency = 187500000/60
3120 Calibrating delay loop... 49.77 BogoMIPS
3121 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3124 If you want to boot a Linux kernel with initial ram disk, you pass
3125 the memory addresses of both the kernel and the initrd image (PPBCOOT
3126 format!) to the "bootm" command:
3128 => imi 40100000 40200000
3130 ## Checking Image at 40100000 ...
3131 Image Name: 2.2.13 for initrd on TQM850L
3132 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3133 Data Size: 335725 Bytes = 327 kB = 0 MB
3134 Load Address: 00000000
3135 Entry Point: 0000000c
3136 Verifying Checksum ... OK
3138 ## Checking Image at 40200000 ...
3139 Image Name: Simple Ramdisk Image
3140 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3141 Data Size: 566530 Bytes = 553 kB = 0 MB
3142 Load Address: 00000000
3143 Entry Point: 00000000
3144 Verifying Checksum ... OK
3146 => bootm 40100000 40200000
3147 ## Booting Linux kernel at 40100000 ...
3148 Image Name: 2.2.13 for initrd on TQM850L
3149 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3150 Data Size: 335725 Bytes = 327 kB = 0 MB
3151 Load Address: 00000000
3152 Entry Point: 0000000c
3153 Verifying Checksum ... OK
3154 Uncompressing Kernel Image ... OK
3155 ## Loading RAMDisk Image at 40200000 ...
3156 Image Name: Simple Ramdisk Image
3157 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3158 Data Size: 566530 Bytes = 553 kB = 0 MB
3159 Load Address: 00000000
3160 Entry Point: 00000000
3161 Verifying Checksum ... OK
3162 Loading Ramdisk ... OK
3163 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
3164 Boot arguments: root=/dev/ram
3165 time_init: decrementer frequency = 187500000/60
3166 Calibrating delay loop... 49.77 BogoMIPS
3168 RAMDISK: Compressed image found at block 0
3169 VFS: Mounted root (ext2 filesystem).
3173 Boot Linux and pass a flat device tree:
3176 First, U-Boot must be compiled with the appropriate defines. See the section
3177 titled "Linux Kernel Interface" above for a more in depth explanation. The
3178 following is an example of how to start a kernel and pass an updated
3184 oft=oftrees/mpc8540ads.dtb
3185 => tftp $oftaddr $oft
3186 Speed: 1000, full duplex
3188 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3189 Filename 'oftrees/mpc8540ads.dtb'.
3190 Load address: 0x300000
3193 Bytes transferred = 4106 (100a hex)
3194 => tftp $loadaddr $bootfile
3195 Speed: 1000, full duplex
3197 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3199 Load address: 0x200000
3200 Loading:############
3202 Bytes transferred = 1029407 (fb51f hex)
3207 => bootm $loadaddr - $oftaddr
3208 ## Booting image at 00200000 ...
3209 Image Name: Linux-2.6.17-dirty
3210 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3211 Data Size: 1029343 Bytes = 1005.2 kB
3212 Load Address: 00000000
3213 Entry Point: 00000000
3214 Verifying Checksum ... OK
3215 Uncompressing Kernel Image ... OK
3216 Booting using flat device tree at 0x300000
3217 Using MPC85xx ADS machine description
3218 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3222 More About U-Boot Image Types:
3223 ------------------------------
3225 U-Boot supports the following image types:
3227 "Standalone Programs" are directly runnable in the environment
3228 provided by U-Boot; it is expected that (if they behave
3229 well) you can continue to work in U-Boot after return from
3230 the Standalone Program.
3231 "OS Kernel Images" are usually images of some Embedded OS which
3232 will take over control completely. Usually these programs
3233 will install their own set of exception handlers, device
3234 drivers, set up the MMU, etc. - this means, that you cannot
3235 expect to re-enter U-Boot except by resetting the CPU.
3236 "RAMDisk Images" are more or less just data blocks, and their
3237 parameters (address, size) are passed to an OS kernel that is
3239 "Multi-File Images" contain several images, typically an OS
3240 (Linux) kernel image and one or more data images like
3241 RAMDisks. This construct is useful for instance when you want
3242 to boot over the network using BOOTP etc., where the boot
3243 server provides just a single image file, but you want to get
3244 for instance an OS kernel and a RAMDisk image.
3246 "Multi-File Images" start with a list of image sizes, each
3247 image size (in bytes) specified by an "uint32_t" in network
3248 byte order. This list is terminated by an "(uint32_t)0".
3249 Immediately after the terminating 0 follow the images, one by
3250 one, all aligned on "uint32_t" boundaries (size rounded up to
3251 a multiple of 4 bytes).
3253 "Firmware Images" are binary images containing firmware (like
3254 U-Boot or FPGA images) which usually will be programmed to
3257 "Script files" are command sequences that will be executed by
3258 U-Boot's command interpreter; this feature is especially
3259 useful when you configure U-Boot to use a real shell (hush)
3260 as command interpreter.
3266 One of the features of U-Boot is that you can dynamically load and
3267 run "standalone" applications, which can use some resources of
3268 U-Boot like console I/O functions or interrupt services.
3270 Two simple examples are included with the sources:
3275 'examples/hello_world.c' contains a small "Hello World" Demo
3276 application; it is automatically compiled when you build U-Boot.
3277 It's configured to run at address 0x00040004, so you can play with it
3281 ## Ready for S-Record download ...
3282 ~>examples/hello_world.srec
3283 1 2 3 4 5 6 7 8 9 10 11 ...
3284 [file transfer complete]
3286 ## Start Addr = 0x00040004
3288 => go 40004 Hello World! This is a test.
3289 ## Starting application at 0x00040004 ...
3300 Hit any key to exit ...
3302 ## Application terminated, rc = 0x0
3304 Another example, which demonstrates how to register a CPM interrupt
3305 handler with the U-Boot code, can be found in 'examples/timer.c'.
3306 Here, a CPM timer is set up to generate an interrupt every second.
3307 The interrupt service routine is trivial, just printing a '.'
3308 character, but this is just a demo program. The application can be
3309 controlled by the following keys:
3311 ? - print current values og the CPM Timer registers
3312 b - enable interrupts and start timer
3313 e - stop timer and disable interrupts
3314 q - quit application
3317 ## Ready for S-Record download ...
3318 ~>examples/timer.srec
3319 1 2 3 4 5 6 7 8 9 10 11 ...
3320 [file transfer complete]
3322 ## Start Addr = 0x00040004
3325 ## Starting application at 0x00040004 ...
3328 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3331 [q, b, e, ?] Set interval 1000000 us
3334 [q, b, e, ?] ........
3335 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3338 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3341 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3344 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3346 [q, b, e, ?] ...Stopping timer
3348 [q, b, e, ?] ## Application terminated, rc = 0x0
3354 Over time, many people have reported problems when trying to use the
3355 "minicom" terminal emulation program for serial download. I (wd)
3356 consider minicom to be broken, and recommend not to use it. Under
3357 Unix, I recommend to use C-Kermit for general purpose use (and
3358 especially for kermit binary protocol download ("loadb" command), and
3359 use "cu" for S-Record download ("loads" command).
3361 Nevertheless, if you absolutely want to use it try adding this
3362 configuration to your "File transfer protocols" section:
3364 Name Program Name U/D FullScr IO-Red. Multi
3365 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3366 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3372 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3373 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3375 Building requires a cross environment; it is known to work on
3376 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3377 need gmake since the Makefiles are not compatible with BSD make).
3378 Note that the cross-powerpc package does not install include files;
3379 attempting to build U-Boot will fail because <machine/ansi.h> is
3380 missing. This file has to be installed and patched manually:
3382 # cd /usr/pkg/cross/powerpc-netbsd/include
3384 # ln -s powerpc machine
3385 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3386 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3388 Native builds *don't* work due to incompatibilities between native
3389 and U-Boot include files.
3391 Booting assumes that (the first part of) the image booted is a
3392 stage-2 loader which in turn loads and then invokes the kernel
3393 proper. Loader sources will eventually appear in the NetBSD source
3394 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3395 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3398 Implementation Internals:
3399 =========================
3401 The following is not intended to be a complete description of every
3402 implementation detail. However, it should help to understand the
3403 inner workings of U-Boot and make it easier to port it to custom
3407 Initial Stack, Global Data:
3408 ---------------------------
3410 The implementation of U-Boot is complicated by the fact that U-Boot
3411 starts running out of ROM (flash memory), usually without access to
3412 system RAM (because the memory controller is not initialized yet).
3413 This means that we don't have writable Data or BSS segments, and BSS
3414 is not initialized as zero. To be able to get a C environment working
3415 at all, we have to allocate at least a minimal stack. Implementation
3416 options for this are defined and restricted by the CPU used: Some CPU
3417 models provide on-chip memory (like the IMMR area on MPC8xx and
3418 MPC826x processors), on others (parts of) the data cache can be
3419 locked as (mis-) used as memory, etc.
3421 Chris Hallinan posted a good summary of these issues to the
3422 u-boot-users mailing list:
3424 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3425 From: "Chris Hallinan" <clh@net1plus.com>
3426 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3429 Correct me if I'm wrong, folks, but the way I understand it
3430 is this: Using DCACHE as initial RAM for Stack, etc, does not
3431 require any physical RAM backing up the cache. The cleverness
3432 is that the cache is being used as a temporary supply of
3433 necessary storage before the SDRAM controller is setup. It's
3434 beyond the scope of this list to expain the details, but you
3435 can see how this works by studying the cache architecture and
3436 operation in the architecture and processor-specific manuals.
3438 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3439 is another option for the system designer to use as an
3440 initial stack/ram area prior to SDRAM being available. Either
3441 option should work for you. Using CS 4 should be fine if your
3442 board designers haven't used it for something that would
3443 cause you grief during the initial boot! It is frequently not
3446 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3447 with your processor/board/system design. The default value
3448 you will find in any recent u-boot distribution in
3449 walnut.h should work for you. I'd set it to a value larger
3450 than your SDRAM module. If you have a 64MB SDRAM module, set
3451 it above 400_0000. Just make sure your board has no resources
3452 that are supposed to respond to that address! That code in
3453 start.S has been around a while and should work as is when
3454 you get the config right.
3459 It is essential to remember this, since it has some impact on the C
3460 code for the initialization procedures:
3462 * Initialized global data (data segment) is read-only. Do not attempt
3465 * Do not use any unitialized global data (or implicitely initialized
3466 as zero data - BSS segment) at all - this is undefined, initiali-
3467 zation is performed later (when relocating to RAM).
3469 * Stack space is very limited. Avoid big data buffers or things like
3472 Having only the stack as writable memory limits means we cannot use
3473 normal global data to share information beween the code. But it
3474 turned out that the implementation of U-Boot can be greatly
3475 simplified by making a global data structure (gd_t) available to all
3476 functions. We could pass a pointer to this data as argument to _all_
3477 functions, but this would bloat the code. Instead we use a feature of
3478 the GCC compiler (Global Register Variables) to share the data: we
3479 place a pointer (gd) to the global data into a register which we
3480 reserve for this purpose.
3482 When choosing a register for such a purpose we are restricted by the
3483 relevant (E)ABI specifications for the current architecture, and by
3484 GCC's implementation.
3486 For PowerPC, the following registers have specific use:
3489 R3-R4: parameter passing and return values
3490 R5-R10: parameter passing
3491 R13: small data area pointer
3495 (U-Boot also uses R14 as internal GOT pointer.)
3497 ==> U-Boot will use R29 to hold a pointer to the global data
3499 Note: on PPC, we could use a static initializer (since the
3500 address of the global data structure is known at compile time),
3501 but it turned out that reserving a register results in somewhat
3502 smaller code - although the code savings are not that big (on
3503 average for all boards 752 bytes for the whole U-Boot image,
3504 624 text + 127 data).
3506 On ARM, the following registers are used:
3508 R0: function argument word/integer result
3509 R1-R3: function argument word
3511 R10: stack limit (used only if stack checking if enabled)
3512 R11: argument (frame) pointer
3513 R12: temporary workspace
3516 R15: program counter
3518 ==> U-Boot will use R8 to hold a pointer to the global data
3520 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3521 or current versions of GCC may "optimize" the code too much.
3526 U-Boot runs in system state and uses physical addresses, i.e. the
3527 MMU is not used either for address mapping nor for memory protection.
3529 The available memory is mapped to fixed addresses using the memory
3530 controller. In this process, a contiguous block is formed for each
3531 memory type (Flash, SDRAM, SRAM), even when it consists of several
3532 physical memory banks.
3534 U-Boot is installed in the first 128 kB of the first Flash bank (on
3535 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3536 booting and sizing and initializing DRAM, the code relocates itself
3537 to the upper end of DRAM. Immediately below the U-Boot code some
3538 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3539 configuration setting]. Below that, a structure with global Board
3540 Info data is placed, followed by the stack (growing downward).
3542 Additionally, some exception handler code is copied to the low 8 kB
3543 of DRAM (0x00000000 ... 0x00001FFF).
3545 So a typical memory configuration with 16 MB of DRAM could look like
3548 0x0000 0000 Exception Vector code
3551 0x0000 2000 Free for Application Use
3557 0x00FB FF20 Monitor Stack (Growing downward)
3558 0x00FB FFAC Board Info Data and permanent copy of global data
3559 0x00FC 0000 Malloc Arena
3562 0x00FE 0000 RAM Copy of Monitor Code
3563 ... eventually: LCD or video framebuffer
3564 ... eventually: pRAM (Protected RAM - unchanged by reset)
3565 0x00FF FFFF [End of RAM]
3568 System Initialization:
3569 ----------------------
3571 In the reset configuration, U-Boot starts at the reset entry point
3572 (on most PowerPC systens at address 0x00000100). Because of the reset
3573 configuration for CS0# this is a mirror of the onboard Flash memory.
3574 To be able to re-map memory U-Boot then jumps to its link address.
3575 To be able to implement the initialization code in C, a (small!)
3576 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3577 which provide such a feature like MPC8xx or MPC8260), or in a locked
3578 part of the data cache. After that, U-Boot initializes the CPU core,
3579 the caches and the SIU.
3581 Next, all (potentially) available memory banks are mapped using a
3582 preliminary mapping. For example, we put them on 512 MB boundaries
3583 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3584 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3585 programmed for SDRAM access. Using the temporary configuration, a
3586 simple memory test is run that determines the size of the SDRAM
3589 When there is more than one SDRAM bank, and the banks are of
3590 different size, the largest is mapped first. For equal size, the first
3591 bank (CS2#) is mapped first. The first mapping is always for address
3592 0x00000000, with any additional banks following immediately to create
3593 contiguous memory starting from 0.
3595 Then, the monitor installs itself at the upper end of the SDRAM area
3596 and allocates memory for use by malloc() and for the global Board
3597 Info data; also, the exception vector code is copied to the low RAM
3598 pages, and the final stack is set up.
3600 Only after this relocation will you have a "normal" C environment;
3601 until that you are restricted in several ways, mostly because you are
3602 running from ROM, and because the code will have to be relocated to a
3606 U-Boot Porting Guide:
3607 ----------------------
3609 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3613 int main (int argc, char *argv[])
3615 sighandler_t no_more_time;
3617 signal (SIGALRM, no_more_time);
3618 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3620 if (available_money > available_manpower) {
3621 pay consultant to port U-Boot;
3625 Download latest U-Boot source;
3627 Subscribe to u-boot-users mailing list;
3630 email ("Hi, I am new to U-Boot, how do I get started?");
3634 Read the README file in the top level directory;
3635 Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3636 Read the source, Luke;
3639 if (available_money > toLocalCurrency ($2500)) {
3642 Add a lot of aggravation and time;
3645 Create your own board support subdirectory;
3647 Create your own board config file;
3651 Add / modify source code;
3655 email ("Hi, I am having problems...");
3657 Send patch file to Wolfgang;
3662 void no_more_time (int sig)
3671 All contributions to U-Boot should conform to the Linux kernel
3672 coding style; see the file "Documentation/CodingStyle" and the script
3673 "scripts/Lindent" in your Linux kernel source directory. In sources
3674 originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3675 spaces before parameters to function calls) is actually used.
3677 Source files originating from a different project (for example the
3678 MTD subsystem) are generally exempt from these guidelines and are not
3679 reformated to ease subsequent migration to newer versions of those
3682 Please note that U-Boot is implemented in C (and to some small parts in
3683 Assembler); no C++ is used, so please do not use C++ style comments (//)
3686 Please also stick to the following formatting rules:
3687 - remove any trailing white space
3688 - use TAB characters for indentation, not spaces
3689 - make sure NOT to use DOS '\r\n' line feeds
3690 - do not add more than 2 empty lines to source files
3691 - do not add trailing empty lines to source files
3693 Submissions which do not conform to the standards may be returned
3694 with a request to reformat the changes.
3700 Since the number of patches for U-Boot is growing, we need to
3701 establish some rules. Submissions which do not conform to these rules
3702 may be rejected, even when they contain important and valuable stuff.
3704 Patches shall be sent to the u-boot-users mailing list.
3706 When you send a patch, please include the following information with
3709 * For bug fixes: a description of the bug and how your patch fixes
3710 this bug. Please try to include a way of demonstrating that the
3711 patch actually fixes something.
3713 * For new features: a description of the feature and your
3716 * A CHANGELOG entry as plaintext (separate from the patch)
3718 * For major contributions, your entry to the CREDITS file
3720 * When you add support for a new board, don't forget to add this
3721 board to the MAKEALL script, too.
3723 * If your patch adds new configuration options, don't forget to
3724 document these in the README file.
3726 * The patch itself. If you are accessing the CVS repository use "cvs
3727 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3728 version of diff does not support these options, then get the latest
3729 version of GNU diff.
3731 The current directory when running this command shall be the top
3732 level directory of the U-Boot source tree, or it's parent directory
3733 (i. e. please make sure that your patch includes sufficient
3734 directory information for the affected files).
3736 We accept patches as plain text, MIME attachments or as uuencoded
3739 * If one logical set of modifications affects or creates several
3740 files, all these changes shall be submitted in a SINGLE patch file.
3742 * Changesets that contain different, unrelated modifications shall be
3743 submitted as SEPARATE patches, one patch per changeset.
3748 * Before sending the patch, run the MAKEALL script on your patched
3749 source tree and make sure that no errors or warnings are reported
3750 for any of the boards.
3752 * Keep your modifications to the necessary minimum: A patch
3753 containing several unrelated changes or arbitrary reformats will be
3754 returned with a request to re-formatting / split it.
3756 * If you modify existing code, make sure that your new code does not
3757 add to the memory footprint of the code ;-) Small is beautiful!
3758 When adding new features, these should compile conditionally only
3759 (using #ifdef), and the resulting code with the new feature
3760 disabled must not need more memory than the old code without your
3763 * Remember that there is a size limit of 40 kB per message on the
3764 u-boot-users mailing list. Compression may help.
projects / people / ms / u-boot.git / blob