2 # (C) Copyright 2000 - 2004
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # See file CREDITS for list of people who contributed to this
8 # This program is free software; you can redistribute it and/or
9 # modify it under the terms of the GNU General Public License as
10 # published by the Free Software Foundation; either version 2 of
11 # the License, or (at your option) any later version.
13 # This program is distributed in the hope that it will be useful,
14 # but WITHOUT ANY WARRANTY; without even the implied warranty of
15 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 # GNU General Public License for more details.
18 # You should have received a copy of the GNU General Public License
19 # along with this program; if not, write to the Free Software
20 # Foundation, Inc., 59 Temple Place, Suite 330, Boston,
27 This directory contains the source code for U-Boot, a boot loader for
28 Embedded boards based on PowerPC and ARM processors, which can be
29 installed in a boot ROM and used to initialize and test the hardware
30 or to download and run application code.
32 The development of U-Boot is closely related to Linux: some parts of
33 the source code originate in the Linux source tree, we have some
34 header files in common, and special provision has been made to
35 support booting of Linux images.
37 Some attention has been paid to make this software easily
38 configurable and extendable. For instance, all monitor commands are
39 implemented with the same call interface, so that it's very easy to
40 add new commands. Also, instead of permanently adding rarely used
41 code (for instance hardware test utilities) to the monitor, you can
42 load and run it dynamically.
48 In general, all boards for which a configuration option exists in the
49 Makefile have been tested to some extent and can be considered
50 "working". In fact, many of them are used in production systems.
52 In case of problems see the CHANGELOG and CREDITS files to find out
53 who contributed the specific port.
59 In case you have questions about, problems with or contributions for
60 U-Boot you should send a message to the U-Boot mailing list at
61 <u-boot-users@lists.sourceforge.net>. There is also an archive of
62 previous traffic on the mailing list - please search the archive
63 before asking FAQ's. Please see
64 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
70 - start from 8xxrom sources
71 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73 - make it easier to add custom boards
74 - make it possible to add other [PowerPC] CPUs
75 - extend functions, especially:
76 * Provide extended interface to Linux boot loader
79 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80 - create ARMBoot project (http://sourceforge.net/projects/armboot)
81 - add other CPU families (starting with ARM)
82 - create U-Boot project (http://sourceforge.net/projects/u-boot)
88 The "official" name of this project is "Das U-Boot". The spelling
89 "U-Boot" shall be used in all written text (documentation, comments
90 in source files etc.). Example:
92 This is the README file for the U-Boot project.
94 File names etc. shall be based on the string "u-boot". Examples:
96 include/asm-ppc/u-boot.h
98 #include <asm/u-boot.h>
100 Variable names, preprocessor constants etc. shall be either based on
101 the string "u_boot" or on "U_BOOT". Example:
103 U_BOOT_VERSION u_boot_logo
104 IH_OS_U_BOOT u_boot_hush_start
110 U-Boot uses a 3 level version number containing a version, a
111 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112 sub-version "34", and patchlevel "4".
114 The patchlevel is used to indicate certain stages of development
115 between released versions, i. e. officially released versions of
116 U-Boot will always have a patchlevel of "0".
122 - board Board dependent files
123 - common Misc architecture independent functions
124 - cpu CPU specific files
125 - 74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
126 - arm720t Files specific to ARM 720 CPUs
127 - arm920t Files specific to ARM 920 CPUs
128 - arm925t Files specific to ARM 925 CPUs
129 - arm926ejs Files specific to ARM 926 CPUs
130 - at91rm9200 Files specific to Atmel AT91RM9200 CPUs
131 - i386 Files specific to i386 CPUs
132 - ixp Files specific to Intel XScale IXP CPUs
133 - mcf52x2 Files specific to Motorola ColdFire MCF52x2 CPUs
134 - mips Files specific to MIPS CPUs
135 - mpc5xx Files specific to Motorola MPC5xx CPUs
136 - mpc5xxx Files specific to Motorola MPC5xxx CPUs
137 - mpc8xx Files specific to Motorola MPC8xx CPUs
138 - mpc824x Files specific to Motorola MPC824x CPUs
139 - mpc8260 Files specific to Motorola MPC8260 CPUs
140 - mpc85xx Files specific to Motorola MPC85xx CPUs
141 - nios Files specific to Altera NIOS CPUs
142 - ppc4xx Files specific to IBM PowerPC 4xx CPUs
143 - pxa Files specific to Intel XScale PXA CPUs
144 - s3c44b0 Files specific to Samsung S3C44B0 CPUs
145 - sa1100 Files specific to Intel StrongARM SA1100 CPUs
146 - disk Code for disk drive partition handling
147 - doc Documentation (don't expect too much)
148 - drivers Commonly used device drivers
149 - dtt Digital Thermometer and Thermostat drivers
150 - examples Example code for standalone applications, etc.
151 - include Header Files
152 - lib_arm Files generic to ARM architecture
153 - lib_generic Files generic to all architectures
154 - lib_i386 Files generic to i386 architecture
155 - lib_m68k Files generic to m68k architecture
156 - lib_mips Files generic to MIPS architecture
157 - lib_nios Files generic to NIOS architecture
158 - lib_ppc Files generic to PowerPC architecture
159 - net Networking code
160 - post Power On Self Test
161 - rtc Real Time Clock drivers
162 - tools Tools to build S-Record or U-Boot images, etc.
164 Software Configuration:
165 =======================
167 Configuration is usually done using C preprocessor defines; the
168 rationale behind that is to avoid dead code whenever possible.
170 There are two classes of configuration variables:
172 * Configuration _OPTIONS_:
173 These are selectable by the user and have names beginning with
176 * Configuration _SETTINGS_:
177 These depend on the hardware etc. and should not be meddled with if
178 you don't know what you're doing; they have names beginning with
181 Later we will add a configuration tool - probably similar to or even
182 identical to what's used for the Linux kernel. Right now, we have to
183 do the configuration by hand, which means creating some symbolic
184 links and editing some configuration files. We use the TQM8xxL boards
188 Selection of Processor Architecture and Board Type:
189 ---------------------------------------------------
191 For all supported boards there are ready-to-use default
192 configurations available; just type "make <board_name>_config".
194 Example: For a TQM823L module type:
199 For the Cogent platform, you need to specify the cpu type as well;
200 e.g. "make cogent_mpc8xx_config". And also configure the cogent
201 directory according to the instructions in cogent/README.
204 Configuration Options:
205 ----------------------
207 Configuration depends on the combination of board and CPU type; all
208 such information is kept in a configuration file
209 "include/configs/<board_name>.h".
211 Example: For a TQM823L module, all configuration settings are in
212 "include/configs/TQM823L.h".
215 Many of the options are named exactly as the corresponding Linux
216 kernel configuration options. The intention is to make it easier to
217 build a config tool - later.
220 The following options need to be configured:
222 - CPU Type: Define exactly one of
226 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
228 or CONFIG_MPC824X, CONFIG_MPC8260
244 - Board Type: Define exactly one of
246 PowerPC based boards:
247 ---------------------
249 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
250 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
251 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
252 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
253 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
254 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
255 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
256 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
257 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
258 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
259 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
260 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
261 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
262 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
263 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
264 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
265 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
266 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
267 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
268 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
269 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
270 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
271 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
272 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
273 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
274 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
275 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
276 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
277 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
278 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
279 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
280 CONFIG_NETVIA, CONFIG_RBC823, CONFIG_ZPC1900,
281 CONFIG_MPC8540ADS, CONFIG_MPC8560ADS, CONFIG_QS850,
282 CONFIG_QS823, CONFIG_QS860T, CONFIG_DB64360,
283 CONFIG_DB64460, CONFIG_DUET_ADS
288 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
289 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
290 CONFIG_INNOVATOROMAP1510, CONFIG_INNOVATOROMAP1610,
291 CONFIG_H2_OMAP1610, CONFIG_SHANNON, CONFIG_SMDK2400,
292 CONFIG_SMDK2410, CONFIG_TRAB, CONFIG_VCMA9,
296 - CPU Module Type: (if CONFIG_COGENT is defined)
297 Define exactly one of
299 --- FIXME --- not tested yet:
300 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
301 CONFIG_CMA287_23, CONFIG_CMA287_50
303 - Motherboard Type: (if CONFIG_COGENT is defined)
304 Define exactly one of
305 CONFIG_CMA101, CONFIG_CMA102
307 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
308 Define one or more of
311 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
312 Define one or more of
313 CONFIG_LCD_HEARTBEAT - update a character position on
314 the lcd display every second with
317 - Board flavour: (if CONFIG_MPC8260ADS is defined)
320 CFG_8260ADS - original MPC8260ADS
321 CFG_8266ADS - MPC8266ADS
322 CFG_PQ2FADS - PQ2FADS-ZU or PQ2FADS-VR
325 - MPC824X Family Member (if CONFIG_MPC824X is defined)
326 Define exactly one of
327 CONFIG_MPC8240, CONFIG_MPC8245
329 - 8xx CPU Options: (if using an MPC8xx cpu)
330 Define one or more of
331 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() cannot work
332 e.g. if there is no 32KHz
333 reference PIT/RTC clock
335 - 859/866 CPU options: (if using a MPC859 or MPC866 CPU):
339 CFG_866_CPUCLK_DEFAULT
340 See doc/README.MPC866
344 Define this to measure the actual CPU clock instead
345 of relying on the correctness of the configured
346 values. Mostly useful for board bringup to make sure
347 the PLL is locked at the intended frequency. Note
348 that this requires a (stable) reference clock (32 kHz
351 - Linux Kernel Interface:
354 U-Boot stores all clock information in Hz
355 internally. For binary compatibility with older Linux
356 kernels (which expect the clocks passed in the
357 bd_info data to be in MHz) the environment variable
358 "clocks_in_mhz" can be defined so that U-Boot
359 converts clock data to MHZ before passing it to the
361 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
362 "clocks_in_mhz=1" is automatically included in the
365 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
367 When transfering memsize parameter to linux, some versions
368 expect it to be in bytes, others in MB.
369 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
372 Depending on board, define exactly one serial port
373 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
374 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
375 console by defining CONFIG_8xx_CONS_NONE
377 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
378 port routines must be defined elsewhere
379 (i.e. serial_init(), serial_getc(), ...)
382 Enables console device for a color framebuffer. Needs following
383 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
384 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
386 VIDEO_HW_RECTFILL graphic chip supports
389 VIDEO_HW_BITBLT graphic chip supports
390 bit-blit (cf. smiLynxEM)
391 VIDEO_VISIBLE_COLS visible pixel columns
393 VIDEO_VISIBLE_ROWS visible pixel rows
394 VIDEO_PIXEL_SIZE bytes per pixel
395 VIDEO_DATA_FORMAT graphic data format
396 (0-5, cf. cfb_console.c)
397 VIDEO_FB_ADRS framebuffer address
398 VIDEO_KBD_INIT_FCT keyboard int fct
399 (i.e. i8042_kbd_init())
400 VIDEO_TSTC_FCT test char fct
402 VIDEO_GETC_FCT get char fct
404 CONFIG_CONSOLE_CURSOR cursor drawing on/off
405 (requires blink timer
407 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
408 CONFIG_CONSOLE_TIME display time/date info in
410 (requires CFG_CMD_DATE)
411 CONFIG_VIDEO_LOGO display Linux logo in
413 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
414 linux_logo.h for logo.
415 Requires CONFIG_VIDEO_LOGO
416 CONFIG_CONSOLE_EXTRA_INFO
417 addional board info beside
420 When CONFIG_CFB_CONSOLE is defined, video console is
421 default i/o. Serial console can be forced with
422 environment 'console=serial'.
424 When CONFIG_SILENT_CONSOLE is defined, all console
425 messages (by U-Boot and Linux!) can be silenced with
426 the "silent" environment variable. See
427 doc/README.silent for more information.
430 CONFIG_BAUDRATE - in bps
431 Select one of the baudrates listed in
432 CFG_BAUDRATE_TABLE, see below.
433 CFG_BRGCLK_PRESCALE, baudrate prescale
435 - Interrupt driven serial port input:
436 CONFIG_SERIAL_SOFTWARE_FIFO
439 Use an interrupt handler for receiving data on the
440 serial port. It also enables using hardware handshake
441 (RTS/CTS) and UART's built-in FIFO. Set the number of
442 bytes the interrupt driven input buffer should have.
444 Set to 0 to disable this feature (this is the default).
445 This will also disable hardware handshake.
447 - Console UART Number:
451 If defined internal UART1 (and not UART0) is used
452 as default U-Boot console.
454 - Boot Delay: CONFIG_BOOTDELAY - in seconds
455 Delay before automatically booting the default image;
456 set to -1 to disable autoboot.
458 See doc/README.autoboot for these options that
459 work with CONFIG_BOOTDELAY. None are required.
460 CONFIG_BOOT_RETRY_TIME
461 CONFIG_BOOT_RETRY_MIN
462 CONFIG_AUTOBOOT_KEYED
463 CONFIG_AUTOBOOT_PROMPT
464 CONFIG_AUTOBOOT_DELAY_STR
465 CONFIG_AUTOBOOT_STOP_STR
466 CONFIG_AUTOBOOT_DELAY_STR2
467 CONFIG_AUTOBOOT_STOP_STR2
468 CONFIG_ZERO_BOOTDELAY_CHECK
469 CONFIG_RESET_TO_RETRY
473 Only needed when CONFIG_BOOTDELAY is enabled;
474 define a command string that is automatically executed
475 when no character is read on the console interface
476 within "Boot Delay" after reset.
479 This can be used to pass arguments to the bootm
480 command. The value of CONFIG_BOOTARGS goes into the
481 environment value "bootargs".
483 CONFIG_RAMBOOT and CONFIG_NFSBOOT
484 The value of these goes into the environment as
485 "ramboot" and "nfsboot" respectively, and can be used
486 as a convenience, when switching between booting from
492 When this option is #defined, the existence of the
493 environment variable "preboot" will be checked
494 immediately before starting the CONFIG_BOOTDELAY
495 countdown and/or running the auto-boot command resp.
496 entering interactive mode.
498 This feature is especially useful when "preboot" is
499 automatically generated or modified. For an example
500 see the LWMON board specific code: here "preboot" is
501 modified when the user holds down a certain
502 combination of keys on the (special) keyboard when
505 - Serial Download Echo Mode:
507 If defined to 1, all characters received during a
508 serial download (using the "loads" command) are
509 echoed back. This might be needed by some terminal
510 emulations (like "cu"), but may as well just take
511 time on others. This setting #define's the initial
512 value of the "loads_echo" environment variable.
514 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
516 Select one of the baudrates listed in
517 CFG_BAUDRATE_TABLE, see below.
521 Most monitor functions can be selected (or
522 de-selected) by adjusting the definition of
523 CONFIG_COMMANDS; to select individual functions,
524 #define CONFIG_COMMANDS by "OR"ing any of the
527 #define enables commands:
528 -------------------------
529 CFG_CMD_ASKENV * ask for env variable
530 CFG_CMD_AUTOSCRIPT Autoscript Support
532 CFG_CMD_BEDBUG Include BedBug Debugger
533 CFG_CMD_BMP * BMP support
535 CFG_CMD_CACHE icache, dcache
536 CFG_CMD_CONSOLE coninfo
537 CFG_CMD_DATE * support for RTC, date/time...
538 CFG_CMD_DHCP DHCP support
539 CFG_CMD_DIAG * Diagnostics
540 CFG_CMD_DOC * Disk-On-Chip Support
541 CFG_CMD_DTT Digital Therm and Thermostat
542 CFG_CMD_ECHO * echo arguments
543 CFG_CMD_EEPROM * EEPROM read/write support
544 CFG_CMD_ELF bootelf, bootvx
546 CFG_CMD_FDC * Floppy Disk Support
547 CFG_CMD_FAT FAT partition support
548 CFG_CMD_FDOS * Dos diskette Support
549 CFG_CMD_FLASH flinfo, erase, protect
550 CFG_CMD_FPGA FPGA device initialization support
551 CFG_CMD_HWFLOW * RTS/CTS hw flow control
552 CFG_CMD_I2C * I2C serial bus support
553 CFG_CMD_IDE * IDE harddisk support
555 CFG_CMD_IMLS List all found images
556 CFG_CMD_IMMAP * IMMR dump support
557 CFG_CMD_IRQ * irqinfo
558 CFG_CMD_ITEST * Integer/string test of 2 values
559 CFG_CMD_JFFS2 * JFFS2 Support
563 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
565 CFG_CMD_MISC Misc functions like sleep etc
566 CFG_CMD_MMC MMC memory mapped support
567 CFG_CMD_MII MII utility commands
568 CFG_CMD_NAND * NAND support
569 CFG_CMD_NET bootp, tftpboot, rarpboot
570 CFG_CMD_PCI * pciinfo
571 CFG_CMD_PCMCIA * PCMCIA support
572 CFG_CMD_PING * send ICMP ECHO_REQUEST to network host
573 CFG_CMD_PORTIO * Port I/O
574 CFG_CMD_REGINFO * Register dump
575 CFG_CMD_RUN run command in env variable
576 CFG_CMD_SAVES save S record dump
577 CFG_CMD_SCSI * SCSI Support
578 CFG_CMD_SDRAM * print SDRAM configuration information
579 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
580 CFG_CMD_SPI * SPI serial bus support
581 CFG_CMD_USB * USB support
582 CFG_CMD_VFD * VFD support (TRAB)
583 CFG_CMD_BSP * Board SPecific functions
584 -----------------------------------------------
587 CFG_CMD_DFL Default configuration; at the moment
588 this is includes all commands, except
589 the ones marked with "*" in the list
592 If you don't define CONFIG_COMMANDS it defaults to
593 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
594 override the default settings in the respective
597 EXAMPLE: If you want all functions except of network
598 support you can write:
600 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
603 Note: Don't enable the "icache" and "dcache" commands
604 (configuration option CFG_CMD_CACHE) unless you know
605 what you (and your U-Boot users) are doing. Data
606 cache cannot be enabled on systems like the 8xx or
607 8260 (where accesses to the IMMR region must be
608 uncached), and it cannot be disabled on all other
609 systems where we (mis-) use the data cache to hold an
610 initial stack and some data.
613 XXX - this list needs to get updated!
617 If this variable is defined, it enables watchdog
618 support. There must be support in the platform specific
619 code for a watchdog. For the 8xx and 8260 CPUs, the
620 SIU Watchdog feature is enabled in the SYPCR
624 CONFIG_VERSION_VARIABLE
625 If this variable is defined, an environment variable
626 named "ver" is created by U-Boot showing the U-Boot
627 version as printed by the "version" command.
628 This variable is readonly.
632 When CFG_CMD_DATE is selected, the type of the RTC
633 has to be selected, too. Define exactly one of the
636 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
637 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
638 CONFIG_RTC_MC146818 - use MC146818 RTC
639 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
640 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
641 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
642 CONFIG_RTC_DS164x - use Dallas DS164x RTC
644 Note that if the RTC uses I2C, then the I2C interface
645 must also be configured. See I2C Support, below.
649 When CONFIG_TIMESTAMP is selected, the timestamp
650 (date and time) of an image is printed by image
651 commands like bootm or iminfo. This option is
652 automatically enabled when you select CFG_CMD_DATE .
655 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
656 and/or CONFIG_ISO_PARTITION
658 If IDE or SCSI support is enabled (CFG_CMD_IDE or
659 CFG_CMD_SCSI) you must configure support for at least
660 one partition type as well.
663 CONFIG_IDE_RESET_ROUTINE
665 Set this to define that instead of a reset Pin, the
666 routine ide_set_reset(int idereset) will be used.
671 Set this to enable ATAPI support.
674 At the moment only there is only support for the
675 SYM53C8XX SCSI controller; define
676 CONFIG_SCSI_SYM53C8XX to enable it.
678 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
679 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
680 CFG_SCSI_MAX_LUN] can be adjusted to define the
681 maximum numbers of LUNs, SCSI ID's and target
683 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
685 - NETWORK Support (PCI):
687 Support for Intel 8254x gigabit chips.
690 Support for Intel 82557/82559/82559ER chips.
691 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
692 write routine for first time initialisation.
695 Support for Digital 2114x chips.
696 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
697 modem chip initialisation (KS8761/QS6611).
700 Support for National dp83815 chips.
703 Support for National dp8382[01] gigabit chips.
705 - NETWORK Support (other):
707 CONFIG_DRIVER_LAN91C96
708 Support for SMSC's LAN91C96 chips.
711 Define this to hold the physical address
712 of the LAN91C96's I/O space
714 CONFIG_LAN91C96_USE_32_BIT
715 Define this to enable 32 bit addressing
718 At the moment only the UHCI host controller is
719 supported (PIP405, MIP405); define
720 CONFIG_USB_UHCI to enable it.
721 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
722 end define CONFIG_USB_STORAGE to enable the USB
725 Supported are USB Keyboards and USB Floppy drives
729 The MMC controller on the Intel PXA is supported. To
730 enable this define CONFIG_MMC. The MMC can be
731 accessed from the boot prompt by mapping the device
732 to physical memory similar to flash. Command line is
733 enabled with CFG_CMD_MMC. The MMC driver also works with
734 the FAT fs. This is enabled with CFG_CMD_FAT.
739 Define this to enable standard (PC-Style) keyboard
743 Standard PC keyboard driver with US (is default) and
744 GERMAN key layout (switch via environment 'keymap=de') support.
745 Export function i8042_kbd_init, i8042_tstc and i8042_getc
746 for cfb_console. Supports cursor blinking.
751 Define this to enable video support (for output to
756 Enable Chips & Technologies 69000 Video chip
758 CONFIG_VIDEO_SMI_LYNXEM
759 Enable Silicon Motion SMI 712/710/810 Video chip
760 Videomode are selected via environment 'videomode' with
761 standard LiLo mode numbers.
762 Following modes are supported (* is default):
764 800x600 1024x768 1280x1024
765 256 (8bit) 303* 305 307
766 65536 (16bit) 314 317 31a
767 16,7 Mill (24bit) 315 318 31b
768 (i.e. setenv videomode 317; saveenv; reset;)
770 CONFIG_VIDEO_SED13806
771 Enable Epson SED13806 driver. This driver supports 8bpp
772 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
773 or CONFIG_VIDEO_SED13806_16BPP
778 Define this to enable a custom keyboard support.
779 This simply calls drv_keyboard_init() which must be
780 defined in your board-specific files.
781 The only board using this so far is RBC823.
783 - LCD Support: CONFIG_LCD
785 Define this to enable LCD support (for output to LCD
786 display); also select one of the supported displays
787 by defining one of these:
789 CONFIG_NEC_NL6448AC33:
791 NEC NL6448AC33-18. Active, color, single scan.
793 CONFIG_NEC_NL6448BC20
795 NEC NL6448BC20-08. 6.5", 640x480.
796 Active, color, single scan.
798 CONFIG_NEC_NL6448BC33_54
800 NEC NL6448BC33-54. 10.4", 640x480.
801 Active, color, single scan.
805 Sharp 320x240. Active, color, single scan.
806 It isn't 16x9, and I am not sure what it is.
808 CONFIG_SHARP_LQ64D341
810 Sharp LQ64D341 display, 640x480.
811 Active, color, single scan.
815 HLD1045 display, 640x480.
816 Active, color, single scan.
820 Optrex CBL50840-2 NF-FW 99 22 M5
822 Hitachi LMG6912RPFC-00T
826 320x240. Black & white.
828 Normally display is black on white background; define
829 CFG_WHITE_ON_BLACK to get it inverted.
831 - Splash Screen Support: CONFIG_SPLASH_SCREEN
833 If this option is set, the environment is checked for
834 a variable "splashimage". If found, the usual display
835 of logo, copyright and system information on the LCD
836 is supressed and the BMP image at the address
837 specified in "splashimage" is loaded instead. The
838 console is redirected to the "nulldev", too. This
839 allows for a "silent" boot where a splash screen is
840 loaded very quickly after power-on.
842 - Compression support:
845 If this option is set, support for bzip2 compressed
846 images is included. If not, only uncompressed and gzip
847 compressed images are supported.
849 NOTE: the bzip2 algorithm requires a lot of RAM, so
850 the malloc area (as defined by CFG_MALLOC_LEN) should
858 Define a default value for ethernet address to use
859 for the respective ethernet interface, in case this
860 is not determined automatically.
865 Define a default value for the IP address to use for
866 the default ethernet interface, in case this is not
867 determined through e.g. bootp.
872 Defines a default value for theIP address of a TFTP
873 server to contact when using the "tftboot" command.
875 - BOOTP Recovery Mode:
876 CONFIG_BOOTP_RANDOM_DELAY
878 If you have many targets in a network that try to
879 boot using BOOTP, you may want to avoid that all
880 systems send out BOOTP requests at precisely the same
881 moment (which would happen for instance at recovery
882 from a power failure, when all systems will try to
883 boot, thus flooding the BOOTP server. Defining
884 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
885 inserted before sending out BOOTP requests. The
886 following delays are insterted then:
888 1st BOOTP request: delay 0 ... 1 sec
889 2nd BOOTP request: delay 0 ... 2 sec
890 3rd BOOTP request: delay 0 ... 4 sec
892 BOOTP requests: delay 0 ... 8 sec
894 - DHCP Advanced Options:
897 You can fine tune the DHCP functionality by adding
898 these flags to the CONFIG_BOOTP_MASK define:
900 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
901 serverip from a DHCP server, it is possible that more
902 than one DNS serverip is offered to the client.
903 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
904 serverip will be stored in the additional environment
905 variable "dnsip2". The first DNS serverip is always
906 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
907 is added to the CONFIG_BOOTP_MASK.
909 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
910 to do a dynamic update of a DNS server. To do this, they
911 need the hostname of the DHCP requester.
912 If CONFIG_BOOP_SEND_HOSTNAME is added to the
913 CONFIG_BOOTP_MASK, the content of the "hostname"
914 environment variable is passed as option 12 to
917 - Status LED: CONFIG_STATUS_LED
919 Several configurations allow to display the current
920 status using a LED. For instance, the LED will blink
921 fast while running U-Boot code, stop blinking as
922 soon as a reply to a BOOTP request was received, and
923 start blinking slow once the Linux kernel is running
924 (supported by a status LED driver in the Linux
925 kernel). Defining CONFIG_STATUS_LED enables this
928 - CAN Support: CONFIG_CAN_DRIVER
930 Defining CONFIG_CAN_DRIVER enables CAN driver support
931 on those systems that support this (optional)
932 feature, like the TQM8xxL modules.
934 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
936 These enable I2C serial bus commands. Defining either of
937 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
938 include the appropriate I2C driver for the selected cpu.
940 This will allow you to use i2c commands at the u-boot
941 command line (as long as you set CFG_CMD_I2C in
942 CONFIG_COMMANDS) and communicate with i2c based realtime
943 clock chips. See common/cmd_i2c.c for a description of the
944 command line interface.
946 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
948 CONFIG_SOFT_I2C configures u-boot to use a software (aka
949 bit-banging) driver instead of CPM or similar hardware
952 There are several other quantities that must also be
953 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
955 In both cases you will need to define CFG_I2C_SPEED
956 to be the frequency (in Hz) at which you wish your i2c bus
957 to run and CFG_I2C_SLAVE to be the address of this node (ie
958 the cpu's i2c node address).
960 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
961 sets the cpu up as a master node and so its address should
962 therefore be cleared to 0 (See, eg, MPC823e User's Manual
963 p.16-473). So, set CFG_I2C_SLAVE to 0.
965 That's all that's required for CONFIG_HARD_I2C.
967 If you use the software i2c interface (CONFIG_SOFT_I2C)
968 then the following macros need to be defined (examples are
969 from include/configs/lwmon.h):
973 (Optional). Any commands necessary to enable the I2C
974 controller or configure ports.
976 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
980 (Only for MPC8260 CPU). The I/O port to use (the code
981 assumes both bits are on the same port). Valid values
982 are 0..3 for ports A..D.
986 The code necessary to make the I2C data line active
987 (driven). If the data line is open collector, this
990 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
994 The code necessary to make the I2C data line tri-stated
995 (inactive). If the data line is open collector, this
998 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1002 Code that returns TRUE if the I2C data line is high,
1005 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1009 If <bit> is TRUE, sets the I2C data line high. If it
1010 is FALSE, it clears it (low).
1012 eg: #define I2C_SDA(bit) \
1013 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1014 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1018 If <bit> is TRUE, sets the I2C clock line high. If it
1019 is FALSE, it clears it (low).
1021 eg: #define I2C_SCL(bit) \
1022 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1023 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1027 This delay is invoked four times per clock cycle so this
1028 controls the rate of data transfer. The data rate thus
1029 is 1 / (I2C_DELAY * 4). Often defined to be something
1032 #define I2C_DELAY udelay(2)
1036 When a board is reset during an i2c bus transfer
1037 chips might think that the current transfer is still
1038 in progress. On some boards it is possible to access
1039 the i2c SCLK line directly, either by using the
1040 processor pin as a GPIO or by having a second pin
1041 connected to the bus. If this option is defined a
1042 custom i2c_init_board() routine in boards/xxx/board.c
1043 is run early in the boot sequence.
1045 - SPI Support: CONFIG_SPI
1047 Enables SPI driver (so far only tested with
1048 SPI EEPROM, also an instance works with Crystal A/D and
1049 D/As on the SACSng board)
1053 Enables extended (16-bit) SPI EEPROM addressing.
1054 (symmetrical to CONFIG_I2C_X)
1058 Enables a software (bit-bang) SPI driver rather than
1059 using hardware support. This is a general purpose
1060 driver that only requires three general I/O port pins
1061 (two outputs, one input) to function. If this is
1062 defined, the board configuration must define several
1063 SPI configuration items (port pins to use, etc). For
1064 an example, see include/configs/sacsng.h.
1066 - FPGA Support: CONFIG_FPGA_COUNT
1068 Specify the number of FPGA devices to support.
1072 Used to specify the types of FPGA devices. For example,
1073 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1075 CFG_FPGA_PROG_FEEDBACK
1077 Enable printing of hash marks during FPGA configuration.
1081 Enable checks on FPGA configuration interface busy
1082 status by the configuration function. This option
1083 will require a board or device specific function to
1088 If defined, a function that provides delays in the FPGA
1089 configuration driver.
1091 CFG_FPGA_CHECK_CTRLC
1092 Allow Control-C to interrupt FPGA configuration
1094 CFG_FPGA_CHECK_ERROR
1096 Check for configuration errors during FPGA bitfile
1097 loading. For example, abort during Virtex II
1098 configuration if the INIT_B line goes low (which
1099 indicated a CRC error).
1103 Maximum time to wait for the INIT_B line to deassert
1104 after PROB_B has been deasserted during a Virtex II
1105 FPGA configuration sequence. The default time is 500
1110 Maximum time to wait for BUSY to deassert during
1111 Virtex II FPGA configuration. The default is 5 mS.
1113 CFG_FPGA_WAIT_CONFIG
1115 Time to wait after FPGA configuration. The default is
1118 - Configuration Management:
1121 If defined, this string will be added to the U-Boot
1122 version information (U_BOOT_VERSION)
1124 - Vendor Parameter Protection:
1126 U-Boot considers the values of the environment
1127 variables "serial#" (Board Serial Number) and
1128 "ethaddr" (Ethernet Address) to be parameters that
1129 are set once by the board vendor / manufacturer, and
1130 protects these variables from casual modification by
1131 the user. Once set, these variables are read-only,
1132 and write or delete attempts are rejected. You can
1133 change this behviour:
1135 If CONFIG_ENV_OVERWRITE is #defined in your config
1136 file, the write protection for vendor parameters is
1137 completely disabled. Anybody can change or delete
1140 Alternatively, if you #define _both_ CONFIG_ETHADDR
1141 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1142 ethernet address is installed in the environment,
1143 which can be changed exactly ONCE by the user. [The
1144 serial# is unaffected by this, i. e. it remains
1150 Define this variable to enable the reservation of
1151 "protected RAM", i. e. RAM which is not overwritten
1152 by U-Boot. Define CONFIG_PRAM to hold the number of
1153 kB you want to reserve for pRAM. You can overwrite
1154 this default value by defining an environment
1155 variable "pram" to the number of kB you want to
1156 reserve. Note that the board info structure will
1157 still show the full amount of RAM. If pRAM is
1158 reserved, a new environment variable "mem" will
1159 automatically be defined to hold the amount of
1160 remaining RAM in a form that can be passed as boot
1161 argument to Linux, for instance like that:
1163 setenv bootargs ... mem=\$(mem)
1166 This way you can tell Linux not to use this memory,
1167 either, which results in a memory region that will
1168 not be affected by reboots.
1170 *WARNING* If your board configuration uses automatic
1171 detection of the RAM size, you must make sure that
1172 this memory test is non-destructive. So far, the
1173 following board configurations are known to be
1176 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1177 HERMES, IP860, RPXlite, LWMON, LANTEC,
1178 PCU_E, FLAGADM, TQM8260
1183 Define this variable to stop the system in case of a
1184 fatal error, so that you have to reset it manually.
1185 This is probably NOT a good idea for an embedded
1186 system where you want to system to reboot
1187 automatically as fast as possible, but it may be
1188 useful during development since you can try to debug
1189 the conditions that lead to the situation.
1191 CONFIG_NET_RETRY_COUNT
1193 This variable defines the number of retries for
1194 network operations like ARP, RARP, TFTP, or BOOTP
1195 before giving up the operation. If not defined, a
1196 default value of 5 is used.
1198 - Command Interpreter:
1201 Define this variable to enable the "hush" shell (from
1202 Busybox) as command line interpreter, thus enabling
1203 powerful command line syntax like
1204 if...then...else...fi conditionals or `&&' and '||'
1205 constructs ("shell scripts").
1207 If undefined, you get the old, much simpler behaviour
1208 with a somewhat smaller memory footprint.
1213 This defines the secondary prompt string, which is
1214 printed when the command interpreter needs more input
1215 to complete a command. Usually "> ".
1219 In the current implementation, the local variables
1220 space and global environment variables space are
1221 separated. Local variables are those you define by
1222 simply typing `name=value'. To access a local
1223 variable later on, you have write `$name' or
1224 `${name}'; to execute the contents of a variable
1225 directly type `$name' at the command prompt.
1227 Global environment variables are those you use
1228 setenv/printenv to work with. To run a command stored
1229 in such a variable, you need to use the run command,
1230 and you must not use the '$' sign to access them.
1232 To store commands and special characters in a
1233 variable, please use double quotation marks
1234 surrounding the whole text of the variable, instead
1235 of the backslashes before semicolons and special
1238 - Default Environment:
1239 CONFIG_EXTRA_ENV_SETTINGS
1241 Define this to contain any number of null terminated
1242 strings (variable = value pairs) that will be part of
1243 the default environment compiled into the boot image.
1245 For example, place something like this in your
1246 board's config file:
1248 #define CONFIG_EXTRA_ENV_SETTINGS \
1252 Warning: This method is based on knowledge about the
1253 internal format how the environment is stored by the
1254 U-Boot code. This is NOT an official, exported
1255 interface! Although it is unlikely that this format
1256 will change soon, there is no guarantee either.
1257 You better know what you are doing here.
1259 Note: overly (ab)use of the default environment is
1260 discouraged. Make sure to check other ways to preset
1261 the environment like the autoscript function or the
1264 - DataFlash Support:
1265 CONFIG_HAS_DATAFLASH
1267 Defining this option enables DataFlash features and
1268 allows to read/write in Dataflash via the standard
1271 - SystemACE Support:
1274 Adding this option adds support for Xilinx SystemACE
1275 chips attached via some sort of local bus. The address
1276 of the chip must alsh be defined in the
1277 CFG_SYSTEMACE_BASE macro. For example:
1279 #define CONFIG_SYSTEMACE
1280 #define CFG_SYSTEMACE_BASE 0xf0000000
1282 When SystemACE support is added, the "ace" device type
1283 becomes available to the fat commands, i.e. fatls.
1285 - Show boot progress:
1286 CONFIG_SHOW_BOOT_PROGRESS
1288 Defining this option allows to add some board-
1289 specific code (calling a user-provided function
1290 "show_boot_progress(int)") that enables you to show
1291 the system's boot progress on some display (for
1292 example, some LED's) on your board. At the moment,
1293 the following checkpoints are implemented:
1296 1 common/cmd_bootm.c before attempting to boot an image
1297 -1 common/cmd_bootm.c Image header has bad magic number
1298 2 common/cmd_bootm.c Image header has correct magic number
1299 -2 common/cmd_bootm.c Image header has bad checksum
1300 3 common/cmd_bootm.c Image header has correct checksum
1301 -3 common/cmd_bootm.c Image data has bad checksum
1302 4 common/cmd_bootm.c Image data has correct checksum
1303 -4 common/cmd_bootm.c Image is for unsupported architecture
1304 5 common/cmd_bootm.c Architecture check OK
1305 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1306 6 common/cmd_bootm.c Image Type check OK
1307 -6 common/cmd_bootm.c gunzip uncompression error
1308 -7 common/cmd_bootm.c Unimplemented compression type
1309 7 common/cmd_bootm.c Uncompression OK
1310 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1311 8 common/cmd_bootm.c Image Type check OK
1312 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1313 9 common/cmd_bootm.c Start initial ramdisk verification
1314 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1315 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1316 10 common/cmd_bootm.c Ramdisk header is OK
1317 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1318 11 common/cmd_bootm.c Ramdisk data has correct checksum
1319 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1320 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1321 13 common/cmd_bootm.c Start multifile image verification
1322 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1323 15 common/cmd_bootm.c All preparation done, transferring control to OS
1325 -30 lib_ppc/board.c Fatal error, hang the system
1326 -31 post/post.c POST test failed, detected by post_output_backlog()
1327 -32 post/post.c POST test failed, detected by post_run_single()
1329 -1 common/cmd_doc.c Bad usage of "doc" command
1330 -1 common/cmd_doc.c No boot device
1331 -1 common/cmd_doc.c Unknown Chip ID on boot device
1332 -1 common/cmd_doc.c Read Error on boot device
1333 -1 common/cmd_doc.c Image header has bad magic number
1335 -1 common/cmd_ide.c Bad usage of "ide" command
1336 -1 common/cmd_ide.c No boot device
1337 -1 common/cmd_ide.c Unknown boot device
1338 -1 common/cmd_ide.c Unknown partition table
1339 -1 common/cmd_ide.c Invalid partition type
1340 -1 common/cmd_ide.c Read Error on boot device
1341 -1 common/cmd_ide.c Image header has bad magic number
1343 -1 common/cmd_nand.c Bad usage of "nand" command
1344 -1 common/cmd_nand.c No boot device
1345 -1 common/cmd_nand.c Unknown Chip ID on boot device
1346 -1 common/cmd_nand.c Read Error on boot device
1347 -1 common/cmd_nand.c Image header has bad magic number
1349 -1 common/env_common.c Environment has a bad CRC, using default
1355 [so far only for SMDK2400 and TRAB boards]
1357 - Modem support endable:
1358 CONFIG_MODEM_SUPPORT
1360 - RTS/CTS Flow control enable:
1363 - Modem debug support:
1364 CONFIG_MODEM_SUPPORT_DEBUG
1366 Enables debugging stuff (char screen[1024], dbg())
1367 for modem support. Useful only with BDI2000.
1369 - Interrupt support (PPC):
1371 There are common interrupt_init() and timer_interrupt()
1372 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1373 for cpu specific initialization. interrupt_init_cpu()
1374 should set decrementer_count to appropriate value. If
1375 cpu resets decrementer automatically after interrupt
1376 (ppc4xx) it should set decrementer_count to zero.
1377 timer_interrupt() calls timer_interrupt_cpu() for cpu
1378 specific handling. If board has watchdog / status_led
1379 / other_activity_monitor it works automatically from
1380 general timer_interrupt().
1384 In the target system modem support is enabled when a
1385 specific key (key combination) is pressed during
1386 power-on. Otherwise U-Boot will boot normally
1387 (autoboot). The key_pressed() fuction is called from
1388 board_init(). Currently key_pressed() is a dummy
1389 function, returning 1 and thus enabling modem
1392 If there are no modem init strings in the
1393 environment, U-Boot proceed to autoboot; the
1394 previous output (banner, info printfs) will be
1397 See also: doc/README.Modem
1400 Configuration Settings:
1401 -----------------------
1403 - CFG_LONGHELP: Defined when you want long help messages included;
1404 undefine this when you're short of memory.
1406 - CFG_PROMPT: This is what U-Boot prints on the console to
1407 prompt for user input.
1409 - CFG_CBSIZE: Buffer size for input from the Console
1411 - CFG_PBSIZE: Buffer size for Console output
1413 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1415 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1416 the application (usually a Linux kernel) when it is
1419 - CFG_BAUDRATE_TABLE:
1420 List of legal baudrate settings for this board.
1422 - CFG_CONSOLE_INFO_QUIET
1423 Suppress display of console information at boot.
1425 - CFG_CONSOLE_IS_IN_ENV
1426 If the board specific function
1427 extern int overwrite_console (void);
1428 returns 1, the stdin, stderr and stdout are switched to the
1429 serial port, else the settings in the environment are used.
1431 - CFG_CONSOLE_OVERWRITE_ROUTINE
1432 Enable the call to overwrite_console().
1434 - CFG_CONSOLE_ENV_OVERWRITE
1435 Enable overwrite of previous console environment settings.
1437 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1438 Begin and End addresses of the area used by the
1442 Enable an alternate, more extensive memory test.
1444 - CFG_MEMTEST_SCRATCH:
1445 Scratch address used by the alternate memory test
1446 You only need to set this if address zero isn't writeable
1448 - CFG_TFTP_LOADADDR:
1449 Default load address for network file downloads
1451 - CFG_LOADS_BAUD_CHANGE:
1452 Enable temporary baudrate change while serial download
1455 Physical start address of SDRAM. _Must_ be 0 here.
1458 Physical start address of Motherboard I/O (if using a
1462 Physical start address of Flash memory.
1465 Physical start address of boot monitor code (set by
1466 make config files to be same as the text base address
1467 (TEXT_BASE) used when linking) - same as
1468 CFG_FLASH_BASE when booting from flash.
1471 Size of memory reserved for monitor code, used to
1472 determine _at_compile_time_ (!) if the environment is
1473 embedded within the U-Boot image, or in a separate
1477 Size of DRAM reserved for malloc() use.
1480 Maximum size of memory mapped by the startup code of
1481 the Linux kernel; all data that must be processed by
1482 the Linux kernel (bd_info, boot arguments, eventually
1483 initrd image) must be put below this limit.
1485 - CFG_MAX_FLASH_BANKS:
1486 Max number of Flash memory banks
1488 - CFG_MAX_FLASH_SECT:
1489 Max number of sectors on a Flash chip
1491 - CFG_FLASH_ERASE_TOUT:
1492 Timeout for Flash erase operations (in ms)
1494 - CFG_FLASH_WRITE_TOUT:
1495 Timeout for Flash write operations (in ms)
1497 - CFG_FLASH_LOCK_TOUT
1498 Timeout for Flash set sector lock bit operation (in ms)
1500 - CFG_FLASH_UNLOCK_TOUT
1501 Timeout for Flash clear lock bits operation (in ms)
1503 - CFG_FLASH_PROTECTION
1504 If defined, hardware flash sectors protection is used
1505 instead of U-Boot software protection.
1507 - CFG_DIRECT_FLASH_TFTP:
1509 Enable TFTP transfers directly to flash memory;
1510 without this option such a download has to be
1511 performed in two steps: (1) download to RAM, and (2)
1512 copy from RAM to flash.
1514 The two-step approach is usually more reliable, since
1515 you can check if the download worked before you erase
1516 the flash, but in some situations (when sytem RAM is
1517 too limited to allow for a tempory copy of the
1518 downloaded image) this option may be very useful.
1521 Define if the flash driver uses extra elements in the
1522 common flash structure for storing flash geometry.
1524 - CFG_FLASH_CFI_DRIVER
1525 This option also enables the building of the cfi_flash driver
1526 in the drivers directory
1528 - CFG_RX_ETH_BUFFER:
1529 Defines the number of ethernet receive buffers. On some
1530 ethernet controllers it is recommended to set this value
1531 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1532 buffers can be full shortly after enabling the interface
1533 on high ethernet traffic.
1534 Defaults to 4 if not defined.
1536 The following definitions that deal with the placement and management
1537 of environment data (variable area); in general, we support the
1538 following configurations:
1540 - CFG_ENV_IS_IN_FLASH:
1542 Define this if the environment is in flash memory.
1544 a) The environment occupies one whole flash sector, which is
1545 "embedded" in the text segment with the U-Boot code. This
1546 happens usually with "bottom boot sector" or "top boot
1547 sector" type flash chips, which have several smaller
1548 sectors at the start or the end. For instance, such a
1549 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1550 such a case you would place the environment in one of the
1551 4 kB sectors - with U-Boot code before and after it. With
1552 "top boot sector" type flash chips, you would put the
1553 environment in one of the last sectors, leaving a gap
1554 between U-Boot and the environment.
1558 Offset of environment data (variable area) to the
1559 beginning of flash memory; for instance, with bottom boot
1560 type flash chips the second sector can be used: the offset
1561 for this sector is given here.
1563 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1567 This is just another way to specify the start address of
1568 the flash sector containing the environment (instead of
1571 - CFG_ENV_SECT_SIZE:
1573 Size of the sector containing the environment.
1576 b) Sometimes flash chips have few, equal sized, BIG sectors.
1577 In such a case you don't want to spend a whole sector for
1582 If you use this in combination with CFG_ENV_IS_IN_FLASH
1583 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1584 of this flash sector for the environment. This saves
1585 memory for the RAM copy of the environment.
1587 It may also save flash memory if you decide to use this
1588 when your environment is "embedded" within U-Boot code,
1589 since then the remainder of the flash sector could be used
1590 for U-Boot code. It should be pointed out that this is
1591 STRONGLY DISCOURAGED from a robustness point of view:
1592 updating the environment in flash makes it always
1593 necessary to erase the WHOLE sector. If something goes
1594 wrong before the contents has been restored from a copy in
1595 RAM, your target system will be dead.
1597 - CFG_ENV_ADDR_REDUND
1600 These settings describe a second storage area used to hold
1601 a redundand copy of the environment data, so that there is
1602 a valid backup copy in case there is a power failure during
1603 a "saveenv" operation.
1605 BE CAREFUL! Any changes to the flash layout, and some changes to the
1606 source code will make it necessary to adapt <board>/u-boot.lds*
1610 - CFG_ENV_IS_IN_NVRAM:
1612 Define this if you have some non-volatile memory device
1613 (NVRAM, battery buffered SRAM) which you want to use for the
1619 These two #defines are used to determin the memory area you
1620 want to use for environment. It is assumed that this memory
1621 can just be read and written to, without any special
1624 BE CAREFUL! The first access to the environment happens quite early
1625 in U-Boot initalization (when we try to get the setting of for the
1626 console baudrate). You *MUST* have mappend your NVRAM area then, or
1629 Please note that even with NVRAM we still use a copy of the
1630 environment in RAM: we could work on NVRAM directly, but we want to
1631 keep settings there always unmodified except somebody uses "saveenv"
1632 to save the current settings.
1635 - CFG_ENV_IS_IN_EEPROM:
1637 Use this if you have an EEPROM or similar serial access
1638 device and a driver for it.
1643 These two #defines specify the offset and size of the
1644 environment area within the total memory of your EEPROM.
1646 - CFG_I2C_EEPROM_ADDR:
1647 If defined, specified the chip address of the EEPROM device.
1648 The default address is zero.
1650 - CFG_EEPROM_PAGE_WRITE_BITS:
1651 If defined, the number of bits used to address bytes in a
1652 single page in the EEPROM device. A 64 byte page, for example
1653 would require six bits.
1655 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1656 If defined, the number of milliseconds to delay between
1657 page writes. The default is zero milliseconds.
1659 - CFG_I2C_EEPROM_ADDR_LEN:
1660 The length in bytes of the EEPROM memory array address. Note
1661 that this is NOT the chip address length!
1664 The size in bytes of the EEPROM device.
1667 - CFG_ENV_IS_IN_DATAFLASH:
1669 Define this if you have a DataFlash memory device which you
1670 want to use for the environment.
1676 These three #defines specify the offset and size of the
1677 environment area within the total memory of your DataFlash placed
1678 at the specified address.
1681 - CFG_SPI_INIT_OFFSET
1683 Defines offset to the initial SPI buffer area in DPRAM. The
1684 area is used at an early stage (ROM part) if the environment
1685 is configured to reside in the SPI EEPROM: We need a 520 byte
1686 scratch DPRAM area. It is used between the two initialization
1687 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1688 to be a good choice since it makes it far enough from the
1689 start of the data area as well as from the stack pointer.
1691 Please note that the environment is read-only as long as the monitor
1692 has been relocated to RAM and a RAM copy of the environment has been
1693 created; also, when using EEPROM you will have to use getenv_r()
1694 until then to read environment variables.
1696 The environment is protected by a CRC32 checksum. Before the monitor
1697 is relocated into RAM, as a result of a bad CRC you will be working
1698 with the compiled-in default environment - *silently*!!! [This is
1699 necessary, because the first environment variable we need is the
1700 "baudrate" setting for the console - if we have a bad CRC, we don't
1701 have any device yet where we could complain.]
1703 Note: once the monitor has been relocated, then it will complain if
1704 the default environment is used; a new CRC is computed as soon as you
1705 use the "saveenv" command to store a valid environment.
1707 - CFG_FAULT_ECHO_LINK_DOWN:
1708 Echo the inverted Ethernet link state to the fault LED.
1710 Note: If this option is active, then CFG_FAULT_MII_ADDR
1711 also needs to be defined.
1713 - CFG_FAULT_MII_ADDR:
1714 MII address of the PHY to check for the Ethernet link state.
1716 Low Level (hardware related) configuration options:
1717 ---------------------------------------------------
1719 - CFG_CACHELINE_SIZE:
1720 Cache Line Size of the CPU.
1723 Default address of the IMMR after system reset.
1725 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1726 and RPXsuper) to be able to adjust the position of
1727 the IMMR register after a reset.
1729 - Floppy Disk Support:
1730 CFG_FDC_DRIVE_NUMBER
1732 the default drive number (default value 0)
1736 defines the spacing between fdc chipset registers
1741 defines the offset of register from address. It
1742 depends on which part of the data bus is connected to
1743 the fdc chipset. (default value 0)
1745 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1746 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1749 if CFG_FDC_HW_INIT is defined, then the function
1750 fdc_hw_init() is called at the beginning of the FDC
1751 setup. fdc_hw_init() must be provided by the board
1752 source code. It is used to make hardware dependant
1755 - CFG_IMMR: Physical address of the Internal Memory Mapped
1756 Register; DO NOT CHANGE! (11-4)
1757 [MPC8xx systems only]
1759 - CFG_INIT_RAM_ADDR:
1761 Start address of memory area that can be used for
1762 initial data and stack; please note that this must be
1763 writable memory that is working WITHOUT special
1764 initialization, i. e. you CANNOT use normal RAM which
1765 will become available only after programming the
1766 memory controller and running certain initialization
1769 U-Boot uses the following memory types:
1770 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1771 - MPC824X: data cache
1772 - PPC4xx: data cache
1774 - CFG_GBL_DATA_OFFSET:
1776 Offset of the initial data structure in the memory
1777 area defined by CFG_INIT_RAM_ADDR. Usually
1778 CFG_GBL_DATA_OFFSET is chosen such that the initial
1779 data is located at the end of the available space
1780 (sometimes written as (CFG_INIT_RAM_END -
1781 CFG_INIT_DATA_SIZE), and the initial stack is just
1782 below that area (growing from (CFG_INIT_RAM_ADDR +
1783 CFG_GBL_DATA_OFFSET) downward.
1786 On the MPC824X (or other systems that use the data
1787 cache for initial memory) the address chosen for
1788 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1789 point to an otherwise UNUSED address space between
1790 the top of RAM and the start of the PCI space.
1792 - CFG_SIUMCR: SIU Module Configuration (11-6)
1794 - CFG_SYPCR: System Protection Control (11-9)
1796 - CFG_TBSCR: Time Base Status and Control (11-26)
1798 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1800 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1802 - CFG_SCCR: System Clock and reset Control Register (15-27)
1804 - CFG_OR_TIMING_SDRAM:
1808 periodic timer for refresh
1810 - CFG_DER: Debug Event Register (37-47)
1812 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1813 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1814 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1816 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1818 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1819 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1820 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1821 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1823 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1824 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1825 Machine Mode Register and Memory Periodic Timer
1826 Prescaler definitions (SDRAM timing)
1828 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1829 enable I2C microcode relocation patch (MPC8xx);
1830 define relocation offset in DPRAM [DSP2]
1832 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1833 enable SPI microcode relocation patch (MPC8xx);
1834 define relocation offset in DPRAM [SCC4]
1837 Use OSCM clock mode on MBX8xx board. Be careful,
1838 wrong setting might damage your board. Read
1839 doc/README.MBX before setting this variable!
1841 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1842 Offset of the bootmode word in DPRAM used by post
1843 (Power On Self Tests). This definition overrides
1844 #define'd default value in commproc.h resp.
1847 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1848 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1849 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1850 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1851 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1852 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1853 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1854 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1855 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1857 Building the Software:
1858 ======================
1860 Building U-Boot has been tested in native PPC environments (on a
1861 PowerBook G3 running LinuxPPC 2000) and in cross environments
1862 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1865 If you are not using a native PPC environment, it is assumed that you
1866 have the GNU cross compiling tools available in your path and named
1867 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1868 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1869 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1872 CROSS_COMPILE = ppc_4xx-
1875 U-Boot is intended to be simple to build. After installing the
1876 sources you must configure U-Boot for one specific board type. This
1881 where "NAME_config" is the name of one of the existing
1882 configurations; the following names are supported:
1884 ADCIOP_config GTH_config TQM850L_config
1885 ADS860_config IP860_config TQM855L_config
1886 AR405_config IVML24_config TQM860L_config
1887 CANBT_config IVMS8_config WALNUT405_config
1888 CPCI405_config LANTEC_config cogent_common_config
1889 CPCIISER4_config MBX_config cogent_mpc8260_config
1890 CU824_config MBX860T_config cogent_mpc8xx_config
1891 ESTEEM192E_config RPXlite_config hermes_config
1892 ETX094_config RPXsuper_config hymod_config
1893 FADS823_config SM850_config lwmon_config
1894 FADS850SAR_config SPD823TS_config pcu_e_config
1895 FADS860T_config SXNI855T_config rsdproto_config
1896 FPS850L_config Sandpoint8240_config sbc8260_config
1897 GENIETV_config TQM823L_config PIP405_config
1898 GEN860T_config EBONY_config FPS860L_config
1899 ELPT860_config cmi_mpc5xx_config NETVIA_config
1900 at91rm9200dk_config omap1510inn_config MPC8260ADS_config
1901 omap1610inn_config ZPC1900_config MPC8540ADS_config
1902 MPC8560ADS_config QS850_config QS823_config
1903 QS860T_config DUET_ADS_config omap1610h2_config
1905 Note: for some board special configuration names may exist; check if
1906 additional information is available from the board vendor; for
1907 instance, the TQM8xxL systems run normally at 50 MHz and use a
1908 SCC for 10baseT ethernet; there are also systems with 80 MHz
1909 CPU clock, and an optional Fast Ethernet module is available
1910 for CPU's with FEC. You can select such additional "features"
1911 when chosing the configuration, i. e.
1914 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1916 make TQM860L_FEC_config
1917 - will configure for a TQM860L at 50MHz with FEC for ethernet
1919 make TQM860L_80MHz_config
1920 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1923 make TQM860L_FEC_80MHz_config
1924 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1926 make TQM823L_LCD_config
1927 - will configure for a TQM823L with U-Boot console on LCD
1929 make TQM823L_LCD_80MHz_config
1930 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1935 Finally, type "make all", and you should get some working U-Boot
1936 images ready for download to / installation on your system:
1938 - "u-boot.bin" is a raw binary image
1939 - "u-boot" is an image in ELF binary format
1940 - "u-boot.srec" is in Motorola S-Record format
1943 Please be aware that the Makefiles assume you are using GNU make, so
1944 for instance on NetBSD you might need to use "gmake" instead of
1948 If the system board that you have is not listed, then you will need
1949 to port U-Boot to your hardware platform. To do this, follow these
1952 1. Add a new configuration option for your board to the toplevel
1953 "Makefile" and to the "MAKEALL" script, using the existing
1954 entries as examples. Note that here and at many other places
1955 boards and other names are listed in alphabetical sort order. Please
1957 2. Create a new directory to hold your board specific code. Add any
1958 files you need. In your board directory, you will need at least
1959 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1960 3. Create a new configuration file "include/configs/<board>.h" for
1962 3. If you're porting U-Boot to a new CPU, then also create a new
1963 directory to hold your CPU specific code. Add any files you need.
1964 4. Run "make <board>_config" with your new name.
1965 5. Type "make", and you should get a working "u-boot.srec" file
1966 to be installed on your target system.
1967 6. Debug and solve any problems that might arise.
1968 [Of course, this last step is much harder than it sounds.]
1971 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1972 ==============================================================
1974 If you have modified U-Boot sources (for instance added a new board
1975 or support for new devices, a new CPU, etc.) you are expected to
1976 provide feedback to the other developers. The feedback normally takes
1977 the form of a "patch", i. e. a context diff against a certain (latest
1978 official or latest in CVS) version of U-Boot sources.
1980 But before you submit such a patch, please verify that your modifi-
1981 cation did not break existing code. At least make sure that *ALL* of
1982 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1983 just run the "MAKEALL" script, which will configure and build U-Boot
1984 for ALL supported system. Be warned, this will take a while. You can
1985 select which (cross) compiler to use by passing a `CROSS_COMPILE'
1986 environment variable to the script, i. e. to use the cross tools from
1987 MontaVista's Hard Hat Linux you can type
1989 CROSS_COMPILE=ppc_8xx- MAKEALL
1991 or to build on a native PowerPC system you can type
1993 CROSS_COMPILE=' ' MAKEALL
1995 See also "U-Boot Porting Guide" below.
1998 Monitor Commands - Overview:
1999 ============================
2001 go - start application at address 'addr'
2002 run - run commands in an environment variable
2003 bootm - boot application image from memory
2004 bootp - boot image via network using BootP/TFTP protocol
2005 tftpboot- boot image via network using TFTP protocol
2006 and env variables "ipaddr" and "serverip"
2007 (and eventually "gatewayip")
2008 rarpboot- boot image via network using RARP/TFTP protocol
2009 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2010 loads - load S-Record file over serial line
2011 loadb - load binary file over serial line (kermit mode)
2013 mm - memory modify (auto-incrementing)
2014 nm - memory modify (constant address)
2015 mw - memory write (fill)
2017 cmp - memory compare
2018 crc32 - checksum calculation
2019 imd - i2c memory display
2020 imm - i2c memory modify (auto-incrementing)
2021 inm - i2c memory modify (constant address)
2022 imw - i2c memory write (fill)
2023 icrc32 - i2c checksum calculation
2024 iprobe - probe to discover valid I2C chip addresses
2025 iloop - infinite loop on address range
2026 isdram - print SDRAM configuration information
2027 sspi - SPI utility commands
2028 base - print or set address offset
2029 printenv- print environment variables
2030 setenv - set environment variables
2031 saveenv - save environment variables to persistent storage
2032 protect - enable or disable FLASH write protection
2033 erase - erase FLASH memory
2034 flinfo - print FLASH memory information
2035 bdinfo - print Board Info structure
2036 iminfo - print header information for application image
2037 coninfo - print console devices and informations
2038 ide - IDE sub-system
2039 loop - infinite loop on address range
2040 mtest - simple RAM test
2041 icache - enable or disable instruction cache
2042 dcache - enable or disable data cache
2043 reset - Perform RESET of the CPU
2044 echo - echo args to console
2045 version - print monitor version
2046 help - print online help
2047 ? - alias for 'help'
2050 Monitor Commands - Detailed Description:
2051 ========================================
2055 For now: just type "help <command>".
2058 Environment Variables:
2059 ======================
2061 U-Boot supports user configuration using Environment Variables which
2062 can be made persistent by saving to Flash memory.
2064 Environment Variables are set using "setenv", printed using
2065 "printenv", and saved to Flash using "saveenv". Using "setenv"
2066 without a value can be used to delete a variable from the
2067 environment. As long as you don't save the environment you are
2068 working with an in-memory copy. In case the Flash area containing the
2069 environment is erased by accident, a default environment is provided.
2071 Some configuration options can be set using Environment Variables:
2073 baudrate - see CONFIG_BAUDRATE
2075 bootdelay - see CONFIG_BOOTDELAY
2077 bootcmd - see CONFIG_BOOTCOMMAND
2079 bootargs - Boot arguments when booting an RTOS image
2081 bootfile - Name of the image to load with TFTP
2083 autoload - if set to "no" (any string beginning with 'n'),
2084 "bootp" will just load perform a lookup of the
2085 configuration from the BOOTP server, but not try to
2086 load any image using TFTP
2088 autostart - if set to "yes", an image loaded using the "bootp",
2089 "rarpboot", "tftpboot" or "diskboot" commands will
2090 be automatically started (by internally calling
2093 If set to "no", a standalone image passed to the
2094 "bootm" command will be copied to the load address
2095 (and eventually uncompressed), but NOT be started.
2096 This can be used to load and uncompress arbitrary
2099 initrd_high - restrict positioning of initrd images:
2100 If this variable is not set, initrd images will be
2101 copied to the highest possible address in RAM; this
2102 is usually what you want since it allows for
2103 maximum initrd size. If for some reason you want to
2104 make sure that the initrd image is loaded below the
2105 CFG_BOOTMAPSZ limit, you can set this environment
2106 variable to a value of "no" or "off" or "0".
2107 Alternatively, you can set it to a maximum upper
2108 address to use (U-Boot will still check that it
2109 does not overwrite the U-Boot stack and data).
2111 For instance, when you have a system with 16 MB
2112 RAM, and want to reserve 4 MB from use by Linux,
2113 you can do this by adding "mem=12M" to the value of
2114 the "bootargs" variable. However, now you must make
2115 sure that the initrd image is placed in the first
2116 12 MB as well - this can be done with
2118 setenv initrd_high 00c00000
2120 If you set initrd_high to 0xFFFFFFFF, this is an
2121 indication to U-Boot that all addresses are legal
2122 for the Linux kernel, including addresses in flash
2123 memory. In this case U-Boot will NOT COPY the
2124 ramdisk at all. This may be useful to reduce the
2125 boot time on your system, but requires that this
2126 feature is supported by your Linux kernel.
2128 ipaddr - IP address; needed for tftpboot command
2130 loadaddr - Default load address for commands like "bootp",
2131 "rarpboot", "tftpboot", "loadb" or "diskboot"
2133 loads_echo - see CONFIG_LOADS_ECHO
2135 serverip - TFTP server IP address; needed for tftpboot command
2137 bootretry - see CONFIG_BOOT_RETRY_TIME
2139 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2141 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2144 The following environment variables may be used and automatically
2145 updated by the network boot commands ("bootp" and "rarpboot"),
2146 depending the information provided by your boot server:
2148 bootfile - see above
2149 dnsip - IP address of your Domain Name Server
2150 dnsip2 - IP address of your secondary Domain Name Server
2151 gatewayip - IP address of the Gateway (Router) to use
2152 hostname - Target hostname
2154 netmask - Subnet Mask
2155 rootpath - Pathname of the root filesystem on the NFS server
2156 serverip - see above
2159 There are two special Environment Variables:
2161 serial# - contains hardware identification information such
2162 as type string and/or serial number
2163 ethaddr - Ethernet address
2165 These variables can be set only once (usually during manufacturing of
2166 the board). U-Boot refuses to delete or overwrite these variables
2167 once they have been set once.
2170 Further special Environment Variables:
2172 ver - Contains the U-Boot version string as printed
2173 with the "version" command. This variable is
2174 readonly (see CONFIG_VERSION_VARIABLE).
2177 Please note that changes to some configuration parameters may take
2178 only effect after the next boot (yes, that's just like Windoze :-).
2181 Command Line Parsing:
2182 =====================
2184 There are two different command line parsers available with U-Boot:
2185 the old "simple" one, and the much more powerful "hush" shell:
2187 Old, simple command line parser:
2188 --------------------------------
2190 - supports environment variables (through setenv / saveenv commands)
2191 - several commands on one line, separated by ';'
2192 - variable substitution using "... $(name) ..." syntax
2193 - special characters ('$', ';') can be escaped by prefixing with '\',
2195 setenv bootcmd bootm \$(address)
2196 - You can also escape text by enclosing in single apostrophes, for example:
2197 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2202 - similar to Bourne shell, with control structures like
2203 if...then...else...fi, for...do...done; while...do...done,
2204 until...do...done, ...
2205 - supports environment ("global") variables (through setenv / saveenv
2206 commands) and local shell variables (through standard shell syntax
2207 "name=value"); only environment variables can be used with "run"
2213 (1) If a command line (or an environment variable executed by a "run"
2214 command) contains several commands separated by semicolon, and
2215 one of these commands fails, then the remaining commands will be
2218 (2) If you execute several variables with one call to run (i. e.
2219 calling run with a list af variables as arguments), any failing
2220 command will cause "run" to terminate, i. e. the remaining
2221 variables are not executed.
2223 Note for Redundant Ethernet Interfaces:
2224 =======================================
2226 Some boards come with redundant ethernet interfaces; U-Boot supports
2227 such configurations and is capable of automatic selection of a
2228 "working" interface when needed. MAC assignment works as follows:
2230 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2231 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2232 "eth1addr" (=>eth1), "eth2addr", ...
2234 If the network interface stores some valid MAC address (for instance
2235 in SROM), this is used as default address if there is NO correspon-
2236 ding setting in the environment; if the corresponding environment
2237 variable is set, this overrides the settings in the card; that means:
2239 o If the SROM has a valid MAC address, and there is no address in the
2240 environment, the SROM's address is used.
2242 o If there is no valid address in the SROM, and a definition in the
2243 environment exists, then the value from the environment variable is
2246 o If both the SROM and the environment contain a MAC address, and
2247 both addresses are the same, this MAC address is used.
2249 o If both the SROM and the environment contain a MAC address, and the
2250 addresses differ, the value from the environment is used and a
2253 o If neither SROM nor the environment contain a MAC address, an error
2260 The "boot" commands of this monitor operate on "image" files which
2261 can be basicly anything, preceeded by a special header; see the
2262 definitions in include/image.h for details; basicly, the header
2263 defines the following image properties:
2265 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2266 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2267 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2268 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2269 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2270 IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2271 Currently supported: ARM, Intel x86, MIPS, NIOS, PowerPC).
2272 * Compression Type (uncompressed, gzip, bzip2)
2278 The header is marked by a special Magic Number, and both the header
2279 and the data portions of the image are secured against corruption by
2286 Although U-Boot should support any OS or standalone application
2287 easily, the main focus has always been on Linux during the design of
2290 U-Boot includes many features that so far have been part of some
2291 special "boot loader" code within the Linux kernel. Also, any
2292 "initrd" images to be used are no longer part of one big Linux image;
2293 instead, kernel and "initrd" are separate images. This implementation
2294 serves several purposes:
2296 - the same features can be used for other OS or standalone
2297 applications (for instance: using compressed images to reduce the
2298 Flash memory footprint)
2300 - it becomes much easier to port new Linux kernel versions because
2301 lots of low-level, hardware dependent stuff are done by U-Boot
2303 - the same Linux kernel image can now be used with different "initrd"
2304 images; of course this also means that different kernel images can
2305 be run with the same "initrd". This makes testing easier (you don't
2306 have to build a new "zImage.initrd" Linux image when you just
2307 change a file in your "initrd"). Also, a field-upgrade of the
2308 software is easier now.
2314 Porting Linux to U-Boot based systems:
2315 ---------------------------------------
2317 U-Boot cannot save you from doing all the necessary modifications to
2318 configure the Linux device drivers for use with your target hardware
2319 (no, we don't intend to provide a full virtual machine interface to
2322 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2324 Just make sure your machine specific header file (for instance
2325 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2326 Information structure as we define in include/u-boot.h, and make
2327 sure that your definition of IMAP_ADDR uses the same value as your
2328 U-Boot configuration in CFG_IMMR.
2331 Configuring the Linux kernel:
2332 -----------------------------
2334 No specific requirements for U-Boot. Make sure you have some root
2335 device (initial ramdisk, NFS) for your target system.
2338 Building a Linux Image:
2339 -----------------------
2341 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2342 not used. If you use recent kernel source, a new build target
2343 "uImage" will exist which automatically builds an image usable by
2344 U-Boot. Most older kernels also have support for a "pImage" target,
2345 which was introduced for our predecessor project PPCBoot and uses a
2346 100% compatible format.
2355 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2356 encapsulate a compressed Linux kernel image with header information,
2357 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2359 * build a standard "vmlinux" kernel image (in ELF binary format):
2361 * convert the kernel into a raw binary image:
2363 ${CROSS_COMPILE}-objcopy -O binary \
2364 -R .note -R .comment \
2365 -S vmlinux linux.bin
2367 * compress the binary image:
2371 * package compressed binary image for U-Boot:
2373 mkimage -A ppc -O linux -T kernel -C gzip \
2374 -a 0 -e 0 -n "Linux Kernel Image" \
2375 -d linux.bin.gz uImage
2378 The "mkimage" tool can also be used to create ramdisk images for use
2379 with U-Boot, either separated from the Linux kernel image, or
2380 combined into one file. "mkimage" encapsulates the images with a 64
2381 byte header containing information about target architecture,
2382 operating system, image type, compression method, entry points, time
2383 stamp, CRC32 checksums, etc.
2385 "mkimage" can be called in two ways: to verify existing images and
2386 print the header information, or to build new images.
2388 In the first form (with "-l" option) mkimage lists the information
2389 contained in the header of an existing U-Boot image; this includes
2390 checksum verification:
2392 tools/mkimage -l image
2393 -l ==> list image header information
2395 The second form (with "-d" option) is used to build a U-Boot image
2396 from a "data file" which is used as image payload:
2398 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2399 -n name -d data_file image
2400 -A ==> set architecture to 'arch'
2401 -O ==> set operating system to 'os'
2402 -T ==> set image type to 'type'
2403 -C ==> set compression type 'comp'
2404 -a ==> set load address to 'addr' (hex)
2405 -e ==> set entry point to 'ep' (hex)
2406 -n ==> set image name to 'name'
2407 -d ==> use image data from 'datafile'
2409 Right now, all Linux kernels use the same load address (0x00000000),
2410 but the entry point address depends on the kernel version:
2412 - 2.2.x kernels have the entry point at 0x0000000C,
2413 - 2.3.x and later kernels have the entry point at 0x00000000.
2415 So a typical call to build a U-Boot image would read:
2417 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2418 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2419 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2420 > examples/uImage.TQM850L
2421 Image Name: 2.4.4 kernel for TQM850L
2422 Created: Wed Jul 19 02:34:59 2000
2423 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2424 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2425 Load Address: 0x00000000
2426 Entry Point: 0x00000000
2428 To verify the contents of the image (or check for corruption):
2430 -> tools/mkimage -l examples/uImage.TQM850L
2431 Image Name: 2.4.4 kernel for TQM850L
2432 Created: Wed Jul 19 02:34:59 2000
2433 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2434 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2435 Load Address: 0x00000000
2436 Entry Point: 0x00000000
2438 NOTE: for embedded systems where boot time is critical you can trade
2439 speed for memory and install an UNCOMPRESSED image instead: this
2440 needs more space in Flash, but boots much faster since it does not
2441 need to be uncompressed:
2443 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2444 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2445 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2446 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2447 > examples/uImage.TQM850L-uncompressed
2448 Image Name: 2.4.4 kernel for TQM850L
2449 Created: Wed Jul 19 02:34:59 2000
2450 Image Type: PowerPC Linux Kernel Image (uncompressed)
2451 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2452 Load Address: 0x00000000
2453 Entry Point: 0x00000000
2456 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2457 when your kernel is intended to use an initial ramdisk:
2459 -> tools/mkimage -n 'Simple Ramdisk Image' \
2460 > -A ppc -O linux -T ramdisk -C gzip \
2461 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2462 Image Name: Simple Ramdisk Image
2463 Created: Wed Jan 12 14:01:50 2000
2464 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2465 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2466 Load Address: 0x00000000
2467 Entry Point: 0x00000000
2470 Installing a Linux Image:
2471 -------------------------
2473 To downloading a U-Boot image over the serial (console) interface,
2474 you must convert the image to S-Record format:
2476 objcopy -I binary -O srec examples/image examples/image.srec
2478 The 'objcopy' does not understand the information in the U-Boot
2479 image header, so the resulting S-Record file will be relative to
2480 address 0x00000000. To load it to a given address, you need to
2481 specify the target address as 'offset' parameter with the 'loads'
2484 Example: install the image to address 0x40100000 (which on the
2485 TQM8xxL is in the first Flash bank):
2487 => erase 40100000 401FFFFF
2493 ## Ready for S-Record download ...
2494 ~>examples/image.srec
2495 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2497 15989 15990 15991 15992
2498 [file transfer complete]
2500 ## Start Addr = 0x00000000
2503 You can check the success of the download using the 'iminfo' command;
2504 this includes a checksum verification so you can be sure no data
2505 corruption happened:
2509 ## Checking Image at 40100000 ...
2510 Image Name: 2.2.13 for initrd on TQM850L
2511 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2512 Data Size: 335725 Bytes = 327 kB = 0 MB
2513 Load Address: 00000000
2514 Entry Point: 0000000c
2515 Verifying Checksum ... OK
2521 The "bootm" command is used to boot an application that is stored in
2522 memory (RAM or Flash). In case of a Linux kernel image, the contents
2523 of the "bootargs" environment variable is passed to the kernel as
2524 parameters. You can check and modify this variable using the
2525 "printenv" and "setenv" commands:
2528 => printenv bootargs
2529 bootargs=root=/dev/ram
2531 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2533 => printenv bootargs
2534 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2537 ## Booting Linux kernel at 40020000 ...
2538 Image Name: 2.2.13 for NFS on TQM850L
2539 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2540 Data Size: 381681 Bytes = 372 kB = 0 MB
2541 Load Address: 00000000
2542 Entry Point: 0000000c
2543 Verifying Checksum ... OK
2544 Uncompressing Kernel Image ... OK
2545 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
2546 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2547 time_init: decrementer frequency = 187500000/60
2548 Calibrating delay loop... 49.77 BogoMIPS
2549 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2552 If you want to boot a Linux kernel with initial ram disk, you pass
2553 the memory addresses of both the kernel and the initrd image (PPBCOOT
2554 format!) to the "bootm" command:
2556 => imi 40100000 40200000
2558 ## Checking Image at 40100000 ...
2559 Image Name: 2.2.13 for initrd on TQM850L
2560 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2561 Data Size: 335725 Bytes = 327 kB = 0 MB
2562 Load Address: 00000000
2563 Entry Point: 0000000c
2564 Verifying Checksum ... OK
2566 ## Checking Image at 40200000 ...
2567 Image Name: Simple Ramdisk Image
2568 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2569 Data Size: 566530 Bytes = 553 kB = 0 MB
2570 Load Address: 00000000
2571 Entry Point: 00000000
2572 Verifying Checksum ... OK
2574 => bootm 40100000 40200000
2575 ## Booting Linux kernel at 40100000 ...
2576 Image Name: 2.2.13 for initrd on TQM850L
2577 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2578 Data Size: 335725 Bytes = 327 kB = 0 MB
2579 Load Address: 00000000
2580 Entry Point: 0000000c
2581 Verifying Checksum ... OK
2582 Uncompressing Kernel Image ... OK
2583 ## Loading RAMDisk Image at 40200000 ...
2584 Image Name: Simple Ramdisk Image
2585 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2586 Data Size: 566530 Bytes = 553 kB = 0 MB
2587 Load Address: 00000000
2588 Entry Point: 00000000
2589 Verifying Checksum ... OK
2590 Loading Ramdisk ... OK
2591 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
2592 Boot arguments: root=/dev/ram
2593 time_init: decrementer frequency = 187500000/60
2594 Calibrating delay loop... 49.77 BogoMIPS
2596 RAMDISK: Compressed image found at block 0
2597 VFS: Mounted root (ext2 filesystem).
2601 More About U-Boot Image Types:
2602 ------------------------------
2604 U-Boot supports the following image types:
2606 "Standalone Programs" are directly runnable in the environment
2607 provided by U-Boot; it is expected that (if they behave
2608 well) you can continue to work in U-Boot after return from
2609 the Standalone Program.
2610 "OS Kernel Images" are usually images of some Embedded OS which
2611 will take over control completely. Usually these programs
2612 will install their own set of exception handlers, device
2613 drivers, set up the MMU, etc. - this means, that you cannot
2614 expect to re-enter U-Boot except by resetting the CPU.
2615 "RAMDisk Images" are more or less just data blocks, and their
2616 parameters (address, size) are passed to an OS kernel that is
2618 "Multi-File Images" contain several images, typically an OS
2619 (Linux) kernel image and one or more data images like
2620 RAMDisks. This construct is useful for instance when you want
2621 to boot over the network using BOOTP etc., where the boot
2622 server provides just a single image file, but you want to get
2623 for instance an OS kernel and a RAMDisk image.
2625 "Multi-File Images" start with a list of image sizes, each
2626 image size (in bytes) specified by an "uint32_t" in network
2627 byte order. This list is terminated by an "(uint32_t)0".
2628 Immediately after the terminating 0 follow the images, one by
2629 one, all aligned on "uint32_t" boundaries (size rounded up to
2630 a multiple of 4 bytes).
2632 "Firmware Images" are binary images containing firmware (like
2633 U-Boot or FPGA images) which usually will be programmed to
2636 "Script files" are command sequences that will be executed by
2637 U-Boot's command interpreter; this feature is especially
2638 useful when you configure U-Boot to use a real shell (hush)
2639 as command interpreter.
2645 One of the features of U-Boot is that you can dynamically load and
2646 run "standalone" applications, which can use some resources of
2647 U-Boot like console I/O functions or interrupt services.
2649 Two simple examples are included with the sources:
2654 'examples/hello_world.c' contains a small "Hello World" Demo
2655 application; it is automatically compiled when you build U-Boot.
2656 It's configured to run at address 0x00040004, so you can play with it
2660 ## Ready for S-Record download ...
2661 ~>examples/hello_world.srec
2662 1 2 3 4 5 6 7 8 9 10 11 ...
2663 [file transfer complete]
2665 ## Start Addr = 0x00040004
2667 => go 40004 Hello World! This is a test.
2668 ## Starting application at 0x00040004 ...
2679 Hit any key to exit ...
2681 ## Application terminated, rc = 0x0
2683 Another example, which demonstrates how to register a CPM interrupt
2684 handler with the U-Boot code, can be found in 'examples/timer.c'.
2685 Here, a CPM timer is set up to generate an interrupt every second.
2686 The interrupt service routine is trivial, just printing a '.'
2687 character, but this is just a demo program. The application can be
2688 controlled by the following keys:
2690 ? - print current values og the CPM Timer registers
2691 b - enable interrupts and start timer
2692 e - stop timer and disable interrupts
2693 q - quit application
2696 ## Ready for S-Record download ...
2697 ~>examples/timer.srec
2698 1 2 3 4 5 6 7 8 9 10 11 ...
2699 [file transfer complete]
2701 ## Start Addr = 0x00040004
2704 ## Starting application at 0x00040004 ...
2707 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2710 [q, b, e, ?] Set interval 1000000 us
2713 [q, b, e, ?] ........
2714 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2717 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2720 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2723 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2725 [q, b, e, ?] ...Stopping timer
2727 [q, b, e, ?] ## Application terminated, rc = 0x0
2733 Over time, many people have reported problems when trying to use the
2734 "minicom" terminal emulation program for serial download. I (wd)
2735 consider minicom to be broken, and recommend not to use it. Under
2736 Unix, I recommend to use C-Kermit for general purpose use (and
2737 especially for kermit binary protocol download ("loadb" command), and
2738 use "cu" for S-Record download ("loads" command).
2740 Nevertheless, if you absolutely want to use it try adding this
2741 configuration to your "File transfer protocols" section:
2743 Name Program Name U/D FullScr IO-Red. Multi
2744 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2745 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2751 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2752 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2754 Building requires a cross environment; it is known to work on
2755 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2756 need gmake since the Makefiles are not compatible with BSD make).
2757 Note that the cross-powerpc package does not install include files;
2758 attempting to build U-Boot will fail because <machine/ansi.h> is
2759 missing. This file has to be installed and patched manually:
2761 # cd /usr/pkg/cross/powerpc-netbsd/include
2763 # ln -s powerpc machine
2764 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2765 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2767 Native builds *don't* work due to incompatibilities between native
2768 and U-Boot include files.
2770 Booting assumes that (the first part of) the image booted is a
2771 stage-2 loader which in turn loads and then invokes the kernel
2772 proper. Loader sources will eventually appear in the NetBSD source
2773 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2774 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2778 Implementation Internals:
2779 =========================
2781 The following is not intended to be a complete description of every
2782 implementation detail. However, it should help to understand the
2783 inner workings of U-Boot and make it easier to port it to custom
2787 Initial Stack, Global Data:
2788 ---------------------------
2790 The implementation of U-Boot is complicated by the fact that U-Boot
2791 starts running out of ROM (flash memory), usually without access to
2792 system RAM (because the memory controller is not initialized yet).
2793 This means that we don't have writable Data or BSS segments, and BSS
2794 is not initialized as zero. To be able to get a C environment working
2795 at all, we have to allocate at least a minimal stack. Implementation
2796 options for this are defined and restricted by the CPU used: Some CPU
2797 models provide on-chip memory (like the IMMR area on MPC8xx and
2798 MPC826x processors), on others (parts of) the data cache can be
2799 locked as (mis-) used as memory, etc.
2801 Chris Hallinan posted a good summary of these issues to the
2802 u-boot-users mailing list:
2804 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2805 From: "Chris Hallinan" <clh@net1plus.com>
2806 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2809 Correct me if I'm wrong, folks, but the way I understand it
2810 is this: Using DCACHE as initial RAM for Stack, etc, does not
2811 require any physical RAM backing up the cache. The cleverness
2812 is that the cache is being used as a temporary supply of
2813 necessary storage before the SDRAM controller is setup. It's
2814 beyond the scope of this list to expain the details, but you
2815 can see how this works by studying the cache architecture and
2816 operation in the architecture and processor-specific manuals.
2818 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2819 is another option for the system designer to use as an
2820 initial stack/ram area prior to SDRAM being available. Either
2821 option should work for you. Using CS 4 should be fine if your
2822 board designers haven't used it for something that would
2823 cause you grief during the initial boot! It is frequently not
2826 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2827 with your processor/board/system design. The default value
2828 you will find in any recent u-boot distribution in
2829 Walnut405.h should work for you. I'd set it to a value larger
2830 than your SDRAM module. If you have a 64MB SDRAM module, set
2831 it above 400_0000. Just make sure your board has no resources
2832 that are supposed to respond to that address! That code in
2833 start.S has been around a while and should work as is when
2834 you get the config right.
2839 It is essential to remember this, since it has some impact on the C
2840 code for the initialization procedures:
2842 * Initialized global data (data segment) is read-only. Do not attempt
2845 * Do not use any unitialized global data (or implicitely initialized
2846 as zero data - BSS segment) at all - this is undefined, initiali-
2847 zation is performed later (when relocating to RAM).
2849 * Stack space is very limited. Avoid big data buffers or things like
2852 Having only the stack as writable memory limits means we cannot use
2853 normal global data to share information beween the code. But it
2854 turned out that the implementation of U-Boot can be greatly
2855 simplified by making a global data structure (gd_t) available to all
2856 functions. We could pass a pointer to this data as argument to _all_
2857 functions, but this would bloat the code. Instead we use a feature of
2858 the GCC compiler (Global Register Variables) to share the data: we
2859 place a pointer (gd) to the global data into a register which we
2860 reserve for this purpose.
2862 When choosing a register for such a purpose we are restricted by the
2863 relevant (E)ABI specifications for the current architecture, and by
2864 GCC's implementation.
2866 For PowerPC, the following registers have specific use:
2869 R3-R4: parameter passing and return values
2870 R5-R10: parameter passing
2871 R13: small data area pointer
2875 (U-Boot also uses R14 as internal GOT pointer.)
2877 ==> U-Boot will use R29 to hold a pointer to the global data
2879 Note: on PPC, we could use a static initializer (since the
2880 address of the global data structure is known at compile time),
2881 but it turned out that reserving a register results in somewhat
2882 smaller code - although the code savings are not that big (on
2883 average for all boards 752 bytes for the whole U-Boot image,
2884 624 text + 127 data).
2886 On ARM, the following registers are used:
2888 R0: function argument word/integer result
2889 R1-R3: function argument word
2891 R10: stack limit (used only if stack checking if enabled)
2892 R11: argument (frame) pointer
2893 R12: temporary workspace
2896 R15: program counter
2898 ==> U-Boot will use R8 to hold a pointer to the global data
2904 U-Boot runs in system state and uses physical addresses, i.e. the
2905 MMU is not used either for address mapping nor for memory protection.
2907 The available memory is mapped to fixed addresses using the memory
2908 controller. In this process, a contiguous block is formed for each
2909 memory type (Flash, SDRAM, SRAM), even when it consists of several
2910 physical memory banks.
2912 U-Boot is installed in the first 128 kB of the first Flash bank (on
2913 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2914 booting and sizing and initializing DRAM, the code relocates itself
2915 to the upper end of DRAM. Immediately below the U-Boot code some
2916 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2917 configuration setting]. Below that, a structure with global Board
2918 Info data is placed, followed by the stack (growing downward).
2920 Additionally, some exception handler code is copied to the low 8 kB
2921 of DRAM (0x00000000 ... 0x00001FFF).
2923 So a typical memory configuration with 16 MB of DRAM could look like
2926 0x0000 0000 Exception Vector code
2929 0x0000 2000 Free for Application Use
2935 0x00FB FF20 Monitor Stack (Growing downward)
2936 0x00FB FFAC Board Info Data and permanent copy of global data
2937 0x00FC 0000 Malloc Arena
2940 0x00FE 0000 RAM Copy of Monitor Code
2941 ... eventually: LCD or video framebuffer
2942 ... eventually: pRAM (Protected RAM - unchanged by reset)
2943 0x00FF FFFF [End of RAM]
2946 System Initialization:
2947 ----------------------
2949 In the reset configuration, U-Boot starts at the reset entry point
2950 (on most PowerPC systens at address 0x00000100). Because of the reset
2951 configuration for CS0# this is a mirror of the onboard Flash memory.
2952 To be able to re-map memory U-Boot then jumps to its link address.
2953 To be able to implement the initialization code in C, a (small!)
2954 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2955 which provide such a feature like MPC8xx or MPC8260), or in a locked
2956 part of the data cache. After that, U-Boot initializes the CPU core,
2957 the caches and the SIU.
2959 Next, all (potentially) available memory banks are mapped using a
2960 preliminary mapping. For example, we put them on 512 MB boundaries
2961 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2962 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2963 programmed for SDRAM access. Using the temporary configuration, a
2964 simple memory test is run that determines the size of the SDRAM
2967 When there is more than one SDRAM bank, and the banks are of
2968 different size, the largest is mapped first. For equal size, the first
2969 bank (CS2#) is mapped first. The first mapping is always for address
2970 0x00000000, with any additional banks following immediately to create
2971 contiguous memory starting from 0.
2973 Then, the monitor installs itself at the upper end of the SDRAM area
2974 and allocates memory for use by malloc() and for the global Board
2975 Info data; also, the exception vector code is copied to the low RAM
2976 pages, and the final stack is set up.
2978 Only after this relocation will you have a "normal" C environment;
2979 until that you are restricted in several ways, mostly because you are
2980 running from ROM, and because the code will have to be relocated to a
2984 U-Boot Porting Guide:
2985 ----------------------
2987 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2991 int main (int argc, char *argv[])
2993 sighandler_t no_more_time;
2995 signal (SIGALRM, no_more_time);
2996 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2998 if (available_money > available_manpower) {
2999 pay consultant to port U-Boot;
3003 Download latest U-Boot source;
3005 Subscribe to u-boot-users mailing list;
3008 email ("Hi, I am new to U-Boot, how do I get started?");
3012 Read the README file in the top level directory;
3013 Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3014 Read the source, Luke;
3017 if (available_money > toLocalCurrency ($2500)) {
3020 Add a lot of aggravation and time;
3023 Create your own board support subdirectory;
3025 Create your own board config file;
3029 Add / modify source code;
3033 email ("Hi, I am having problems...");
3035 Send patch file to Wolfgang;
3040 void no_more_time (int sig)
3049 All contributions to U-Boot should conform to the Linux kernel
3050 coding style; see the file "Documentation/CodingStyle" in your Linux
3051 kernel source directory.
3053 Please note that U-Boot is implemented in C (and to some small parts
3054 in Assembler); no C++ is used, so please do not use C++ style
3055 comments (//) in your code.
3057 Please also stick to the following formatting rules:
3058 - remove any trailing white space
3059 - use TAB characters for indentation, not spaces
3060 - make sure NOT to use DOS '\r\n' line feeds
3061 - do not add more than 2 empty lines to source files
3062 - do not add trailing empty lines to source files
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
projects / karo-tx-uboot.git / blob