2 # (C) Copyright 2000 - 2002
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # See file CREDITS for list of people who contributed to this
8 # This program is free software; you can redistribute it and/or
9 # modify it under the terms of the GNU General Public License as
10 # published by the Free Software Foundation; either version 2 of
11 # the License, or (at your option) any later version.
13 # This program is distributed in the hope that it will be useful,
14 # but WITHOUT ANY WARRANTY; without even the implied warranty of
15 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 # GNU General Public License for more details.
18 # You should have received a copy of the GNU General Public License
19 # along with this program; if not, write to the Free Software
20 # Foundation, Inc., 59 Temple Place, Suite 330, Boston,
27 This directory contains the source code for U-Boot, a boot loader for
28 Embedded boards based on PowerPC and ARM processors, which can be
29 installed in a boot ROM and used to initialize and test the hardware
30 or to download and run application code.
32 The development of U-Boot is closely related to Linux: some parts of
33 the source code originate in the Linux source tree, we have some
34 header files in common, and special provision has been made to
35 support booting of Linux images.
37 Some attention has been paid to make this software easily
38 configurable and extendable. For instance, all monitor commands are
39 implemented with the same call interface, so that it's very easy to
40 add new commands. Also, instead of permanently adding rarely used
41 code (for instance hardware test utilities) to the monitor, you can
42 load and run it dynamically.
48 In general, all boards for which a configuration option exists in the
49 Makefile have been tested to some extent and can be considered
50 "working". In fact, many of them are used in production systems.
52 In case of problems see the CHANGELOG and CREDITS files to find out
53 who contributed the specific port.
59 In case you have questions about, problems with or contributions for
60 U-Boot you should send a message to the U-Boot mailing list at
61 <u-boot-users@lists.sourceforge.net>. There is also an archive of
62 previous traffic on the mailing list - please search the archive
63 before asking FAQ's. Please see
64 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
70 - start from 8xxrom sources
71 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73 - make it easier to add custom boards
74 - make it possible to add other [PowerPC] CPUs
75 - extend functions, especially:
76 * Provide extended interface to Linux boot loader
79 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80 - create ARMBoot project (http://sourceforge.net/projects/armboot)
81 - add other CPU families (starting with ARM)
82 - create U-Boot project (http://sourceforge.net/projects/u-boot)
88 The "official" name of this project is "Das U-Boot". The spelling
89 "U-Boot" shall be used in all written text (documentation, comments
90 in source files etc.). Example:
92 This is the README file for the U-Boot project.
94 File names etc. shall be based on the string "u-boot". Examples:
96 include/asm-ppc/u-boot.h
98 #include <asm/u-boot.h>
100 Variable names, preprocessor constants etc. shall be either based on
101 the string "u_boot" or on "U_BOOT". Example:
103 U_BOOT_VERSION u_boot_logo
104 IH_OS_U_BOOT u_boot_hush_start
110 U-Boot uses a 3 level version number containing a version, a
111 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112 sub-version "34", and patchlevel "4".
114 The patchlevel is used to indicate certain stages of development
115 between released versions, i. e. officially released versions of
116 U-Boot will always have a patchlevel of "0".
122 - board Board dependend files
123 - common Misc architecture independend functions
124 - cpu CPU specific files
125 - disk Code for disk drive partition handling
126 - doc Documentation (don't expect too much)
127 - drivers Common used device drivers
128 - dtt Digital Thermometer and Thermostat drivers
129 - examples Example code for standalone applications, etc.
130 - include Header Files
131 - disk Harddisk interface code
132 - net Networking code
133 - ppc Files generic to PowerPC architecture
134 - post Power On Self Test
135 - post/arch Symlink to architecture specific Power On Self Test
136 - post/arch-ppc PowerPC architecture specific Power On Self Test
137 - post/cpu/mpc8260 MPC8260 CPU specific Power On Self Test
138 - post/cpu/mpc8xx MPC8xx CPU specific Power On Self Test
139 - rtc Real Time Clock drivers
140 - tools Tools to build S-Record or U-Boot images, etc.
142 - cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
143 - cpu/arm925t Files specific to ARM 925 CPUs
144 - cpu/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/musenki Files specific to MUSEKNI boards
207 - board/mvs1 Files specific to MVS1 boards
208 - board/nx823 Files specific to NX823 boards
209 - board/oxc Files specific to OXC boards
211 Files specific to OMAP 1510 Innovator boards
213 Files specific to OMAP 1610 Innovator boards
214 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
215 - board/pm826 Files specific to PM826 boards
217 Files specific to PPMC8260 boards
219 Files specific to RPXsuper boards
221 Files specific to RSDproto boards
223 Files specific to Sandpoint boards
224 - board/sbc8260 Files specific to SBC8260 boards
225 - board/sacsng Files specific to SACSng boards
226 - board/siemens Files specific to boards manufactured by Siemens AG
227 - board/siemens/CCM Files specific to CCM boards
228 - board/siemens/IAD210 Files specific to IAD210 boards
229 - board/siemens/SCM Files specific to SCM boards
230 - board/siemens/pcu_e Files specific to PCU_E boards
231 - board/sixnet Files specific to SIXNET boards
232 - board/spd8xx Files specific to SPD8xxTS boards
233 - board/tqm8260 Files specific to TQM8260 boards
234 - board/tqm8xx Files specific to TQM8xxL boards
235 - board/w7o Files specific to W7O boards
237 Files specific to Walnut405 boards
238 - board/westel/ Files specific to boards manufactured by Westel Wireless
239 - board/westel/amx860 Files specific to AMX860 boards
240 - board/utx8245 Files specific to UTX8245 boards
242 Software Configuration:
243 =======================
245 Configuration is usually done using C preprocessor defines; the
246 rationale behind that is to avoid dead code whenever possible.
248 There are two classes of configuration variables:
250 * Configuration _OPTIONS_:
251 These are selectable by the user and have names beginning with
254 * Configuration _SETTINGS_:
255 These depend on the hardware etc. and should not be meddled with if
256 you don't know what you're doing; they have names beginning with
259 Later we will add a configuration tool - probably similar to or even
260 identical to what's used for the Linux kernel. Right now, we have to
261 do the configuration by hand, which means creating some symbolic
262 links and editing some configuration files. We use the TQM8xxL boards
266 Selection of Processor Architecture and Board Type:
267 ---------------------------------------------------
269 For all supported boards there are ready-to-use default
270 configurations available; just type "make <board_name>_config".
272 Example: For a TQM823L module type:
277 For the Cogent platform, you need to specify the cpu type as well;
278 e.g. "make cogent_mpc8xx_config". And also configure the cogent
279 directory according to the instructions in cogent/README.
282 Configuration Options:
283 ----------------------
285 Configuration depends on the combination of board and CPU type; all
286 such information is kept in a configuration file
287 "include/configs/<board_name>.h".
289 Example: For a TQM823L module, all configuration settings are in
290 "include/configs/TQM823L.h".
293 Many of the options are named exactly as the corresponding Linux
294 kernel configuration options. The intention is to make it easier to
295 build a config tool - later.
298 The following options need to be configured:
300 - CPU Type: Define exactly one of
304 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
306 or CONFIG_MPC824X, CONFIG_MPC8260
320 - Board Type: Define exactly one of
322 PowerPC based boards:
323 ---------------------
325 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
326 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
327 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
328 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
329 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
330 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
331 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
332 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
333 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
334 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
335 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
336 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
337 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
338 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
339 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
340 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
341 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
342 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
343 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
344 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
345 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
346 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
347 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
348 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
349 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
350 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
351 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
352 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
353 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
354 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
355 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
356 CONFIG_NETVIA, CONFIG_RBC823
361 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
362 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
363 CONFIG_INNOVATOROMAP1510, CONFIG_INNOVATOROMAP1610
364 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
365 CONFIG_TRAB, CONFIG_AT91RM9200DK
368 - CPU Module Type: (if CONFIG_COGENT is defined)
369 Define exactly one of
371 --- FIXME --- not tested yet:
372 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
373 CONFIG_CMA287_23, CONFIG_CMA287_50
375 - Motherboard Type: (if CONFIG_COGENT is defined)
376 Define exactly one of
377 CONFIG_CMA101, CONFIG_CMA102
379 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
380 Define one or more of
383 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
384 Define one or more of
385 CONFIG_LCD_HEARTBEAT - update a character position on
386 the lcd display every second with
389 - Board flavour: (if CONFIG_MPC8260ADS is defined)
392 CFG_8260ADS - original MPC8260ADS
393 CFG_8266ADS - MPC8266ADS (untested)
394 CFG_PQ2FADS - PQ2FADS-ZU
397 - MPC824X Family Member (if CONFIG_MPC824X is defined)
398 Define exactly one of
399 CONFIG_MPC8240, CONFIG_MPC8245
401 - 8xx CPU Options: (if using an 8xx cpu)
402 Define one or more of
403 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
404 no 32KHz reference PIT/RTC clock
409 U-Boot stores all clock information in Hz
410 internally. For binary compatibility with older Linux
411 kernels (which expect the clocks passed in the
412 bd_info data to be in MHz) the environment variable
413 "clocks_in_mhz" can be defined so that U-Boot
414 converts clock data to MHZ before passing it to the
417 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
418 "clocks_in_mhz=1" is automatically included in the
422 Depending on board, define exactly one serial port
423 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
424 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
425 console by defining CONFIG_8xx_CONS_NONE
427 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
428 port routines must be defined elsewhere
429 (i.e. serial_init(), serial_getc(), ...)
432 Enables console device for a color framebuffer. Needs following
433 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
434 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
436 VIDEO_HW_RECTFILL graphic chip supports
439 VIDEO_HW_BITBLT graphic chip supports
440 bit-blit (cf. smiLynxEM)
441 VIDEO_VISIBLE_COLS visible pixel columns
443 VIDEO_VISIBLE_ROWS visible pixel rows
444 VIDEO_PIXEL_SIZE bytes per pixel
445 VIDEO_DATA_FORMAT graphic data format
446 (0-5, cf. cfb_console.c)
447 VIDEO_FB_ADRS framebuffer address
448 VIDEO_KBD_INIT_FCT keyboard int fct
449 (i.e. i8042_kbd_init())
450 VIDEO_TSTC_FCT test char fct
452 VIDEO_GETC_FCT get char fct
454 CONFIG_CONSOLE_CURSOR cursor drawing on/off
455 (requires blink timer
457 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
458 CONFIG_CONSOLE_TIME display time/date info in
460 (requires CFG_CMD_DATE)
461 CONFIG_VIDEO_LOGO display Linux logo in
463 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
464 linux_logo.h for logo.
465 Requires CONFIG_VIDEO_LOGO
466 CONFIG_CONSOLE_EXTRA_INFO
467 addional board info beside
470 When CONFIG_CFB_CONSOLE is defined, video console is
471 default i/o. Serial console can be forced with
472 environment 'console=serial'.
475 CONFIG_BAUDRATE - in bps
476 Select one of the baudrates listed in
477 CFG_BAUDRATE_TABLE, see below.
479 - Interrupt driven serial port input:
480 CONFIG_SERIAL_SOFTWARE_FIFO
483 Use an interrupt handler for receiving data on the
484 serial port. It also enables using hardware handshake
485 (RTS/CTS) and UART's built-in FIFO. Set the number of
486 bytes the interrupt driven input buffer should have.
488 Set to 0 to disable this feature (this is the default).
489 This will also disable hardware handshake.
491 - Console UART Number:
495 If defined internal UART1 (and not UART0) is used
496 as default U-Boot console.
498 - Boot Delay: CONFIG_BOOTDELAY - in seconds
499 Delay before automatically booting the default image;
500 set to -1 to disable autoboot.
502 See doc/README.autoboot for these options that
503 work with CONFIG_BOOTDELAY. None are required.
504 CONFIG_BOOT_RETRY_TIME
505 CONFIG_BOOT_RETRY_MIN
506 CONFIG_AUTOBOOT_KEYED
507 CONFIG_AUTOBOOT_PROMPT
508 CONFIG_AUTOBOOT_DELAY_STR
509 CONFIG_AUTOBOOT_STOP_STR
510 CONFIG_AUTOBOOT_DELAY_STR2
511 CONFIG_AUTOBOOT_STOP_STR2
512 CONFIG_ZERO_BOOTDELAY_CHECK
513 CONFIG_RESET_TO_RETRY
517 Only needed when CONFIG_BOOTDELAY is enabled;
518 define a command string that is automatically executed
519 when no character is read on the console interface
520 within "Boot Delay" after reset.
523 This can be used to pass arguments to the bootm
524 command. The value of CONFIG_BOOTARGS goes into the
525 environment value "bootargs".
527 CONFIG_RAMBOOT and CONFIG_NFSBOOT
528 The value of these goes into the environment as
529 "ramboot" and "nfsboot" respectively, and can be used
530 as a convenience, when switching between booting from
536 When this option is #defined, the existence of the
537 environment variable "preboot" will be checked
538 immediately before starting the CONFIG_BOOTDELAY
539 countdown and/or running the auto-boot command resp.
540 entering interactive mode.
542 This feature is especially useful when "preboot" is
543 automatically generated or modified. For an example
544 see the LWMON board specific code: here "preboot" is
545 modified when the user holds down a certain
546 combination of keys on the (special) keyboard when
549 - Serial Download Echo Mode:
551 If defined to 1, all characters received during a
552 serial download (using the "loads" command) are
553 echoed back. This might be needed by some terminal
554 emulations (like "cu"), but may as well just take
555 time on others. This setting #define's the initial
556 value of the "loads_echo" environment variable.
558 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
560 Select one of the baudrates listed in
561 CFG_BAUDRATE_TABLE, see below.
565 Most monitor functions can be selected (or
566 de-selected) by adjusting the definition of
567 CONFIG_COMMANDS; to select individual functions,
568 #define CONFIG_COMMANDS by "OR"ing any of the
571 #define enables commands:
572 -------------------------
573 CFG_CMD_ASKENV * ask for env variable
575 CFG_CMD_BEDBUG Include BedBug Debugger
577 CFG_CMD_CACHE icache, dcache
578 CFG_CMD_CONSOLE coninfo
579 CFG_CMD_DATE * support for RTC, date/time...
580 CFG_CMD_DHCP DHCP support
581 CFG_CMD_ECHO * echo arguments
582 CFG_CMD_EEPROM * EEPROM read/write support
583 CFG_CMD_ELF bootelf, bootvx
585 CFG_CMD_FDC * Floppy Disk Support
586 CFG_CMD_FAT FAT partition support
587 CFG_CMD_FDOS * Dos diskette Support
588 CFG_CMD_FLASH flinfo, erase, protect
589 CFG_CMD_FPGA FPGA device initialization support
590 CFG_CMD_I2C * I2C serial bus support
591 CFG_CMD_IDE * IDE harddisk support
593 CFG_CMD_IMMAP * IMMR dump support
594 CFG_CMD_IRQ * irqinfo
598 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
600 CFG_CMD_MMC MMC memory mapped support
601 CFG_CMD_MII MII utility commands
602 CFG_CMD_NET bootp, tftpboot, rarpboot
603 CFG_CMD_PCI * pciinfo
604 CFG_CMD_PCMCIA * PCMCIA support
605 CFG_CMD_REGINFO * Register dump
606 CFG_CMD_RUN run command in env variable
607 CFG_CMD_SCSI * SCSI Support
608 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
609 CFG_CMD_SPI * SPI serial bus support
610 CFG_CMD_USB * USB support
611 CFG_CMD_BSP * Board SPecific functions
612 -----------------------------------------------
615 CFG_CMD_DFL Default configuration; at the moment
616 this is includes all commands, except
617 the ones marked with "*" in the list
620 If you don't define CONFIG_COMMANDS it defaults to
621 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
622 override the default settings in the respective
625 EXAMPLE: If you want all functions except of network
626 support you can write:
628 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
631 Note: Don't enable the "icache" and "dcache" commands
632 (configuration option CFG_CMD_CACHE) unless you know
633 what you (and your U-Boot users) are doing. Data
634 cache cannot be enabled on systems like the 8xx or
635 8260 (where accesses to the IMMR region must be
636 uncached), and it cannot be disabled on all other
637 systems where we (mis-) use the data cache to hold an
638 initial stack and some data.
641 XXX - this list needs to get updated!
645 If this variable is defined, it enables watchdog
646 support. There must support in the platform specific
647 code for a watchdog. For the 8xx and 8260 CPUs, the
648 SIU Watchdog feature is enabled in the SYPCR
652 CONFIG_VERSION_VARIABLE
653 If this variable is defined, an environment variable
654 named "ver" is created by U-Boot showing the U-Boot
655 version as printed by the "version" command.
656 This variable is readonly.
660 When CFG_CMD_DATE is selected, the type of the RTC
661 has to be selected, too. Define exactly one of the
664 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
665 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
666 CONFIG_RTC_MC146818 - use MC146818 RTC
667 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
668 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
669 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
670 CONFIG_RTC_DS164x - use Dallas DS164x RTC
672 Note that if the RTC uses I2C, then the I2C interface
673 must also be configured. See I2C Support, below.
677 When CONFIG_TIMESTAMP is selected, the timestamp
678 (date and time) of an image is printed by image
679 commands like bootm or iminfo. This option is
680 automatically enabled when you select CFG_CMD_DATE .
683 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
684 and/or CONFIG_ISO_PARTITION
686 If IDE or SCSI support is enabled (CFG_CMD_IDE or
687 CFG_CMD_SCSI) you must configure support for at least
688 one partition type as well.
691 CONFIG_IDE_RESET_ROUTINE
693 Set this to define that instead of a reset Pin, the
694 routine ide_set_reset(int idereset) will be used.
699 Set this to enable ATAPI support.
702 At the moment only there is only support for the
703 SYM53C8XX SCSI controller; define
704 CONFIG_SCSI_SYM53C8XX to enable it.
706 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
707 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
708 CFG_SCSI_MAX_LUN] can be adjusted to define the
709 maximum numbers of LUNs, SCSI ID's and target
711 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
713 - NETWORK Support (PCI):
715 Support for Intel 8254x gigabit chips.
718 Support for Intel 82557/82559/82559ER chips.
719 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
720 write routine for first time initialisation.
723 Support for Digital 2114x chips.
724 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
725 modem chip initialisation (KS8761/QS6611).
728 Support for National dp83815 chips.
731 Support for National dp8382[01] gigabit chips.
733 - NETWORK Support (other):
735 CONFIG_DRIVER_LAN91C96
736 Support for SMSC's LAN91C96 chips.
739 Define this to hold the physical address
740 of the LAN91C96's I/O space
742 CONFIG_LAN91C96_USE_32_BIT
743 Define this to enable 32 bit addressing
746 At the moment only the UHCI host controller is
747 supported (PIP405, MIP405); define
748 CONFIG_USB_UHCI to enable it.
749 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
750 end define CONFIG_USB_STORAGE to enable the USB
753 Supported are USB Keyboards and USB Floppy drives
757 The MMC controller on the Intel PXA is supported. To
758 enable this define CONFIG_MMC. The MMC can be
759 accessed from the boot prompt by mapping the device
760 to physical memory similar to flash. Command line is
761 enabled with CFG_CMD_MMC. The MMC driver also works with
762 the FAT fs. This is enabled with CFG_CMD_FAT.
767 Define this to enable standard (PC-Style) keyboard
771 Standard PC keyboard driver with US (is default) and
772 GERMAN key layout (switch via environment 'keymap=de') support.
773 Export function i8042_kbd_init, i8042_tstc and i8042_getc
774 for cfb_console. Supports cursor blinking.
779 Define this to enable video support (for output to
784 Enable Chips & Technologies 69000 Video chip
786 CONFIG_VIDEO_SMI_LYNXEM
787 Enable Silicon Motion SMI 712/710/810 Video chip
788 Videomode are selected via environment 'videomode' with
789 standard LiLo mode numbers.
790 Following modes are supported (* is default):
792 800x600 1024x768 1280x1024
793 256 (8bit) 303* 305 307
794 65536 (16bit) 314 317 31a
795 16,7 Mill (24bit) 315 318 31b
796 (i.e. setenv videomode 317; saveenv; reset;)
798 CONFIG_VIDEO_SED13806
799 Enable Epson SED13806 driver. This driver supports 8bpp
800 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
801 or CONFIG_VIDEO_SED13806_16BPP
806 Define this to enable a custom keyboard support.
807 This simply calls drv_keyboard_init() which must be
808 defined in your board-specific files.
809 The only board using this so far is RBC823.
811 - LCD Support: CONFIG_LCD
813 Define this to enable LCD support (for output to LCD
814 display); also select one of the supported displays
815 by defining one of these:
817 CONFIG_NEC_NL6648AC33:
819 NEC NL6648AC33-18. Active, color, single scan.
821 CONFIG_NEC_NL6648BC20
823 NEC NL6648BC20-08. 6.5", 640x480.
824 Active, color, single scan.
828 Sharp 320x240. Active, color, single scan.
829 It isn't 16x9, and I am not sure what it is.
831 CONFIG_SHARP_LQ64D341
833 Sharp LQ64D341 display, 640x480.
834 Active, color, single scan.
838 HLD1045 display, 640x480.
839 Active, color, single scan.
843 Optrex CBL50840-2 NF-FW 99 22 M5
845 Hitachi LMG6912RPFC-00T
849 320x240. Black & white.
851 Normally display is black on white background; define
852 CFG_WHITE_ON_BLACK to get it inverted.
854 - Spash Screen Support: CONFIG_SPLASH_SCREEN
856 If this option is set, the environment is checked for
857 a variable "splashimage". If found, the usual display
858 of logo, copyright and system information on the LCD
859 is supressed and the BMP image at the address
860 specified in "splashimage" is loaded instead. The
861 console is redirected to the "nulldev", too. This
862 allows for a "silent" boot where a splash screen is
863 loaded very quickly after power-on.
865 - Compression support:
868 If this option is set, support for bzip2 compressed
869 images is included. If not, only uncompressed and gzip
870 compressed images are supported.
872 NOTE: the bzip2 algorithm requires a lot of RAM, so
873 the malloc area (as defined by CFG_MALLOC_LEN) should
881 Define a default value for ethernet address to use
882 for the respective ethernet interface, in case this
883 is not determined automatically.
888 Define a default value for the IP address to use for
889 the default ethernet interface, in case this is not
890 determined through e.g. bootp.
895 Defines a default value for theIP address of a TFTP
896 server to contact when using the "tftboot" command.
898 - BOOTP Recovery Mode:
899 CONFIG_BOOTP_RANDOM_DELAY
901 If you have many targets in a network that try to
902 boot using BOOTP, you may want to avoid that all
903 systems send out BOOTP requests at precisely the same
904 moment (which would happen for instance at recovery
905 from a power failure, when all systems will try to
906 boot, thus flooding the BOOTP server. Defining
907 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
908 inserted before sending out BOOTP requests. The
909 following delays are insterted then:
911 1st BOOTP request: delay 0 ... 1 sec
912 2nd BOOTP request: delay 0 ... 2 sec
913 3rd BOOTP request: delay 0 ... 4 sec
915 BOOTP requests: delay 0 ... 8 sec
917 - DHCP Advanced Options:
920 You can fine tune the DHCP functionality by adding
921 these flags to the CONFIG_BOOTP_MASK define:
923 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
924 serverip from a DHCP server, it is possible that more
925 than one DNS serverip is offered to the client.
926 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
927 serverip will be stored in the additional environment
928 variable "dnsip2". The first DNS serverip is always
929 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
930 is added to the CONFIG_BOOTP_MASK.
932 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
933 to do a dynamic update of a DNS server. To do this, they
934 need the hostname of the DHCP requester.
935 If CONFIG_BOOP_SEND_HOSTNAME is added to the
936 CONFIG_BOOTP_MASK, the content of the "hostname"
937 environment variable is passed as option 12 to
940 - Status LED: CONFIG_STATUS_LED
942 Several configurations allow to display the current
943 status using a LED. For instance, the LED will blink
944 fast while running U-Boot code, stop blinking as
945 soon as a reply to a BOOTP request was received, and
946 start blinking slow once the Linux kernel is running
947 (supported by a status LED driver in the Linux
948 kernel). Defining CONFIG_STATUS_LED enables this
951 - CAN Support: CONFIG_CAN_DRIVER
953 Defining CONFIG_CAN_DRIVER enables CAN driver support
954 on those systems that support this (optional)
955 feature, like the TQM8xxL modules.
957 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
959 These enable I2C serial bus commands. Defining either of
960 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
961 include the appropriate I2C driver for the selected cpu.
963 This will allow you to use i2c commands at the u-boot
964 command line (as long as you set CFG_CMD_I2C in
965 CONFIG_COMMANDS) and communicate with i2c based realtime
966 clock chips. See common/cmd_i2c.c for a description of the
967 command line interface.
969 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
971 CONFIG_SOFT_I2C configures u-boot to use a software (aka
972 bit-banging) driver instead of CPM or similar hardware
975 There are several other quantities that must also be
976 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
978 In both cases you will need to define CFG_I2C_SPEED
979 to be the frequency (in Hz) at which you wish your i2c bus
980 to run and CFG_I2C_SLAVE to be the address of this node (ie
981 the cpu's i2c node address).
983 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
984 sets the cpu up as a master node and so its address should
985 therefore be cleared to 0 (See, eg, MPC823e User's Manual
986 p.16-473). So, set CFG_I2C_SLAVE to 0.
988 That's all that's required for CONFIG_HARD_I2C.
990 If you use the software i2c interface (CONFIG_SOFT_I2C)
991 then the following macros need to be defined (examples are
992 from include/configs/lwmon.h):
996 (Optional). Any commands necessary to enable the I2C
997 controller or configure ports.
999 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1003 (Only for MPC8260 CPU). The I/O port to use (the code
1004 assumes both bits are on the same port). Valid values
1005 are 0..3 for ports A..D.
1009 The code necessary to make the I2C data line active
1010 (driven). If the data line is open collector, this
1013 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1017 The code necessary to make the I2C data line tri-stated
1018 (inactive). If the data line is open collector, this
1021 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1025 Code that returns TRUE if the I2C data line is high,
1028 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1032 If <bit> is TRUE, sets the I2C data line high. If it
1033 is FALSE, it clears it (low).
1035 eg: #define I2C_SDA(bit) \
1036 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1037 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1041 If <bit> is TRUE, sets the I2C clock line high. If it
1042 is FALSE, it clears it (low).
1044 eg: #define I2C_SCL(bit) \
1045 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1046 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1050 This delay is invoked four times per clock cycle so this
1051 controls the rate of data transfer. The data rate thus
1052 is 1 / (I2C_DELAY * 4). Often defined to be something
1055 #define I2C_DELAY udelay(2)
1059 When a board is reset during an i2c bus transfer
1060 chips might think that the current transfer is still
1061 in progress. On some boards it is possible to access
1062 the i2c SCLK line directly, either by using the
1063 processor pin as a GPIO or by having a second pin
1064 connected to the bus. If this option is defined a
1065 custom i2c_init_board() routine in boards/xxx/board.c
1066 is run early in the boot sequence.
1068 - SPI Support: CONFIG_SPI
1070 Enables SPI driver (so far only tested with
1071 SPI EEPROM, also an instance works with Crystal A/D and
1072 D/As on the SACSng board)
1076 Enables extended (16-bit) SPI EEPROM addressing.
1077 (symmetrical to CONFIG_I2C_X)
1081 Enables a software (bit-bang) SPI driver rather than
1082 using hardware support. This is a general purpose
1083 driver that only requires three general I/O port pins
1084 (two outputs, one input) to function. If this is
1085 defined, the board configuration must define several
1086 SPI configuration items (port pins to use, etc). For
1087 an example, see include/configs/sacsng.h.
1089 - FPGA Support: CONFIG_FPGA_COUNT
1091 Specify the number of FPGA devices to support.
1095 Used to specify the types of FPGA devices. For
1097 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1099 CFG_FPGA_PROG_FEEDBACK
1101 Enable printing of hash marks during FPGA
1106 Enable checks on FPGA configuration interface busy
1107 status by the configuration function. This option
1108 will require a board or device specific function to
1113 If defined, a function that provides delays in the
1114 FPGA configuration driver.
1116 CFG_FPGA_CHECK_CTRLC
1118 Allow Control-C to interrupt FPGA configuration
1120 CFG_FPGA_CHECK_ERROR
1122 Check for configuration errors during FPGA bitfile
1123 loading. For example, abort during Virtex II
1124 configuration if the INIT_B line goes low (which
1125 indicated a CRC error).
1129 Maximum time to wait for the INIT_B line to deassert
1130 after PROB_B has been deasserted during a Virtex II
1131 FPGA configuration sequence. The default time is 500 mS.
1135 Maximum time to wait for BUSY to deassert during
1136 Virtex II FPGA configuration. The default is 5 mS.
1138 CFG_FPGA_WAIT_CONFIG
1140 Time to wait after FPGA configuration. The default is
1143 - FPGA Support: CONFIG_FPGA_COUNT
1145 Specify the number of FPGA devices to support.
1149 Used to specify the types of FPGA devices. For example,
1150 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1152 CFG_FPGA_PROG_FEEDBACK
1154 Enable printing of hash marks during FPGA configuration.
1158 Enable checks on FPGA configuration interface busy
1159 status by the configuration function. This option
1160 will require a board or device specific function to
1165 If defined, a function that provides delays in the FPGA
1166 configuration driver.
1168 CFG_FPGA_CHECK_CTRLC
1169 Allow Control-C to interrupt FPGA configuration
1171 CFG_FPGA_CHECK_ERROR
1173 Check for configuration errors during FPGA bitfile
1174 loading. For example, abort during Virtex II
1175 configuration if the INIT_B line goes low (which
1176 indicated a CRC error).
1180 Maximum time to wait for the INIT_B line to deassert
1181 after PROB_B has been deasserted during a Virtex II
1182 FPGA configuration sequence. The default time is 500
1187 Maximum time to wait for BUSY to deassert during
1188 Virtex II FPGA configuration. The default is 5 mS.
1190 CFG_FPGA_WAIT_CONFIG
1192 Time to wait after FPGA configuration. The default is
1195 - Configuration Management:
1198 If defined, this string will be added to the U-Boot
1199 version information (U_BOOT_VERSION)
1201 - Vendor Parameter Protection:
1203 U-Boot considers the values of the environment
1204 variables "serial#" (Board Serial Number) and
1205 "ethaddr" (Ethernet Address) to bb parameters that
1206 are set once by the board vendor / manufacturer, and
1207 protects these variables from casual modification by
1208 the user. Once set, these variables are read-only,
1209 and write or delete attempts are rejected. You can
1210 change this behviour:
1212 If CONFIG_ENV_OVERWRITE is #defined in your config
1213 file, the write protection for vendor parameters is
1214 completely disabled. Anybody can change or delete
1217 Alternatively, if you #define _both_ CONFIG_ETHADDR
1218 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1219 ethernet address is installed in the environment,
1220 which can be changed exactly ONCE by the user. [The
1221 serial# is unaffected by this, i. e. it remains
1227 Define this variable to enable the reservation of
1228 "protected RAM", i. e. RAM which is not overwritten
1229 by U-Boot. Define CONFIG_PRAM to hold the number of
1230 kB you want to reserve for pRAM. You can overwrite
1231 this default value by defining an environment
1232 variable "pram" to the number of kB you want to
1233 reserve. Note that the board info structure will
1234 still show the full amount of RAM. If pRAM is
1235 reserved, a new environment variable "mem" will
1236 automatically be defined to hold the amount of
1237 remaining RAM in a form that can be passed as boot
1238 argument to Linux, for instance like that:
1240 setenv bootargs ... mem=\$(mem)
1243 This way you can tell Linux not to use this memory,
1244 either, which results in a memory region that will
1245 not be affected by reboots.
1247 *WARNING* If your board configuration uses automatic
1248 detection of the RAM size, you must make sure that
1249 this memory test is non-destructive. So far, the
1250 following board configurations are known to be
1253 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1254 HERMES, IP860, RPXlite, LWMON, LANTEC,
1255 PCU_E, FLAGADM, TQM8260
1260 Define this variable to stop the system in case of a
1261 fatal error, so that you have to reset it manually.
1262 This is probably NOT a good idea for an embedded
1263 system where you want to system to reboot
1264 automatically as fast as possible, but it may be
1265 useful during development since you can try to debug
1266 the conditions that lead to the situation.
1268 CONFIG_NET_RETRY_COUNT
1270 This variable defines the number of retries for
1271 network operations like ARP, RARP, TFTP, or BOOTP
1272 before giving up the operation. If not defined, a
1273 default value of 5 is used.
1275 - Command Interpreter:
1278 Define this variable to enable the "hush" shell (from
1279 Busybox) as command line interpreter, thus enabling
1280 powerful command line syntax like
1281 if...then...else...fi conditionals or `&&' and '||'
1282 constructs ("shell scripts").
1284 If undefined, you get the old, much simpler behaviour
1285 with a somewhat smaller memory footprint.
1290 This defines the secondary prompt string, which is
1291 printed when the command interpreter needs more input
1292 to complete a command. Usually "> ".
1296 In the current implementation, the local variables
1297 space and global environment variables space are
1298 separated. Local variables are those you define by
1299 simply typing `name=value'. To access a local
1300 variable later on, you have write `$name' or
1301 `${name}'; to execute the contents of a variable
1302 directly type `$name' at the command prompt.
1304 Global environment variables are those you use
1305 setenv/printenv to work with. To run a command stored
1306 in such a variable, you need to use the run command,
1307 and you must not use the '$' sign to access them.
1309 To store commands and special characters in a
1310 variable, please use double quotation marks
1311 surrounding the whole text of the variable, instead
1312 of the backslashes before semicolons and special
1315 - Default Environment
1316 CONFIG_EXTRA_ENV_SETTINGS
1318 Define this to contain any number of null terminated
1319 strings (variable = value pairs) that will be part of
1320 the default enviroment compiled into the boot image.
1322 For example, place something like this in your
1323 board's config file:
1325 #define CONFIG_EXTRA_ENV_SETTINGS \
1329 Warning: This method is based on knowledge about the
1330 internal format how the environment is stored by the
1331 U-Boot code. This is NOT an official, exported
1332 interface! Although it is unlikely that this format
1333 will change soon, but there is no guarantee either.
1334 You better know what you are doing here.
1336 Note: overly (ab)use of the default environment is
1337 discouraged. Make sure to check other ways to preset
1338 the environment like the autoscript function or the
1342 CONFIG_HAS_DATAFLASH
1344 Defining this option enables DataFlash features and
1345 allows to read/write in Dataflash via the standard
1348 - Show boot progress
1349 CONFIG_SHOW_BOOT_PROGRESS
1351 Defining this option allows to add some board-
1352 specific code (calling a user-provided function
1353 "show_boot_progress(int)") that enables you to show
1354 the system's boot progress on some display (for
1355 example, some LED's) on your board. At the moment,
1356 the following checkpoints are implemented:
1359 1 common/cmd_bootm.c before attempting to boot an image
1360 -1 common/cmd_bootm.c Image header has bad magic number
1361 2 common/cmd_bootm.c Image header has correct magic number
1362 -2 common/cmd_bootm.c Image header has bad checksum
1363 3 common/cmd_bootm.c Image header has correct checksum
1364 -3 common/cmd_bootm.c Image data has bad checksum
1365 4 common/cmd_bootm.c Image data has correct checksum
1366 -4 common/cmd_bootm.c Image is for unsupported architecture
1367 5 common/cmd_bootm.c Architecture check OK
1368 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1369 6 common/cmd_bootm.c Image Type check OK
1370 -6 common/cmd_bootm.c gunzip uncompression error
1371 -7 common/cmd_bootm.c Unimplemented compression type
1372 7 common/cmd_bootm.c Uncompression OK
1373 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1374 8 common/cmd_bootm.c Image Type check OK
1375 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1376 9 common/cmd_bootm.c Start initial ramdisk verification
1377 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1378 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1379 10 common/cmd_bootm.c Ramdisk header is OK
1380 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1381 11 common/cmd_bootm.c Ramdisk data has correct checksum
1382 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1383 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1384 13 common/cmd_bootm.c Start multifile image verification
1385 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1386 15 common/cmd_bootm.c All preparation done, transferring control to OS
1388 -1 common/cmd_doc.c Bad usage of "doc" command
1389 -1 common/cmd_doc.c No boot device
1390 -1 common/cmd_doc.c Unknown Chip ID on boot device
1391 -1 common/cmd_doc.c Read Error on boot device
1392 -1 common/cmd_doc.c Image header has bad magic number
1394 -1 common/cmd_ide.c Bad usage of "ide" command
1395 -1 common/cmd_ide.c No boot device
1396 -1 common/cmd_ide.c Unknown boot device
1397 -1 common/cmd_ide.c Unknown partition table
1398 -1 common/cmd_ide.c Invalid partition type
1399 -1 common/cmd_ide.c Read Error on boot device
1400 -1 common/cmd_ide.c Image header has bad magic number
1402 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1408 [so far only for SMDK2400 and TRAB boards]
1410 - Modem support endable:
1411 CONFIG_MODEM_SUPPORT
1413 - RTS/CTS Flow control enable:
1416 - Modem debug support:
1417 CONFIG_MODEM_SUPPORT_DEBUG
1419 Enables debugging stuff (char screen[1024], dbg())
1420 for modem support. Useful only with BDI2000.
1424 In the target system modem support is enabled when a
1425 specific key (key combination) is pressed during
1426 power-on. Otherwise U-Boot will boot normally
1427 (autoboot). The key_pressed() fuction is called from
1428 board_init(). Currently key_pressed() is a dummy
1429 function, returning 1 and thus enabling modem
1432 If there are no modem init strings in the
1433 environment, U-Boot proceed to autoboot; the
1434 previous output (banner, info printfs) will be
1437 See also: doc/README.Modem
1440 Configuration Settings:
1441 -----------------------
1443 - CFG_LONGHELP: Defined when you want long help messages included;
1444 undefine this when you're short of memory.
1446 - CFG_PROMPT: This is what U-Boot prints on the console to
1447 prompt for user input.
1449 - CFG_CBSIZE: Buffer size for input from the Console
1451 - CFG_PBSIZE: Buffer size for Console output
1453 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1455 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1456 the application (usually a Linux kernel) when it is
1459 - CFG_BAUDRATE_TABLE:
1460 List of legal baudrate settings for this board.
1462 - CFG_CONSOLE_INFO_QUIET
1463 Suppress display of console information at boot.
1465 - CFG_CONSOLE_IS_IN_ENV
1466 If the board specific function
1467 extern int overwrite_console (void);
1468 returns 1, the stdin, stderr and stdout are switched to the
1469 serial port, else the settings in the environment are used.
1471 - CFG_CONSOLE_OVERWRITE_ROUTINE
1472 Enable the call to overwrite_console().
1474 - CFG_CONSOLE_ENV_OVERWRITE
1475 Enable overwrite of previous console environment settings.
1477 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1478 Begin and End addresses of the area used by the
1482 Enable an alternate, more extensive memory test.
1484 - CFG_TFTP_LOADADDR:
1485 Default load address for network file downloads
1487 - CFG_LOADS_BAUD_CHANGE:
1488 Enable temporary baudrate change while serial download
1491 Physical start address of SDRAM. _Must_ be 0 here.
1494 Physical start address of Motherboard I/O (if using a
1498 Physical start address of Flash memory.
1501 Physical start address of boot monitor code (set by
1502 make config files to be same as the text base address
1503 (TEXT_BASE) used when linking) - same as
1504 CFG_FLASH_BASE when booting from flash.
1507 Size of memory reserved for monitor code, used to
1508 determine _at_compile_time_ (!) if the environment is
1509 embedded within the U-Boot image, or in a separate
1513 Size of DRAM reserved for malloc() use.
1516 Maximum size of memory mapped by the startup code of
1517 the Linux kernel; all data that must be processed by
1518 the Linux kernel (bd_info, boot arguments, eventually
1519 initrd image) must be put below this limit.
1521 - CFG_MAX_FLASH_BANKS:
1522 Max number of Flash memory banks
1524 - CFG_MAX_FLASH_SECT:
1525 Max number of sectors on a Flash chip
1527 - CFG_FLASH_ERASE_TOUT:
1528 Timeout for Flash erase operations (in ms)
1530 - CFG_FLASH_WRITE_TOUT:
1531 Timeout for Flash write operations (in ms)
1533 - CFG_FLASH_LOCK_TOUT
1534 Timeout for Flash set sector lock bit operation (in ms)
1536 - CFG_FLASH_UNLOCK_TOUT
1537 Timeout for Flash clear lock bits operation (in ms)
1539 - CFG_FLASH_PROTECTION
1540 If defined, hardware flash sectors protection is used
1541 instead of U-Boot software protection.
1543 - CFG_DIRECT_FLASH_TFTP:
1545 Enable TFTP transfers directly to flash memory;
1546 without this option such a download has to be
1547 performed in two steps: (1) download to RAM, and (2)
1548 copy from RAM to flash.
1550 The two-step approach is usually more reliable, since
1551 you can check if the download worked before you erase
1552 the flash, but in some situations (when sytem RAM is
1553 too limited to allow for a tempory copy of the
1554 downloaded image) this option may be very useful.
1557 Define if the flash driver uses extra elements in the
1558 common flash structure for storing flash geometry
1560 - CFG_RX_ETH_BUFFER:
1561 Defines the number of ethernet receive buffers. On some
1562 ethernet controllers it is recommended to set this value
1563 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1564 buffers can be full shortly after enabling the interface
1565 on high ethernet traffic.
1566 Defaults to 4 if not defined.
1568 The following definitions that deal with the placement and management
1569 of environment data (variable area); in general, we support the
1570 following configurations:
1572 - CFG_ENV_IS_IN_FLASH:
1574 Define this if the environment is in flash memory.
1576 a) The environment occupies one whole flash sector, which is
1577 "embedded" in the text segment with the U-Boot code. This
1578 happens usually with "bottom boot sector" or "top boot
1579 sector" type flash chips, which have several smaller
1580 sectors at the start or the end. For instance, such a
1581 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1582 such a case you would place the environment in one of the
1583 4 kB sectors - with U-Boot code before and after it. With
1584 "top boot sector" type flash chips, you would put the
1585 environment in one of the last sectors, leaving a gap
1586 between U-Boot and the environment.
1590 Offset of environment data (variable area) to the
1591 beginning of flash memory; for instance, with bottom boot
1592 type flash chips the second sector can be used: the offset
1593 for this sector is given here.
1595 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1599 This is just another way to specify the start address of
1600 the flash sector containing the environment (instead of
1603 - CFG_ENV_SECT_SIZE:
1605 Size of the sector containing the environment.
1608 b) Sometimes flash chips have few, equal sized, BIG sectors.
1609 In such a case you don't want to spend a whole sector for
1614 If you use this in combination with CFG_ENV_IS_IN_FLASH
1615 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1616 of this flash sector for the environment. This saves
1617 memory for the RAM copy of the environment.
1619 It may also save flash memory if you decide to use this
1620 when your environment is "embedded" within U-Boot code,
1621 since then the remainder of the flash sector could be used
1622 for U-Boot code. It should be pointed out that this is
1623 STRONGLY DISCOURAGED from a robustness point of view:
1624 updating the environment in flash makes it always
1625 necessary to erase the WHOLE sector. If something goes
1626 wrong before the contents has been restored from a copy in
1627 RAM, your target system will be dead.
1629 - CFG_ENV_ADDR_REDUND
1632 These settings describe a second storage area used to hold
1633 a redundand copy of the environment data, so that there is
1634 a valid backup copy in case there is a power failure during
1635 a "saveenv" operation.
1637 BE CAREFUL! Any changes to the flash layout, and some changes to the
1638 source code will make it necessary to adapt <board>/u-boot.lds*
1642 - CFG_ENV_IS_IN_NVRAM:
1644 Define this if you have some non-volatile memory device
1645 (NVRAM, battery buffered SRAM) which you want to use for the
1651 These two #defines are used to determin the memory area you
1652 want to use for environment. It is assumed that this memory
1653 can just be read and written to, without any special
1656 BE CAREFUL! The first access to the environment happens quite early
1657 in U-Boot initalization (when we try to get the setting of for the
1658 console baudrate). You *MUST* have mappend your NVRAM area then, or
1661 Please note that even with NVRAM we still use a copy of the
1662 environment in RAM: we could work on NVRAM directly, but we want to
1663 keep settings there always unmodified except somebody uses "saveenv"
1664 to save the current settings.
1667 - CFG_ENV_IS_IN_EEPROM:
1669 Use this if you have an EEPROM or similar serial access
1670 device and a driver for it.
1675 These two #defines specify the offset and size of the
1676 environment area within the total memory of your EEPROM.
1678 - CFG_I2C_EEPROM_ADDR:
1679 If defined, specified the chip address of the EEPROM device.
1680 The default address is zero.
1682 - CFG_EEPROM_PAGE_WRITE_BITS:
1683 If defined, the number of bits used to address bytes in a
1684 single page in the EEPROM device. A 64 byte page, for example
1685 would require six bits.
1687 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1688 If defined, the number of milliseconds to delay between
1689 page writes. The default is zero milliseconds.
1691 - CFG_I2C_EEPROM_ADDR_LEN:
1692 The length in bytes of the EEPROM memory array address. Note
1693 that this is NOT the chip address length!
1696 The size in bytes of the EEPROM device.
1699 - CFG_SPI_INIT_OFFSET
1701 Defines offset to the initial SPI buffer area in DPRAM. The
1702 area is used at an early stage (ROM part) if the environment
1703 is configured to reside in the SPI EEPROM: We need a 520 byte
1704 scratch DPRAM area. It is used between the two initialization
1705 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1706 to be a good choice since it makes it far enough from the
1707 start of the data area as well as from the stack pointer.
1709 Please note that the environment is read-only as long as the monitor
1710 has been relocated to RAM and a RAM copy of the environment has been
1711 created; also, when using EEPROM you will have to use getenv_r()
1712 until then to read environment variables.
1714 The environment is protected by a CRC32 checksum. Before the monitor
1715 is relocated into RAM, as a result of a bad CRC you will be working
1716 with the compiled-in default environment - *silently*!!! [This is
1717 necessary, because the first environment variable we need is the
1718 "baudrate" setting for the console - if we have a bad CRC, we don't
1719 have any device yet where we could complain.]
1721 Note: once the monitor has been relocated, then it will complain if
1722 the default environment is used; a new CRC is computed as soon as you
1723 use the "saveenv" command to store a valid environment.
1726 Low Level (hardware related) configuration options:
1727 ---------------------------------------------------
1729 - CFG_CACHELINE_SIZE:
1730 Cache Line Size of the CPU.
1733 Default address of the IMMR after system reset.
1735 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1736 and RPXsuper) to be able to adjust the position of
1737 the IMMR register after a reset.
1739 - Floppy Disk Support:
1740 CFG_FDC_DRIVE_NUMBER
1742 the default drive number (default value 0)
1746 defines the spacing between fdc chipset registers
1751 defines the offset of register from address. It
1752 depends on which part of the data bus is connected to
1753 the fdc chipset. (default value 0)
1755 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1756 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1759 if CFG_FDC_HW_INIT is defined, then the function
1760 fdc_hw_init() is called at the beginning of the FDC
1761 setup. fdc_hw_init() must be provided by the board
1762 source code. It is used to make hardware dependant
1765 - CFG_IMMR: Physical address of the Internal Memory Mapped
1766 Register; DO NOT CHANGE! (11-4)
1767 [MPC8xx systems only]
1769 - CFG_INIT_RAM_ADDR:
1771 Start address of memory area tha can be used for
1772 initial data and stack; please note that this must be
1773 writable memory that is working WITHOUT special
1774 initialization, i. e. you CANNOT use normal RAM which
1775 will become available only after programming the
1776 memory controller and running certain initialization
1779 U-Boot uses the following memory types:
1780 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1781 - MPC824X: data cache
1782 - PPC4xx: data cache
1784 - CFG_GBL_DATA_OFFSET:
1786 Offset of the initial data structure in the memory
1787 area defined by CFG_INIT_RAM_ADDR. Usually
1788 CFG_GBL_DATA_OFFSET is chosen such that the initial
1789 data is located at the end of the available space
1790 (sometimes written as (CFG_INIT_RAM_END -
1791 CFG_INIT_DATA_SIZE), and the initial stack is just
1792 below that area (growing from (CFG_INIT_RAM_ADDR +
1793 CFG_GBL_DATA_OFFSET) downward.
1796 On the MPC824X (or other systems that use the data
1797 cache for initial memory) the address chosen for
1798 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1799 point to an otherwise UNUSED address space between
1800 the top of RAM and the start of the PCI space.
1802 - CFG_SIUMCR: SIU Module Configuration (11-6)
1804 - CFG_SYPCR: System Protection Control (11-9)
1806 - CFG_TBSCR: Time Base Status and Control (11-26)
1808 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1810 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1812 - CFG_SCCR: System Clock and reset Control Register (15-27)
1814 - CFG_OR_TIMING_SDRAM:
1818 periodic timer for refresh
1820 - CFG_DER: Debug Event Register (37-47)
1822 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1823 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1824 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1826 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1828 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1829 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1830 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1831 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1833 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1834 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1835 Machine Mode Register and Memory Periodic Timer
1836 Prescaler definitions (SDRAM timing)
1838 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1839 enable I2C microcode relocation patch (MPC8xx);
1840 define relocation offset in DPRAM [DSP2]
1842 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1843 enable SPI microcode relocation patch (MPC8xx);
1844 define relocation offset in DPRAM [SCC4]
1847 Use OSCM clock mode on MBX8xx board. Be careful,
1848 wrong setting might damage your board. Read
1849 doc/README.MBX before setting this variable!
1851 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1852 Offset of the bootmode word in DPRAM used by post
1853 (Power On Self Tests). This definition overrides
1854 #define'd default value in commproc.h resp.
1857 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1858 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1859 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1860 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1861 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1862 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1863 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1864 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1865 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1867 Building the Software:
1868 ======================
1870 Building U-Boot has been tested in native PPC environments (on a
1871 PowerBook G3 running LinuxPPC 2000) and in cross environments
1872 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1875 If you are not using a native PPC environment, it is assumed that you
1876 have the GNU cross compiling tools available in your path and named
1877 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1878 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1879 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1882 CROSS_COMPILE = ppc_4xx-
1885 U-Boot is intended to be simple to build. After installing the
1886 sources you must configure U-Boot for one specific board type. This
1891 where "NAME_config" is the name of one of the existing
1892 configurations; the following names are supported:
1894 ADCIOP_config GTH_config TQM850L_config
1895 ADS860_config IP860_config TQM855L_config
1896 AR405_config IVML24_config TQM860L_config
1897 CANBT_config IVMS8_config WALNUT405_config
1898 CPCI405_config LANTEC_config cogent_common_config
1899 CPCIISER4_config MBX_config cogent_mpc8260_config
1900 CU824_config MBX860T_config cogent_mpc8xx_config
1901 ESTEEM192E_config RPXlite_config hermes_config
1902 ETX094_config RPXsuper_config hymod_config
1903 FADS823_config SM850_config lwmon_config
1904 FADS850SAR_config SPD823TS_config pcu_e_config
1905 FADS860T_config SXNI855T_config rsdproto_config
1906 FPS850L_config Sandpoint8240_config sbc8260_config
1907 GENIETV_config TQM823L_config PIP405_config
1908 GEN860T_config EBONY_config FPS860L_config
1909 ELPT860_config cmi_mpc5xx_config NETVIA_config
1910 at91rm9200dk_config omap1510inn_config MPC8260ADS_config
1912 Note: for some board special configuration names may exist; check if
1913 additional information is available from the board vendor; for
1914 instance, the TQM8xxL systems run normally at 50 MHz and use a
1915 SCC for 10baseT ethernet; there are also systems with 80 MHz
1916 CPU clock, and an optional Fast Ethernet module is available
1917 for CPU's with FEC. You can select such additional "features"
1918 when chosing the configuration, i. e.
1921 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1923 make TQM860L_FEC_config
1924 - will configure for a TQM860L at 50MHz with FEC for ethernet
1926 make TQM860L_80MHz_config
1927 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1930 make TQM860L_FEC_80MHz_config
1931 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1933 make TQM823L_LCD_config
1934 - will configure for a TQM823L with U-Boot console on LCD
1936 make TQM823L_LCD_80MHz_config
1937 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1942 Finally, type "make all", and you should get some working U-Boot
1943 images ready for downlod to / installation on your system:
1945 - "u-boot.bin" is a raw binary image
1946 - "u-boot" is an image in ELF binary format
1947 - "u-boot.srec" is in Motorola S-Record format
1950 Please be aware that the Makefiles assume you are using GNU make, so
1951 for instance on NetBSD you might need to use "gmake" instead of
1955 If the system board that you have is not listed, then you will need
1956 to port U-Boot to your hardware platform. To do this, follow these
1959 1. Add a new configuration option for your board to the toplevel
1960 "Makefile" and to the "MAKEALL" script, using the existing
1961 entries as examples. Note that here and at many other places
1962 boards and other names are listed alphabetically sorted. Please
1964 2. Create a new directory to hold your board specific code. Add any
1965 files you need. In your board directory, you will need at least
1966 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1967 3. Create a new configuration file "include/configs/<board>.h" for
1969 3. If you're porting U-Boot to a new CPU, then also create a new
1970 directory to hold your CPU specific code. Add any files you need.
1971 4. Run "make <board>_config" with your new name.
1972 5. Type "make", and you should get a working "u-boot.srec" file
1973 to be installed on your target system.
1974 6. Debug and solve any problems that might arise.
1975 [Of course, this last step is much harder than it sounds.]
1978 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1979 ==============================================================
1981 If you have modified U-Boot sources (for instance added a new board
1982 or support for new devices, a new CPU, etc.) you are expected to
1983 provide feedback to the other developers. The feedback normally takes
1984 the form of a "patch", i. e. a context diff against a certain (latest
1985 official or latest in CVS) version of U-Boot sources.
1987 But before you submit such a patch, please verify that your modifi-
1988 cation did not break existing code. At least make sure that *ALL* of
1989 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1990 just run the "MAKEALL" script, which will configure and build U-Boot
1991 for ALL supported system. Be warned, this will take a while. You can
1992 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1993 environment variable to the script, i. e. to use the cross tools from
1994 MontaVista's Hard Hat Linux you can type
1996 CROSS_COMPILE=ppc_8xx- MAKEALL
1998 or to build on a native PowerPC system you can type
2000 CROSS_COMPILE=' ' MAKEALL
2002 See also "U-Boot Porting Guide" below.
2005 Monitor Commands - Overview:
2006 ============================
2008 go - start application at address 'addr'
2009 run - run commands in an environment variable
2010 bootm - boot application image from memory
2011 bootp - boot image via network using BootP/TFTP protocol
2012 tftpboot- boot image via network using TFTP protocol
2013 and env variables "ipaddr" and "serverip"
2014 (and eventually "gatewayip")
2015 rarpboot- boot image via network using RARP/TFTP protocol
2016 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2017 loads - load S-Record file over serial line
2018 loadb - load binary file over serial line (kermit mode)
2020 mm - memory modify (auto-incrementing)
2021 nm - memory modify (constant address)
2022 mw - memory write (fill)
2024 cmp - memory compare
2025 crc32 - checksum calculation
2026 imd - i2c memory display
2027 imm - i2c memory modify (auto-incrementing)
2028 inm - i2c memory modify (constant address)
2029 imw - i2c memory write (fill)
2030 icrc32 - i2c checksum calculation
2031 iprobe - probe to discover valid I2C chip addresses
2032 iloop - infinite loop on address range
2033 isdram - print SDRAM configuration information
2034 sspi - SPI utility commands
2035 base - print or set address offset
2036 printenv- print environment variables
2037 setenv - set environment variables
2038 saveenv - save environment variables to persistent storage
2039 protect - enable or disable FLASH write protection
2040 erase - erase FLASH memory
2041 flinfo - print FLASH memory information
2042 bdinfo - print Board Info structure
2043 iminfo - print header information for application image
2044 coninfo - print console devices and informations
2045 ide - IDE sub-system
2046 loop - infinite loop on address range
2047 mtest - simple RAM test
2048 icache - enable or disable instruction cache
2049 dcache - enable or disable data cache
2050 reset - Perform RESET of the CPU
2051 echo - echo args to console
2052 version - print monitor version
2053 help - print online help
2054 ? - alias for 'help'
2057 Monitor Commands - Detailed Description:
2058 ========================================
2062 For now: just type "help <command>".
2065 Environment Variables:
2066 ======================
2068 U-Boot supports user configuration using Environment Variables which
2069 can be made persistent by saving to Flash memory.
2071 Environment Variables are set using "setenv", printed using
2072 "printenv", and saved to Flash using "saveenv". Using "setenv"
2073 without a value can be used to delete a variable from the
2074 environment. As long as you don't save the environment you are
2075 working with an in-memory copy. In case the Flash area containing the
2076 environment is erased by accident, a default environment is provided.
2078 Some configuration options can be set using Environment Variables:
2080 baudrate - see CONFIG_BAUDRATE
2082 bootdelay - see CONFIG_BOOTDELAY
2084 bootcmd - see CONFIG_BOOTCOMMAND
2086 bootargs - Boot arguments when booting an RTOS image
2088 bootfile - Name of the image to load with TFTP
2090 autoload - if set to "no" (any string beginning with 'n'),
2091 "bootp" will just load perform a lookup of the
2092 configuration from the BOOTP server, but not try to
2093 load any image using TFTP
2095 autostart - if set to "yes", an image loaded using the "bootp",
2096 "rarpboot", "tftpboot" or "diskboot" commands will
2097 be automatically started (by internally calling
2100 If set to "no", a standalone image passed to the
2101 "bootm" command will be copied to the load address
2102 (and eventually uncompressed), but NOT be started.
2103 This can be used to load and uncompress arbitrary
2106 initrd_high - restrict positioning of initrd images:
2107 If this variable is not set, initrd images will be
2108 copied to the highest possible address in RAM; this
2109 is usually what you want since it allows for
2110 maximum initrd size. If for some reason you want to
2111 make sure that the initrd image is loaded below the
2112 CFG_BOOTMAPSZ limit, you can set this environment
2113 variable to a value of "no" or "off" or "0".
2114 Alternatively, you can set it to a maximum upper
2115 address to use (U-Boot will still check that it
2116 does not overwrite the U-Boot stack and data).
2118 For instance, when you have a system with 16 MB
2119 RAM, and want to reseve 4 MB from use by Linux,
2120 you can do this by adding "mem=12M" to the value of
2121 the "bootargs" variable. However, now you must make
2122 sure, that the initrd image is placed in the first
2123 12 MB as well - this can be done with
2125 setenv initrd_high 00c00000
2127 If you set initrd_high to 0xFFFFFFFF, this is an
2128 indication to U-Boot that all addresses are legal
2129 for the Linux kernel, including addresses in flash
2130 memory. In this case U-Boot will NOT COPY the
2131 ramdisk at all. This may be useful to reduce the
2132 boot time on your system, but requires that this
2133 feature is supported by your Linux kernel.
2135 ipaddr - IP address; needed for tftpboot command
2137 loadaddr - Default load address for commands like "bootp",
2138 "rarpboot", "tftpboot", "loadb" or "diskboot"
2140 loads_echo - see CONFIG_LOADS_ECHO
2142 serverip - TFTP server IP address; needed for tftpboot command
2144 bootretry - see CONFIG_BOOT_RETRY_TIME
2146 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2148 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2151 The following environment variables may be used and automatically
2152 updated by the network boot commands ("bootp" and "rarpboot"),
2153 depending the information provided by your boot server:
2155 bootfile - see above
2156 dnsip - IP address of your Domain Name Server
2157 dnsip2 - IP address of your secondary Domain Name Server
2158 gatewayip - IP address of the Gateway (Router) to use
2159 hostname - Target hostname
2161 netmask - Subnet Mask
2162 rootpath - Pathname of the root filesystem on the NFS server
2163 serverip - see above
2166 There are two special Environment Variables:
2168 serial# - contains hardware identification information such
2169 as type string and/or serial number
2170 ethaddr - Ethernet address
2172 These variables can be set only once (usually during manufacturing of
2173 the board). U-Boot refuses to delete or overwrite these variables
2174 once they have been set once.
2177 Further special Environment Variables:
2179 ver - Contains the U-Boot version string as printed
2180 with the "version" command. This variable is
2181 readonly (see CONFIG_VERSION_VARIABLE).
2184 Please note that changes to some configuration parameters may take
2185 only effect after the next boot (yes, that's just like Windoze :-).
2188 Command Line Parsing:
2189 =====================
2191 There are two different command line parsers available with U-Boot:
2192 the old "simple" one, and the much more pwerful "hush" shell:
2194 Old, simple command line parser:
2195 --------------------------------
2197 - supports environment variables (through setenv / saveenv commands)
2198 - several commands on one line, separated by ';'
2199 - variable substitution using "... $(name) ..." syntax
2200 - special characters ('$', ';') can be escaped by prefixing with '\',
2202 setenv bootcmd bootm \$(address)
2203 - You can also escape text by enclosing in single apostrophes, for example:
2204 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2209 - similar to Bourne shell, with control structures like
2210 if...then...else...fi, for...do...done; while...do...done,
2211 until...do...done, ...
2212 - supports environment ("global") variables (through setenv / saveenv
2213 commands) and local shell variables (through standard shell syntax
2214 "name=value"); only environment variables can be used with "run"
2220 (1) If a command line (or an environment variable executed by a "run"
2221 command) contains several commands separated by semicolon, and
2222 one of these commands fails, then the remaining commands will be
2225 (2) If you execute several variables with one call to run (i. e.
2226 calling run with a list af variables as arguments), any failing
2227 command will cause "run" to terminate, i. e. the remaining
2228 variables are not executed.
2230 Note for Redundant Ethernet Interfaces:
2231 =======================================
2233 Some boards come with redundand ethernet interfaces; U-Boot supports
2234 such configurations and is capable of automatic selection of a
2235 "working" interface when needed. MAC assignemnt works as follows:
2237 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2238 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2239 "eth1addr" (=>eth1), "eth2addr", ...
2241 If the network interface stores some valid MAC address (for instance
2242 in SROM), this is used as default address if there is NO correspon-
2243 ding setting in the environment; if the corresponding environment
2244 variable is set, this overrides the settings in the card; that means:
2246 o If the SROM has a valid MAC address, and there is no address in the
2247 environment, the SROM's address is used.
2249 o If there is no valid address in the SROM, and a definition in the
2250 environment exists, then the value from the environment variable is
2253 o If both the SROM and the environment contain a MAC address, and
2254 both addresses are the same, this MAC address is used.
2256 o If both the SROM and the environment contain a MAC address, and the
2257 addresses differ, the value from the environment is used and a
2260 o If neither SROM nor the environment contain a MAC address, an error
2267 The "boot" commands of this monitor operate on "image" files which
2268 can be basicly anything, preceeded by a special header; see the
2269 definitions in include/image.h for details; basicly, the header
2270 defines the following image properties:
2272 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2273 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2274 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2275 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2276 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2277 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2278 Currently supported: PowerPC).
2279 * Compression Type (uncompressed, gzip, bzip2)
2285 The header is marked by a special Magic Number, and both the header
2286 and the data portions of the image are secured against corruption by
2293 Although U-Boot should support any OS or standalone application
2294 easily, Linux has always been in the focus during the design of
2297 U-Boot includes many features that so far have been part of some
2298 special "boot loader" code within the Linux kernel. Also, any
2299 "initrd" images to be used are no longer part of one big Linux image;
2300 instead, kernel and "initrd" are separate images. This implementation
2301 serves serveral purposes:
2303 - the same features can be used for other OS or standalone
2304 applications (for instance: using compressed images to reduce the
2305 Flash memory footprint)
2307 - it becomes much easier to port new Linux kernel versions because
2308 lots of low-level, hardware dependend stuff are done by U-Boot
2310 - the same Linux kernel image can now be used with different "initrd"
2311 images; of course this also means that different kernel images can
2312 be run with the same "initrd". This makes testing easier (you don't
2313 have to build a new "zImage.initrd" Linux image when you just
2314 change a file in your "initrd"). Also, a field-upgrade of the
2315 software is easier now.
2321 Porting Linux to U-Boot based systems:
2322 ---------------------------------------
2324 U-Boot cannot save you from doing all the necessary modifications to
2325 configure the Linux device drivers for use with your target hardware
2326 (no, we don't intend to provide a full virtual machine interface to
2329 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2331 Just make sure your machine specific header file (for instance
2332 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2333 Information structure as we define in include/u-boot.h, and make
2334 sure that your definition of IMAP_ADDR uses the same value as your
2335 U-Boot configuration in CFG_IMMR.
2338 Configuring the Linux kernel:
2339 -----------------------------
2341 No specific requirements for U-Boot. Make sure you have some root
2342 device (initial ramdisk, NFS) for your target system.
2345 Building a Linux Image:
2346 -----------------------
2348 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2349 not used. If you use recent kernel source, a new build target
2350 "uImage" will exist which automatically builds an image usable by
2351 U-Boot. Most older kernels also have support for a "pImage" target,
2352 which was introduced for our predecessor project PPCBoot and uses a
2353 100% compatible format.
2362 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2363 encapsulate a compressed Linux kernel image with header information,
2364 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2366 * build a standard "vmlinux" kernel image (in ELF binary format):
2368 * convert the kernel into a raw binary image:
2370 ${CROSS_COMPILE}-objcopy -O binary \
2371 -R .note -R .comment \
2372 -S vmlinux linux.bin
2374 * compress the binary image:
2378 * package compressed binary image for U-Boot:
2380 mkimage -A ppc -O linux -T kernel -C gzip \
2381 -a 0 -e 0 -n "Linux Kernel Image" \
2382 -d linux.bin.gz uImage
2385 The "mkimage" tool can also be used to create ramdisk images for use
2386 with U-Boot, either separated from the Linux kernel image, or
2387 combined into one file. "mkimage" encapsulates the images with a 64
2388 byte header containing information about target architecture,
2389 operating system, image type, compression method, entry points, time
2390 stamp, CRC32 checksums, etc.
2392 "mkimage" can be called in two ways: to verify existing images and
2393 print the header information, or to build new images.
2395 In the first form (with "-l" option) mkimage lists the information
2396 contained in the header of an existing U-Boot image; this includes
2397 checksum verification:
2399 tools/mkimage -l image
2400 -l ==> list image header information
2402 The second form (with "-d" option) is used to build a U-Boot image
2403 from a "data file" which is used as image payload:
2405 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2406 -n name -d data_file image
2407 -A ==> set architecture to 'arch'
2408 -O ==> set operating system to 'os'
2409 -T ==> set image type to 'type'
2410 -C ==> set compression type 'comp'
2411 -a ==> set load address to 'addr' (hex)
2412 -e ==> set entry point to 'ep' (hex)
2413 -n ==> set image name to 'name'
2414 -d ==> use image data from 'datafile'
2416 Right now, all Linux kernels use the same load address (0x00000000),
2417 but the entry point address depends on the kernel version:
2419 - 2.2.x kernels have the entry point at 0x0000000C,
2420 - 2.3.x and later kernels have the entry point at 0x00000000.
2422 So a typical call to build a U-Boot image would read:
2424 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2425 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2426 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2427 > examples/uImage.TQM850L
2428 Image Name: 2.4.4 kernel for TQM850L
2429 Created: Wed Jul 19 02:34:59 2000
2430 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2431 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2432 Load Address: 0x00000000
2433 Entry Point: 0x00000000
2435 To verify the contents of the image (or check for corruption):
2437 -> tools/mkimage -l examples/uImage.TQM850L
2438 Image Name: 2.4.4 kernel for TQM850L
2439 Created: Wed Jul 19 02:34:59 2000
2440 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2441 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2442 Load Address: 0x00000000
2443 Entry Point: 0x00000000
2445 NOTE: for embedded systems where boot time is critical you can trade
2446 speed for memory and install an UNCOMPRESSED image instead: this
2447 needs more space in Flash, but boots much faster since it does not
2448 need to be uncompressed:
2450 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2451 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2452 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2453 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2454 > examples/uImage.TQM850L-uncompressed
2455 Image Name: 2.4.4 kernel for TQM850L
2456 Created: Wed Jul 19 02:34:59 2000
2457 Image Type: PowerPC Linux Kernel Image (uncompressed)
2458 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2459 Load Address: 0x00000000
2460 Entry Point: 0x00000000
2463 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2464 when your kernel is intended to use an initial ramdisk:
2466 -> tools/mkimage -n 'Simple Ramdisk Image' \
2467 > -A ppc -O linux -T ramdisk -C gzip \
2468 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2469 Image Name: Simple Ramdisk Image
2470 Created: Wed Jan 12 14:01:50 2000
2471 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2472 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2473 Load Address: 0x00000000
2474 Entry Point: 0x00000000
2477 Installing a Linux Image:
2478 -------------------------
2480 To downloading a U-Boot image over the serial (console) interface,
2481 you must convert the image to S-Record format:
2483 objcopy -I binary -O srec examples/image examples/image.srec
2485 The 'objcopy' does not understand the information in the U-Boot
2486 image header, so the resulting S-Record file will be relative to
2487 address 0x00000000. To load it to a given address, you need to
2488 specify the target address as 'offset' parameter with the 'loads'
2491 Example: install the image to address 0x40100000 (which on the
2492 TQM8xxL is in the first Flash bank):
2494 => erase 40100000 401FFFFF
2500 ## Ready for S-Record download ...
2501 ~>examples/image.srec
2502 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2504 15989 15990 15991 15992
2505 [file transfer complete]
2507 ## Start Addr = 0x00000000
2510 You can check the success of the download using the 'iminfo' command;
2511 this includes a checksum verification so you can be sure no data
2512 corruption happened:
2516 ## Checking Image at 40100000 ...
2517 Image Name: 2.2.13 for initrd on TQM850L
2518 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2519 Data Size: 335725 Bytes = 327 kB = 0 MB
2520 Load Address: 00000000
2521 Entry Point: 0000000c
2522 Verifying Checksum ... OK
2528 The "bootm" command is used to boot an application that is stored in
2529 memory (RAM or Flash). In case of a Linux kernel image, the contents
2530 of the "bootargs" environment variable is passed to the kernel as
2531 parameters. You can check and modify this variable using the
2532 "printenv" and "setenv" commands:
2535 => printenv bootargs
2536 bootargs=root=/dev/ram
2538 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2540 => printenv bootargs
2541 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2544 ## Booting Linux kernel at 40020000 ...
2545 Image Name: 2.2.13 for NFS on TQM850L
2546 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2547 Data Size: 381681 Bytes = 372 kB = 0 MB
2548 Load Address: 00000000
2549 Entry Point: 0000000c
2550 Verifying Checksum ... OK
2551 Uncompressing Kernel Image ... OK
2552 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
2553 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2554 time_init: decrementer frequency = 187500000/60
2555 Calibrating delay loop... 49.77 BogoMIPS
2556 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2559 If you want to boot a Linux kernel with initial ram disk, you pass
2560 the memory addreses of both the kernel and the initrd image (PPBCOOT
2561 format!) to the "bootm" command:
2563 => imi 40100000 40200000
2565 ## Checking Image at 40100000 ...
2566 Image Name: 2.2.13 for initrd on TQM850L
2567 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2568 Data Size: 335725 Bytes = 327 kB = 0 MB
2569 Load Address: 00000000
2570 Entry Point: 0000000c
2571 Verifying Checksum ... OK
2573 ## Checking Image at 40200000 ...
2574 Image Name: Simple Ramdisk Image
2575 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2576 Data Size: 566530 Bytes = 553 kB = 0 MB
2577 Load Address: 00000000
2578 Entry Point: 00000000
2579 Verifying Checksum ... OK
2581 => bootm 40100000 40200000
2582 ## Booting Linux kernel at 40100000 ...
2583 Image Name: 2.2.13 for initrd on TQM850L
2584 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2585 Data Size: 335725 Bytes = 327 kB = 0 MB
2586 Load Address: 00000000
2587 Entry Point: 0000000c
2588 Verifying Checksum ... OK
2589 Uncompressing Kernel Image ... OK
2590 ## Loading RAMDisk Image at 40200000 ...
2591 Image Name: Simple Ramdisk Image
2592 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2593 Data Size: 566530 Bytes = 553 kB = 0 MB
2594 Load Address: 00000000
2595 Entry Point: 00000000
2596 Verifying Checksum ... OK
2597 Loading Ramdisk ... OK
2598 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
2599 Boot arguments: root=/dev/ram
2600 time_init: decrementer frequency = 187500000/60
2601 Calibrating delay loop... 49.77 BogoMIPS
2603 RAMDISK: Compressed image found at block 0
2604 VFS: Mounted root (ext2 filesystem).
2608 More About U-Boot Image Types:
2609 ------------------------------
2611 U-Boot supports the following image types:
2613 "Standalone Programs" are directly runnable in the environment
2614 provided by U-Boot; it is expected that (if they behave
2615 well) you can continue to work in U-Boot after return from
2616 the Standalone Program.
2617 "OS Kernel Images" are usually images of some Embedded OS which
2618 will take over control completely. Usually these programs
2619 will install their own set of exception handlers, device
2620 drivers, set up the MMU, etc. - this means, that you cannot
2621 expect to re-enter U-Boot except by resetting the CPU.
2622 "RAMDisk Images" are more or less just data blocks, and their
2623 parameters (address, size) are passed to an OS kernel that is
2625 "Multi-File Images" contain several images, typically an OS
2626 (Linux) kernel image and one or more data images like
2627 RAMDisks. This construct is useful for instance when you want
2628 to boot over the network using BOOTP etc., where the boot
2629 server provides just a single image file, but you want to get
2630 for instance an OS kernel and a RAMDisk image.
2632 "Multi-File Images" start with a list of image sizes, each
2633 image size (in bytes) specified by an "uint32_t" in network
2634 byte order. This list is terminated by an "(uint32_t)0".
2635 Immediately after the terminating 0 follow the images, one by
2636 one, all aligned on "uint32_t" boundaries (size rounded up to
2637 a multiple of 4 bytes).
2639 "Firmware Images" are binary images containing firmware (like
2640 U-Boot or FPGA images) which usually will be programmed to
2643 "Script files" are command sequences that will be executed by
2644 U-Boot's command interpreter; this feature is especially
2645 useful when you configure U-Boot to use a real shell (hush)
2646 as command interpreter.
2652 One of the features of U-Boot is that you can dynamically load and
2653 run "standalone" applications, which can use some resources of
2654 U-Boot like console I/O functions or interrupt services.
2656 Two simple examples are included with the sources:
2661 'examples/hello_world.c' contains a small "Hello World" Demo
2662 application; it is automatically compiled when you build U-Boot.
2663 It's configured to run at address 0x00040004, so you can play with it
2667 ## Ready for S-Record download ...
2668 ~>examples/hello_world.srec
2669 1 2 3 4 5 6 7 8 9 10 11 ...
2670 [file transfer complete]
2672 ## Start Addr = 0x00040004
2674 => go 40004 Hello World! This is a test.
2675 ## Starting application at 0x00040004 ...
2686 Hit any key to exit ...
2688 ## Application terminated, rc = 0x0
2690 Another example, which demonstrates how to register a CPM interrupt
2691 handler with the U-Boot code, can be found in 'examples/timer.c'.
2692 Here, a CPM timer is set up to generate an interrupt every second.
2693 The interrupt service routine is trivial, just printing a '.'
2694 character, but this is just a demo program. The application can be
2695 controlled by the following keys:
2697 ? - print current values og the CPM Timer registers
2698 b - enable interrupts and start timer
2699 e - stop timer and disable interrupts
2700 q - quit application
2703 ## Ready for S-Record download ...
2704 ~>examples/timer.srec
2705 1 2 3 4 5 6 7 8 9 10 11 ...
2706 [file transfer complete]
2708 ## Start Addr = 0x00040004
2711 ## Starting application at 0x00040004 ...
2714 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2717 [q, b, e, ?] Set interval 1000000 us
2720 [q, b, e, ?] ........
2721 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2724 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2727 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2730 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2732 [q, b, e, ?] ...Stopping timer
2734 [q, b, e, ?] ## Application terminated, rc = 0x0
2740 Over time, many people have reported problems when trying to used the
2741 "minicom" terminal emulation program for serial download. I (wd)
2742 consider minicom to be broken, and recommend not to use it. Under
2743 Unix, I recommend to use C-Kermit for general purpose use (and
2744 especially for kermit binary protocol download ("loadb" command), and
2745 use "cu" for S-Record download ("loads" command).
2747 Nevertheless, if you absolutely want to use it try adding this
2748 configuration to your "File transfer protocols" section:
2750 Name Program Name U/D FullScr IO-Red. Multi
2751 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2752 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2758 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2759 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2761 Building requires a cross environment; it is known to work on
2762 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2763 need gmake since the Makefiles are not compatible with BSD make).
2764 Note that the cross-powerpc package does not install include files;
2765 attempting to build U-Boot will fail because <machine/ansi.h> is
2766 missing. This file has to be installed and patched manually:
2768 # cd /usr/pkg/cross/powerpc-netbsd/include
2770 # ln -s powerpc machine
2771 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2772 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2774 Native builds *don't* work due to incompatibilities between native
2775 and U-Boot include files.
2777 Booting assumes that (the first part of) the image booted is a
2778 stage-2 loader which in turn loads and then invokes the kernel
2779 proper. Loader sources will eventually appear in the NetBSD source
2780 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2781 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2785 Implementation Internals:
2786 =========================
2788 The following is not intended to be a complete description of every
2789 implementation detail. However, it should help to understand the
2790 inner workings of U-Boot and make it easier to port it to custom
2794 Initial Stack, Global Data:
2795 ---------------------------
2797 The implementation of U-Boot is complicated by the fact that U-Boot
2798 starts running out of ROM (flash memory), usually without access to
2799 system RAM (because the memory controller is not initialized yet).
2800 This means that we don't have writable Data or BSS segments, and BSS
2801 is not initialized as zero. To be able to get a C environment working
2802 at all, we have to allocate at least a minimal stack. Implementation
2803 options for this are defined and restricted by the CPU used: Some CPU
2804 models provide on-chip memory (like the IMMR area on MPC8xx and
2805 MPC826x processors), on others (parts of) the data cache can be
2806 locked as (mis-) used as memory, etc.
2808 Chris Hallinan posted a good summy of these issues to the
2809 u-boot-users mailing list:
2811 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2812 From: "Chris Hallinan" <clh@net1plus.com>
2813 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2816 Correct me if I'm wrong, folks, but the way I understand it
2817 is this: Using DCACHE as initial RAM for Stack, etc, does not
2818 require any physical RAM backing up the cache. The cleverness
2819 is that the cache is being used as a temporary supply of
2820 necessary storage before the SDRAM controller is setup. It's
2821 beyond the scope of this list to expain the details, but you
2822 can see how this works by studying the cache architecture and
2823 operation in the architecture and processor-specific manuals.
2825 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2826 is another option for the system designer to use as an
2827 initial stack/ram area prior to SDRAM being available. Either
2828 option should work for you. Using CS 4 should be fine if your
2829 board designers haven't used it for something that would
2830 cause you grief during the initial boot! It is frequently not
2833 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2834 with your processor/board/system design. The default value
2835 you will find in any recent u-boot distribution in
2836 Walnut405.h should work for you. I'd set it to a value larger
2837 than your SDRAM module. If you have a 64MB SDRAM module, set
2838 it above 400_0000. Just make sure your board has no resources
2839 that are supposed to respond to that address! That code in
2840 start.S has been around a while and should work as is when
2841 you get the config right.
2846 It is essential to remember this, since it has some impact on the C
2847 code for the initialization procedures:
2849 * Initialized global data (data segment) is read-only. Do not attempt
2852 * Do not use any unitialized global data (or implicitely initialized
2853 as zero data - BSS segment) at all - this is undefined, initiali-
2854 zation is performed later (when relocationg to RAM).
2856 * Stack space is very limited. Avoid big data buffers or things like
2859 Having only the stack as writable memory limits means we cannot use
2860 normal global data to share information beween the code. But it
2861 turned out that the implementation of U-Boot can be greatly
2862 simplified by making a global data structure (gd_t) available to all
2863 functions. We could pass a pointer to this data as argument to _all_
2864 functions, but this would bloat the code. Instead we use a feature of
2865 the GCC compiler (Global Register Variables) to share the data: we
2866 place a pointer (gd) to the global data into a register which we
2867 reserve for this purpose.
2869 When chosing a register for such a purpose we are restricted by the
2870 relevant (E)ABI specifications for the current architecture, and by
2871 GCC's implementation.
2873 For PowerPC, the following registers have specific use:
2876 R3-R4: parameter passing and return values
2877 R5-R10: parameter passing
2878 R13: small data area pointer
2882 (U-Boot also uses R14 as internal GOT pointer.)
2884 ==> U-Boot will use R29 to hold a pointer to the global data
2886 Note: on PPC, we could use a static initializer (since the
2887 address of the global data structure is known at compile time),
2888 but it turned out that reserving a register results in somewhat
2889 smaller code - although the code savings are not that big (on
2890 average for all boards 752 bytes for the whole U-Boot image,
2891 624 text + 127 data).
2893 On ARM, the following registers are used:
2895 R0: function argument word/integer result
2896 R1-R3: function argument word
2898 R10: stack limit (used only if stack checking if enabled)
2899 R11: argument (frame) pointer
2900 R12: temporary workspace
2903 R15: program counter
2905 ==> U-Boot will use R8 to hold a pointer to the global data
2911 U-Boot runs in system state and uses physical addresses, i.e. the
2912 MMU is not used either for address mapping nor for memory protection.
2914 The available memory is mapped to fixed addresses using the memory
2915 controller. In this process, a contiguous block is formed for each
2916 memory type (Flash, SDRAM, SRAM), even when it consists of several
2917 physical memory banks.
2919 U-Boot is installed in the first 128 kB of the first Flash bank (on
2920 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2921 booting and sizing and initializing DRAM, the code relocates itself
2922 to the upper end of DRAM. Immediately below the U-Boot code some
2923 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2924 configuration setting]. Below that, a structure with global Board
2925 Info data is placed, followed by the stack (growing downward).
2927 Additionally, some exception handler code is copied to the low 8 kB
2928 of DRAM (0x00000000 ... 0x00001FFF).
2930 So a typical memory configuration with 16 MB of DRAM could look like
2933 0x0000 0000 Exception Vector code
2936 0x0000 2000 Free for Application Use
2942 0x00FB FF20 Monitor Stack (Growing downward)
2943 0x00FB FFAC Board Info Data and permanent copy of global data
2944 0x00FC 0000 Malloc Arena
2947 0x00FE 0000 RAM Copy of Monitor Code
2948 ... eventually: LCD or video framebuffer
2949 ... eventually: pRAM (Protected RAM - unchanged by reset)
2950 0x00FF FFFF [End of RAM]
2953 System Initialization:
2954 ----------------------
2956 In the reset configuration, U-Boot starts at the reset entry point
2957 (on most PowerPC systens at address 0x00000100). Because of the reset
2958 configuration for CS0# this is a mirror of the onboard Flash memory.
2959 To be able to re-map memory U-Boot then jumps to it's link address.
2960 To be able to implement the initialization code in C, a (small!)
2961 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2962 which provide such a feature like MPC8xx or MPC8260), or in a locked
2963 part of the data cache. After that, U-Boot initializes the CPU core,
2964 the caches and the SIU.
2966 Next, all (potentially) available memory banks are mapped using a
2967 preliminary mapping. For example, we put them on 512 MB boundaries
2968 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2969 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2970 programmed for SDRAM access. Using the temporary configuration, a
2971 simple memory test is run that determines the size of the SDRAM
2974 When there is more than one SDRAM bank, and the banks are of
2975 different size, the larger is mapped first. For equal size, the first
2976 bank (CS2#) is mapped first. The first mapping is always for address
2977 0x00000000, with any additional banks following immediately to create
2978 contiguous memory starting from 0.
2980 Then, the monitor installs itself at the upper end of the SDRAM area
2981 and allocates memory for use by malloc() and for the global Board
2982 Info data; also, the exception vector code is copied to the low RAM
2983 pages, and the final stack is set up.
2985 Only after this relocation will you have a "normal" C environment;
2986 until that you are restricted in several ways, mostly because you are
2987 running from ROM, and because the code will have to be relocated to a
2991 U-Boot Porting Guide:
2992 ----------------------
2994 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2998 int main (int argc, char *argv[])
3000 sighandler_t no_more_time;
3002 signal (SIGALRM, no_more_time);
3003 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3005 if (available_money > available_manpower) {
3006 pay consultant to port U-Boot;
3010 Download latest U-Boot source;
3012 Subscribe to u-boot-users mailing list;
3015 email ("Hi, I am new to U-Boot, how do I get started?");
3019 Read the README file in the top level directory;
3020 Read http://www.denx.de/re/DPLG.html
3021 Read the source, Luke;
3024 if (available_money > toLocalCurrency ($2500)) {
3027 Add a lot of aggravation and time;
3030 Create your own board support subdirectory;
3032 Create your own board config file;
3036 Add / modify source code;
3040 email ("Hi, I am having problems...");
3042 Send patch file to Wolfgang;
3047 void no_more_time (int sig)
3056 All contributions to U-Boot should conform to the Linux kernel
3057 coding style; see the file "Documentation/CodingStyle" in your Linux
3058 kernel source directory.
3060 Please note that U-Boot is implemented in C (and to some small parts
3061 in Assembler); no C++ is used, so please do not use C++ style
3062 comments (//) in your code.
3064 Submissions which do not conform to the standards may be returned
3065 with a request to reformat the changes.
3071 Since the number of patches for U-Boot is growing, we need to
3072 establish some rules. Submissions which do not conform to these rules
3073 may be rejected, even when they contain important and valuable stuff.
3076 When you send a patch, please include the following information with
3079 * For bug fixes: a description of the bug and how your patch fixes
3080 this bug. Please try to include a way of demonstrating that the
3081 patch actually fixes something.
3083 * For new features: a description of the feature and your
3086 * A CHANGELOG entry as plaintext (separate from the patch)
3088 * For major contributions, your entry to the CREDITS file
3090 * When you add support for a new board, don't forget to add this
3091 board to the MAKEALL script, too.
3093 * If your patch adds new configuration options, don't forget to
3094 document these in the README file.
3096 * The patch itself. If you are accessing the CVS repository use "cvs
3097 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3098 version of diff does not support these options, then get the latest
3099 version of GNU diff.
3101 The current directory when running this command shall be the top
3102 level directory of the U-Boot source tree, or it's parent directory
3103 (i. e. please make sure that your patch includes sufficient
3104 directory information for the affected files).
3106 We accept patches as plain text, MIME attachments or as uuencoded
3109 * If one logical set of modifications affects or creates several
3110 files, all these changes shall be submitted in a SINGLE patch file.
3112 * Changesets that contain different, unrelated modifications shall be
3113 submitted as SEPARATE patches, one patch per changeset.
3118 * Before sending the patch, run the MAKEALL script on your patched
3119 source tree and make sure that no errors or warnings are reported
3120 for any of the boards.
3122 * Keep your modifications to the necessary minimum: A patch
3123 containing several unrelated changes or arbitrary reformats will be
3124 returned with a request to re-formatting / split it.
3126 * If you modify existing code, make sure that your new code does not
3127 add to the memory footprint of the code ;-) Small is beautiful!
3128 When adding new features, these should compile conditionally only
3129 (using #ifdef), and the resulting code with the new feature
3130 disabled must not need more memory than the old code without your