2 # (C) Copyright 2000 - 2002
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 and ARM processors, which can be
29 installed in a boot ROM and used to initialize and test the hardware
30 or to download and run application code.
32 The development of U-Boot is closely related to Linux: some parts of
33 the source code originate in the Linux source tree, we have some
34 header files in common, and special provision has been made to
35 support booting of Linux images.
37 Some attention has been paid to make this software easily
38 configurable and extendable. For instance, all monitor commands are
39 implemented with the same call interface, so that it's very easy to
40 add new commands. Also, instead of permanently adding rarely used
41 code (for instance hardware test utilities) to the monitor, you can
42 load and run it dynamically.
48 In general, all boards for which a configuration option exists in the
49 Makefile have been tested to some extent and can be considered
50 "working". In fact, many of them are used in production systems.
52 In case of problems see the CHANGELOG and CREDITS files to find out
53 who contributed the specific port.
59 In case you have questions about, problems with or contributions for
60 U-Boot you should send a message to the U-Boot mailing list at
61 <u-boot-users@lists.sourceforge.net>. There is also an archive of
62 previous traffic on the mailing list - please search the archive
63 before asking FAQ's. Please see
64 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
70 - start from 8xxrom sources
71 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73 - make it easier to add custom boards
74 - make it possible to add other [PowerPC] CPUs
75 - extend functions, especially:
76 * Provide extended interface to Linux boot loader
79 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80 - create ARMBoot project (http://sourceforge.net/projects/armboot)
81 - add other CPU families (starting with ARM)
82 - create U-Boot project (http://sourceforge.net/projects/u-boot)
88 The "official" name of this project is "Das U-Boot". The spelling
89 "U-Boot" shall be used in all written text (documentation, comments
90 in source files etc.). Example:
92 This is the README file for the U-Boot project.
94 File names etc. shall be based on the string "u-boot". Examples:
96 include/asm-ppc/u-boot.h
98 #include <asm/u-boot.h>
100 Variable names, preprocessor constants etc. shall be either based on
101 the string "u_boot" or on "U_BOOT". Example:
103 U_BOOT_VERSION u_boot_logo
104 IH_OS_U_BOOT u_boot_hush_start
110 U-Boot uses a 3 level version number containing a version, a
111 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112 sub-version "34", and patchlevel "4".
114 The patchlevel is used to indicate certain stages of development
115 between released versions, i. e. officially released versions of
116 U-Boot will always have a patchlevel of "0".
122 - board Board dependend files
123 - common Misc architecture independend functions
124 - cpu CPU specific files
125 - disk Code for disk drive partition handling
126 - doc Documentation (don't expect too much)
127 - drivers Common used device drivers
128 - dtt Digital Thermometer and Thermostat drivers
129 - examples Example code for standalone applications, etc.
130 - include Header Files
131 - disk Harddisk interface code
132 - net Networking code
133 - ppc Files generic to PowerPC architecture
134 - post Power On Self Test
135 - post/arch Symlink to architecture specific Power On Self Test
136 - post/arch-ppc PowerPC architecture specific Power On Self Test
137 - post/cpu/mpc8260 MPC8260 CPU specific Power On Self Test
138 - post/cpu/mpc8xx MPC8xx CPU specific Power On Self Test
139 - rtc Real Time Clock drivers
140 - tools Tools to build S-Record or U-Boot images, etc.
142 - cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
143 - cpu/arm925t Files specific to ARM 925 CPUs
144 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
145 - cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
146 - cpu/mpc824x Files specific to Motorola MPC824x CPUs
147 - cpu/mpc8260 Files specific to Motorola MPC8260 CPU
148 - cpu/ppc4xx Files specific to IBM 4xx CPUs
151 - board/LEOX/ Files specific to boards manufactured by The LEOX team
152 - board/LEOX/elpt860 Files specific to ELPT860 boards
154 Files specific to RPXClassic boards
155 - board/RPXlite Files specific to RPXlite boards
156 - board/at91rm9200dk Files specific to AT91RM9200DK boards
157 - board/c2mon Files specific to c2mon boards
158 - board/cmi Files specific to cmi boards
159 - board/cogent Files specific to Cogent boards
160 (need further configuration)
161 Files specific to CPCIISER4 boards
162 - board/cpu86 Files specific to CPU86 boards
163 - board/cray/ Files specific to boards manufactured by Cray
164 - board/cray/L1 Files specific to L1 boards
165 - board/cu824 Files specific to CU824 boards
166 - board/ebony Files specific to IBM Ebony board
167 - board/eric Files specific to ERIC boards
168 - board/esd/ Files specific to boards manufactured by ESD
169 - board/esd/adciop Files specific to ADCIOP boards
170 - board/esd/ar405 Files specific to AR405 boards
171 - board/esd/canbt Files specific to CANBT boards
172 - board/esd/cpci405 Files specific to CPCI405 boards
173 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
174 - board/esd/common Common files for ESD boards
175 - board/esd/dasa_sim Files specific to DASA_SIM boards
176 - board/esd/du405 Files specific to DU405 boards
177 - board/esd/ocrtc Files specific to OCRTC boards
178 - board/esd/pci405 Files specific to PCI405 boards
180 Files specific to ESTEEM192E boards
181 - board/etx094 Files specific to ETX_094 boards
183 Files specific to EVB64260 boards
184 - board/fads Files specific to FADS boards
185 - board/flagadm Files specific to FLAGADM boards
186 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
187 - board/genietv Files specific to GENIETV boards
188 - board/gth Files specific to GTH boards
189 - board/hermes Files specific to HERMES boards
190 - board/hymod Files specific to HYMOD boards
191 - board/icu862 Files specific to ICU862 boards
192 - board/ip860 Files specific to IP860 boards
194 Files specific to Interphase4539 boards
195 - board/ivm Files specific to IVMS8/IVML24 boards
196 - board/lantec Files specific to LANTEC boards
197 - board/lwmon Files specific to LWMON boards
198 - board/mbx8xx Files specific to MBX boards
200 Files specific to MMPC8260ADS boards
201 - board/mpl/ Files specific to boards manufactured by MPL
202 - board/mpl/common Common files for MPL boards
203 - board/mpl/pip405 Files specific to PIP405 boards
204 - board/mpl/mip405 Files specific to MIP405 boards
205 - board/musenki Files specific to MUSEKNI boards
206 - board/mvs1 Files specific to MVS1 boards
207 - board/nx823 Files specific to NX823 boards
208 - board/oxc Files specific to OXC boards
210 Files specific to OMAP 1510 Innovator boards
211 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
212 - board/pm826 Files specific to PM826 boards
214 Files specific to PPMC8260 boards
216 Files specific to RPXsuper boards
218 Files specific to RSDproto boards
220 Files specific to Sandpoint boards
221 - board/sbc8260 Files specific to SBC8260 boards
222 - board/sacsng Files specific to SACSng boards
223 - board/siemens Files specific to boards manufactured by Siemens AG
224 - board/siemens/CCM Files specific to CCM boards
225 - board/siemens/IAD210 Files specific to IAD210 boards
226 - board/siemens/SCM Files specific to SCM boards
227 - board/siemens/pcu_e Files specific to PCU_E boards
228 - board/sixnet Files specific to SIXNET boards
229 - board/spd8xx Files specific to SPD8xxTS boards
230 - board/tqm8260 Files specific to TQM8260 boards
231 - board/tqm8xx Files specific to TQM8xxL boards
232 - board/w7o Files specific to W7O boards
234 Files specific to Walnut405 boards
235 - board/westel/ Files specific to boards manufactured by Westel Wireless
236 - board/westel/amx860 Files specific to AMX860 boards
237 - board/utx8245 Files specific to UTX8245 boards
239 Software Configuration:
240 =======================
242 Configuration is usually done using C preprocessor defines; the
243 rationale behind that is to avoid dead code whenever possible.
245 There are two classes of configuration variables:
247 * Configuration _OPTIONS_:
248 These are selectable by the user and have names beginning with
251 * Configuration _SETTINGS_:
252 These depend on the hardware etc. and should not be meddled with if
253 you don't know what you're doing; they have names beginning with
256 Later we will add a configuration tool - probably similar to or even
257 identical to what's used for the Linux kernel. Right now, we have to
258 do the configuration by hand, which means creating some symbolic
259 links and editing some configuration files. We use the TQM8xxL boards
263 Selection of Processor Architecture and Board Type:
264 ---------------------------------------------------
266 For all supported boards there are ready-to-use default
267 configurations available; just type "make <board_name>_config".
269 Example: For a TQM823L module type:
274 For the Cogent platform, you need to specify the cpu type as well;
275 e.g. "make cogent_mpc8xx_config". And also configure the cogent
276 directory according to the instructions in cogent/README.
279 Configuration Options:
280 ----------------------
282 Configuration depends on the combination of board and CPU type; all
283 such information is kept in a configuration file
284 "include/configs/<board_name>.h".
286 Example: For a TQM823L module, all configuration settings are in
287 "include/configs/TQM823L.h".
290 Many of the options are named exactly as the corresponding Linux
291 kernel configuration options. The intention is to make it easier to
292 build a config tool - later.
295 The following options need to be configured:
297 - CPU Type: Define exactly one of
301 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
303 or CONFIG_MPC824X, CONFIG_MPC8260
317 - Board Type: Define exactly one of
319 PowerPC based boards:
320 ---------------------
322 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
323 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
324 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
325 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
326 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
327 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
328 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
329 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
330 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
331 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
332 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
333 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
334 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
335 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
336 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
337 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
338 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
339 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
340 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
341 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
342 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
343 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
344 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
345 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
346 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
347 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
348 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
349 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
350 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
351 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
352 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
353 CONFIG_NETVIA, CONFIG_RBC823
358 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
359 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
360 CONFIG_INNOVATOROMAP1510,
361 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
362 CONFIG_TRAB, CONFIG_AT91RM9200DK
365 - CPU Module Type: (if CONFIG_COGENT is defined)
366 Define exactly one of
368 --- FIXME --- not tested yet:
369 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
370 CONFIG_CMA287_23, CONFIG_CMA287_50
372 - Motherboard Type: (if CONFIG_COGENT is defined)
373 Define exactly one of
374 CONFIG_CMA101, CONFIG_CMA102
376 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
377 Define one or more of
380 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
381 Define one or more of
382 CONFIG_LCD_HEARTBEAT - update a character position on
383 the lcd display every second with
386 - MPC824X Family Member (if CONFIG_MPC824X is defined)
387 Define exactly one of
388 CONFIG_MPC8240, CONFIG_MPC8245
390 - 8xx CPU Options: (if using an 8xx cpu)
391 Define one or more of
392 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
393 no 32KHz reference PIT/RTC clock
398 U-Boot stores all clock information in Hz
399 internally. For binary compatibility with older Linux
400 kernels (which expect the clocks passed in the
401 bd_info data to be in MHz) the environment variable
402 "clocks_in_mhz" can be defined so that U-Boot
403 converts clock data to MHZ before passing it to the
406 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
407 "clocks_in_mhz=1" is automatically included in the
411 Depending on board, define exactly one serial port
412 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
413 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
414 console by defining CONFIG_8xx_CONS_NONE
416 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
417 port routines must be defined elsewhere
418 (i.e. serial_init(), serial_getc(), ...)
421 Enables console device for a color framebuffer. Needs following
422 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
423 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
425 VIDEO_HW_RECTFILL graphic chip supports
428 VIDEO_HW_BITBLT graphic chip supports
429 bit-blit (cf. smiLynxEM)
430 VIDEO_VISIBLE_COLS visible pixel columns
432 VIDEO_VISIBLE_ROWS visible pixel rows
433 VIDEO_PIXEL_SIZE bytes per pixel
434 VIDEO_DATA_FORMAT graphic data format
435 (0-5, cf. cfb_console.c)
436 VIDEO_FB_ADRS framebuffer address
437 VIDEO_KBD_INIT_FCT keyboard int fct
438 (i.e. i8042_kbd_init())
439 VIDEO_TSTC_FCT test char fct
441 VIDEO_GETC_FCT get char fct
443 CONFIG_CONSOLE_CURSOR cursor drawing on/off
444 (requires blink timer
446 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
447 CONFIG_CONSOLE_TIME display time/date info in
449 (requires CFG_CMD_DATE)
450 CONFIG_VIDEO_LOGO display Linux logo in
452 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
453 linux_logo.h for logo.
454 Requires CONFIG_VIDEO_LOGO
455 CONFIG_CONSOLE_EXTRA_INFO
456 addional board info beside
459 When CONFIG_CFB_CONSOLE is defined, video console is
460 default i/o. Serial console can be forced with
461 environment 'console=serial'.
464 CONFIG_BAUDRATE - in bps
465 Select one of the baudrates listed in
466 CFG_BAUDRATE_TABLE, see below.
468 - Interrupt driven serial port input:
469 CONFIG_SERIAL_SOFTWARE_FIFO
472 Use an interrupt handler for receiving data on the
473 serial port. It also enables using hardware handshake
474 (RTS/CTS) and UART's built-in FIFO. Set the number of
475 bytes the interrupt driven input buffer should have.
477 Set to 0 to disable this feature (this is the default).
478 This will also disable hardware handshake.
480 - Console UART Number:
484 If defined internal UART1 (and not UART0) is used
485 as default U-Boot console.
487 - Boot Delay: CONFIG_BOOTDELAY - in seconds
488 Delay before automatically booting the default image;
489 set to -1 to disable autoboot.
491 See doc/README.autoboot for these options that
492 work with CONFIG_BOOTDELAY. None are required.
493 CONFIG_BOOT_RETRY_TIME
494 CONFIG_BOOT_RETRY_MIN
495 CONFIG_AUTOBOOT_KEYED
496 CONFIG_AUTOBOOT_PROMPT
497 CONFIG_AUTOBOOT_DELAY_STR
498 CONFIG_AUTOBOOT_STOP_STR
499 CONFIG_AUTOBOOT_DELAY_STR2
500 CONFIG_AUTOBOOT_STOP_STR2
501 CONFIG_ZERO_BOOTDELAY_CHECK
502 CONFIG_RESET_TO_RETRY
506 Only needed when CONFIG_BOOTDELAY is enabled;
507 define a command string that is automatically executed
508 when no character is read on the console interface
509 within "Boot Delay" after reset.
512 This can be used to pass arguments to the bootm
513 command. The value of CONFIG_BOOTARGS goes into the
514 environment value "bootargs".
516 CONFIG_RAMBOOT and CONFIG_NFSBOOT
517 The value of these goes into the environment as
518 "ramboot" and "nfsboot" respectively, and can be used
519 as a convenience, when switching between booting from
525 When this option is #defined, the existence of the
526 environment variable "preboot" will be checked
527 immediately before starting the CONFIG_BOOTDELAY
528 countdown and/or running the auto-boot command resp.
529 entering interactive mode.
531 This feature is especially useful when "preboot" is
532 automatically generated or modified. For an example
533 see the LWMON board specific code: here "preboot" is
534 modified when the user holds down a certain
535 combination of keys on the (special) keyboard when
538 - Serial Download Echo Mode:
540 If defined to 1, all characters received during a
541 serial download (using the "loads" command) are
542 echoed back. This might be needed by some terminal
543 emulations (like "cu"), but may as well just take
544 time on others. This setting #define's the initial
545 value of the "loads_echo" environment variable.
547 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
549 Select one of the baudrates listed in
550 CFG_BAUDRATE_TABLE, see below.
554 Most monitor functions can be selected (or
555 de-selected) by adjusting the definition of
556 CONFIG_COMMANDS; to select individual functions,
557 #define CONFIG_COMMANDS by "OR"ing any of the
560 #define enables commands:
561 -------------------------
562 CFG_CMD_ASKENV * ask for env variable
564 CFG_CMD_BEDBUG Include BedBug Debugger
566 CFG_CMD_CACHE icache, dcache
567 CFG_CMD_CONSOLE coninfo
568 CFG_CMD_DATE * support for RTC, date/time...
569 CFG_CMD_DHCP DHCP support
570 CFG_CMD_ECHO * echo arguments
571 CFG_CMD_EEPROM * EEPROM read/write support
572 CFG_CMD_ELF bootelf, bootvx
574 CFG_CMD_FDC * Floppy Disk Support
575 CFG_CMD_FAT FAT partition support
576 CFG_CMD_FDOS * Dos diskette Support
577 CFG_CMD_FLASH flinfo, erase, protect
578 CFG_CMD_FPGA FPGA device initialization support
579 CFG_CMD_I2C * I2C serial bus support
580 CFG_CMD_IDE * IDE harddisk support
582 CFG_CMD_IMMAP * IMMR dump support
583 CFG_CMD_IRQ * irqinfo
587 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
589 CFG_CMD_MMC MMC memory mapped support
590 CFG_CMD_MII MII utility commands
591 CFG_CMD_NET bootp, tftpboot, rarpboot
592 CFG_CMD_PCI * pciinfo
593 CFG_CMD_PCMCIA * PCMCIA support
594 CFG_CMD_REGINFO * Register dump
595 CFG_CMD_RUN run command in env variable
596 CFG_CMD_SCSI * SCSI Support
597 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
598 CFG_CMD_SPI * SPI serial bus support
599 CFG_CMD_USB * USB support
600 CFG_CMD_BSP * Board SPecific functions
601 -----------------------------------------------
604 CFG_CMD_DFL Default configuration; at the moment
605 this is includes all commands, except
606 the ones marked with "*" in the list
609 If you don't define CONFIG_COMMANDS it defaults to
610 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
611 override the default settings in the respective
614 EXAMPLE: If you want all functions except of network
615 support you can write:
617 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
620 Note: Don't enable the "icache" and "dcache" commands
621 (configuration option CFG_CMD_CACHE) unless you know
622 what you (and your U-Boot users) are doing. Data
623 cache cannot be enabled on systems like the 8xx or
624 8260 (where accesses to the IMMR region must be
625 uncached), and it cannot be disabled on all other
626 systems where we (mis-) use the data cache to hold an
627 initial stack and some data.
630 XXX - this list needs to get updated!
634 If this variable is defined, it enables watchdog
635 support. There must support in the platform specific
636 code for a watchdog. For the 8xx and 8260 CPUs, the
637 SIU Watchdog feature is enabled in the SYPCR
641 CONFIG_VERSION_VARIABLE
642 If this variable is defined, an environment variable
643 named "ver" is created by U-Boot showing the U-Boot
644 version as printed by the "version" command.
645 This variable is readonly.
649 When CFG_CMD_DATE is selected, the type of the RTC
650 has to be selected, too. Define exactly one of the
653 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
654 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
655 CONFIG_RTC_MC146818 - use MC146818 RTC
656 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
657 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
658 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
659 CONFIG_RTC_DS164x - use Dallas DS164x RTC
661 Note that if the RTC uses I2C, then the I2C interface
662 must also be configured. See I2C Support, below.
666 When CONFIG_TIMESTAMP is selected, the timestamp
667 (date and time) of an image is printed by image
668 commands like bootm or iminfo. This option is
669 automatically enabled when you select CFG_CMD_DATE .
672 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
673 and/or CONFIG_ISO_PARTITION
675 If IDE or SCSI support is enabled (CFG_CMD_IDE or
676 CFG_CMD_SCSI) you must configure support for at least
677 one partition type as well.
680 CONFIG_IDE_RESET_ROUTINE
682 Set this to define that instead of a reset Pin, the
683 routine ide_set_reset(int idereset) will be used.
688 Set this to enable ATAPI support.
691 At the moment only there is only support for the
692 SYM53C8XX SCSI controller; define
693 CONFIG_SCSI_SYM53C8XX to enable it.
695 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
696 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
697 CFG_SCSI_MAX_LUN] can be adjusted to define the
698 maximum numbers of LUNs, SCSI ID's and target
700 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
702 - NETWORK Support (PCI):
704 Support for Intel 8254x gigabit chips.
707 Support for Intel 82557/82559/82559ER chips.
708 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
709 write routine for first time initialisation.
712 Support for Digital 2114x chips.
713 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
714 modem chip initialisation (KS8761/QS6611).
717 Support for National dp83815 chips.
720 Support for National dp8382[01] gigabit chips.
722 - NETWORK Support (other):
724 CONFIG_DRIVER_LAN91C96
725 Support for SMSC's LAN91C96 chips.
728 Define this to hold the physical address
729 of the LAN91C96's I/O space
731 CONFIG_LAN91C96_USE_32_BIT
732 Define this to enable 32 bit addressing
735 At the moment only the UHCI host controller is
736 supported (PIP405, MIP405); define
737 CONFIG_USB_UHCI to enable it.
738 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
739 end define CONFIG_USB_STORAGE to enable the USB
742 Supported are USB Keyboards and USB Floppy drives
746 The MMC controller on the Intel PXA is supported. To
747 enable this define CONFIG_MMC. The MMC can be
748 accessed from the boot prompt by mapping the device
749 to physical memory similar to flash. Command line is
750 enabled with CFG_CMD_MMC. The MMC driver also works with
751 the FAT fs. This is enabled with CFG_CMD_FAT.
756 Define this to enable standard (PC-Style) keyboard
760 Standard PC keyboard driver with US (is default) and
761 GERMAN key layout (switch via environment 'keymap=de') support.
762 Export function i8042_kbd_init, i8042_tstc and i8042_getc
763 for cfb_console. Supports cursor blinking.
768 Define this to enable video support (for output to
773 Enable Chips & Technologies 69000 Video chip
775 CONFIG_VIDEO_SMI_LYNXEM
776 Enable Silicon Motion SMI 712/710/810 Video chip
777 Videomode are selected via environment 'videomode' with
778 standard LiLo mode numbers.
779 Following modes are supported (* is default):
781 800x600 1024x768 1280x1024
782 256 (8bit) 303* 305 307
783 65536 (16bit) 314 317 31a
784 16,7 Mill (24bit) 315 318 31b
785 (i.e. setenv videomode 317; saveenv; reset;)
787 CONFIG_VIDEO_SED13806
788 Enable Epson SED13806 driver. This driver supports 8bpp
789 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
790 or CONFIG_VIDEO_SED13806_16BPP
795 Define this to enable a custom keyboard support.
796 This simply calls drv_keyboard_init() which must be
797 defined in your board-specific files.
798 The only board using this so far is RBC823.
800 - LCD Support: CONFIG_LCD
802 Define this to enable LCD support (for output to LCD
803 display); also select one of the supported displays
804 by defining one of these:
806 CONFIG_NEC_NL6648AC33:
808 NEC NL6648AC33-18. Active, color, single scan.
810 CONFIG_NEC_NL6648BC20
812 NEC NL6648BC20-08. 6.5", 640x480.
813 Active, color, single scan.
817 Sharp 320x240. Active, color, single scan.
818 It isn't 16x9, and I am not sure what it is.
820 CONFIG_SHARP_LQ64D341
822 Sharp LQ64D341 display, 640x480.
823 Active, color, single scan.
827 HLD1045 display, 640x480.
828 Active, color, single scan.
832 Optrex CBL50840-2 NF-FW 99 22 M5
834 Hitachi LMG6912RPFC-00T
838 320x240. Black & white.
840 Normally display is black on white background; define
841 CFG_WHITE_ON_BLACK to get it inverted.
843 - Spash Screen Support: CONFIG_SPLASH_SCREEN
845 If this option is set, the environment is checked for
846 a variable "splashimage". If found, the usual display
847 of logo, copyright and system information on the LCD
848 is supressed and the BMP image at the address
849 specified in "splashimage" is loaded instead. The
850 console is redirected to the "nulldev", too. This
851 allows for a "silent" boot where a splash screen is
852 loaded very quickly after power-on.
860 Define a default value for ethernet address to use
861 for the respective ethernet interface, in case this
862 is not determined automatically.
867 Define a default value for the IP address to use for
868 the default ethernet interface, in case this is not
869 determined through e.g. bootp.
874 Defines a default value for theIP address of a TFTP
875 server to contact when using the "tftboot" command.
877 - BOOTP Recovery Mode:
878 CONFIG_BOOTP_RANDOM_DELAY
880 If you have many targets in a network that try to
881 boot using BOOTP, you may want to avoid that all
882 systems send out BOOTP requests at precisely the same
883 moment (which would happen for instance at recovery
884 from a power failure, when all systems will try to
885 boot, thus flooding the BOOTP server. Defining
886 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
887 inserted before sending out BOOTP requests. The
888 following delays are insterted then:
890 1st BOOTP request: delay 0 ... 1 sec
891 2nd BOOTP request: delay 0 ... 2 sec
892 3rd BOOTP request: delay 0 ... 4 sec
894 BOOTP requests: delay 0 ... 8 sec
896 - Status LED: CONFIG_STATUS_LED
898 Several configurations allow to display the current
899 status using a LED. For instance, the LED will blink
900 fast while running U-Boot code, stop blinking as
901 soon as a reply to a BOOTP request was received, and
902 start blinking slow once the Linux kernel is running
903 (supported by a status LED driver in the Linux
904 kernel). Defining CONFIG_STATUS_LED enables this
907 - CAN Support: CONFIG_CAN_DRIVER
909 Defining CONFIG_CAN_DRIVER enables CAN driver support
910 on those systems that support this (optional)
911 feature, like the TQM8xxL modules.
913 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
915 These enable I2C serial bus commands. Defining either of
916 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
917 include the appropriate I2C driver for the selected cpu.
919 This will allow you to use i2c commands at the u-boot
920 command line (as long as you set CFG_CMD_I2C in
921 CONFIG_COMMANDS) and communicate with i2c based realtime
922 clock chips. See common/cmd_i2c.c for a description of the
923 command line interface.
925 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
927 CONFIG_SOFT_I2C configures u-boot to use a software (aka
928 bit-banging) driver instead of CPM or similar hardware
931 There are several other quantities that must also be
932 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
934 In both cases you will need to define CFG_I2C_SPEED
935 to be the frequency (in Hz) at which you wish your i2c bus
936 to run and CFG_I2C_SLAVE to be the address of this node (ie
937 the cpu's i2c node address).
939 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
940 sets the cpu up as a master node and so its address should
941 therefore be cleared to 0 (See, eg, MPC823e User's Manual
942 p.16-473). So, set CFG_I2C_SLAVE to 0.
944 That's all that's required for CONFIG_HARD_I2C.
946 If you use the software i2c interface (CONFIG_SOFT_I2C)
947 then the following macros need to be defined (examples are
948 from include/configs/lwmon.h):
952 (Optional). Any commands necessary to enable the I2C
953 controller or configure ports.
955 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
959 (Only for MPC8260 CPU). The I/O port to use (the code
960 assumes both bits are on the same port). Valid values
961 are 0..3 for ports A..D.
965 The code necessary to make the I2C data line active
966 (driven). If the data line is open collector, this
969 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
973 The code necessary to make the I2C data line tri-stated
974 (inactive). If the data line is open collector, this
977 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
981 Code that returns TRUE if the I2C data line is high,
984 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
988 If <bit> is TRUE, sets the I2C data line high. If it
989 is FALSE, it clears it (low).
991 eg: #define I2C_SDA(bit) \
992 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
993 else immr->im_cpm.cp_pbdat &= ~PB_SDA
997 If <bit> is TRUE, sets the I2C clock line high. If it
998 is FALSE, it clears it (low).
1000 eg: #define I2C_SCL(bit) \
1001 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1002 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1006 This delay is invoked four times per clock cycle so this
1007 controls the rate of data transfer. The data rate thus
1008 is 1 / (I2C_DELAY * 4). Often defined to be something
1011 #define I2C_DELAY udelay(2)
1015 When a board is reset during an i2c bus transfer
1016 chips might think that the current transfer is still
1017 in progress. On some boards it is possible to access
1018 the i2c SCLK line directly, either by using the
1019 processor pin as a GPIO or by having a second pin
1020 connected to the bus. If this option is defined a
1021 custom i2c_init_board() routine in boards/xxx/board.c
1022 is run early in the boot sequence.
1024 - SPI Support: CONFIG_SPI
1026 Enables SPI driver (so far only tested with
1027 SPI EEPROM, also an instance works with Crystal A/D and
1028 D/As on the SACSng board)
1032 Enables extended (16-bit) SPI EEPROM addressing.
1033 (symmetrical to CONFIG_I2C_X)
1037 Enables a software (bit-bang) SPI driver rather than
1038 using hardware support. This is a general purpose
1039 driver that only requires three general I/O port pins
1040 (two outputs, one input) to function. If this is
1041 defined, the board configuration must define several
1042 SPI configuration items (port pins to use, etc). For
1043 an example, see include/configs/sacsng.h.
1045 - FPGA Support: CONFIG_FPGA_COUNT
1047 Specify the number of FPGA devices to support.
1051 Used to specify the types of FPGA devices. For
1053 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1055 CFG_FPGA_PROG_FEEDBACK
1057 Enable printing of hash marks during FPGA
1062 Enable checks on FPGA configuration interface busy
1063 status by the configuration function. This option
1064 will require a board or device specific function to
1069 If defined, a function that provides delays in the
1070 FPGA configuration driver.
1072 CFG_FPGA_CHECK_CTRLC
1074 Allow Control-C to interrupt FPGA configuration
1076 CFG_FPGA_CHECK_ERROR
1078 Check for configuration errors during FPGA bitfile
1079 loading. For example, abort during Virtex II
1080 configuration if the INIT_B line goes low (which
1081 indicated a CRC error).
1085 Maximum time to wait for the INIT_B line to deassert
1086 after PROB_B has been deasserted during a Virtex II
1087 FPGA configuration sequence. The default time is 500 mS.
1091 Maximum time to wait for BUSY to deassert during
1092 Virtex II FPGA configuration. The default is 5 mS.
1094 CFG_FPGA_WAIT_CONFIG
1096 Time to wait after FPGA configuration. The default is
1099 - FPGA Support: CONFIG_FPGA_COUNT
1101 Specify the number of FPGA devices to support.
1105 Used to specify the types of FPGA devices. For example,
1106 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1108 CFG_FPGA_PROG_FEEDBACK
1110 Enable printing of hash marks during FPGA configuration.
1114 Enable checks on FPGA configuration interface busy
1115 status by the configuration function. This option
1116 will require a board or device specific function to
1121 If defined, a function that provides delays in the FPGA
1122 configuration driver.
1124 CFG_FPGA_CHECK_CTRLC
1125 Allow Control-C to interrupt FPGA configuration
1127 CFG_FPGA_CHECK_ERROR
1129 Check for configuration errors during FPGA bitfile
1130 loading. For example, abort during Virtex II
1131 configuration if the INIT_B line goes low (which
1132 indicated a CRC error).
1136 Maximum time to wait for the INIT_B line to deassert
1137 after PROB_B has been deasserted during a Virtex II
1138 FPGA configuration sequence. The default time is 500
1143 Maximum time to wait for BUSY to deassert during
1144 Virtex II FPGA configuration. The default is 5 mS.
1146 CFG_FPGA_WAIT_CONFIG
1148 Time to wait after FPGA configuration. The default is
1151 - Configuration Management:
1154 If defined, this string will be added to the U-Boot
1155 version information (U_BOOT_VERSION)
1157 - Vendor Parameter Protection:
1159 U-Boot considers the values of the environment
1160 variables "serial#" (Board Serial Number) and
1161 "ethaddr" (Ethernet Address) to bb parameters that
1162 are set once by the board vendor / manufacturer, and
1163 protects these variables from casual modification by
1164 the user. Once set, these variables are read-only,
1165 and write or delete attempts are rejected. You can
1166 change this behviour:
1168 If CONFIG_ENV_OVERWRITE is #defined in your config
1169 file, the write protection for vendor parameters is
1170 completely disabled. Anybody can change or delete
1173 Alternatively, if you #define _both_ CONFIG_ETHADDR
1174 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1175 ethernet address is installed in the environment,
1176 which can be changed exactly ONCE by the user. [The
1177 serial# is unaffected by this, i. e. it remains
1183 Define this variable to enable the reservation of
1184 "protected RAM", i. e. RAM which is not overwritten
1185 by U-Boot. Define CONFIG_PRAM to hold the number of
1186 kB you want to reserve for pRAM. You can overwrite
1187 this default value by defining an environment
1188 variable "pram" to the number of kB you want to
1189 reserve. Note that the board info structure will
1190 still show the full amount of RAM. If pRAM is
1191 reserved, a new environment variable "mem" will
1192 automatically be defined to hold the amount of
1193 remaining RAM in a form that can be passed as boot
1194 argument to Linux, for instance like that:
1196 setenv bootargs ... mem=\$(mem)
1199 This way you can tell Linux not to use this memory,
1200 either, which results in a memory region that will
1201 not be affected by reboots.
1203 *WARNING* If your board configuration uses automatic
1204 detection of the RAM size, you must make sure that
1205 this memory test is non-destructive. So far, the
1206 following board configurations are known to be
1209 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1210 HERMES, IP860, RPXlite, LWMON, LANTEC,
1211 PCU_E, FLAGADM, TQM8260
1216 Define this variable to stop the system in case of a
1217 fatal error, so that you have to reset it manually.
1218 This is probably NOT a good idea for an embedded
1219 system where you want to system to reboot
1220 automatically as fast as possible, but it may be
1221 useful during development since you can try to debug
1222 the conditions that lead to the situation.
1224 CONFIG_NET_RETRY_COUNT
1226 This variable defines the number of retries for
1227 network operations like ARP, RARP, TFTP, or BOOTP
1228 before giving up the operation. If not defined, a
1229 default value of 5 is used.
1231 - Command Interpreter:
1234 Define this variable to enable the "hush" shell (from
1235 Busybox) as command line interpreter, thus enabling
1236 powerful command line syntax like
1237 if...then...else...fi conditionals or `&&' and '||'
1238 constructs ("shell scripts").
1240 If undefined, you get the old, much simpler behaviour
1241 with a somewhat smaller memory footprint.
1246 This defines the secondary prompt string, which is
1247 printed when the command interpreter needs more input
1248 to complete a command. Usually "> ".
1252 In the current implementation, the local variables
1253 space and global environment variables space are
1254 separated. Local variables are those you define by
1255 simply typing `name=value'. To access a local
1256 variable later on, you have write `$name' or
1257 `${name}'; to execute the contents of a variable
1258 directly type `$name' at the command prompt.
1260 Global environment variables are those you use
1261 setenv/printenv to work with. To run a command stored
1262 in such a variable, you need to use the run command,
1263 and you must not use the '$' sign to access them.
1265 To store commands and special characters in a
1266 variable, please use double quotation marks
1267 surrounding the whole text of the variable, instead
1268 of the backslashes before semicolons and special
1271 - Default Environment
1272 CONFIG_EXTRA_ENV_SETTINGS
1274 Define this to contain any number of null terminated
1275 strings (variable = value pairs) that will be part of
1276 the default enviroment compiled into the boot image.
1278 For example, place something like this in your
1279 board's config file:
1281 #define CONFIG_EXTRA_ENV_SETTINGS \
1285 Warning: This method is based on knowledge about the
1286 internal format how the environment is stored by the
1287 U-Boot code. This is NOT an official, exported
1288 interface! Although it is unlikely that this format
1289 will change soon, but there is no guarantee either.
1290 You better know what you are doing here.
1292 Note: overly (ab)use of the default environment is
1293 discouraged. Make sure to check other ways to preset
1294 the environment like the autoscript function or the
1298 CONFIG_HAS_DATAFLASH
1300 Defining this option enables DataFlash features and
1301 allows to read/write in Dataflash via the standard
1304 - Show boot progress
1305 CONFIG_SHOW_BOOT_PROGRESS
1307 Defining this option allows to add some board-
1308 specific code (calling a user-provided function
1309 "show_boot_progress(int)") that enables you to show
1310 the system's boot progress on some display (for
1311 example, some LED's) on your board. At the moment,
1312 the following checkpoints are implemented:
1315 1 common/cmd_bootm.c before attempting to boot an image
1316 -1 common/cmd_bootm.c Image header has bad magic number
1317 2 common/cmd_bootm.c Image header has correct magic number
1318 -2 common/cmd_bootm.c Image header has bad checksum
1319 3 common/cmd_bootm.c Image header has correct checksum
1320 -3 common/cmd_bootm.c Image data has bad checksum
1321 4 common/cmd_bootm.c Image data has correct checksum
1322 -4 common/cmd_bootm.c Image is for unsupported architecture
1323 5 common/cmd_bootm.c Architecture check OK
1324 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1325 6 common/cmd_bootm.c Image Type check OK
1326 -6 common/cmd_bootm.c gunzip uncompression error
1327 -7 common/cmd_bootm.c Unimplemented compression type
1328 7 common/cmd_bootm.c Uncompression OK
1329 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1330 8 common/cmd_bootm.c Image Type check OK
1331 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1332 9 common/cmd_bootm.c Start initial ramdisk verification
1333 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1334 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1335 10 common/cmd_bootm.c Ramdisk header is OK
1336 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1337 11 common/cmd_bootm.c Ramdisk data has correct checksum
1338 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1339 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1340 13 common/cmd_bootm.c Start multifile image verification
1341 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1342 15 common/cmd_bootm.c All preparation done, transferring control to OS
1344 -1 common/cmd_doc.c Bad usage of "doc" command
1345 -1 common/cmd_doc.c No boot device
1346 -1 common/cmd_doc.c Unknown Chip ID on boot device
1347 -1 common/cmd_doc.c Read Error on boot device
1348 -1 common/cmd_doc.c Image header has bad magic number
1350 -1 common/cmd_ide.c Bad usage of "ide" command
1351 -1 common/cmd_ide.c No boot device
1352 -1 common/cmd_ide.c Unknown boot device
1353 -1 common/cmd_ide.c Unknown partition table
1354 -1 common/cmd_ide.c Invalid partition type
1355 -1 common/cmd_ide.c Read Error on boot device
1356 -1 common/cmd_ide.c Image header has bad magic number
1358 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1364 [so far only for SMDK2400 and TRAB boards]
1366 - Modem support endable:
1367 CONFIG_MODEM_SUPPORT
1369 - RTS/CTS Flow control enable:
1372 - Modem debug support:
1373 CONFIG_MODEM_SUPPORT_DEBUG
1375 Enables debugging stuff (char screen[1024], dbg())
1376 for modem support. Useful only with BDI2000.
1380 In the target system modem support is enabled when a
1381 specific key (key combination) is pressed during
1382 power-on. Otherwise U-Boot will boot normally
1383 (autoboot). The key_pressed() fuction is called from
1384 board_init(). Currently key_pressed() is a dummy
1385 function, returning 1 and thus enabling modem
1388 If there are no modem init strings in the
1389 environment, U-Boot proceed to autoboot; the
1390 previous output (banner, info printfs) will be
1393 See also: doc/README.Modem
1396 Configuration Settings:
1397 -----------------------
1399 - CFG_LONGHELP: Defined when you want long help messages included;
1400 undefine this when you're short of memory.
1402 - CFG_PROMPT: This is what U-Boot prints on the console to
1403 prompt for user input.
1405 - CFG_CBSIZE: Buffer size for input from the Console
1407 - CFG_PBSIZE: Buffer size for Console output
1409 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1411 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1412 the application (usually a Linux kernel) when it is
1415 - CFG_BAUDRATE_TABLE:
1416 List of legal baudrate settings for this board.
1418 - CFG_CONSOLE_INFO_QUIET
1419 Suppress display of console information at boot.
1421 - CFG_CONSOLE_IS_IN_ENV
1422 If the board specific function
1423 extern int overwrite_console (void);
1424 returns 1, the stdin, stderr and stdout are switched to the
1425 serial port, else the settings in the environment are used.
1427 - CFG_CONSOLE_OVERWRITE_ROUTINE
1428 Enable the call to overwrite_console().
1430 - CFG_CONSOLE_ENV_OVERWRITE
1431 Enable overwrite of previous console environment settings.
1433 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1434 Begin and End addresses of the area used by the
1438 Enable an alternate, more extensive memory test.
1440 - CFG_TFTP_LOADADDR:
1441 Default load address for network file downloads
1443 - CFG_LOADS_BAUD_CHANGE:
1444 Enable temporary baudrate change while serial download
1447 Physical start address of SDRAM. _Must_ be 0 here.
1450 Physical start address of Motherboard I/O (if using a
1454 Physical start address of Flash memory.
1457 Physical start address of boot monitor code (set by
1458 make config files to be same as the text base address
1459 (TEXT_BASE) used when linking) - same as
1460 CFG_FLASH_BASE when booting from flash.
1463 Size of memory reserved for monitor code, used to
1464 determine _at_compile_time_ (!) if the environment is
1465 embedded within the U-Boot image, or in a separate
1469 Size of DRAM reserved for malloc() use.
1472 Maximum size of memory mapped by the startup code of
1473 the Linux kernel; all data that must be processed by
1474 the Linux kernel (bd_info, boot arguments, eventually
1475 initrd image) must be put below this limit.
1477 - CFG_MAX_FLASH_BANKS:
1478 Max number of Flash memory banks
1480 - CFG_MAX_FLASH_SECT:
1481 Max number of sectors on a Flash chip
1483 - CFG_FLASH_ERASE_TOUT:
1484 Timeout for Flash erase operations (in ms)
1486 - CFG_FLASH_WRITE_TOUT:
1487 Timeout for Flash write operations (in ms)
1489 - CFG_FLASH_LOCK_TOUT
1490 Timeout for Flash set sector lock bit operation (in ms)
1492 - CFG_FLASH_UNLOCK_TOUT
1493 Timeout for Flash clear lock bits operation (in ms)
1495 - CFG_FLASH_PROTECTION
1496 If defined, hardware flash sectors protection is used
1497 instead of U-Boot software protection.
1499 - CFG_DIRECT_FLASH_TFTP:
1501 Enable TFTP transfers directly to flash memory;
1502 without this option such a download has to be
1503 performed in two steps: (1) download to RAM, and (2)
1504 copy from RAM to flash.
1506 The two-step approach is usually more reliable, since
1507 you can check if the download worked before you erase
1508 the flash, but in some situations (when sytem RAM is
1509 too limited to allow for a tempory copy of the
1510 downloaded image) this option may be very useful.
1513 Define if the flash driver uses extra elements in the
1514 common flash structure for storing flash geometry
1516 - CFG_RX_ETH_BUFFER:
1517 Defines the number of ethernet receive buffers. On some
1518 ethernet controllers it is recommended to set this value
1519 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1520 buffers can be full shortly after enabling the interface
1521 on high ethernet traffic.
1522 Defaults to 4 if not defined.
1524 The following definitions that deal with the placement and management
1525 of environment data (variable area); in general, we support the
1526 following configurations:
1528 - CFG_ENV_IS_IN_FLASH:
1530 Define this if the environment is in flash memory.
1532 a) The environment occupies one whole flash sector, which is
1533 "embedded" in the text segment with the U-Boot code. This
1534 happens usually with "bottom boot sector" or "top boot
1535 sector" type flash chips, which have several smaller
1536 sectors at the start or the end. For instance, such a
1537 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1538 such a case you would place the environment in one of the
1539 4 kB sectors - with U-Boot code before and after it. With
1540 "top boot sector" type flash chips, you would put the
1541 environment in one of the last sectors, leaving a gap
1542 between U-Boot and the environment.
1546 Offset of environment data (variable area) to the
1547 beginning of flash memory; for instance, with bottom boot
1548 type flash chips the second sector can be used: the offset
1549 for this sector is given here.
1551 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1555 This is just another way to specify the start address of
1556 the flash sector containing the environment (instead of
1559 - CFG_ENV_SECT_SIZE:
1561 Size of the sector containing the environment.
1564 b) Sometimes flash chips have few, equal sized, BIG sectors.
1565 In such a case you don't want to spend a whole sector for
1570 If you use this in combination with CFG_ENV_IS_IN_FLASH
1571 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1572 of this flash sector for the environment. This saves
1573 memory for the RAM copy of the environment.
1575 It may also save flash memory if you decide to use this
1576 when your environment is "embedded" within U-Boot code,
1577 since then the remainder of the flash sector could be used
1578 for U-Boot code. It should be pointed out that this is
1579 STRONGLY DISCOURAGED from a robustness point of view:
1580 updating the environment in flash makes it always
1581 necessary to erase the WHOLE sector. If something goes
1582 wrong before the contents has been restored from a copy in
1583 RAM, your target system will be dead.
1585 - CFG_ENV_ADDR_REDUND
1588 These settings describe a second storage area used to hold
1589 a redundand copy of the environment data, so that there is
1590 a valid backup copy in case there is a power failure during
1591 a "saveenv" operation.
1593 BE CAREFUL! Any changes to the flash layout, and some changes to the
1594 source code will make it necessary to adapt <board>/u-boot.lds*
1598 - CFG_ENV_IS_IN_NVRAM:
1600 Define this if you have some non-volatile memory device
1601 (NVRAM, battery buffered SRAM) which you want to use for the
1607 These two #defines are used to determin the memory area you
1608 want to use for environment. It is assumed that this memory
1609 can just be read and written to, without any special
1612 BE CAREFUL! The first access to the environment happens quite early
1613 in U-Boot initalization (when we try to get the setting of for the
1614 console baudrate). You *MUST* have mappend your NVRAM area then, or
1617 Please note that even with NVRAM we still use a copy of the
1618 environment in RAM: we could work on NVRAM directly, but we want to
1619 keep settings there always unmodified except somebody uses "saveenv"
1620 to save the current settings.
1623 - CFG_ENV_IS_IN_EEPROM:
1625 Use this if you have an EEPROM or similar serial access
1626 device and a driver for it.
1631 These two #defines specify the offset and size of the
1632 environment area within the total memory of your EEPROM.
1634 - CFG_I2C_EEPROM_ADDR:
1635 If defined, specified the chip address of the EEPROM device.
1636 The default address is zero.
1638 - CFG_EEPROM_PAGE_WRITE_BITS:
1639 If defined, the number of bits used to address bytes in a
1640 single page in the EEPROM device. A 64 byte page, for example
1641 would require six bits.
1643 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1644 If defined, the number of milliseconds to delay between
1645 page writes. The default is zero milliseconds.
1647 - CFG_I2C_EEPROM_ADDR_LEN:
1648 The length in bytes of the EEPROM memory array address. Note
1649 that this is NOT the chip address length!
1652 The size in bytes of the EEPROM device.
1655 - CFG_SPI_INIT_OFFSET
1657 Defines offset to the initial SPI buffer area in DPRAM. The
1658 area is used at an early stage (ROM part) if the environment
1659 is configured to reside in the SPI EEPROM: We need a 520 byte
1660 scratch DPRAM area. It is used between the two initialization
1661 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1662 to be a good choice since it makes it far enough from the
1663 start of the data area as well as from the stack pointer.
1665 Please note that the environment is read-only as long as the monitor
1666 has been relocated to RAM and a RAM copy of the environment has been
1667 created; also, when using EEPROM you will have to use getenv_r()
1668 until then to read environment variables.
1670 The environment is protected by a CRC32 checksum. Before the monitor
1671 is relocated into RAM, as a result of a bad CRC you will be working
1672 with the compiled-in default environment - *silently*!!! [This is
1673 necessary, because the first environment variable we need is the
1674 "baudrate" setting for the console - if we have a bad CRC, we don't
1675 have any device yet where we could complain.]
1677 Note: once the monitor has been relocated, then it will complain if
1678 the default environment is used; a new CRC is computed as soon as you
1679 use the "saveenv" command to store a valid environment.
1682 Low Level (hardware related) configuration options:
1683 ---------------------------------------------------
1685 - CFG_CACHELINE_SIZE:
1686 Cache Line Size of the CPU.
1689 Default address of the IMMR after system reset.
1690 Needed on some 8260 systems (MPC8260ADS and RPXsuper)
1691 to be able to adjust the position of the IMMR
1692 register after a reset.
1694 - Floppy Disk Support:
1695 CFG_FDC_DRIVE_NUMBER
1697 the default drive number (default value 0)
1701 defines the spacing between fdc chipset registers
1706 defines the offset of register from address. It
1707 depends on which part of the data bus is connected to
1708 the fdc chipset. (default value 0)
1710 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1711 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1714 if CFG_FDC_HW_INIT is defined, then the function
1715 fdc_hw_init() is called at the beginning of the FDC
1716 setup. fdc_hw_init() must be provided by the board
1717 source code. It is used to make hardware dependant
1720 - CFG_IMMR: Physical address of the Internal Memory Mapped
1721 Register; DO NOT CHANGE! (11-4)
1722 [MPC8xx systems only]
1724 - CFG_INIT_RAM_ADDR:
1726 Start address of memory area tha can be used for
1727 initial data and stack; please note that this must be
1728 writable memory that is working WITHOUT special
1729 initialization, i. e. you CANNOT use normal RAM which
1730 will become available only after programming the
1731 memory controller and running certain initialization
1734 U-Boot uses the following memory types:
1735 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1736 - MPC824X: data cache
1737 - PPC4xx: data cache
1739 - CFG_GBL_DATA_OFFSET:
1741 Offset of the initial data structure in the memory
1742 area defined by CFG_INIT_RAM_ADDR. Usually
1743 CFG_GBL_DATA_OFFSET is chosen such that the initial
1744 data is located at the end of the available space
1745 (sometimes written as (CFG_INIT_RAM_END -
1746 CFG_INIT_DATA_SIZE), and the initial stack is just
1747 below that area (growing from (CFG_INIT_RAM_ADDR +
1748 CFG_GBL_DATA_OFFSET) downward.
1751 On the MPC824X (or other systems that use the data
1752 cache for initial memory) the address chosen for
1753 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1754 point to an otherwise UNUSED address space between
1755 the top of RAM and the start of the PCI space.
1757 - CFG_SIUMCR: SIU Module Configuration (11-6)
1759 - CFG_SYPCR: System Protection Control (11-9)
1761 - CFG_TBSCR: Time Base Status and Control (11-26)
1763 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1765 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1767 - CFG_SCCR: System Clock and reset Control Register (15-27)
1769 - CFG_OR_TIMING_SDRAM:
1773 periodic timer for refresh
1775 - CFG_DER: Debug Event Register (37-47)
1777 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1778 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1779 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1781 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1783 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1784 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1785 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1786 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1788 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1789 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1790 Machine Mode Register and Memory Periodic Timer
1791 Prescaler definitions (SDRAM timing)
1793 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1794 enable I2C microcode relocation patch (MPC8xx);
1795 define relocation offset in DPRAM [DSP2]
1797 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1798 enable SPI microcode relocation patch (MPC8xx);
1799 define relocation offset in DPRAM [SCC4]
1802 Use OSCM clock mode on MBX8xx board. Be careful,
1803 wrong setting might damage your board. Read
1804 doc/README.MBX before setting this variable!
1806 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1807 Offset of the bootmode word in DPRAM used by post
1808 (Power On Self Tests). This definition overrides
1809 #define'd default value in commproc.h resp.
1812 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1813 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1814 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1815 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1816 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1817 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1818 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1819 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1820 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1822 Building the Software:
1823 ======================
1825 Building U-Boot has been tested in native PPC environments (on a
1826 PowerBook G3 running LinuxPPC 2000) and in cross environments
1827 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1830 If you are not using a native PPC environment, it is assumed that you
1831 have the GNU cross compiling tools available in your path and named
1832 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1833 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1834 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1837 CROSS_COMPILE = ppc_4xx-
1840 U-Boot is intended to be simple to build. After installing the
1841 sources you must configure U-Boot for one specific board type. This
1846 where "NAME_config" is the name of one of the existing
1847 configurations; the following names are supported:
1849 ADCIOP_config GTH_config TQM850L_config
1850 ADS860_config IP860_config TQM855L_config
1851 AR405_config IVML24_config TQM860L_config
1852 CANBT_config IVMS8_config WALNUT405_config
1853 CPCI405_config LANTEC_config cogent_common_config
1854 CPCIISER4_config MBX_config cogent_mpc8260_config
1855 CU824_config MBX860T_config cogent_mpc8xx_config
1856 ESTEEM192E_config RPXlite_config hermes_config
1857 ETX094_config RPXsuper_config hymod_config
1858 FADS823_config SM850_config lwmon_config
1859 FADS850SAR_config SPD823TS_config pcu_e_config
1860 FADS860T_config SXNI855T_config rsdproto_config
1861 FPS850L_config Sandpoint8240_config sbc8260_config
1862 GENIETV_config TQM823L_config PIP405_config
1863 GEN860T_config EBONY_config FPS860L_config
1864 ELPT860_config cmi_mpc5xx_config NETVIA_config
1865 at91rm9200dk_config omap1510inn_config
1867 Note: for some board special configuration names may exist; check if
1868 additional information is available from the board vendor; for
1869 instance, the TQM8xxL systems run normally at 50 MHz and use a
1870 SCC for 10baseT ethernet; there are also systems with 80 MHz
1871 CPU clock, and an optional Fast Ethernet module is available
1872 for CPU's with FEC. You can select such additional "features"
1873 when chosing the configuration, i. e.
1876 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1878 make TQM860L_FEC_config
1879 - will configure for a TQM860L at 50MHz with FEC for ethernet
1881 make TQM860L_80MHz_config
1882 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1885 make TQM860L_FEC_80MHz_config
1886 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1888 make TQM823L_LCD_config
1889 - will configure for a TQM823L with U-Boot console on LCD
1891 make TQM823L_LCD_80MHz_config
1892 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1897 Finally, type "make all", and you should get some working U-Boot
1898 images ready for downlod to / installation on your system:
1900 - "u-boot.bin" is a raw binary image
1901 - "u-boot" is an image in ELF binary format
1902 - "u-boot.srec" is in Motorola S-Record format
1905 Please be aware that the Makefiles assume you are using GNU make, so
1906 for instance on NetBSD you might need to use "gmake" instead of
1910 If the system board that you have is not listed, then you will need
1911 to port U-Boot to your hardware platform. To do this, follow these
1914 1. Add a new configuration option for your board to the toplevel
1915 "Makefile" and to the "MAKEALL" script, using the existing
1916 entries as examples. Note that here and at many other places
1917 boards and other names are listed alphabetically sorted. Please
1919 2. Create a new directory to hold your board specific code. Add any
1920 files you need. In your board directory, you will need at least
1921 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1922 3. Create a new configuration file "include/configs/<board>.h" for
1924 3. If you're porting U-Boot to a new CPU, then also create a new
1925 directory to hold your CPU specific code. Add any files you need.
1926 4. Run "make <board>_config" with your new name.
1927 5. Type "make", and you should get a working "u-boot.srec" file
1928 to be installed on your target system.
1929 6. Debug and solve any problems that might arise.
1930 [Of course, this last step is much harder than it sounds.]
1933 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1934 ==============================================================
1936 If you have modified U-Boot sources (for instance added a new board
1937 or support for new devices, a new CPU, etc.) you are expected to
1938 provide feedback to the other developers. The feedback normally takes
1939 the form of a "patch", i. e. a context diff against a certain (latest
1940 official or latest in CVS) version of U-Boot sources.
1942 But before you submit such a patch, please verify that your modifi-
1943 cation did not break existing code. At least make sure that *ALL* of
1944 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1945 just run the "MAKEALL" script, which will configure and build U-Boot
1946 for ALL supported system. Be warned, this will take a while. You can
1947 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1948 environment variable to the script, i. e. to use the cross tools from
1949 MontaVista's Hard Hat Linux you can type
1951 CROSS_COMPILE=ppc_8xx- MAKEALL
1953 or to build on a native PowerPC system you can type
1955 CROSS_COMPILE=' ' MAKEALL
1957 See also "U-Boot Porting Guide" below.
1960 Monitor Commands - Overview:
1961 ============================
1963 go - start application at address 'addr'
1964 run - run commands in an environment variable
1965 bootm - boot application image from memory
1966 bootp - boot image via network using BootP/TFTP protocol
1967 tftpboot- boot image via network using TFTP protocol
1968 and env variables "ipaddr" and "serverip"
1969 (and eventually "gatewayip")
1970 rarpboot- boot image via network using RARP/TFTP protocol
1971 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
1972 loads - load S-Record file over serial line
1973 loadb - load binary file over serial line (kermit mode)
1975 mm - memory modify (auto-incrementing)
1976 nm - memory modify (constant address)
1977 mw - memory write (fill)
1979 cmp - memory compare
1980 crc32 - checksum calculation
1981 imd - i2c memory display
1982 imm - i2c memory modify (auto-incrementing)
1983 inm - i2c memory modify (constant address)
1984 imw - i2c memory write (fill)
1985 icrc32 - i2c checksum calculation
1986 iprobe - probe to discover valid I2C chip addresses
1987 iloop - infinite loop on address range
1988 isdram - print SDRAM configuration information
1989 sspi - SPI utility commands
1990 base - print or set address offset
1991 printenv- print environment variables
1992 setenv - set environment variables
1993 saveenv - save environment variables to persistent storage
1994 protect - enable or disable FLASH write protection
1995 erase - erase FLASH memory
1996 flinfo - print FLASH memory information
1997 bdinfo - print Board Info structure
1998 iminfo - print header information for application image
1999 coninfo - print console devices and informations
2000 ide - IDE sub-system
2001 loop - infinite loop on address range
2002 mtest - simple RAM test
2003 icache - enable or disable instruction cache
2004 dcache - enable or disable data cache
2005 reset - Perform RESET of the CPU
2006 echo - echo args to console
2007 version - print monitor version
2008 help - print online help
2009 ? - alias for 'help'
2012 Monitor Commands - Detailed Description:
2013 ========================================
2017 For now: just type "help <command>".
2020 Environment Variables:
2021 ======================
2023 U-Boot supports user configuration using Environment Variables which
2024 can be made persistent by saving to Flash memory.
2026 Environment Variables are set using "setenv", printed using
2027 "printenv", and saved to Flash using "saveenv". Using "setenv"
2028 without a value can be used to delete a variable from the
2029 environment. As long as you don't save the environment you are
2030 working with an in-memory copy. In case the Flash area containing the
2031 environment is erased by accident, a default environment is provided.
2033 Some configuration options can be set using Environment Variables:
2035 baudrate - see CONFIG_BAUDRATE
2037 bootdelay - see CONFIG_BOOTDELAY
2039 bootcmd - see CONFIG_BOOTCOMMAND
2041 bootargs - Boot arguments when booting an RTOS image
2043 bootfile - Name of the image to load with TFTP
2045 autoload - if set to "no" (any string beginning with 'n'),
2046 "bootp" will just load perform a lookup of the
2047 configuration from the BOOTP server, but not try to
2048 load any image using TFTP
2050 autostart - if set to "yes", an image loaded using the "bootp",
2051 "rarpboot", "tftpboot" or "diskboot" commands will
2052 be automatically started (by internally calling
2055 If set to "no", a standalone image passed to the
2056 "bootm" command will be copied to the load address
2057 (and eventually uncompressed), but NOT be started.
2058 This can be used to load and uncompress arbitrary
2061 initrd_high - restrict positioning of initrd images:
2062 If this variable is not set, initrd images will be
2063 copied to the highest possible address in RAM; this
2064 is usually what you want since it allows for
2065 maximum initrd size. If for some reason you want to
2066 make sure that the initrd image is loaded below the
2067 CFG_BOOTMAPSZ limit, you can set this environment
2068 variable to a value of "no" or "off" or "0".
2069 Alternatively, you can set it to a maximum upper
2070 address to use (U-Boot will still check that it
2071 does not overwrite the U-Boot stack and data).
2073 For instance, when you have a system with 16 MB
2074 RAM, and want to reseve 4 MB from use by Linux,
2075 you can do this by adding "mem=12M" to the value of
2076 the "bootargs" variable. However, now you must make
2077 sure, that the initrd image is placed in the first
2078 12 MB as well - this can be done with
2080 setenv initrd_high 00c00000
2082 If you set initrd_high to 0xFFFFFFFF, this is an
2083 indication to U-Boot that all addresses are legal
2084 for the Linux kernel, including addresses in flash
2085 memory. In this case U-Boot will NOT COPY the
2086 ramdisk at all. This may be useful to reduce the
2087 boot time on your system, but requires that this
2088 feature is supported by your Linux kernel.
2090 ipaddr - IP address; needed for tftpboot command
2092 loadaddr - Default load address for commands like "bootp",
2093 "rarpboot", "tftpboot", "loadb" or "diskboot"
2095 loads_echo - see CONFIG_LOADS_ECHO
2097 serverip - TFTP server IP address; needed for tftpboot command
2099 bootretry - see CONFIG_BOOT_RETRY_TIME
2101 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2103 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2106 The following environment variables may be used and automatically
2107 updated by the network boot commands ("bootp" and "rarpboot"),
2108 depending the information provided by your boot server:
2110 bootfile - see above
2111 dnsip - IP address of your Domain Name Server
2112 gatewayip - IP address of the Gateway (Router) to use
2113 hostname - Target hostname
2115 netmask - Subnet Mask
2116 rootpath - Pathname of the root filesystem on the NFS server
2117 serverip - see above
2120 There are two special Environment Variables:
2122 serial# - contains hardware identification information such
2123 as type string and/or serial number
2124 ethaddr - Ethernet address
2126 These variables can be set only once (usually during manufacturing of
2127 the board). U-Boot refuses to delete or overwrite these variables
2128 once they have been set once.
2131 Further special Environment Variables:
2133 ver - Contains the U-Boot version string as printed
2134 with the "version" command. This variable is
2135 readonly (see CONFIG_VERSION_VARIABLE).
2138 Please note that changes to some configuration parameters may take
2139 only effect after the next boot (yes, that's just like Windoze :-).
2142 Command Line Parsing:
2143 =====================
2145 There are two different command line parsers available with U-Boot:
2146 the old "simple" one, and the much more pwerful "hush" shell:
2148 Old, simple command line parser:
2149 --------------------------------
2151 - supports environment variables (through setenv / saveenv commands)
2152 - several commands on one line, separated by ';'
2153 - variable substitution using "... $(name) ..." syntax
2154 - special characters ('$', ';') can be escaped by prefixing with '\',
2156 setenv bootcmd bootm \$(address)
2157 - You can also escape text by enclosing in single apostrophes, for example:
2158 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2163 - similar to Bourne shell, with control structures like
2164 if...then...else...fi, for...do...done; while...do...done,
2165 until...do...done, ...
2166 - supports environment ("global") variables (through setenv / saveenv
2167 commands) and local shell variables (through standard shell syntax
2168 "name=value"); only environment variables can be used with "run"
2174 (1) If a command line (or an environment variable executed by a "run"
2175 command) contains several commands separated by semicolon, and
2176 one of these commands fails, then the remaining commands will be
2179 (2) If you execute several variables with one call to run (i. e.
2180 calling run with a list af variables as arguments), any failing
2181 command will cause "run" to terminate, i. e. the remaining
2182 variables are not executed.
2184 Note for Redundant Ethernet Interfaces:
2185 =======================================
2187 Some boards come with redundand ethernet interfaces; U-Boot supports
2188 such configurations and is capable of automatic selection of a
2189 "working" interface when needed. MAC assignemnt works as follows:
2191 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2192 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2193 "eth1addr" (=>eth1), "eth2addr", ...
2195 If the network interface stores some valid MAC address (for instance
2196 in SROM), this is used as default address if there is NO correspon-
2197 ding setting in the environment; if the corresponding environment
2198 variable is set, this overrides the settings in the card; that means:
2200 o If the SROM has a valid MAC address, and there is no address in the
2201 environment, the SROM's address is used.
2203 o If there is no valid address in the SROM, and a definition in the
2204 environment exists, then the value from the environment variable is
2207 o If both the SROM and the environment contain a MAC address, and
2208 both addresses are the same, this MAC address is used.
2210 o If both the SROM and the environment contain a MAC address, and the
2211 addresses differ, the value from the environment is used and a
2214 o If neither SROM nor the environment contain a MAC address, an error
2221 The "boot" commands of this monitor operate on "image" files which
2222 can be basicly anything, preceeded by a special header; see the
2223 definitions in include/image.h for details; basicly, the header
2224 defines the following image properties:
2226 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2227 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2228 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2229 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS).
2230 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2231 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2232 Currently supported: PowerPC).
2233 * Compression Type (Provisions for uncompressed, gzip, bzip2;
2234 Currently supported: uncompressed, gzip).
2240 The header is marked by a special Magic Number, and both the header
2241 and the data portions of the image are secured against corruption by
2248 Although U-Boot should support any OS or standalone application
2249 easily, Linux has always been in the focus during the design of
2252 U-Boot includes many features that so far have been part of some
2253 special "boot loader" code within the Linux kernel. Also, any
2254 "initrd" images to be used are no longer part of one big Linux image;
2255 instead, kernel and "initrd" are separate images. This implementation
2256 serves serveral purposes:
2258 - the same features can be used for other OS or standalone
2259 applications (for instance: using compressed images to reduce the
2260 Flash memory footprint)
2262 - it becomes much easier to port new Linux kernel versions because
2263 lots of low-level, hardware dependend stuff are done by U-Boot
2265 - the same Linux kernel image can now be used with different "initrd"
2266 images; of course this also means that different kernel images can
2267 be run with the same "initrd". This makes testing easier (you don't
2268 have to build a new "zImage.initrd" Linux image when you just
2269 change a file in your "initrd"). Also, a field-upgrade of the
2270 software is easier now.
2276 Porting Linux to U-Boot based systems:
2277 ---------------------------------------
2279 U-Boot cannot save you from doing all the necessary modifications to
2280 configure the Linux device drivers for use with your target hardware
2281 (no, we don't intend to provide a full virtual machine interface to
2284 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2286 Just make sure your machine specific header file (for instance
2287 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2288 Information structure as we define in include/u-boot.h, and make
2289 sure that your definition of IMAP_ADDR uses the same value as your
2290 U-Boot configuration in CFG_IMMR.
2293 Configuring the Linux kernel:
2294 -----------------------------
2296 No specific requirements for U-Boot. Make sure you have some root
2297 device (initial ramdisk, NFS) for your target system.
2300 Building a Linux Image:
2301 -----------------------
2303 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2304 not used. If you use recent kernel source, a new build target
2305 "uImage" will exist which automatically builds an image usable by
2306 U-Boot. Most older kernels also have support for a "pImage" target,
2307 which was introduced for our predecessor project PPCBoot and uses a
2308 100% compatible format.
2317 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2318 encapsulate a compressed Linux kernel image with header information,
2319 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2321 * build a standard "vmlinux" kernel image (in ELF binary format):
2323 * convert the kernel into a raw binary image:
2325 ${CROSS_COMPILE}-objcopy -O binary \
2326 -R .note -R .comment \
2327 -S vmlinux linux.bin
2329 * compress the binary image:
2333 * package compressed binary image for U-Boot:
2335 mkimage -A ppc -O linux -T kernel -C gzip \
2336 -a 0 -e 0 -n "Linux Kernel Image" \
2337 -d linux.bin.gz uImage
2340 The "mkimage" tool can also be used to create ramdisk images for use
2341 with U-Boot, either separated from the Linux kernel image, or
2342 combined into one file. "mkimage" encapsulates the images with a 64
2343 byte header containing information about target architecture,
2344 operating system, image type, compression method, entry points, time
2345 stamp, CRC32 checksums, etc.
2347 "mkimage" can be called in two ways: to verify existing images and
2348 print the header information, or to build new images.
2350 In the first form (with "-l" option) mkimage lists the information
2351 contained in the header of an existing U-Boot image; this includes
2352 checksum verification:
2354 tools/mkimage -l image
2355 -l ==> list image header information
2357 The second form (with "-d" option) is used to build a U-Boot image
2358 from a "data file" which is used as image payload:
2360 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2361 -n name -d data_file image
2362 -A ==> set architecture to 'arch'
2363 -O ==> set operating system to 'os'
2364 -T ==> set image type to 'type'
2365 -C ==> set compression type 'comp'
2366 -a ==> set load address to 'addr' (hex)
2367 -e ==> set entry point to 'ep' (hex)
2368 -n ==> set image name to 'name'
2369 -d ==> use image data from 'datafile'
2371 Right now, all Linux kernels use the same load address (0x00000000),
2372 but the entry point address depends on the kernel version:
2374 - 2.2.x kernels have the entry point at 0x0000000C,
2375 - 2.3.x and later kernels have the entry point at 0x00000000.
2377 So a typical call to build a U-Boot image would read:
2379 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2380 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2381 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2382 > examples/uImage.TQM850L
2383 Image Name: 2.4.4 kernel for TQM850L
2384 Created: Wed Jul 19 02:34:59 2000
2385 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2386 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2387 Load Address: 0x00000000
2388 Entry Point: 0x00000000
2390 To verify the contents of the image (or check for corruption):
2392 -> tools/mkimage -l examples/uImage.TQM850L
2393 Image Name: 2.4.4 kernel for TQM850L
2394 Created: Wed Jul 19 02:34:59 2000
2395 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2396 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2397 Load Address: 0x00000000
2398 Entry Point: 0x00000000
2400 NOTE: for embedded systems where boot time is critical you can trade
2401 speed for memory and install an UNCOMPRESSED image instead: this
2402 needs more space in Flash, but boots much faster since it does not
2403 need to be uncompressed:
2405 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2406 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2407 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2408 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2409 > examples/uImage.TQM850L-uncompressed
2410 Image Name: 2.4.4 kernel for TQM850L
2411 Created: Wed Jul 19 02:34:59 2000
2412 Image Type: PowerPC Linux Kernel Image (uncompressed)
2413 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2414 Load Address: 0x00000000
2415 Entry Point: 0x00000000
2418 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2419 when your kernel is intended to use an initial ramdisk:
2421 -> tools/mkimage -n 'Simple Ramdisk Image' \
2422 > -A ppc -O linux -T ramdisk -C gzip \
2423 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2424 Image Name: Simple Ramdisk Image
2425 Created: Wed Jan 12 14:01:50 2000
2426 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2427 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2428 Load Address: 0x00000000
2429 Entry Point: 0x00000000
2432 Installing a Linux Image:
2433 -------------------------
2435 To downloading a U-Boot image over the serial (console) interface,
2436 you must convert the image to S-Record format:
2438 objcopy -I binary -O srec examples/image examples/image.srec
2440 The 'objcopy' does not understand the information in the U-Boot
2441 image header, so the resulting S-Record file will be relative to
2442 address 0x00000000. To load it to a given address, you need to
2443 specify the target address as 'offset' parameter with the 'loads'
2446 Example: install the image to address 0x40100000 (which on the
2447 TQM8xxL is in the first Flash bank):
2449 => erase 40100000 401FFFFF
2455 ## Ready for S-Record download ...
2456 ~>examples/image.srec
2457 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2459 15989 15990 15991 15992
2460 [file transfer complete]
2462 ## Start Addr = 0x00000000
2465 You can check the success of the download using the 'iminfo' command;
2466 this includes a checksum verification so you can be sure no data
2467 corruption happened:
2471 ## Checking Image at 40100000 ...
2472 Image Name: 2.2.13 for initrd on TQM850L
2473 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2474 Data Size: 335725 Bytes = 327 kB = 0 MB
2475 Load Address: 00000000
2476 Entry Point: 0000000c
2477 Verifying Checksum ... OK
2483 The "bootm" command is used to boot an application that is stored in
2484 memory (RAM or Flash). In case of a Linux kernel image, the contents
2485 of the "bootargs" environment variable is passed to the kernel as
2486 parameters. You can check and modify this variable using the
2487 "printenv" and "setenv" commands:
2490 => printenv bootargs
2491 bootargs=root=/dev/ram
2493 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2495 => printenv bootargs
2496 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2499 ## Booting Linux kernel at 40020000 ...
2500 Image Name: 2.2.13 for NFS on TQM850L
2501 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2502 Data Size: 381681 Bytes = 372 kB = 0 MB
2503 Load Address: 00000000
2504 Entry Point: 0000000c
2505 Verifying Checksum ... OK
2506 Uncompressing Kernel Image ... OK
2507 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
2508 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2509 time_init: decrementer frequency = 187500000/60
2510 Calibrating delay loop... 49.77 BogoMIPS
2511 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2514 If you want to boot a Linux kernel with initial ram disk, you pass
2515 the memory addreses of both the kernel and the initrd image (PPBCOOT
2516 format!) to the "bootm" command:
2518 => imi 40100000 40200000
2520 ## Checking Image at 40100000 ...
2521 Image Name: 2.2.13 for initrd on TQM850L
2522 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2523 Data Size: 335725 Bytes = 327 kB = 0 MB
2524 Load Address: 00000000
2525 Entry Point: 0000000c
2526 Verifying Checksum ... OK
2528 ## Checking Image at 40200000 ...
2529 Image Name: Simple Ramdisk Image
2530 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2531 Data Size: 566530 Bytes = 553 kB = 0 MB
2532 Load Address: 00000000
2533 Entry Point: 00000000
2534 Verifying Checksum ... OK
2536 => bootm 40100000 40200000
2537 ## Booting Linux kernel at 40100000 ...
2538 Image Name: 2.2.13 for initrd on TQM850L
2539 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2540 Data Size: 335725 Bytes = 327 kB = 0 MB
2541 Load Address: 00000000
2542 Entry Point: 0000000c
2543 Verifying Checksum ... OK
2544 Uncompressing Kernel Image ... OK
2545 ## Loading RAMDisk Image at 40200000 ...
2546 Image Name: Simple Ramdisk Image
2547 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2548 Data Size: 566530 Bytes = 553 kB = 0 MB
2549 Load Address: 00000000
2550 Entry Point: 00000000
2551 Verifying Checksum ... OK
2552 Loading Ramdisk ... OK
2553 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
2554 Boot arguments: root=/dev/ram
2555 time_init: decrementer frequency = 187500000/60
2556 Calibrating delay loop... 49.77 BogoMIPS
2558 RAMDISK: Compressed image found at block 0
2559 VFS: Mounted root (ext2 filesystem).
2563 More About U-Boot Image Types:
2564 ------------------------------
2566 U-Boot supports the following image types:
2568 "Standalone Programs" are directly runnable in the environment
2569 provided by U-Boot; it is expected that (if they behave
2570 well) you can continue to work in U-Boot after return from
2571 the Standalone Program.
2572 "OS Kernel Images" are usually images of some Embedded OS which
2573 will take over control completely. Usually these programs
2574 will install their own set of exception handlers, device
2575 drivers, set up the MMU, etc. - this means, that you cannot
2576 expect to re-enter U-Boot except by resetting the CPU.
2577 "RAMDisk Images" are more or less just data blocks, and their
2578 parameters (address, size) are passed to an OS kernel that is
2580 "Multi-File Images" contain several images, typically an OS
2581 (Linux) kernel image and one or more data images like
2582 RAMDisks. This construct is useful for instance when you want
2583 to boot over the network using BOOTP etc., where the boot
2584 server provides just a single image file, but you want to get
2585 for instance an OS kernel and a RAMDisk image.
2587 "Multi-File Images" start with a list of image sizes, each
2588 image size (in bytes) specified by an "uint32_t" in network
2589 byte order. This list is terminated by an "(uint32_t)0".
2590 Immediately after the terminating 0 follow the images, one by
2591 one, all aligned on "uint32_t" boundaries (size rounded up to
2592 a multiple of 4 bytes).
2594 "Firmware Images" are binary images containing firmware (like
2595 U-Boot or FPGA images) which usually will be programmed to
2598 "Script files" are command sequences that will be executed by
2599 U-Boot's command interpreter; this feature is especially
2600 useful when you configure U-Boot to use a real shell (hush)
2601 as command interpreter.
2607 One of the features of U-Boot is that you can dynamically load and
2608 run "standalone" applications, which can use some resources of
2609 U-Boot like console I/O functions or interrupt services.
2611 Two simple examples are included with the sources:
2616 'examples/hello_world.c' contains a small "Hello World" Demo
2617 application; it is automatically compiled when you build U-Boot.
2618 It's configured to run at address 0x00040004, so you can play with it
2622 ## Ready for S-Record download ...
2623 ~>examples/hello_world.srec
2624 1 2 3 4 5 6 7 8 9 10 11 ...
2625 [file transfer complete]
2627 ## Start Addr = 0x00040004
2629 => go 40004 Hello World! This is a test.
2630 ## Starting application at 0x00040004 ...
2641 Hit any key to exit ...
2643 ## Application terminated, rc = 0x0
2645 Another example, which demonstrates how to register a CPM interrupt
2646 handler with the U-Boot code, can be found in 'examples/timer.c'.
2647 Here, a CPM timer is set up to generate an interrupt every second.
2648 The interrupt service routine is trivial, just printing a '.'
2649 character, but this is just a demo program. The application can be
2650 controlled by the following keys:
2652 ? - print current values og the CPM Timer registers
2653 b - enable interrupts and start timer
2654 e - stop timer and disable interrupts
2655 q - quit application
2658 ## Ready for S-Record download ...
2659 ~>examples/timer.srec
2660 1 2 3 4 5 6 7 8 9 10 11 ...
2661 [file transfer complete]
2663 ## Start Addr = 0x00040004
2666 ## Starting application at 0x00040004 ...
2669 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2672 [q, b, e, ?] Set interval 1000000 us
2675 [q, b, e, ?] ........
2676 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2679 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2682 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2685 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2687 [q, b, e, ?] ...Stopping timer
2689 [q, b, e, ?] ## Application terminated, rc = 0x0
2695 Over time, many people have reported problems when trying to used the
2696 "minicom" terminal emulation program for serial download. I (wd)
2697 consider minicom to be broken, and recommend not to use it. Under
2698 Unix, I recommend to use C-Kermit for general purpose use (and
2699 especially for kermit binary protocol download ("loadb" command), and
2700 use "cu" for S-Record download ("loads" command).
2702 Nevertheless, if you absolutely want to use it try adding this
2703 configuration to your "File transfer protocols" section:
2705 Name Program Name U/D FullScr IO-Red. Multi
2706 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2707 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2713 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2714 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2716 Building requires a cross environment; it is known to work on
2717 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2718 need gmake since the Makefiles are not compatible with BSD make).
2719 Note that the cross-powerpc package does not install include files;
2720 attempting to build U-Boot will fail because <machine/ansi.h> is
2721 missing. This file has to be installed and patched manually:
2723 # cd /usr/pkg/cross/powerpc-netbsd/include
2725 # ln -s powerpc machine
2726 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2727 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2729 Native builds *don't* work due to incompatibilities between native
2730 and U-Boot include files.
2732 Booting assumes that (the first part of) the image booted is a
2733 stage-2 loader which in turn loads and then invokes the kernel
2734 proper. Loader sources will eventually appear in the NetBSD source
2735 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2736 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2740 Implementation Internals:
2741 =========================
2743 The following is not intended to be a complete description of every
2744 implementation detail. However, it should help to understand the
2745 inner workings of U-Boot and make it easier to port it to custom
2749 Initial Stack, Global Data:
2750 ---------------------------
2752 The implementation of U-Boot is complicated by the fact that U-Boot
2753 starts running out of ROM (flash memory), usually without access to
2754 system RAM (because the memory controller is not initialized yet).
2755 This means that we don't have writable Data or BSS segments, and BSS
2756 is not initialized as zero. To be able to get a C environment working
2757 at all, we have to allocate at least a minimal stack. Implementation
2758 options for this are defined and restricted by the CPU used: Some CPU
2759 models provide on-chip memory (like the IMMR area on MPC8xx and
2760 MPC826x processors), on others (parts of) the data cache can be
2761 locked as (mis-) used as memory, etc.
2763 Chris Hallinan posted a good summy of these issues to the
2764 u-boot-users mailing list:
2766 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2767 From: "Chris Hallinan" <clh@net1plus.com>
2768 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2771 Correct me if I'm wrong, folks, but the way I understand it
2772 is this: Using DCACHE as initial RAM for Stack, etc, does not
2773 require any physical RAM backing up the cache. The cleverness
2774 is that the cache is being used as a temporary supply of
2775 necessary storage before the SDRAM controller is setup. It's
2776 beyond the scope of this list to expain the details, but you
2777 can see how this works by studying the cache architecture and
2778 operation in the architecture and processor-specific manuals.
2780 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2781 is another option for the system designer to use as an
2782 initial stack/ram area prior to SDRAM being available. Either
2783 option should work for you. Using CS 4 should be fine if your
2784 board designers haven't used it for something that would
2785 cause you grief during the initial boot! It is frequently not
2788 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2789 with your processor/board/system design. The default value
2790 you will find in any recent u-boot distribution in
2791 Walnut405.h should work for you. I'd set it to a value larger
2792 than your SDRAM module. If you have a 64MB SDRAM module, set
2793 it above 400_0000. Just make sure your board has no resources
2794 that are supposed to respond to that address! That code in
2795 start.S has been around a while and should work as is when
2796 you get the config right.
2801 It is essential to remember this, since it has some impact on the C
2802 code for the initialization procedures:
2804 * Initialized global data (data segment) is read-only. Do not attempt
2807 * Do not use any unitialized global data (or implicitely initialized
2808 as zero data - BSS segment) at all - this is undefined, initiali-
2809 zation is performed later (when relocationg to RAM).
2811 * Stack space is very limited. Avoid big data buffers or things like
2814 Having only the stack as writable memory limits means we cannot use
2815 normal global data to share information beween the code. But it
2816 turned out that the implementation of U-Boot can be greatly
2817 simplified by making a global data structure (gd_t) available to all
2818 functions. We could pass a pointer to this data as argument to _all_
2819 functions, but this would bloat the code. Instead we use a feature of
2820 the GCC compiler (Global Register Variables) to share the data: we
2821 place a pointer (gd) to the global data into a register which we
2822 reserve for this purpose.
2824 When chosing a register for such a purpose we are restricted by the
2825 relevant (E)ABI specifications for the current architecture, and by
2826 GCC's implementation.
2828 For PowerPC, the following registers have specific use:
2831 R3-R4: parameter passing and return values
2832 R5-R10: parameter passing
2833 R13: small data area pointer
2837 (U-Boot also uses R14 as internal GOT pointer.)
2839 ==> U-Boot will use R29 to hold a pointer to the global data
2841 Note: on PPC, we could use a static initializer (since the
2842 address of the global data structure is known at compile time),
2843 but it turned out that reserving a register results in somewhat
2844 smaller code - although the code savings are not that big (on
2845 average for all boards 752 bytes for the whole U-Boot image,
2846 624 text + 127 data).
2848 On ARM, the following registers are used:
2850 R0: function argument word/integer result
2851 R1-R3: function argument word
2853 R10: stack limit (used only if stack checking if enabled)
2854 R11: argument (frame) pointer
2855 R12: temporary workspace
2858 R15: program counter
2860 ==> U-Boot will use R8 to hold a pointer to the global data
2866 U-Boot runs in system state and uses physical addresses, i.e. the
2867 MMU is not used either for address mapping nor for memory protection.
2869 The available memory is mapped to fixed addresses using the memory
2870 controller. In this process, a contiguous block is formed for each
2871 memory type (Flash, SDRAM, SRAM), even when it consists of several
2872 physical memory banks.
2874 U-Boot is installed in the first 128 kB of the first Flash bank (on
2875 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2876 booting and sizing and initializing DRAM, the code relocates itself
2877 to the upper end of DRAM. Immediately below the U-Boot code some
2878 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2879 configuration setting]. Below that, a structure with global Board
2880 Info data is placed, followed by the stack (growing downward).
2882 Additionally, some exception handler code is copied to the low 8 kB
2883 of DRAM (0x00000000 ... 0x00001FFF).
2885 So a typical memory configuration with 16 MB of DRAM could look like
2888 0x0000 0000 Exception Vector code
2891 0x0000 2000 Free for Application Use
2897 0x00FB FF20 Monitor Stack (Growing downward)
2898 0x00FB FFAC Board Info Data and permanent copy of global data
2899 0x00FC 0000 Malloc Arena
2902 0x00FE 0000 RAM Copy of Monitor Code
2903 ... eventually: LCD or video framebuffer
2904 ... eventually: pRAM (Protected RAM - unchanged by reset)
2905 0x00FF FFFF [End of RAM]
2908 System Initialization:
2909 ----------------------
2911 In the reset configuration, U-Boot starts at the reset entry point
2912 (on most PowerPC systens at address 0x00000100). Because of the reset
2913 configuration for CS0# this is a mirror of the onboard Flash memory.
2914 To be able to re-map memory U-Boot then jumps to it's link address.
2915 To be able to implement the initialization code in C, a (small!)
2916 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2917 which provide such a feature like MPC8xx or MPC8260), or in a locked
2918 part of the data cache. After that, U-Boot initializes the CPU core,
2919 the caches and the SIU.
2921 Next, all (potentially) available memory banks are mapped using a
2922 preliminary mapping. For example, we put them on 512 MB boundaries
2923 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2924 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2925 programmed for SDRAM access. Using the temporary configuration, a
2926 simple memory test is run that determines the size of the SDRAM
2929 When there is more than one SDRAM bank, and the banks are of
2930 different size, the larger is mapped first. For equal size, the first
2931 bank (CS2#) is mapped first. The first mapping is always for address
2932 0x00000000, with any additional banks following immediately to create
2933 contiguous memory starting from 0.
2935 Then, the monitor installs itself at the upper end of the SDRAM area
2936 and allocates memory for use by malloc() and for the global Board
2937 Info data; also, the exception vector code is copied to the low RAM
2938 pages, and the final stack is set up.
2940 Only after this relocation will you have a "normal" C environment;
2941 until that you are restricted in several ways, mostly because you are
2942 running from ROM, and because the code will have to be relocated to a
2946 U-Boot Porting Guide:
2947 ----------------------
2949 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2953 int main (int argc, char *argv[])
2955 sighandler_t no_more_time;
2957 signal (SIGALRM, no_more_time);
2958 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2960 if (available_money > available_manpower) {
2961 pay consultant to port U-Boot;
2965 Download latest U-Boot source;
2967 Subscribe to u-boot-users mailing list;
2970 email ("Hi, I am new to U-Boot, how do I get started?");
2974 Read the README file in the top level directory;
2975 Read http://www.denx.de/re/DPLG.html
2976 Read the source, Luke;
2979 if (available_money > toLocalCurrency ($2500)) {
2982 Add a lot of aggravation and time;
2985 Create your own board support subdirectory;
2987 Create your own board config file;
2991 Add / modify source code;
2995 email ("Hi, I am having problems...");
2997 Send patch file to Wolfgang;
3002 void no_more_time (int sig)
3011 All contributions to U-Boot should conform to the Linux kernel
3012 coding style; see the file "Documentation/CodingStyle" in your Linux
3013 kernel source directory.
3015 Please note that U-Boot is implemented in C (and to some small parts
3016 in Assembler); no C++ is used, so please do not use C++ style
3017 comments (//) in your code.
3019 Submissions which do not conform to the standards may be returned
3020 with a request to reformat the changes.
3026 Since the number of patches for U-Boot is growing, we need to
3027 establish some rules. Submissions which do not conform to these rules
3028 may be rejected, even when they contain important and valuable stuff.
3031 When you send a patch, please include the following information with
3034 * For bug fixes: a description of the bug and how your patch fixes
3035 this bug. Please try to include a way of demonstrating that the
3036 patch actually fixes something.
3038 * For new features: a description of the feature and your
3041 * A CHANGELOG entry as plaintext (separate from the patch)
3043 * For major contributions, your entry to the CREDITS file
3045 * When you add support for a new board, don't forget to add this
3046 board to the MAKEALL script, too.
3048 * If your patch adds new configuration options, don't forget to
3049 document these in the README file.
3051 * The patch itself. If you are accessing the CVS repository use "cvs
3052 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3053 version of diff does not support these options, then get the latest
3054 version of GNU diff.
3056 The current directory when running this command shall be the top
3057 level directory of the U-Boot source tree, or it's parent directory
3058 (i. e. please make sure that your patch includes sufficient
3059 directory information for the affected files).
3061 We accept patches as plain text, MIME attachments or as uuencoded
3064 * If one logical set of modifications affects or creates several
3065 files, all these changes shall be submitted in a SINGLE patch file.
3067 * Changesets that contain different, unrelated modifications shall be
3068 submitted as SEPARATE patches, one patch per changeset.
3073 * Before sending the patch, run the MAKEALL script on your patched
3074 source tree and make sure that no errors or warnings are reported
3075 for any of the boards.
3077 * Keep your modifications to the necessary minimum: A patch
3078 containing several unrelated changes or arbitrary reformats will be
3079 returned with a request to re-formatting / split it.
3081 * If you modify existing code, make sure that your new code does not
3082 add to the memory footprint of the code ;-) Small is beautiful!
3083 When adding new features, these should compile conditionally only
3084 (using #ifdef), and the resulting code with the new feature
3085 disabled must not need more memory than the old code without your
projects / people / ms / u-boot.git / blob