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 dependent files
123 - common Misc architecture independent functions
124 - cpu CPU specific files
125 - disk Code for disk drive partition handling
126 - doc Documentation (don't expect too much)
127 - drivers Commonly 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/arm926ejs Files specific to ARM 926 CPUs
145 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
146 - cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
147 - cpu/mpc824x Files specific to Motorola MPC824x CPUs
148 - cpu/mpc8260 Files specific to Motorola MPC8260 CPU
149 - cpu/ppc4xx Files specific to IBM 4xx CPUs
152 - board/LEOX/ Files specific to boards manufactured by The LEOX team
153 - board/LEOX/elpt860 Files specific to ELPT860 boards
155 Files specific to RPXClassic boards
156 - board/RPXlite Files specific to RPXlite boards
157 - board/at91rm9200dk Files specific to AT91RM9200DK boards
158 - board/c2mon Files specific to c2mon boards
159 - board/cmi Files specific to cmi boards
160 - board/cogent Files specific to Cogent boards
161 (need further configuration)
162 Files specific to CPCIISER4 boards
163 - board/cpu86 Files specific to CPU86 boards
164 - board/cray/ Files specific to boards manufactured by Cray
165 - board/cray/L1 Files specific to L1 boards
166 - board/cu824 Files specific to CU824 boards
167 - board/ebony Files specific to IBM Ebony board
168 - board/eric Files specific to ERIC boards
169 - board/esd/ Files specific to boards manufactured by ESD
170 - board/esd/adciop Files specific to ADCIOP boards
171 - board/esd/ar405 Files specific to AR405 boards
172 - board/esd/canbt Files specific to CANBT boards
173 - board/esd/cpci405 Files specific to CPCI405 boards
174 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
175 - board/esd/common Common files for ESD boards
176 - board/esd/dasa_sim Files specific to DASA_SIM boards
177 - board/esd/du405 Files specific to DU405 boards
178 - board/esd/ocrtc Files specific to OCRTC boards
179 - board/esd/pci405 Files specific to PCI405 boards
181 Files specific to ESTEEM192E boards
182 - board/etx094 Files specific to ETX_094 boards
184 Files specific to EVB64260 boards
185 - board/fads Files specific to FADS boards
186 - board/flagadm Files specific to FLAGADM boards
187 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
188 - board/genietv Files specific to GENIETV boards
189 - board/gth Files specific to GTH boards
190 - board/hermes Files specific to HERMES boards
191 - board/hymod Files specific to HYMOD boards
192 - board/icu862 Files specific to ICU862 boards
193 - board/ip860 Files specific to IP860 boards
195 Files specific to Interphase4539 boards
196 - board/ivm Files specific to IVMS8/IVML24 boards
197 - board/lantec Files specific to LANTEC boards
198 - board/lwmon Files specific to LWMON boards
199 - board/mbx8xx Files specific to MBX boards
201 Files specific to MPC8260ADS and PQ2FADS-ZU boards
202 - board/mpl/ Files specific to boards manufactured by MPL
203 - board/mpl/common Common files for MPL boards
204 - board/mpl/pip405 Files specific to PIP405 boards
205 - board/mpl/mip405 Files specific to MIP405 boards
206 - board/mpl/vcma9 Files specific to VCMA9 boards
207 - board/musenki Files specific to MUSEKNI boards
208 - board/mvs1 Files specific to MVS1 boards
209 - board/nx823 Files specific to NX823 boards
210 - board/oxc Files specific to OXC boards
212 Files specific to OMAP 1510 Innovator boards
214 Files specific to OMAP 1610 Innovator boards
215 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
216 - board/pm826 Files specific to PM826 boards
218 Files specific to PPMC8260 boards
220 Files specific to RPXsuper boards
222 Files specific to RSDproto boards
224 Files specific to Sandpoint boards
225 - board/sbc8260 Files specific to SBC8260 boards
226 - board/sacsng Files specific to SACSng boards
227 - board/siemens Files specific to boards manufactured by Siemens AG
228 - board/siemens/CCM Files specific to CCM boards
229 - board/siemens/IAD210 Files specific to IAD210 boards
230 - board/siemens/SCM Files specific to SCM boards
231 - board/siemens/pcu_e Files specific to PCU_E boards
232 - board/sixnet Files specific to SIXNET boards
233 - board/spd8xx Files specific to SPD8xxTS boards
234 - board/tqm8260 Files specific to TQM8260 boards
235 - board/tqm8xx Files specific to TQM8xxL boards
236 - board/w7o Files specific to W7O boards
238 Files specific to Walnut405 boards
239 - board/westel/ Files specific to boards manufactured by Westel Wireless
240 - board/westel/amx860 Files specific to AMX860 boards
241 - board/utx8245 Files specific to UTX8245 boards
243 Software Configuration:
244 =======================
246 Configuration is usually done using C preprocessor defines; the
247 rationale behind that is to avoid dead code whenever possible.
249 There are two classes of configuration variables:
251 * Configuration _OPTIONS_:
252 These are selectable by the user and have names beginning with
255 * Configuration _SETTINGS_:
256 These depend on the hardware etc. and should not be meddled with if
257 you don't know what you're doing; they have names beginning with
260 Later we will add a configuration tool - probably similar to or even
261 identical to what's used for the Linux kernel. Right now, we have to
262 do the configuration by hand, which means creating some symbolic
263 links and editing some configuration files. We use the TQM8xxL boards
267 Selection of Processor Architecture and Board Type:
268 ---------------------------------------------------
270 For all supported boards there are ready-to-use default
271 configurations available; just type "make <board_name>_config".
273 Example: For a TQM823L module type:
278 For the Cogent platform, you need to specify the cpu type as well;
279 e.g. "make cogent_mpc8xx_config". And also configure the cogent
280 directory according to the instructions in cogent/README.
283 Configuration Options:
284 ----------------------
286 Configuration depends on the combination of board and CPU type; all
287 such information is kept in a configuration file
288 "include/configs/<board_name>.h".
290 Example: For a TQM823L module, all configuration settings are in
291 "include/configs/TQM823L.h".
294 Many of the options are named exactly as the corresponding Linux
295 kernel configuration options. The intention is to make it easier to
296 build a config tool - later.
299 The following options need to be configured:
301 - CPU Type: Define exactly one of
305 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
307 or CONFIG_MPC824X, CONFIG_MPC8260
322 - Board Type: Define exactly one of
324 PowerPC based boards:
325 ---------------------
327 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
328 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
329 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
330 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
331 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
332 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
333 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
334 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
335 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
336 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
337 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
338 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
339 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
340 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
341 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
342 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
343 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
344 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
345 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
346 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
347 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
348 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
349 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
350 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
351 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
352 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
353 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
354 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
355 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
356 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
357 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
358 CONFIG_NETVIA, CONFIG_RBC823
363 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
364 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
365 CONFIG_INNOVATOROMAP1510, CONFIG_INNOVATOROMAP1610
366 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
367 CONFIG_TRAB, CONFIG_VCMA9, CONFIG_AT91RM9200DK
370 - CPU Module Type: (if CONFIG_COGENT is defined)
371 Define exactly one of
373 --- FIXME --- not tested yet:
374 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
375 CONFIG_CMA287_23, CONFIG_CMA287_50
377 - Motherboard Type: (if CONFIG_COGENT is defined)
378 Define exactly one of
379 CONFIG_CMA101, CONFIG_CMA102
381 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
382 Define one or more of
385 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
386 Define one or more of
387 CONFIG_LCD_HEARTBEAT - update a character position on
388 the lcd display every second with
391 - Board flavour: (if CONFIG_MPC8260ADS is defined)
394 CFG_8260ADS - original MPC8260ADS
395 CFG_8266ADS - MPC8266ADS (untested)
396 CFG_PQ2FADS - PQ2FADS-ZU
399 - MPC824X Family Member (if CONFIG_MPC824X is defined)
400 Define exactly one of
401 CONFIG_MPC8240, CONFIG_MPC8245
403 - 8xx CPU Options: (if using an 8xx cpu)
404 Define one or more of
405 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
406 no 32KHz reference PIT/RTC clock
411 U-Boot stores all clock information in Hz
412 internally. For binary compatibility with older Linux
413 kernels (which expect the clocks passed in the
414 bd_info data to be in MHz) the environment variable
415 "clocks_in_mhz" can be defined so that U-Boot
416 converts clock data to MHZ before passing it to the
419 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
420 "clocks_in_mhz=1" is automatically included in the
424 Depending on board, define exactly one serial port
425 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
426 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
427 console by defining CONFIG_8xx_CONS_NONE
429 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
430 port routines must be defined elsewhere
431 (i.e. serial_init(), serial_getc(), ...)
434 Enables console device for a color framebuffer. Needs following
435 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
436 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
438 VIDEO_HW_RECTFILL graphic chip supports
441 VIDEO_HW_BITBLT graphic chip supports
442 bit-blit (cf. smiLynxEM)
443 VIDEO_VISIBLE_COLS visible pixel columns
445 VIDEO_VISIBLE_ROWS visible pixel rows
446 VIDEO_PIXEL_SIZE bytes per pixel
447 VIDEO_DATA_FORMAT graphic data format
448 (0-5, cf. cfb_console.c)
449 VIDEO_FB_ADRS framebuffer address
450 VIDEO_KBD_INIT_FCT keyboard int fct
451 (i.e. i8042_kbd_init())
452 VIDEO_TSTC_FCT test char fct
454 VIDEO_GETC_FCT get char fct
456 CONFIG_CONSOLE_CURSOR cursor drawing on/off
457 (requires blink timer
459 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
460 CONFIG_CONSOLE_TIME display time/date info in
462 (requires CFG_CMD_DATE)
463 CONFIG_VIDEO_LOGO display Linux logo in
465 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
466 linux_logo.h for logo.
467 Requires CONFIG_VIDEO_LOGO
468 CONFIG_CONSOLE_EXTRA_INFO
469 addional board info beside
472 When CONFIG_CFB_CONSOLE is defined, video console is
473 default i/o. Serial console can be forced with
474 environment 'console=serial'.
477 CONFIG_BAUDRATE - in bps
478 Select one of the baudrates listed in
479 CFG_BAUDRATE_TABLE, see below.
481 - Interrupt driven serial port input:
482 CONFIG_SERIAL_SOFTWARE_FIFO
485 Use an interrupt handler for receiving data on the
486 serial port. It also enables using hardware handshake
487 (RTS/CTS) and UART's built-in FIFO. Set the number of
488 bytes the interrupt driven input buffer should have.
490 Set to 0 to disable this feature (this is the default).
491 This will also disable hardware handshake.
493 - Console UART Number:
497 If defined internal UART1 (and not UART0) is used
498 as default U-Boot console.
500 - Boot Delay: CONFIG_BOOTDELAY - in seconds
501 Delay before automatically booting the default image;
502 set to -1 to disable autoboot.
504 See doc/README.autoboot for these options that
505 work with CONFIG_BOOTDELAY. None are required.
506 CONFIG_BOOT_RETRY_TIME
507 CONFIG_BOOT_RETRY_MIN
508 CONFIG_AUTOBOOT_KEYED
509 CONFIG_AUTOBOOT_PROMPT
510 CONFIG_AUTOBOOT_DELAY_STR
511 CONFIG_AUTOBOOT_STOP_STR
512 CONFIG_AUTOBOOT_DELAY_STR2
513 CONFIG_AUTOBOOT_STOP_STR2
514 CONFIG_ZERO_BOOTDELAY_CHECK
515 CONFIG_RESET_TO_RETRY
519 Only needed when CONFIG_BOOTDELAY is enabled;
520 define a command string that is automatically executed
521 when no character is read on the console interface
522 within "Boot Delay" after reset.
525 This can be used to pass arguments to the bootm
526 command. The value of CONFIG_BOOTARGS goes into the
527 environment value "bootargs".
529 CONFIG_RAMBOOT and CONFIG_NFSBOOT
530 The value of these goes into the environment as
531 "ramboot" and "nfsboot" respectively, and can be used
532 as a convenience, when switching between booting from
538 When this option is #defined, the existence of the
539 environment variable "preboot" will be checked
540 immediately before starting the CONFIG_BOOTDELAY
541 countdown and/or running the auto-boot command resp.
542 entering interactive mode.
544 This feature is especially useful when "preboot" is
545 automatically generated or modified. For an example
546 see the LWMON board specific code: here "preboot" is
547 modified when the user holds down a certain
548 combination of keys on the (special) keyboard when
551 - Serial Download Echo Mode:
553 If defined to 1, all characters received during a
554 serial download (using the "loads" command) are
555 echoed back. This might be needed by some terminal
556 emulations (like "cu"), but may as well just take
557 time on others. This setting #define's the initial
558 value of the "loads_echo" environment variable.
560 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
562 Select one of the baudrates listed in
563 CFG_BAUDRATE_TABLE, see below.
567 Most monitor functions can be selected (or
568 de-selected) by adjusting the definition of
569 CONFIG_COMMANDS; to select individual functions,
570 #define CONFIG_COMMANDS by "OR"ing any of the
573 #define enables commands:
574 -------------------------
575 CFG_CMD_ASKENV * ask for env variable
577 CFG_CMD_BEDBUG Include BedBug Debugger
579 CFG_CMD_CACHE icache, dcache
580 CFG_CMD_CONSOLE coninfo
581 CFG_CMD_DATE * support for RTC, date/time...
582 CFG_CMD_DHCP DHCP support
583 CFG_CMD_ECHO * echo arguments
584 CFG_CMD_EEPROM * EEPROM read/write support
585 CFG_CMD_ELF bootelf, bootvx
587 CFG_CMD_FDC * Floppy Disk Support
588 CFG_CMD_FAT FAT partition support
589 CFG_CMD_FDOS * Dos diskette Support
590 CFG_CMD_FLASH flinfo, erase, protect
591 CFG_CMD_FPGA FPGA device initialization support
592 CFG_CMD_I2C * I2C serial bus support
593 CFG_CMD_IDE * IDE harddisk support
595 CFG_CMD_IMMAP * IMMR dump support
596 CFG_CMD_IRQ * irqinfo
600 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
602 CFG_CMD_MMC MMC memory mapped support
603 CFG_CMD_MII MII utility commands
604 CFG_CMD_NET bootp, tftpboot, rarpboot
605 CFG_CMD_PCI * pciinfo
606 CFG_CMD_PCMCIA * PCMCIA support
607 CFG_CMD_REGINFO * Register dump
608 CFG_CMD_RUN run command in env variable
609 CFG_CMD_SCSI * SCSI Support
610 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
611 CFG_CMD_SPI * SPI serial bus support
612 CFG_CMD_USB * USB support
613 CFG_CMD_BSP * Board SPecific functions
614 -----------------------------------------------
617 CFG_CMD_DFL Default configuration; at the moment
618 this is includes all commands, except
619 the ones marked with "*" in the list
622 If you don't define CONFIG_COMMANDS it defaults to
623 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
624 override the default settings in the respective
627 EXAMPLE: If you want all functions except of network
628 support you can write:
630 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
633 Note: Don't enable the "icache" and "dcache" commands
634 (configuration option CFG_CMD_CACHE) unless you know
635 what you (and your U-Boot users) are doing. Data
636 cache cannot be enabled on systems like the 8xx or
637 8260 (where accesses to the IMMR region must be
638 uncached), and it cannot be disabled on all other
639 systems where we (mis-) use the data cache to hold an
640 initial stack and some data.
643 XXX - this list needs to get updated!
647 If this variable is defined, it enables watchdog
648 support. There must be support in the platform specific
649 code for a watchdog. For the 8xx and 8260 CPUs, the
650 SIU Watchdog feature is enabled in the SYPCR
654 CONFIG_VERSION_VARIABLE
655 If this variable is defined, an environment variable
656 named "ver" is created by U-Boot showing the U-Boot
657 version as printed by the "version" command.
658 This variable is readonly.
662 When CFG_CMD_DATE is selected, the type of the RTC
663 has to be selected, too. Define exactly one of the
666 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
667 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
668 CONFIG_RTC_MC146818 - use MC146818 RTC
669 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
670 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
671 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
672 CONFIG_RTC_DS164x - use Dallas DS164x RTC
674 Note that if the RTC uses I2C, then the I2C interface
675 must also be configured. See I2C Support, below.
679 When CONFIG_TIMESTAMP is selected, the timestamp
680 (date and time) of an image is printed by image
681 commands like bootm or iminfo. This option is
682 automatically enabled when you select CFG_CMD_DATE .
685 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
686 and/or CONFIG_ISO_PARTITION
688 If IDE or SCSI support is enabled (CFG_CMD_IDE or
689 CFG_CMD_SCSI) you must configure support for at least
690 one partition type as well.
693 CONFIG_IDE_RESET_ROUTINE
695 Set this to define that instead of a reset Pin, the
696 routine ide_set_reset(int idereset) will be used.
701 Set this to enable ATAPI support.
704 At the moment only there is only support for the
705 SYM53C8XX SCSI controller; define
706 CONFIG_SCSI_SYM53C8XX to enable it.
708 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
709 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
710 CFG_SCSI_MAX_LUN] can be adjusted to define the
711 maximum numbers of LUNs, SCSI ID's and target
713 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
715 - NETWORK Support (PCI):
717 Support for Intel 8254x gigabit chips.
720 Support for Intel 82557/82559/82559ER chips.
721 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
722 write routine for first time initialisation.
725 Support for Digital 2114x chips.
726 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
727 modem chip initialisation (KS8761/QS6611).
730 Support for National dp83815 chips.
733 Support for National dp8382[01] gigabit chips.
735 - NETWORK Support (other):
737 CONFIG_DRIVER_LAN91C96
738 Support for SMSC's LAN91C96 chips.
741 Define this to hold the physical address
742 of the LAN91C96's I/O space
744 CONFIG_LAN91C96_USE_32_BIT
745 Define this to enable 32 bit addressing
748 At the moment only the UHCI host controller is
749 supported (PIP405, MIP405); define
750 CONFIG_USB_UHCI to enable it.
751 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
752 end define CONFIG_USB_STORAGE to enable the USB
755 Supported are USB Keyboards and USB Floppy drives
759 The MMC controller on the Intel PXA is supported. To
760 enable this define CONFIG_MMC. The MMC can be
761 accessed from the boot prompt by mapping the device
762 to physical memory similar to flash. Command line is
763 enabled with CFG_CMD_MMC. The MMC driver also works with
764 the FAT fs. This is enabled with CFG_CMD_FAT.
769 Define this to enable standard (PC-Style) keyboard
773 Standard PC keyboard driver with US (is default) and
774 GERMAN key layout (switch via environment 'keymap=de') support.
775 Export function i8042_kbd_init, i8042_tstc and i8042_getc
776 for cfb_console. Supports cursor blinking.
781 Define this to enable video support (for output to
786 Enable Chips & Technologies 69000 Video chip
788 CONFIG_VIDEO_SMI_LYNXEM
789 Enable Silicon Motion SMI 712/710/810 Video chip
790 Videomode are selected via environment 'videomode' with
791 standard LiLo mode numbers.
792 Following modes are supported (* is default):
794 800x600 1024x768 1280x1024
795 256 (8bit) 303* 305 307
796 65536 (16bit) 314 317 31a
797 16,7 Mill (24bit) 315 318 31b
798 (i.e. setenv videomode 317; saveenv; reset;)
800 CONFIG_VIDEO_SED13806
801 Enable Epson SED13806 driver. This driver supports 8bpp
802 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
803 or CONFIG_VIDEO_SED13806_16BPP
808 Define this to enable a custom keyboard support.
809 This simply calls drv_keyboard_init() which must be
810 defined in your board-specific files.
811 The only board using this so far is RBC823.
813 - LCD Support: CONFIG_LCD
815 Define this to enable LCD support (for output to LCD
816 display); also select one of the supported displays
817 by defining one of these:
819 CONFIG_NEC_NL6648AC33:
821 NEC NL6648AC33-18. Active, color, single scan.
823 CONFIG_NEC_NL6648BC20
825 NEC NL6648BC20-08. 6.5", 640x480.
826 Active, color, single scan.
830 Sharp 320x240. Active, color, single scan.
831 It isn't 16x9, and I am not sure what it is.
833 CONFIG_SHARP_LQ64D341
835 Sharp LQ64D341 display, 640x480.
836 Active, color, single scan.
840 HLD1045 display, 640x480.
841 Active, color, single scan.
845 Optrex CBL50840-2 NF-FW 99 22 M5
847 Hitachi LMG6912RPFC-00T
851 320x240. Black & white.
853 Normally display is black on white background; define
854 CFG_WHITE_ON_BLACK to get it inverted.
856 - Splash Screen Support: CONFIG_SPLASH_SCREEN
858 If this option is set, the environment is checked for
859 a variable "splashimage". If found, the usual display
860 of logo, copyright and system information on the LCD
861 is supressed and the BMP image at the address
862 specified in "splashimage" is loaded instead. The
863 console is redirected to the "nulldev", too. This
864 allows for a "silent" boot where a splash screen is
865 loaded very quickly after power-on.
867 - Compression support:
870 If this option is set, support for bzip2 compressed
871 images is included. If not, only uncompressed and gzip
872 compressed images are supported.
874 NOTE: the bzip2 algorithm requires a lot of RAM, so
875 the malloc area (as defined by CFG_MALLOC_LEN) should
883 Define a default value for ethernet address to use
884 for the respective ethernet interface, in case this
885 is not determined automatically.
890 Define a default value for the IP address to use for
891 the default ethernet interface, in case this is not
892 determined through e.g. bootp.
897 Defines a default value for theIP address of a TFTP
898 server to contact when using the "tftboot" command.
900 - BOOTP Recovery Mode:
901 CONFIG_BOOTP_RANDOM_DELAY
903 If you have many targets in a network that try to
904 boot using BOOTP, you may want to avoid that all
905 systems send out BOOTP requests at precisely the same
906 moment (which would happen for instance at recovery
907 from a power failure, when all systems will try to
908 boot, thus flooding the BOOTP server. Defining
909 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
910 inserted before sending out BOOTP requests. The
911 following delays are insterted then:
913 1st BOOTP request: delay 0 ... 1 sec
914 2nd BOOTP request: delay 0 ... 2 sec
915 3rd BOOTP request: delay 0 ... 4 sec
917 BOOTP requests: delay 0 ... 8 sec
919 - DHCP Advanced Options:
922 You can fine tune the DHCP functionality by adding
923 these flags to the CONFIG_BOOTP_MASK define:
925 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
926 serverip from a DHCP server, it is possible that more
927 than one DNS serverip is offered to the client.
928 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
929 serverip will be stored in the additional environment
930 variable "dnsip2". The first DNS serverip is always
931 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
932 is added to the CONFIG_BOOTP_MASK.
934 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
935 to do a dynamic update of a DNS server. To do this, they
936 need the hostname of the DHCP requester.
937 If CONFIG_BOOP_SEND_HOSTNAME is added to the
938 CONFIG_BOOTP_MASK, the content of the "hostname"
939 environment variable is passed as option 12 to
942 - Status LED: CONFIG_STATUS_LED
944 Several configurations allow to display the current
945 status using a LED. For instance, the LED will blink
946 fast while running U-Boot code, stop blinking as
947 soon as a reply to a BOOTP request was received, and
948 start blinking slow once the Linux kernel is running
949 (supported by a status LED driver in the Linux
950 kernel). Defining CONFIG_STATUS_LED enables this
953 - CAN Support: CONFIG_CAN_DRIVER
955 Defining CONFIG_CAN_DRIVER enables CAN driver support
956 on those systems that support this (optional)
957 feature, like the TQM8xxL modules.
959 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
961 These enable I2C serial bus commands. Defining either of
962 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
963 include the appropriate I2C driver for the selected cpu.
965 This will allow you to use i2c commands at the u-boot
966 command line (as long as you set CFG_CMD_I2C in
967 CONFIG_COMMANDS) and communicate with i2c based realtime
968 clock chips. See common/cmd_i2c.c for a description of the
969 command line interface.
971 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
973 CONFIG_SOFT_I2C configures u-boot to use a software (aka
974 bit-banging) driver instead of CPM or similar hardware
977 There are several other quantities that must also be
978 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
980 In both cases you will need to define CFG_I2C_SPEED
981 to be the frequency (in Hz) at which you wish your i2c bus
982 to run and CFG_I2C_SLAVE to be the address of this node (ie
983 the cpu's i2c node address).
985 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
986 sets the cpu up as a master node and so its address should
987 therefore be cleared to 0 (See, eg, MPC823e User's Manual
988 p.16-473). So, set CFG_I2C_SLAVE to 0.
990 That's all that's required for CONFIG_HARD_I2C.
992 If you use the software i2c interface (CONFIG_SOFT_I2C)
993 then the following macros need to be defined (examples are
994 from include/configs/lwmon.h):
998 (Optional). Any commands necessary to enable the I2C
999 controller or configure ports.
1001 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1005 (Only for MPC8260 CPU). The I/O port to use (the code
1006 assumes both bits are on the same port). Valid values
1007 are 0..3 for ports A..D.
1011 The code necessary to make the I2C data line active
1012 (driven). If the data line is open collector, this
1015 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1019 The code necessary to make the I2C data line tri-stated
1020 (inactive). If the data line is open collector, this
1023 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1027 Code that returns TRUE if the I2C data line is high,
1030 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1034 If <bit> is TRUE, sets the I2C data line high. If it
1035 is FALSE, it clears it (low).
1037 eg: #define I2C_SDA(bit) \
1038 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1039 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1043 If <bit> is TRUE, sets the I2C clock line high. If it
1044 is FALSE, it clears it (low).
1046 eg: #define I2C_SCL(bit) \
1047 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1048 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1052 This delay is invoked four times per clock cycle so this
1053 controls the rate of data transfer. The data rate thus
1054 is 1 / (I2C_DELAY * 4). Often defined to be something
1057 #define I2C_DELAY udelay(2)
1061 When a board is reset during an i2c bus transfer
1062 chips might think that the current transfer is still
1063 in progress. On some boards it is possible to access
1064 the i2c SCLK line directly, either by using the
1065 processor pin as a GPIO or by having a second pin
1066 connected to the bus. If this option is defined a
1067 custom i2c_init_board() routine in boards/xxx/board.c
1068 is run early in the boot sequence.
1070 - SPI Support: CONFIG_SPI
1072 Enables SPI driver (so far only tested with
1073 SPI EEPROM, also an instance works with Crystal A/D and
1074 D/As on the SACSng board)
1078 Enables extended (16-bit) SPI EEPROM addressing.
1079 (symmetrical to CONFIG_I2C_X)
1083 Enables a software (bit-bang) SPI driver rather than
1084 using hardware support. This is a general purpose
1085 driver that only requires three general I/O port pins
1086 (two outputs, one input) to function. If this is
1087 defined, the board configuration must define several
1088 SPI configuration items (port pins to use, etc). For
1089 an example, see include/configs/sacsng.h.
1091 - FPGA Support: CONFIG_FPGA_COUNT
1093 Specify the number of FPGA devices to support.
1097 Used to specify the types of FPGA devices. For
1099 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1101 CFG_FPGA_PROG_FEEDBACK
1103 Enable printing of hash marks during FPGA
1108 Enable checks on FPGA configuration interface busy
1109 status by the configuration function. This option
1110 will require a board or device specific function to
1115 If defined, a function that provides delays in the
1116 FPGA configuration driver.
1118 CFG_FPGA_CHECK_CTRLC
1120 Allow Control-C to interrupt FPGA configuration
1122 CFG_FPGA_CHECK_ERROR
1124 Check for configuration errors during FPGA bitfile
1125 loading. For example, abort during Virtex II
1126 configuration if the INIT_B line goes low (which
1127 indicated a CRC error).
1131 Maximum time to wait for the INIT_B line to deassert
1132 after PROB_B has been deasserted during a Virtex II
1133 FPGA configuration sequence. The default time is 500 mS.
1137 Maximum time to wait for BUSY to deassert during
1138 Virtex II FPGA configuration. The default is 5 mS.
1140 CFG_FPGA_WAIT_CONFIG
1142 Time to wait after FPGA configuration. The default is
1145 - FPGA Support: CONFIG_FPGA_COUNT
1147 Specify the number of FPGA devices to support.
1151 Used to specify the types of FPGA devices. For example,
1152 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1154 CFG_FPGA_PROG_FEEDBACK
1156 Enable printing of hash marks during FPGA configuration.
1160 Enable checks on FPGA configuration interface busy
1161 status by the configuration function. This option
1162 will require a board or device specific function to
1167 If defined, a function that provides delays in the FPGA
1168 configuration driver.
1170 CFG_FPGA_CHECK_CTRLC
1171 Allow Control-C to interrupt FPGA configuration
1173 CFG_FPGA_CHECK_ERROR
1175 Check for configuration errors during FPGA bitfile
1176 loading. For example, abort during Virtex II
1177 configuration if the INIT_B line goes low (which
1178 indicated a CRC error).
1182 Maximum time to wait for the INIT_B line to deassert
1183 after PROB_B has been deasserted during a Virtex II
1184 FPGA configuration sequence. The default time is 500
1189 Maximum time to wait for BUSY to deassert during
1190 Virtex II FPGA configuration. The default is 5 mS.
1192 CFG_FPGA_WAIT_CONFIG
1194 Time to wait after FPGA configuration. The default is
1197 - Configuration Management:
1200 If defined, this string will be added to the U-Boot
1201 version information (U_BOOT_VERSION)
1203 - Vendor Parameter Protection:
1205 U-Boot considers the values of the environment
1206 variables "serial#" (Board Serial Number) and
1207 "ethaddr" (Ethernet Address) to be parameters that
1208 are set once by the board vendor / manufacturer, and
1209 protects these variables from casual modification by
1210 the user. Once set, these variables are read-only,
1211 and write or delete attempts are rejected. You can
1212 change this behviour:
1214 If CONFIG_ENV_OVERWRITE is #defined in your config
1215 file, the write protection for vendor parameters is
1216 completely disabled. Anybody can change or delete
1219 Alternatively, if you #define _both_ CONFIG_ETHADDR
1220 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1221 ethernet address is installed in the environment,
1222 which can be changed exactly ONCE by the user. [The
1223 serial# is unaffected by this, i. e. it remains
1229 Define this variable to enable the reservation of
1230 "protected RAM", i. e. RAM which is not overwritten
1231 by U-Boot. Define CONFIG_PRAM to hold the number of
1232 kB you want to reserve for pRAM. You can overwrite
1233 this default value by defining an environment
1234 variable "pram" to the number of kB you want to
1235 reserve. Note that the board info structure will
1236 still show the full amount of RAM. If pRAM is
1237 reserved, a new environment variable "mem" will
1238 automatically be defined to hold the amount of
1239 remaining RAM in a form that can be passed as boot
1240 argument to Linux, for instance like that:
1242 setenv bootargs ... mem=\$(mem)
1245 This way you can tell Linux not to use this memory,
1246 either, which results in a memory region that will
1247 not be affected by reboots.
1249 *WARNING* If your board configuration uses automatic
1250 detection of the RAM size, you must make sure that
1251 this memory test is non-destructive. So far, the
1252 following board configurations are known to be
1255 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1256 HERMES, IP860, RPXlite, LWMON, LANTEC,
1257 PCU_E, FLAGADM, TQM8260
1262 Define this variable to stop the system in case of a
1263 fatal error, so that you have to reset it manually.
1264 This is probably NOT a good idea for an embedded
1265 system where you want to system to reboot
1266 automatically as fast as possible, but it may be
1267 useful during development since you can try to debug
1268 the conditions that lead to the situation.
1270 CONFIG_NET_RETRY_COUNT
1272 This variable defines the number of retries for
1273 network operations like ARP, RARP, TFTP, or BOOTP
1274 before giving up the operation. If not defined, a
1275 default value of 5 is used.
1277 - Command Interpreter:
1280 Define this variable to enable the "hush" shell (from
1281 Busybox) as command line interpreter, thus enabling
1282 powerful command line syntax like
1283 if...then...else...fi conditionals or `&&' and '||'
1284 constructs ("shell scripts").
1286 If undefined, you get the old, much simpler behaviour
1287 with a somewhat smaller memory footprint.
1292 This defines the secondary prompt string, which is
1293 printed when the command interpreter needs more input
1294 to complete a command. Usually "> ".
1298 In the current implementation, the local variables
1299 space and global environment variables space are
1300 separated. Local variables are those you define by
1301 simply typing `name=value'. To access a local
1302 variable later on, you have write `$name' or
1303 `${name}'; to execute the contents of a variable
1304 directly type `$name' at the command prompt.
1306 Global environment variables are those you use
1307 setenv/printenv to work with. To run a command stored
1308 in such a variable, you need to use the run command,
1309 and you must not use the '$' sign to access them.
1311 To store commands and special characters in a
1312 variable, please use double quotation marks
1313 surrounding the whole text of the variable, instead
1314 of the backslashes before semicolons and special
1317 - Default Environment
1318 CONFIG_EXTRA_ENV_SETTINGS
1320 Define this to contain any number of null terminated
1321 strings (variable = value pairs) that will be part of
1322 the default environment compiled into the boot image.
1324 For example, place something like this in your
1325 board's config file:
1327 #define CONFIG_EXTRA_ENV_SETTINGS \
1331 Warning: This method is based on knowledge about the
1332 internal format how the environment is stored by the
1333 U-Boot code. This is NOT an official, exported
1334 interface! Although it is unlikely that this format
1335 will change soon, there is no guarantee either.
1336 You better know what you are doing here.
1338 Note: overly (ab)use of the default environment is
1339 discouraged. Make sure to check other ways to preset
1340 the environment like the autoscript function or the
1344 CONFIG_HAS_DATAFLASH
1346 Defining this option enables DataFlash features and
1347 allows to read/write in Dataflash via the standard
1350 - Show boot progress
1351 CONFIG_SHOW_BOOT_PROGRESS
1353 Defining this option allows to add some board-
1354 specific code (calling a user-provided function
1355 "show_boot_progress(int)") that enables you to show
1356 the system's boot progress on some display (for
1357 example, some LED's) on your board. At the moment,
1358 the following checkpoints are implemented:
1361 1 common/cmd_bootm.c before attempting to boot an image
1362 -1 common/cmd_bootm.c Image header has bad magic number
1363 2 common/cmd_bootm.c Image header has correct magic number
1364 -2 common/cmd_bootm.c Image header has bad checksum
1365 3 common/cmd_bootm.c Image header has correct checksum
1366 -3 common/cmd_bootm.c Image data has bad checksum
1367 4 common/cmd_bootm.c Image data has correct checksum
1368 -4 common/cmd_bootm.c Image is for unsupported architecture
1369 5 common/cmd_bootm.c Architecture check OK
1370 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1371 6 common/cmd_bootm.c Image Type check OK
1372 -6 common/cmd_bootm.c gunzip uncompression error
1373 -7 common/cmd_bootm.c Unimplemented compression type
1374 7 common/cmd_bootm.c Uncompression OK
1375 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1376 8 common/cmd_bootm.c Image Type check OK
1377 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1378 9 common/cmd_bootm.c Start initial ramdisk verification
1379 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1380 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1381 10 common/cmd_bootm.c Ramdisk header is OK
1382 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1383 11 common/cmd_bootm.c Ramdisk data has correct checksum
1384 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1385 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1386 13 common/cmd_bootm.c Start multifile image verification
1387 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1388 15 common/cmd_bootm.c All preparation done, transferring control to OS
1390 -1 common/cmd_doc.c Bad usage of "doc" command
1391 -1 common/cmd_doc.c No boot device
1392 -1 common/cmd_doc.c Unknown Chip ID on boot device
1393 -1 common/cmd_doc.c Read Error on boot device
1394 -1 common/cmd_doc.c Image header has bad magic number
1396 -1 common/cmd_ide.c Bad usage of "ide" command
1397 -1 common/cmd_ide.c No boot device
1398 -1 common/cmd_ide.c Unknown boot device
1399 -1 common/cmd_ide.c Unknown partition table
1400 -1 common/cmd_ide.c Invalid partition type
1401 -1 common/cmd_ide.c Read Error on boot device
1402 -1 common/cmd_ide.c Image header has bad magic number
1404 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1410 [so far only for SMDK2400 and TRAB boards]
1412 - Modem support endable:
1413 CONFIG_MODEM_SUPPORT
1415 - RTS/CTS Flow control enable:
1418 - Modem debug support:
1419 CONFIG_MODEM_SUPPORT_DEBUG
1421 Enables debugging stuff (char screen[1024], dbg())
1422 for modem support. Useful only with BDI2000.
1426 In the target system modem support is enabled when a
1427 specific key (key combination) is pressed during
1428 power-on. Otherwise U-Boot will boot normally
1429 (autoboot). The key_pressed() fuction is called from
1430 board_init(). Currently key_pressed() is a dummy
1431 function, returning 1 and thus enabling modem
1434 If there are no modem init strings in the
1435 environment, U-Boot proceed to autoboot; the
1436 previous output (banner, info printfs) will be
1439 See also: doc/README.Modem
1442 Configuration Settings:
1443 -----------------------
1445 - CFG_LONGHELP: Defined when you want long help messages included;
1446 undefine this when you're short of memory.
1448 - CFG_PROMPT: This is what U-Boot prints on the console to
1449 prompt for user input.
1451 - CFG_CBSIZE: Buffer size for input from the Console
1453 - CFG_PBSIZE: Buffer size for Console output
1455 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1457 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1458 the application (usually a Linux kernel) when it is
1461 - CFG_BAUDRATE_TABLE:
1462 List of legal baudrate settings for this board.
1464 - CFG_CONSOLE_INFO_QUIET
1465 Suppress display of console information at boot.
1467 - CFG_CONSOLE_IS_IN_ENV
1468 If the board specific function
1469 extern int overwrite_console (void);
1470 returns 1, the stdin, stderr and stdout are switched to the
1471 serial port, else the settings in the environment are used.
1473 - CFG_CONSOLE_OVERWRITE_ROUTINE
1474 Enable the call to overwrite_console().
1476 - CFG_CONSOLE_ENV_OVERWRITE
1477 Enable overwrite of previous console environment settings.
1479 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1480 Begin and End addresses of the area used by the
1484 Enable an alternate, more extensive memory test.
1486 - CFG_TFTP_LOADADDR:
1487 Default load address for network file downloads
1489 - CFG_LOADS_BAUD_CHANGE:
1490 Enable temporary baudrate change while serial download
1493 Physical start address of SDRAM. _Must_ be 0 here.
1496 Physical start address of Motherboard I/O (if using a
1500 Physical start address of Flash memory.
1503 Physical start address of boot monitor code (set by
1504 make config files to be same as the text base address
1505 (TEXT_BASE) used when linking) - same as
1506 CFG_FLASH_BASE when booting from flash.
1509 Size of memory reserved for monitor code, used to
1510 determine _at_compile_time_ (!) if the environment is
1511 embedded within the U-Boot image, or in a separate
1515 Size of DRAM reserved for malloc() use.
1518 Maximum size of memory mapped by the startup code of
1519 the Linux kernel; all data that must be processed by
1520 the Linux kernel (bd_info, boot arguments, eventually
1521 initrd image) must be put below this limit.
1523 - CFG_MAX_FLASH_BANKS:
1524 Max number of Flash memory banks
1526 - CFG_MAX_FLASH_SECT:
1527 Max number of sectors on a Flash chip
1529 - CFG_FLASH_ERASE_TOUT:
1530 Timeout for Flash erase operations (in ms)
1532 - CFG_FLASH_WRITE_TOUT:
1533 Timeout for Flash write operations (in ms)
1535 - CFG_FLASH_LOCK_TOUT
1536 Timeout for Flash set sector lock bit operation (in ms)
1538 - CFG_FLASH_UNLOCK_TOUT
1539 Timeout for Flash clear lock bits operation (in ms)
1541 - CFG_FLASH_PROTECTION
1542 If defined, hardware flash sectors protection is used
1543 instead of U-Boot software protection.
1545 - CFG_DIRECT_FLASH_TFTP:
1547 Enable TFTP transfers directly to flash memory;
1548 without this option such a download has to be
1549 performed in two steps: (1) download to RAM, and (2)
1550 copy from RAM to flash.
1552 The two-step approach is usually more reliable, since
1553 you can check if the download worked before you erase
1554 the flash, but in some situations (when sytem RAM is
1555 too limited to allow for a tempory copy of the
1556 downloaded image) this option may be very useful.
1559 Define if the flash driver uses extra elements in the
1560 common flash structure for storing flash geometry
1562 - CFG_RX_ETH_BUFFER:
1563 Defines the number of ethernet receive buffers. On some
1564 ethernet controllers it is recommended to set this value
1565 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1566 buffers can be full shortly after enabling the interface
1567 on high ethernet traffic.
1568 Defaults to 4 if not defined.
1570 The following definitions that deal with the placement and management
1571 of environment data (variable area); in general, we support the
1572 following configurations:
1574 - CFG_ENV_IS_IN_FLASH:
1576 Define this if the environment is in flash memory.
1578 a) The environment occupies one whole flash sector, which is
1579 "embedded" in the text segment with the U-Boot code. This
1580 happens usually with "bottom boot sector" or "top boot
1581 sector" type flash chips, which have several smaller
1582 sectors at the start or the end. For instance, such a
1583 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1584 such a case you would place the environment in one of the
1585 4 kB sectors - with U-Boot code before and after it. With
1586 "top boot sector" type flash chips, you would put the
1587 environment in one of the last sectors, leaving a gap
1588 between U-Boot and the environment.
1592 Offset of environment data (variable area) to the
1593 beginning of flash memory; for instance, with bottom boot
1594 type flash chips the second sector can be used: the offset
1595 for this sector is given here.
1597 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1601 This is just another way to specify the start address of
1602 the flash sector containing the environment (instead of
1605 - CFG_ENV_SECT_SIZE:
1607 Size of the sector containing the environment.
1610 b) Sometimes flash chips have few, equal sized, BIG sectors.
1611 In such a case you don't want to spend a whole sector for
1616 If you use this in combination with CFG_ENV_IS_IN_FLASH
1617 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1618 of this flash sector for the environment. This saves
1619 memory for the RAM copy of the environment.
1621 It may also save flash memory if you decide to use this
1622 when your environment is "embedded" within U-Boot code,
1623 since then the remainder of the flash sector could be used
1624 for U-Boot code. It should be pointed out that this is
1625 STRONGLY DISCOURAGED from a robustness point of view:
1626 updating the environment in flash makes it always
1627 necessary to erase the WHOLE sector. If something goes
1628 wrong before the contents has been restored from a copy in
1629 RAM, your target system will be dead.
1631 - CFG_ENV_ADDR_REDUND
1634 These settings describe a second storage area used to hold
1635 a redundand copy of the environment data, so that there is
1636 a valid backup copy in case there is a power failure during
1637 a "saveenv" operation.
1639 BE CAREFUL! Any changes to the flash layout, and some changes to the
1640 source code will make it necessary to adapt <board>/u-boot.lds*
1644 - CFG_ENV_IS_IN_NVRAM:
1646 Define this if you have some non-volatile memory device
1647 (NVRAM, battery buffered SRAM) which you want to use for the
1653 These two #defines are used to determin the memory area you
1654 want to use for environment. It is assumed that this memory
1655 can just be read and written to, without any special
1658 BE CAREFUL! The first access to the environment happens quite early
1659 in U-Boot initalization (when we try to get the setting of for the
1660 console baudrate). You *MUST* have mappend your NVRAM area then, or
1663 Please note that even with NVRAM we still use a copy of the
1664 environment in RAM: we could work on NVRAM directly, but we want to
1665 keep settings there always unmodified except somebody uses "saveenv"
1666 to save the current settings.
1669 - CFG_ENV_IS_IN_EEPROM:
1671 Use this if you have an EEPROM or similar serial access
1672 device and a driver for it.
1677 These two #defines specify the offset and size of the
1678 environment area within the total memory of your EEPROM.
1680 - CFG_I2C_EEPROM_ADDR:
1681 If defined, specified the chip address of the EEPROM device.
1682 The default address is zero.
1684 - CFG_EEPROM_PAGE_WRITE_BITS:
1685 If defined, the number of bits used to address bytes in a
1686 single page in the EEPROM device. A 64 byte page, for example
1687 would require six bits.
1689 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1690 If defined, the number of milliseconds to delay between
1691 page writes. The default is zero milliseconds.
1693 - CFG_I2C_EEPROM_ADDR_LEN:
1694 The length in bytes of the EEPROM memory array address. Note
1695 that this is NOT the chip address length!
1698 The size in bytes of the EEPROM device.
1701 - CFG_SPI_INIT_OFFSET
1703 Defines offset to the initial SPI buffer area in DPRAM. The
1704 area is used at an early stage (ROM part) if the environment
1705 is configured to reside in the SPI EEPROM: We need a 520 byte
1706 scratch DPRAM area. It is used between the two initialization
1707 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1708 to be a good choice since it makes it far enough from the
1709 start of the data area as well as from the stack pointer.
1711 Please note that the environment is read-only as long as the monitor
1712 has been relocated to RAM and a RAM copy of the environment has been
1713 created; also, when using EEPROM you will have to use getenv_r()
1714 until then to read environment variables.
1716 The environment is protected by a CRC32 checksum. Before the monitor
1717 is relocated into RAM, as a result of a bad CRC you will be working
1718 with the compiled-in default environment - *silently*!!! [This is
1719 necessary, because the first environment variable we need is the
1720 "baudrate" setting for the console - if we have a bad CRC, we don't
1721 have any device yet where we could complain.]
1723 Note: once the monitor has been relocated, then it will complain if
1724 the default environment is used; a new CRC is computed as soon as you
1725 use the "saveenv" command to store a valid environment.
1728 Low Level (hardware related) configuration options:
1729 ---------------------------------------------------
1731 - CFG_CACHELINE_SIZE:
1732 Cache Line Size of the CPU.
1735 Default address of the IMMR after system reset.
1737 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1738 and RPXsuper) to be able to adjust the position of
1739 the IMMR register after a reset.
1741 - Floppy Disk Support:
1742 CFG_FDC_DRIVE_NUMBER
1744 the default drive number (default value 0)
1748 defines the spacing between fdc chipset registers
1753 defines the offset of register from address. It
1754 depends on which part of the data bus is connected to
1755 the fdc chipset. (default value 0)
1757 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1758 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1761 if CFG_FDC_HW_INIT is defined, then the function
1762 fdc_hw_init() is called at the beginning of the FDC
1763 setup. fdc_hw_init() must be provided by the board
1764 source code. It is used to make hardware dependant
1767 - CFG_IMMR: Physical address of the Internal Memory Mapped
1768 Register; DO NOT CHANGE! (11-4)
1769 [MPC8xx systems only]
1771 - CFG_INIT_RAM_ADDR:
1773 Start address of memory area that can be used for
1774 initial data and stack; please note that this must be
1775 writable memory that is working WITHOUT special
1776 initialization, i. e. you CANNOT use normal RAM which
1777 will become available only after programming the
1778 memory controller and running certain initialization
1781 U-Boot uses the following memory types:
1782 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1783 - MPC824X: data cache
1784 - PPC4xx: data cache
1786 - CFG_GBL_DATA_OFFSET:
1788 Offset of the initial data structure in the memory
1789 area defined by CFG_INIT_RAM_ADDR. Usually
1790 CFG_GBL_DATA_OFFSET is chosen such that the initial
1791 data is located at the end of the available space
1792 (sometimes written as (CFG_INIT_RAM_END -
1793 CFG_INIT_DATA_SIZE), and the initial stack is just
1794 below that area (growing from (CFG_INIT_RAM_ADDR +
1795 CFG_GBL_DATA_OFFSET) downward.
1798 On the MPC824X (or other systems that use the data
1799 cache for initial memory) the address chosen for
1800 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1801 point to an otherwise UNUSED address space between
1802 the top of RAM and the start of the PCI space.
1804 - CFG_SIUMCR: SIU Module Configuration (11-6)
1806 - CFG_SYPCR: System Protection Control (11-9)
1808 - CFG_TBSCR: Time Base Status and Control (11-26)
1810 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1812 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1814 - CFG_SCCR: System Clock and reset Control Register (15-27)
1816 - CFG_OR_TIMING_SDRAM:
1820 periodic timer for refresh
1822 - CFG_DER: Debug Event Register (37-47)
1824 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1825 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1826 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1828 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1830 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1831 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1832 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1833 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1835 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1836 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1837 Machine Mode Register and Memory Periodic Timer
1838 Prescaler definitions (SDRAM timing)
1840 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1841 enable I2C microcode relocation patch (MPC8xx);
1842 define relocation offset in DPRAM [DSP2]
1844 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1845 enable SPI microcode relocation patch (MPC8xx);
1846 define relocation offset in DPRAM [SCC4]
1849 Use OSCM clock mode on MBX8xx board. Be careful,
1850 wrong setting might damage your board. Read
1851 doc/README.MBX before setting this variable!
1853 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1854 Offset of the bootmode word in DPRAM used by post
1855 (Power On Self Tests). This definition overrides
1856 #define'd default value in commproc.h resp.
1859 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1860 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1861 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1862 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1863 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1864 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1865 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1866 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1867 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1869 Building the Software:
1870 ======================
1872 Building U-Boot has been tested in native PPC environments (on a
1873 PowerBook G3 running LinuxPPC 2000) and in cross environments
1874 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1877 If you are not using a native PPC environment, it is assumed that you
1878 have the GNU cross compiling tools available in your path and named
1879 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1880 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1881 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1884 CROSS_COMPILE = ppc_4xx-
1887 U-Boot is intended to be simple to build. After installing the
1888 sources you must configure U-Boot for one specific board type. This
1893 where "NAME_config" is the name of one of the existing
1894 configurations; the following names are supported:
1896 ADCIOP_config GTH_config TQM850L_config
1897 ADS860_config IP860_config TQM855L_config
1898 AR405_config IVML24_config TQM860L_config
1899 CANBT_config IVMS8_config WALNUT405_config
1900 CPCI405_config LANTEC_config cogent_common_config
1901 CPCIISER4_config MBX_config cogent_mpc8260_config
1902 CU824_config MBX860T_config cogent_mpc8xx_config
1903 ESTEEM192E_config RPXlite_config hermes_config
1904 ETX094_config RPXsuper_config hymod_config
1905 FADS823_config SM850_config lwmon_config
1906 FADS850SAR_config SPD823TS_config pcu_e_config
1907 FADS860T_config SXNI855T_config rsdproto_config
1908 FPS850L_config Sandpoint8240_config sbc8260_config
1909 GENIETV_config TQM823L_config PIP405_config
1910 GEN860T_config EBONY_config FPS860L_config
1911 ELPT860_config cmi_mpc5xx_config NETVIA_config
1912 at91rm9200dk_config omap1510inn_config MPC8260ADS_config
1914 Note: for some board special configuration names may exist; check if
1915 additional information is available from the board vendor; for
1916 instance, the TQM8xxL systems run normally at 50 MHz and use a
1917 SCC for 10baseT ethernet; there are also systems with 80 MHz
1918 CPU clock, and an optional Fast Ethernet module is available
1919 for CPU's with FEC. You can select such additional "features"
1920 when chosing the configuration, i. e.
1923 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1925 make TQM860L_FEC_config
1926 - will configure for a TQM860L at 50MHz with FEC for ethernet
1928 make TQM860L_80MHz_config
1929 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1932 make TQM860L_FEC_80MHz_config
1933 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1935 make TQM823L_LCD_config
1936 - will configure for a TQM823L with U-Boot console on LCD
1938 make TQM823L_LCD_80MHz_config
1939 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1944 Finally, type "make all", and you should get some working U-Boot
1945 images ready for download to / installation on your system:
1947 - "u-boot.bin" is a raw binary image
1948 - "u-boot" is an image in ELF binary format
1949 - "u-boot.srec" is in Motorola S-Record format
1952 Please be aware that the Makefiles assume you are using GNU make, so
1953 for instance on NetBSD you might need to use "gmake" instead of
1957 If the system board that you have is not listed, then you will need
1958 to port U-Boot to your hardware platform. To do this, follow these
1961 1. Add a new configuration option for your board to the toplevel
1962 "Makefile" and to the "MAKEALL" script, using the existing
1963 entries as examples. Note that here and at many other places
1964 boards and other names are listed in alphabetical sort order. Please
1966 2. Create a new directory to hold your board specific code. Add any
1967 files you need. In your board directory, you will need at least
1968 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1969 3. Create a new configuration file "include/configs/<board>.h" for
1971 3. If you're porting U-Boot to a new CPU, then also create a new
1972 directory to hold your CPU specific code. Add any files you need.
1973 4. Run "make <board>_config" with your new name.
1974 5. Type "make", and you should get a working "u-boot.srec" file
1975 to be installed on your target system.
1976 6. Debug and solve any problems that might arise.
1977 [Of course, this last step is much harder than it sounds.]
1980 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1981 ==============================================================
1983 If you have modified U-Boot sources (for instance added a new board
1984 or support for new devices, a new CPU, etc.) you are expected to
1985 provide feedback to the other developers. The feedback normally takes
1986 the form of a "patch", i. e. a context diff against a certain (latest
1987 official or latest in CVS) version of U-Boot sources.
1989 But before you submit such a patch, please verify that your modifi-
1990 cation did not break existing code. At least make sure that *ALL* of
1991 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1992 just run the "MAKEALL" script, which will configure and build U-Boot
1993 for ALL supported system. Be warned, this will take a while. You can
1994 select which (cross) compiler to use by passing a `CROSS_COMPILE'
1995 environment variable to the script, i. e. to use the cross tools from
1996 MontaVista's Hard Hat Linux you can type
1998 CROSS_COMPILE=ppc_8xx- MAKEALL
2000 or to build on a native PowerPC system you can type
2002 CROSS_COMPILE=' ' MAKEALL
2004 See also "U-Boot Porting Guide" below.
2007 Monitor Commands - Overview:
2008 ============================
2010 go - start application at address 'addr'
2011 run - run commands in an environment variable
2012 bootm - boot application image from memory
2013 bootp - boot image via network using BootP/TFTP protocol
2014 tftpboot- boot image via network using TFTP protocol
2015 and env variables "ipaddr" and "serverip"
2016 (and eventually "gatewayip")
2017 rarpboot- boot image via network using RARP/TFTP protocol
2018 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2019 loads - load S-Record file over serial line
2020 loadb - load binary file over serial line (kermit mode)
2022 mm - memory modify (auto-incrementing)
2023 nm - memory modify (constant address)
2024 mw - memory write (fill)
2026 cmp - memory compare
2027 crc32 - checksum calculation
2028 imd - i2c memory display
2029 imm - i2c memory modify (auto-incrementing)
2030 inm - i2c memory modify (constant address)
2031 imw - i2c memory write (fill)
2032 icrc32 - i2c checksum calculation
2033 iprobe - probe to discover valid I2C chip addresses
2034 iloop - infinite loop on address range
2035 isdram - print SDRAM configuration information
2036 sspi - SPI utility commands
2037 base - print or set address offset
2038 printenv- print environment variables
2039 setenv - set environment variables
2040 saveenv - save environment variables to persistent storage
2041 protect - enable or disable FLASH write protection
2042 erase - erase FLASH memory
2043 flinfo - print FLASH memory information
2044 bdinfo - print Board Info structure
2045 iminfo - print header information for application image
2046 coninfo - print console devices and informations
2047 ide - IDE sub-system
2048 loop - infinite loop on address range
2049 mtest - simple RAM test
2050 icache - enable or disable instruction cache
2051 dcache - enable or disable data cache
2052 reset - Perform RESET of the CPU
2053 echo - echo args to console
2054 version - print monitor version
2055 help - print online help
2056 ? - alias for 'help'
2059 Monitor Commands - Detailed Description:
2060 ========================================
2064 For now: just type "help <command>".
2067 Environment Variables:
2068 ======================
2070 U-Boot supports user configuration using Environment Variables which
2071 can be made persistent by saving to Flash memory.
2073 Environment Variables are set using "setenv", printed using
2074 "printenv", and saved to Flash using "saveenv". Using "setenv"
2075 without a value can be used to delete a variable from the
2076 environment. As long as you don't save the environment you are
2077 working with an in-memory copy. In case the Flash area containing the
2078 environment is erased by accident, a default environment is provided.
2080 Some configuration options can be set using Environment Variables:
2082 baudrate - see CONFIG_BAUDRATE
2084 bootdelay - see CONFIG_BOOTDELAY
2086 bootcmd - see CONFIG_BOOTCOMMAND
2088 bootargs - Boot arguments when booting an RTOS image
2090 bootfile - Name of the image to load with TFTP
2092 autoload - if set to "no" (any string beginning with 'n'),
2093 "bootp" will just load perform a lookup of the
2094 configuration from the BOOTP server, but not try to
2095 load any image using TFTP
2097 autostart - if set to "yes", an image loaded using the "bootp",
2098 "rarpboot", "tftpboot" or "diskboot" commands will
2099 be automatically started (by internally calling
2102 If set to "no", a standalone image passed to the
2103 "bootm" command will be copied to the load address
2104 (and eventually uncompressed), but NOT be started.
2105 This can be used to load and uncompress arbitrary
2108 initrd_high - restrict positioning of initrd images:
2109 If this variable is not set, initrd images will be
2110 copied to the highest possible address in RAM; this
2111 is usually what you want since it allows for
2112 maximum initrd size. If for some reason you want to
2113 make sure that the initrd image is loaded below the
2114 CFG_BOOTMAPSZ limit, you can set this environment
2115 variable to a value of "no" or "off" or "0".
2116 Alternatively, you can set it to a maximum upper
2117 address to use (U-Boot will still check that it
2118 does not overwrite the U-Boot stack and data).
2120 For instance, when you have a system with 16 MB
2121 RAM, and want to reserve 4 MB from use by Linux,
2122 you can do this by adding "mem=12M" to the value of
2123 the "bootargs" variable. However, now you must make
2124 sure that the initrd image is placed in the first
2125 12 MB as well - this can be done with
2127 setenv initrd_high 00c00000
2129 If you set initrd_high to 0xFFFFFFFF, this is an
2130 indication to U-Boot that all addresses are legal
2131 for the Linux kernel, including addresses in flash
2132 memory. In this case U-Boot will NOT COPY the
2133 ramdisk at all. This may be useful to reduce the
2134 boot time on your system, but requires that this
2135 feature is supported by your Linux kernel.
2137 ipaddr - IP address; needed for tftpboot command
2139 loadaddr - Default load address for commands like "bootp",
2140 "rarpboot", "tftpboot", "loadb" or "diskboot"
2142 loads_echo - see CONFIG_LOADS_ECHO
2144 serverip - TFTP server IP address; needed for tftpboot command
2146 bootretry - see CONFIG_BOOT_RETRY_TIME
2148 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2150 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2153 The following environment variables may be used and automatically
2154 updated by the network boot commands ("bootp" and "rarpboot"),
2155 depending the information provided by your boot server:
2157 bootfile - see above
2158 dnsip - IP address of your Domain Name Server
2159 dnsip2 - IP address of your secondary Domain Name Server
2160 gatewayip - IP address of the Gateway (Router) to use
2161 hostname - Target hostname
2163 netmask - Subnet Mask
2164 rootpath - Pathname of the root filesystem on the NFS server
2165 serverip - see above
2168 There are two special Environment Variables:
2170 serial# - contains hardware identification information such
2171 as type string and/or serial number
2172 ethaddr - Ethernet address
2174 These variables can be set only once (usually during manufacturing of
2175 the board). U-Boot refuses to delete or overwrite these variables
2176 once they have been set once.
2179 Further special Environment Variables:
2181 ver - Contains the U-Boot version string as printed
2182 with the "version" command. This variable is
2183 readonly (see CONFIG_VERSION_VARIABLE).
2186 Please note that changes to some configuration parameters may take
2187 only effect after the next boot (yes, that's just like Windoze :-).
2190 Command Line Parsing:
2191 =====================
2193 There are two different command line parsers available with U-Boot:
2194 the old "simple" one, and the much more powerful "hush" shell:
2196 Old, simple command line parser:
2197 --------------------------------
2199 - supports environment variables (through setenv / saveenv commands)
2200 - several commands on one line, separated by ';'
2201 - variable substitution using "... $(name) ..." syntax
2202 - special characters ('$', ';') can be escaped by prefixing with '\',
2204 setenv bootcmd bootm \$(address)
2205 - You can also escape text by enclosing in single apostrophes, for example:
2206 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2211 - similar to Bourne shell, with control structures like
2212 if...then...else...fi, for...do...done; while...do...done,
2213 until...do...done, ...
2214 - supports environment ("global") variables (through setenv / saveenv
2215 commands) and local shell variables (through standard shell syntax
2216 "name=value"); only environment variables can be used with "run"
2222 (1) If a command line (or an environment variable executed by a "run"
2223 command) contains several commands separated by semicolon, and
2224 one of these commands fails, then the remaining commands will be
2227 (2) If you execute several variables with one call to run (i. e.
2228 calling run with a list af variables as arguments), any failing
2229 command will cause "run" to terminate, i. e. the remaining
2230 variables are not executed.
2232 Note for Redundant Ethernet Interfaces:
2233 =======================================
2235 Some boards come with redundant ethernet interfaces; U-Boot supports
2236 such configurations and is capable of automatic selection of a
2237 "working" interface when needed. MAC assignment works as follows:
2239 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2240 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2241 "eth1addr" (=>eth1), "eth2addr", ...
2243 If the network interface stores some valid MAC address (for instance
2244 in SROM), this is used as default address if there is NO correspon-
2245 ding setting in the environment; if the corresponding environment
2246 variable is set, this overrides the settings in the card; that means:
2248 o If the SROM has a valid MAC address, and there is no address in the
2249 environment, the SROM's address is used.
2251 o If there is no valid address in the SROM, and a definition in the
2252 environment exists, then the value from the environment variable is
2255 o If both the SROM and the environment contain a MAC address, and
2256 both addresses are the same, this MAC address is used.
2258 o If both the SROM and the environment contain a MAC address, and the
2259 addresses differ, the value from the environment is used and a
2262 o If neither SROM nor the environment contain a MAC address, an error
2269 The "boot" commands of this monitor operate on "image" files which
2270 can be basicly anything, preceeded by a special header; see the
2271 definitions in include/image.h for details; basicly, the header
2272 defines the following image properties:
2274 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2275 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2276 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2277 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2278 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2279 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2280 Currently supported: PowerPC).
2281 * Compression Type (uncompressed, gzip, bzip2)
2287 The header is marked by a special Magic Number, and both the header
2288 and the data portions of the image are secured against corruption by
2295 Although U-Boot should support any OS or standalone application
2296 easily, the main focus has always been on Linux during the design of
2299 U-Boot includes many features that so far have been part of some
2300 special "boot loader" code within the Linux kernel. Also, any
2301 "initrd" images to be used are no longer part of one big Linux image;
2302 instead, kernel and "initrd" are separate images. This implementation
2303 serves several purposes:
2305 - the same features can be used for other OS or standalone
2306 applications (for instance: using compressed images to reduce the
2307 Flash memory footprint)
2309 - it becomes much easier to port new Linux kernel versions because
2310 lots of low-level, hardware dependent stuff are done by U-Boot
2312 - the same Linux kernel image can now be used with different "initrd"
2313 images; of course this also means that different kernel images can
2314 be run with the same "initrd". This makes testing easier (you don't
2315 have to build a new "zImage.initrd" Linux image when you just
2316 change a file in your "initrd"). Also, a field-upgrade of the
2317 software is easier now.
2323 Porting Linux to U-Boot based systems:
2324 ---------------------------------------
2326 U-Boot cannot save you from doing all the necessary modifications to
2327 configure the Linux device drivers for use with your target hardware
2328 (no, we don't intend to provide a full virtual machine interface to
2331 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2333 Just make sure your machine specific header file (for instance
2334 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2335 Information structure as we define in include/u-boot.h, and make
2336 sure that your definition of IMAP_ADDR uses the same value as your
2337 U-Boot configuration in CFG_IMMR.
2340 Configuring the Linux kernel:
2341 -----------------------------
2343 No specific requirements for U-Boot. Make sure you have some root
2344 device (initial ramdisk, NFS) for your target system.
2347 Building a Linux Image:
2348 -----------------------
2350 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2351 not used. If you use recent kernel source, a new build target
2352 "uImage" will exist which automatically builds an image usable by
2353 U-Boot. Most older kernels also have support for a "pImage" target,
2354 which was introduced for our predecessor project PPCBoot and uses a
2355 100% compatible format.
2364 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2365 encapsulate a compressed Linux kernel image with header information,
2366 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2368 * build a standard "vmlinux" kernel image (in ELF binary format):
2370 * convert the kernel into a raw binary image:
2372 ${CROSS_COMPILE}-objcopy -O binary \
2373 -R .note -R .comment \
2374 -S vmlinux linux.bin
2376 * compress the binary image:
2380 * package compressed binary image for U-Boot:
2382 mkimage -A ppc -O linux -T kernel -C gzip \
2383 -a 0 -e 0 -n "Linux Kernel Image" \
2384 -d linux.bin.gz uImage
2387 The "mkimage" tool can also be used to create ramdisk images for use
2388 with U-Boot, either separated from the Linux kernel image, or
2389 combined into one file. "mkimage" encapsulates the images with a 64
2390 byte header containing information about target architecture,
2391 operating system, image type, compression method, entry points, time
2392 stamp, CRC32 checksums, etc.
2394 "mkimage" can be called in two ways: to verify existing images and
2395 print the header information, or to build new images.
2397 In the first form (with "-l" option) mkimage lists the information
2398 contained in the header of an existing U-Boot image; this includes
2399 checksum verification:
2401 tools/mkimage -l image
2402 -l ==> list image header information
2404 The second form (with "-d" option) is used to build a U-Boot image
2405 from a "data file" which is used as image payload:
2407 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2408 -n name -d data_file image
2409 -A ==> set architecture to 'arch'
2410 -O ==> set operating system to 'os'
2411 -T ==> set image type to 'type'
2412 -C ==> set compression type 'comp'
2413 -a ==> set load address to 'addr' (hex)
2414 -e ==> set entry point to 'ep' (hex)
2415 -n ==> set image name to 'name'
2416 -d ==> use image data from 'datafile'
2418 Right now, all Linux kernels use the same load address (0x00000000),
2419 but the entry point address depends on the kernel version:
2421 - 2.2.x kernels have the entry point at 0x0000000C,
2422 - 2.3.x and later kernels have the entry point at 0x00000000.
2424 So a typical call to build a U-Boot image would read:
2426 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2427 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2428 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2429 > examples/uImage.TQM850L
2430 Image Name: 2.4.4 kernel for TQM850L
2431 Created: Wed Jul 19 02:34:59 2000
2432 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2433 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2434 Load Address: 0x00000000
2435 Entry Point: 0x00000000
2437 To verify the contents of the image (or check for corruption):
2439 -> tools/mkimage -l examples/uImage.TQM850L
2440 Image Name: 2.4.4 kernel for TQM850L
2441 Created: Wed Jul 19 02:34:59 2000
2442 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2443 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2444 Load Address: 0x00000000
2445 Entry Point: 0x00000000
2447 NOTE: for embedded systems where boot time is critical you can trade
2448 speed for memory and install an UNCOMPRESSED image instead: this
2449 needs more space in Flash, but boots much faster since it does not
2450 need to be uncompressed:
2452 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2453 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2454 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2455 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2456 > examples/uImage.TQM850L-uncompressed
2457 Image Name: 2.4.4 kernel for TQM850L
2458 Created: Wed Jul 19 02:34:59 2000
2459 Image Type: PowerPC Linux Kernel Image (uncompressed)
2460 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2461 Load Address: 0x00000000
2462 Entry Point: 0x00000000
2465 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2466 when your kernel is intended to use an initial ramdisk:
2468 -> tools/mkimage -n 'Simple Ramdisk Image' \
2469 > -A ppc -O linux -T ramdisk -C gzip \
2470 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2471 Image Name: Simple Ramdisk Image
2472 Created: Wed Jan 12 14:01:50 2000
2473 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2474 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2475 Load Address: 0x00000000
2476 Entry Point: 0x00000000
2479 Installing a Linux Image:
2480 -------------------------
2482 To downloading a U-Boot image over the serial (console) interface,
2483 you must convert the image to S-Record format:
2485 objcopy -I binary -O srec examples/image examples/image.srec
2487 The 'objcopy' does not understand the information in the U-Boot
2488 image header, so the resulting S-Record file will be relative to
2489 address 0x00000000. To load it to a given address, you need to
2490 specify the target address as 'offset' parameter with the 'loads'
2493 Example: install the image to address 0x40100000 (which on the
2494 TQM8xxL is in the first Flash bank):
2496 => erase 40100000 401FFFFF
2502 ## Ready for S-Record download ...
2503 ~>examples/image.srec
2504 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2506 15989 15990 15991 15992
2507 [file transfer complete]
2509 ## Start Addr = 0x00000000
2512 You can check the success of the download using the 'iminfo' command;
2513 this includes a checksum verification so you can be sure no data
2514 corruption happened:
2518 ## Checking Image at 40100000 ...
2519 Image Name: 2.2.13 for initrd on TQM850L
2520 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2521 Data Size: 335725 Bytes = 327 kB = 0 MB
2522 Load Address: 00000000
2523 Entry Point: 0000000c
2524 Verifying Checksum ... OK
2530 The "bootm" command is used to boot an application that is stored in
2531 memory (RAM or Flash). In case of a Linux kernel image, the contents
2532 of the "bootargs" environment variable is passed to the kernel as
2533 parameters. You can check and modify this variable using the
2534 "printenv" and "setenv" commands:
2537 => printenv bootargs
2538 bootargs=root=/dev/ram
2540 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2542 => printenv bootargs
2543 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2546 ## Booting Linux kernel at 40020000 ...
2547 Image Name: 2.2.13 for NFS on TQM850L
2548 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2549 Data Size: 381681 Bytes = 372 kB = 0 MB
2550 Load Address: 00000000
2551 Entry Point: 0000000c
2552 Verifying Checksum ... OK
2553 Uncompressing Kernel Image ... OK
2554 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
2555 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2556 time_init: decrementer frequency = 187500000/60
2557 Calibrating delay loop... 49.77 BogoMIPS
2558 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2561 If you want to boot a Linux kernel with initial ram disk, you pass
2562 the memory addresses of both the kernel and the initrd image (PPBCOOT
2563 format!) to the "bootm" command:
2565 => imi 40100000 40200000
2567 ## Checking Image at 40100000 ...
2568 Image Name: 2.2.13 for initrd on TQM850L
2569 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2570 Data Size: 335725 Bytes = 327 kB = 0 MB
2571 Load Address: 00000000
2572 Entry Point: 0000000c
2573 Verifying Checksum ... OK
2575 ## Checking Image at 40200000 ...
2576 Image Name: Simple Ramdisk Image
2577 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2578 Data Size: 566530 Bytes = 553 kB = 0 MB
2579 Load Address: 00000000
2580 Entry Point: 00000000
2581 Verifying Checksum ... OK
2583 => bootm 40100000 40200000
2584 ## Booting Linux kernel at 40100000 ...
2585 Image Name: 2.2.13 for initrd on TQM850L
2586 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2587 Data Size: 335725 Bytes = 327 kB = 0 MB
2588 Load Address: 00000000
2589 Entry Point: 0000000c
2590 Verifying Checksum ... OK
2591 Uncompressing Kernel Image ... OK
2592 ## Loading RAMDisk Image at 40200000 ...
2593 Image Name: Simple Ramdisk Image
2594 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2595 Data Size: 566530 Bytes = 553 kB = 0 MB
2596 Load Address: 00000000
2597 Entry Point: 00000000
2598 Verifying Checksum ... OK
2599 Loading Ramdisk ... OK
2600 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
2601 Boot arguments: root=/dev/ram
2602 time_init: decrementer frequency = 187500000/60
2603 Calibrating delay loop... 49.77 BogoMIPS
2605 RAMDISK: Compressed image found at block 0
2606 VFS: Mounted root (ext2 filesystem).
2610 More About U-Boot Image Types:
2611 ------------------------------
2613 U-Boot supports the following image types:
2615 "Standalone Programs" are directly runnable in the environment
2616 provided by U-Boot; it is expected that (if they behave
2617 well) you can continue to work in U-Boot after return from
2618 the Standalone Program.
2619 "OS Kernel Images" are usually images of some Embedded OS which
2620 will take over control completely. Usually these programs
2621 will install their own set of exception handlers, device
2622 drivers, set up the MMU, etc. - this means, that you cannot
2623 expect to re-enter U-Boot except by resetting the CPU.
2624 "RAMDisk Images" are more or less just data blocks, and their
2625 parameters (address, size) are passed to an OS kernel that is
2627 "Multi-File Images" contain several images, typically an OS
2628 (Linux) kernel image and one or more data images like
2629 RAMDisks. This construct is useful for instance when you want
2630 to boot over the network using BOOTP etc., where the boot
2631 server provides just a single image file, but you want to get
2632 for instance an OS kernel and a RAMDisk image.
2634 "Multi-File Images" start with a list of image sizes, each
2635 image size (in bytes) specified by an "uint32_t" in network
2636 byte order. This list is terminated by an "(uint32_t)0".
2637 Immediately after the terminating 0 follow the images, one by
2638 one, all aligned on "uint32_t" boundaries (size rounded up to
2639 a multiple of 4 bytes).
2641 "Firmware Images" are binary images containing firmware (like
2642 U-Boot or FPGA images) which usually will be programmed to
2645 "Script files" are command sequences that will be executed by
2646 U-Boot's command interpreter; this feature is especially
2647 useful when you configure U-Boot to use a real shell (hush)
2648 as command interpreter.
2654 One of the features of U-Boot is that you can dynamically load and
2655 run "standalone" applications, which can use some resources of
2656 U-Boot like console I/O functions or interrupt services.
2658 Two simple examples are included with the sources:
2663 'examples/hello_world.c' contains a small "Hello World" Demo
2664 application; it is automatically compiled when you build U-Boot.
2665 It's configured to run at address 0x00040004, so you can play with it
2669 ## Ready for S-Record download ...
2670 ~>examples/hello_world.srec
2671 1 2 3 4 5 6 7 8 9 10 11 ...
2672 [file transfer complete]
2674 ## Start Addr = 0x00040004
2676 => go 40004 Hello World! This is a test.
2677 ## Starting application at 0x00040004 ...
2688 Hit any key to exit ...
2690 ## Application terminated, rc = 0x0
2692 Another example, which demonstrates how to register a CPM interrupt
2693 handler with the U-Boot code, can be found in 'examples/timer.c'.
2694 Here, a CPM timer is set up to generate an interrupt every second.
2695 The interrupt service routine is trivial, just printing a '.'
2696 character, but this is just a demo program. The application can be
2697 controlled by the following keys:
2699 ? - print current values og the CPM Timer registers
2700 b - enable interrupts and start timer
2701 e - stop timer and disable interrupts
2702 q - quit application
2705 ## Ready for S-Record download ...
2706 ~>examples/timer.srec
2707 1 2 3 4 5 6 7 8 9 10 11 ...
2708 [file transfer complete]
2710 ## Start Addr = 0x00040004
2713 ## Starting application at 0x00040004 ...
2716 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2719 [q, b, e, ?] Set interval 1000000 us
2722 [q, b, e, ?] ........
2723 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2726 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2729 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2732 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2734 [q, b, e, ?] ...Stopping timer
2736 [q, b, e, ?] ## Application terminated, rc = 0x0
2742 Over time, many people have reported problems when trying to use the
2743 "minicom" terminal emulation program for serial download. I (wd)
2744 consider minicom to be broken, and recommend not to use it. Under
2745 Unix, I recommend to use C-Kermit for general purpose use (and
2746 especially for kermit binary protocol download ("loadb" command), and
2747 use "cu" for S-Record download ("loads" command).
2749 Nevertheless, if you absolutely want to use it try adding this
2750 configuration to your "File transfer protocols" section:
2752 Name Program Name U/D FullScr IO-Red. Multi
2753 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2754 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2760 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2761 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2763 Building requires a cross environment; it is known to work on
2764 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2765 need gmake since the Makefiles are not compatible with BSD make).
2766 Note that the cross-powerpc package does not install include files;
2767 attempting to build U-Boot will fail because <machine/ansi.h> is
2768 missing. This file has to be installed and patched manually:
2770 # cd /usr/pkg/cross/powerpc-netbsd/include
2772 # ln -s powerpc machine
2773 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2774 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2776 Native builds *don't* work due to incompatibilities between native
2777 and U-Boot include files.
2779 Booting assumes that (the first part of) the image booted is a
2780 stage-2 loader which in turn loads and then invokes the kernel
2781 proper. Loader sources will eventually appear in the NetBSD source
2782 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2783 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2787 Implementation Internals:
2788 =========================
2790 The following is not intended to be a complete description of every
2791 implementation detail. However, it should help to understand the
2792 inner workings of U-Boot and make it easier to port it to custom
2796 Initial Stack, Global Data:
2797 ---------------------------
2799 The implementation of U-Boot is complicated by the fact that U-Boot
2800 starts running out of ROM (flash memory), usually without access to
2801 system RAM (because the memory controller is not initialized yet).
2802 This means that we don't have writable Data or BSS segments, and BSS
2803 is not initialized as zero. To be able to get a C environment working
2804 at all, we have to allocate at least a minimal stack. Implementation
2805 options for this are defined and restricted by the CPU used: Some CPU
2806 models provide on-chip memory (like the IMMR area on MPC8xx and
2807 MPC826x processors), on others (parts of) the data cache can be
2808 locked as (mis-) used as memory, etc.
2810 Chris Hallinan posted a good summary of these issues to the
2811 u-boot-users mailing list:
2813 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2814 From: "Chris Hallinan" <clh@net1plus.com>
2815 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2818 Correct me if I'm wrong, folks, but the way I understand it
2819 is this: Using DCACHE as initial RAM for Stack, etc, does not
2820 require any physical RAM backing up the cache. The cleverness
2821 is that the cache is being used as a temporary supply of
2822 necessary storage before the SDRAM controller is setup. It's
2823 beyond the scope of this list to expain the details, but you
2824 can see how this works by studying the cache architecture and
2825 operation in the architecture and processor-specific manuals.
2827 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2828 is another option for the system designer to use as an
2829 initial stack/ram area prior to SDRAM being available. Either
2830 option should work for you. Using CS 4 should be fine if your
2831 board designers haven't used it for something that would
2832 cause you grief during the initial boot! It is frequently not
2835 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2836 with your processor/board/system design. The default value
2837 you will find in any recent u-boot distribution in
2838 Walnut405.h should work for you. I'd set it to a value larger
2839 than your SDRAM module. If you have a 64MB SDRAM module, set
2840 it above 400_0000. Just make sure your board has no resources
2841 that are supposed to respond to that address! That code in
2842 start.S has been around a while and should work as is when
2843 you get the config right.
2848 It is essential to remember this, since it has some impact on the C
2849 code for the initialization procedures:
2851 * Initialized global data (data segment) is read-only. Do not attempt
2854 * Do not use any unitialized global data (or implicitely initialized
2855 as zero data - BSS segment) at all - this is undefined, initiali-
2856 zation is performed later (when relocating to RAM).
2858 * Stack space is very limited. Avoid big data buffers or things like
2861 Having only the stack as writable memory limits means we cannot use
2862 normal global data to share information beween the code. But it
2863 turned out that the implementation of U-Boot can be greatly
2864 simplified by making a global data structure (gd_t) available to all
2865 functions. We could pass a pointer to this data as argument to _all_
2866 functions, but this would bloat the code. Instead we use a feature of
2867 the GCC compiler (Global Register Variables) to share the data: we
2868 place a pointer (gd) to the global data into a register which we
2869 reserve for this purpose.
2871 When choosing a register for such a purpose we are restricted by the
2872 relevant (E)ABI specifications for the current architecture, and by
2873 GCC's implementation.
2875 For PowerPC, the following registers have specific use:
2878 R3-R4: parameter passing and return values
2879 R5-R10: parameter passing
2880 R13: small data area pointer
2884 (U-Boot also uses R14 as internal GOT pointer.)
2886 ==> U-Boot will use R29 to hold a pointer to the global data
2888 Note: on PPC, we could use a static initializer (since the
2889 address of the global data structure is known at compile time),
2890 but it turned out that reserving a register results in somewhat
2891 smaller code - although the code savings are not that big (on
2892 average for all boards 752 bytes for the whole U-Boot image,
2893 624 text + 127 data).
2895 On ARM, the following registers are used:
2897 R0: function argument word/integer result
2898 R1-R3: function argument word
2900 R10: stack limit (used only if stack checking if enabled)
2901 R11: argument (frame) pointer
2902 R12: temporary workspace
2905 R15: program counter
2907 ==> U-Boot will use R8 to hold a pointer to the global data
2913 U-Boot runs in system state and uses physical addresses, i.e. the
2914 MMU is not used either for address mapping nor for memory protection.
2916 The available memory is mapped to fixed addresses using the memory
2917 controller. In this process, a contiguous block is formed for each
2918 memory type (Flash, SDRAM, SRAM), even when it consists of several
2919 physical memory banks.
2921 U-Boot is installed in the first 128 kB of the first Flash bank (on
2922 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2923 booting and sizing and initializing DRAM, the code relocates itself
2924 to the upper end of DRAM. Immediately below the U-Boot code some
2925 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2926 configuration setting]. Below that, a structure with global Board
2927 Info data is placed, followed by the stack (growing downward).
2929 Additionally, some exception handler code is copied to the low 8 kB
2930 of DRAM (0x00000000 ... 0x00001FFF).
2932 So a typical memory configuration with 16 MB of DRAM could look like
2935 0x0000 0000 Exception Vector code
2938 0x0000 2000 Free for Application Use
2944 0x00FB FF20 Monitor Stack (Growing downward)
2945 0x00FB FFAC Board Info Data and permanent copy of global data
2946 0x00FC 0000 Malloc Arena
2949 0x00FE 0000 RAM Copy of Monitor Code
2950 ... eventually: LCD or video framebuffer
2951 ... eventually: pRAM (Protected RAM - unchanged by reset)
2952 0x00FF FFFF [End of RAM]
2955 System Initialization:
2956 ----------------------
2958 In the reset configuration, U-Boot starts at the reset entry point
2959 (on most PowerPC systens at address 0x00000100). Because of the reset
2960 configuration for CS0# this is a mirror of the onboard Flash memory.
2961 To be able to re-map memory U-Boot then jumps to its link address.
2962 To be able to implement the initialization code in C, a (small!)
2963 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2964 which provide such a feature like MPC8xx or MPC8260), or in a locked
2965 part of the data cache. After that, U-Boot initializes the CPU core,
2966 the caches and the SIU.
2968 Next, all (potentially) available memory banks are mapped using a
2969 preliminary mapping. For example, we put them on 512 MB boundaries
2970 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2971 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2972 programmed for SDRAM access. Using the temporary configuration, a
2973 simple memory test is run that determines the size of the SDRAM
2976 When there is more than one SDRAM bank, and the banks are of
2977 different size, the largest is mapped first. For equal size, the first
2978 bank (CS2#) is mapped first. The first mapping is always for address
2979 0x00000000, with any additional banks following immediately to create
2980 contiguous memory starting from 0.
2982 Then, the monitor installs itself at the upper end of the SDRAM area
2983 and allocates memory for use by malloc() and for the global Board
2984 Info data; also, the exception vector code is copied to the low RAM
2985 pages, and the final stack is set up.
2987 Only after this relocation will you have a "normal" C environment;
2988 until that you are restricted in several ways, mostly because you are
2989 running from ROM, and because the code will have to be relocated to a
2993 U-Boot Porting Guide:
2994 ----------------------
2996 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3000 int main (int argc, char *argv[])
3002 sighandler_t no_more_time;
3004 signal (SIGALRM, no_more_time);
3005 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3007 if (available_money > available_manpower) {
3008 pay consultant to port U-Boot;
3012 Download latest U-Boot source;
3014 Subscribe to u-boot-users mailing list;
3017 email ("Hi, I am new to U-Boot, how do I get started?");
3021 Read the README file in the top level directory;
3022 Read http://www.denx.de/re/DPLG.html
3023 Read the source, Luke;
3026 if (available_money > toLocalCurrency ($2500)) {
3029 Add a lot of aggravation and time;
3032 Create your own board support subdirectory;
3034 Create your own board config file;
3038 Add / modify source code;
3042 email ("Hi, I am having problems...");
3044 Send patch file to Wolfgang;
3049 void no_more_time (int sig)
3058 All contributions to U-Boot should conform to the Linux kernel
3059 coding style; see the file "Documentation/CodingStyle" in your Linux
3060 kernel source directory.
3062 Please note that U-Boot is implemented in C (and to some small parts
3063 in Assembler); no C++ is used, so please do not use C++ style
3064 comments (//) in your code.
3066 Submissions which do not conform to the standards may be returned
3067 with a request to reformat the changes.
3073 Since the number of patches for U-Boot is growing, we need to
3074 establish some rules. Submissions which do not conform to these rules
3075 may be rejected, even when they contain important and valuable stuff.
3078 When you send a patch, please include the following information with
3081 * For bug fixes: a description of the bug and how your patch fixes
3082 this bug. Please try to include a way of demonstrating that the
3083 patch actually fixes something.
3085 * For new features: a description of the feature and your
3088 * A CHANGELOG entry as plaintext (separate from the patch)
3090 * For major contributions, your entry to the CREDITS file
3092 * When you add support for a new board, don't forget to add this
3093 board to the MAKEALL script, too.
3095 * If your patch adds new configuration options, don't forget to
3096 document these in the README file.
3098 * The patch itself. If you are accessing the CVS repository use "cvs
3099 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3100 version of diff does not support these options, then get the latest
3101 version of GNU diff.
3103 The current directory when running this command shall be the top
3104 level directory of the U-Boot source tree, or it's parent directory
3105 (i. e. please make sure that your patch includes sufficient
3106 directory information for the affected files).
3108 We accept patches as plain text, MIME attachments or as uuencoded
3111 * If one logical set of modifications affects or creates several
3112 files, all these changes shall be submitted in a SINGLE patch file.
3114 * Changesets that contain different, unrelated modifications shall be
3115 submitted as SEPARATE patches, one patch per changeset.
3120 * Before sending the patch, run the MAKEALL script on your patched
3121 source tree and make sure that no errors or warnings are reported
3122 for any of the boards.
3124 * Keep your modifications to the necessary minimum: A patch
3125 containing several unrelated changes or arbitrary reformats will be
3126 returned with a request to re-formatting / split it.
3128 * If you modify existing code, make sure that your new code does not
3129 add to the memory footprint of the code ;-) Small is beautiful!
3130 When adding new features, these should compile conditionally only
3131 (using #ifdef), and the resulting code with the new feature
3132 disabled must not need more memory than the old code without your
projects / platform / kernel / u-boot.git / blob