1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
379 This is the value to write into CCSR offset 0x18600
380 according to the A004510 workaround.
382 CONFIG_SYS_FSL_DSP_DDR_ADDR
383 This value denotes start offset of DDR memory which is
384 connected exclusively to the DSP cores.
386 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
387 This value denotes start offset of M2 memory
388 which is directly connected to the DSP core.
390 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
391 This value denotes start offset of M3 memory which is directly
392 connected to the DSP core.
394 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
395 This value denotes start offset of DSP CCSR space.
397 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
398 Single Source Clock is clocking mode present in some of FSL SoC's.
399 In this mode, a single differential clock is used to supply
400 clocks to the sysclock, ddrclock and usbclock.
402 CONFIG_SYS_CPC_REINIT_F
403 This CONFIG is defined when the CPC is configured as SRAM at the
404 time of U-Boot entry and is required to be re-initialized.
407 Indicates this SoC supports deep sleep feature. If deep sleep is
408 supported, core will start to execute uboot when wakes up.
410 - Generic CPU options:
411 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
413 Defines the endianess of the CPU. Implementation of those
414 values is arch specific.
417 Freescale DDR driver in use. This type of DDR controller is
418 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
420 CONFIG_SYS_FSL_DDR_ADDR
421 Freescale DDR memory-mapped register base.
423 CONFIG_SYS_FSL_DDR_EMU
424 Specify emulator support for DDR. Some DDR features such as
425 deskew training are not available.
427 CONFIG_SYS_FSL_DDRC_GEN1
428 Freescale DDR1 controller.
430 CONFIG_SYS_FSL_DDRC_GEN2
431 Freescale DDR2 controller.
433 CONFIG_SYS_FSL_DDRC_GEN3
434 Freescale DDR3 controller.
436 CONFIG_SYS_FSL_DDRC_GEN4
437 Freescale DDR4 controller.
439 CONFIG_SYS_FSL_DDRC_ARM_GEN3
440 Freescale DDR3 controller for ARM-based SoCs.
443 Board config to use DDR1. It can be enabled for SoCs with
444 Freescale DDR1 or DDR2 controllers, depending on the board
448 Board config to use DDR2. It can be enabled for SoCs with
449 Freescale DDR2 or DDR3 controllers, depending on the board
453 Board config to use DDR3. It can be enabled for SoCs with
454 Freescale DDR3 or DDR3L controllers.
457 Board config to use DDR3L. It can be enabled for SoCs with
460 CONFIG_SYS_FSL_IFC_BE
461 Defines the IFC controller register space as Big Endian
463 CONFIG_SYS_FSL_IFC_LE
464 Defines the IFC controller register space as Little Endian
466 CONFIG_SYS_FSL_IFC_CLK_DIV
467 Defines divider of platform clock(clock input to IFC controller).
469 CONFIG_SYS_FSL_LBC_CLK_DIV
470 Defines divider of platform clock(clock input to eLBC controller).
472 CONFIG_SYS_FSL_DDR_BE
473 Defines the DDR controller register space as Big Endian
475 CONFIG_SYS_FSL_DDR_LE
476 Defines the DDR controller register space as Little Endian
478 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
479 Physical address from the view of DDR controllers. It is the
480 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
481 it could be different for ARM SoCs.
483 CONFIG_SYS_FSL_DDR_INTLV_256B
484 DDR controller interleaving on 256-byte. This is a special
485 interleaving mode, handled by Dickens for Freescale layerscape
488 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
489 Number of controllers used as main memory.
491 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
492 Number of controllers used for other than main memory.
494 CONFIG_SYS_FSL_HAS_DP_DDR
495 Defines the SoC has DP-DDR used for DPAA.
497 CONFIG_SYS_FSL_SEC_BE
498 Defines the SEC controller register space as Big Endian
500 CONFIG_SYS_FSL_SEC_LE
501 Defines the SEC controller register space as Little Endian
504 CONFIG_SYS_INIT_SP_OFFSET
506 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
507 pointer. This is needed for the temporary stack before
510 CONFIG_XWAY_SWAP_BYTES
512 Enable compilation of tools/xway-swap-bytes needed for Lantiq
513 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
514 be swapped if a flash programmer is used.
517 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
519 Select high exception vectors of the ARM core, e.g., do not
520 clear the V bit of the c1 register of CP15.
523 Generic timer clock source frequency.
525 COUNTER_FREQUENCY_REAL
526 Generic timer clock source frequency if the real clock is
527 different from COUNTER_FREQUENCY, and can only be determined
531 CONFIG_TEGRA_SUPPORT_NON_SECURE
533 Support executing U-Boot in non-secure (NS) mode. Certain
534 impossible actions will be skipped if the CPU is in NS mode,
535 such as ARM architectural timer initialization.
537 - Linux Kernel Interface:
538 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
540 When transferring memsize parameter to Linux, some versions
541 expect it to be in bytes, others in MB.
542 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
546 New kernel versions are expecting firmware settings to be
547 passed using flattened device trees (based on open firmware
551 * New libfdt-based support
552 * Adds the "fdt" command
553 * The bootm command automatically updates the fdt
555 OF_TBCLK - The timebase frequency.
557 boards with QUICC Engines require OF_QE to set UCC MAC
562 U-Boot can detect if an IDE device is present or not.
563 If not, and this new config option is activated, U-Boot
564 removes the ATA node from the DTS before booting Linux,
565 so the Linux IDE driver does not probe the device and
566 crash. This is needed for buggy hardware (uc101) where
567 no pull down resistor is connected to the signal IDE5V_DD7.
569 - vxWorks boot parameters:
571 bootvx constructs a valid bootline using the following
572 environments variables: bootdev, bootfile, ipaddr, netmask,
573 serverip, gatewayip, hostname, othbootargs.
574 It loads the vxWorks image pointed bootfile.
576 Note: If a "bootargs" environment is defined, it will override
577 the defaults discussed just above.
579 - Cache Configuration for ARM:
580 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
582 CONFIG_SYS_PL310_BASE - Physical base address of PL310
583 controller register space
588 If you have Amba PrimeCell PL011 UARTs, set this variable to
589 the clock speed of the UARTs.
593 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
594 define this to a list of base addresses for each (supported)
595 port. See e.g. include/configs/versatile.h
597 CONFIG_SERIAL_HW_FLOW_CONTROL
599 Define this variable to enable hw flow control in serial driver.
600 Current user of this option is drivers/serial/nsl16550.c driver
602 - Serial Download Echo Mode:
604 If defined to 1, all characters received during a
605 serial download (using the "loads" command) are
606 echoed back. This might be needed by some terminal
607 emulations (like "cu"), but may as well just take
608 time on others. This setting #define's the initial
609 value of the "loads_echo" environment variable.
611 - Removal of commands
612 If no commands are needed to boot, you can disable
613 CONFIG_CMDLINE to remove them. In this case, the command line
614 will not be available, and when U-Boot wants to execute the
615 boot command (on start-up) it will call board_run_command()
616 instead. This can reduce image size significantly for very
617 simple boot procedures.
619 - Regular expression support:
621 If this variable is defined, U-Boot is linked against
622 the SLRE (Super Light Regular Expression) library,
623 which adds regex support to some commands, as for
624 example "env grep" and "setexpr".
627 CONFIG_SYS_WATCHDOG_FREQ
628 Some platforms automatically call WATCHDOG_RESET()
629 from the timer interrupt handler every
630 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
631 board configuration file, a default of CONFIG_SYS_HZ/2
632 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
633 to 0 disables calling WATCHDOG_RESET() from the timer
638 When CONFIG_CMD_DATE is selected, the type of the RTC
639 has to be selected, too. Define exactly one of the
642 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
643 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
644 CONFIG_RTC_MC146818 - use MC146818 RTC
645 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
646 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
647 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
648 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
649 CONFIG_RTC_DS164x - use Dallas DS164x RTC
650 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
651 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
652 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
653 CONFIG_SYS_RV3029_TCR - enable trickle charger on
656 Note that if the RTC uses I2C, then the I2C interface
657 must also be configured. See I2C Support, below.
660 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
662 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
663 chip-ngpio pairs that tell the PCA953X driver the number of
664 pins supported by a particular chip.
666 Note that if the GPIO device uses I2C, then the I2C interface
667 must also be configured. See I2C Support, below.
670 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
671 accesses and can checksum them or write a list of them out
672 to memory. See the 'iotrace' command for details. This is
673 useful for testing device drivers since it can confirm that
674 the driver behaves the same way before and after a code
675 change. Currently this is supported on sandbox and arm. To
676 add support for your architecture, add '#include <iotrace.h>'
677 to the bottom of arch/<arch>/include/asm/io.h and test.
679 Example output from the 'iotrace stats' command is below.
680 Note that if the trace buffer is exhausted, the checksum will
681 still continue to operate.
684 Start: 10000000 (buffer start address)
685 Size: 00010000 (buffer size)
686 Offset: 00000120 (current buffer offset)
687 Output: 10000120 (start + offset)
688 Count: 00000018 (number of trace records)
689 CRC32: 9526fb66 (CRC32 of all trace records)
693 When CONFIG_TIMESTAMP is selected, the timestamp
694 (date and time) of an image is printed by image
695 commands like bootm or iminfo. This option is
696 automatically enabled when you select CONFIG_CMD_DATE .
698 - Partition Labels (disklabels) Supported:
699 Zero or more of the following:
700 CONFIG_MAC_PARTITION Apple's MacOS partition table.
701 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
702 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
703 bootloader. Note 2TB partition limit; see
705 CONFIG_SCSI) you must configure support for at
706 least one non-MTD partition type as well.
711 Set this to enable support for disks larger than 137GB
712 Also look at CONFIG_SYS_64BIT_LBA.
713 Whithout these , LBA48 support uses 32bit variables and will 'only'
714 support disks up to 2.1TB.
716 CONFIG_SYS_64BIT_LBA:
717 When enabled, makes the IDE subsystem use 64bit sector addresses.
720 - NETWORK Support (PCI):
722 Utility code for direct access to the SPI bus on Intel 8257x.
723 This does not do anything useful unless you set at least one
724 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
727 Support for National dp83815 chips.
730 Support for National dp8382[01] gigabit chips.
732 - NETWORK Support (other):
734 Support for the Calxeda XGMAC device
737 Support for SMSC's LAN91C96 chips.
739 CONFIG_LAN91C96_USE_32_BIT
740 Define this to enable 32 bit addressing
743 Support for SMSC's LAN91C111 chip
746 Define this to hold the physical address
747 of the device (I/O space)
749 CONFIG_SMC_USE_32_BIT
750 Define this if data bus is 32 bits
752 CONFIG_SMC_USE_IOFUNCS
753 Define this to use i/o functions instead of macros
754 (some hardware wont work with macros)
756 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
757 Define this if you have more then 3 PHYs.
760 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
762 CONFIG_FTGMAC100_EGIGA
763 Define this to use GE link update with gigabit PHY.
764 Define this if FTGMAC100 is connected to gigabit PHY.
765 If your system has 10/100 PHY only, it might not occur
766 wrong behavior. Because PHY usually return timeout or
767 useless data when polling gigabit status and gigabit
768 control registers. This behavior won't affect the
769 correctnessof 10/100 link speed update.
772 Support for Renesas on-chip Ethernet controller
774 CONFIG_SH_ETHER_USE_PORT
775 Define the number of ports to be used
777 CONFIG_SH_ETHER_PHY_ADDR
778 Define the ETH PHY's address
780 CONFIG_SH_ETHER_CACHE_WRITEBACK
781 If this option is set, the driver enables cache flush.
787 CONFIG_TPM_TIS_INFINEON
788 Support for Infineon i2c bus TPM devices. Only one device
789 per system is supported at this time.
791 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
792 Define the burst count bytes upper limit
795 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
797 CONFIG_TPM_ST33ZP24_I2C
798 Support for STMicroelectronics ST33ZP24 I2C devices.
799 Requires TPM_ST33ZP24 and I2C.
801 CONFIG_TPM_ST33ZP24_SPI
802 Support for STMicroelectronics ST33ZP24 SPI devices.
803 Requires TPM_ST33ZP24 and SPI.
806 Support for Atmel TWI TPM device. Requires I2C support.
809 Support for generic parallel port TPM devices. Only one device
810 per system is supported at this time.
812 CONFIG_TPM_TIS_BASE_ADDRESS
813 Base address where the generic TPM device is mapped
814 to. Contemporary x86 systems usually map it at
818 Define this to enable the TPM support library which provides
819 functional interfaces to some TPM commands.
820 Requires support for a TPM device.
822 CONFIG_TPM_AUTH_SESSIONS
823 Define this to enable authorized functions in the TPM library.
824 Requires CONFIG_TPM and CONFIG_SHA1.
827 At the moment only the UHCI host controller is
828 supported (PIP405, MIP405); define
829 CONFIG_USB_UHCI to enable it.
830 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
831 and define CONFIG_USB_STORAGE to enable the USB
834 Supported are USB Keyboards and USB Floppy drives
837 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
838 txfilltuning field in the EHCI controller on reset.
840 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
844 Define the below if you wish to use the USB console.
845 Once firmware is rebuilt from a serial console issue the
846 command "setenv stdin usbtty; setenv stdout usbtty" and
847 attach your USB cable. The Unix command "dmesg" should print
848 it has found a new device. The environment variable usbtty
849 can be set to gserial or cdc_acm to enable your device to
850 appear to a USB host as a Linux gserial device or a
851 Common Device Class Abstract Control Model serial device.
852 If you select usbtty = gserial you should be able to enumerate
854 # modprobe usbserial vendor=0xVendorID product=0xProductID
855 else if using cdc_acm, simply setting the environment
856 variable usbtty to be cdc_acm should suffice. The following
857 might be defined in YourBoardName.h
860 Define this to build a UDC device
863 Define this to have a tty type of device available to
864 talk to the UDC device
867 Define this to enable the high speed support for usb
868 device and usbtty. If this feature is enabled, a routine
869 int is_usbd_high_speed(void)
870 also needs to be defined by the driver to dynamically poll
871 whether the enumeration has succeded at high speed or full
874 If you have a USB-IF assigned VendorID then you may wish to
875 define your own vendor specific values either in BoardName.h
876 or directly in usbd_vendor_info.h. If you don't define
877 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
878 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
879 should pretend to be a Linux device to it's target host.
881 CONFIG_USBD_MANUFACTURER
882 Define this string as the name of your company for
883 - CONFIG_USBD_MANUFACTURER "my company"
885 CONFIG_USBD_PRODUCT_NAME
886 Define this string as the name of your product
887 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
890 Define this as your assigned Vendor ID from the USB
891 Implementors Forum. This *must* be a genuine Vendor ID
892 to avoid polluting the USB namespace.
893 - CONFIG_USBD_VENDORID 0xFFFF
895 CONFIG_USBD_PRODUCTID
896 Define this as the unique Product ID
898 - CONFIG_USBD_PRODUCTID 0xFFFF
900 - ULPI Layer Support:
901 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
902 the generic ULPI layer. The generic layer accesses the ULPI PHY
903 via the platform viewport, so you need both the genric layer and
904 the viewport enabled. Currently only Chipidea/ARC based
905 viewport is supported.
906 To enable the ULPI layer support, define CONFIG_USB_ULPI and
907 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
908 If your ULPI phy needs a different reference clock than the
909 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
910 the appropriate value in Hz.
913 The MMC controller on the Intel PXA is supported. To
914 enable this define CONFIG_MMC. The MMC can be
915 accessed from the boot prompt by mapping the device
916 to physical memory similar to flash. Command line is
917 enabled with CONFIG_CMD_MMC. The MMC driver also works with
918 the FAT fs. This is enabled with CONFIG_CMD_FAT.
921 Support for Renesas on-chip MMCIF controller
924 Define the base address of MMCIF registers
927 Define the clock frequency for MMCIF
929 - USB Device Firmware Update (DFU) class support:
931 This enables the USB portion of the DFU USB class
934 This enables support for exposing NAND devices via DFU.
937 This enables support for exposing RAM via DFU.
938 Note: DFU spec refer to non-volatile memory usage, but
939 allow usages beyond the scope of spec - here RAM usage,
940 one that would help mostly the developer.
942 CONFIG_SYS_DFU_DATA_BUF_SIZE
943 Dfu transfer uses a buffer before writing data to the
944 raw storage device. Make the size (in bytes) of this buffer
945 configurable. The size of this buffer is also configurable
946 through the "dfu_bufsiz" environment variable.
948 CONFIG_SYS_DFU_MAX_FILE_SIZE
949 When updating files rather than the raw storage device,
950 we use a static buffer to copy the file into and then write
951 the buffer once we've been given the whole file. Define
952 this to the maximum filesize (in bytes) for the buffer.
953 Default is 4 MiB if undefined.
955 DFU_DEFAULT_POLL_TIMEOUT
956 Poll timeout [ms], is the timeout a device can send to the
957 host. The host must wait for this timeout before sending
958 a subsequent DFU_GET_STATUS request to the device.
960 DFU_MANIFEST_POLL_TIMEOUT
961 Poll timeout [ms], which the device sends to the host when
962 entering dfuMANIFEST state. Host waits this timeout, before
963 sending again an USB request to the device.
965 - Journaling Flash filesystem support:
966 CONFIG_SYS_JFFS2_FIRST_SECTOR,
967 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
968 Define these for a default partition on a NOR device
971 See Kconfig help for available keyboard drivers.
975 Enable the Freescale DIU video driver. Reference boards for
976 SOCs that have a DIU should define this macro to enable DIU
977 support, and should also define these other macros:
982 CONFIG_VIDEO_SW_CURSOR
983 CONFIG_VGA_AS_SINGLE_DEVICE
984 CONFIG_VIDEO_BMP_LOGO
986 The DIU driver will look for the 'video-mode' environment
987 variable, and if defined, enable the DIU as a console during
988 boot. See the documentation file doc/README.video for a
989 description of this variable.
991 - LCD Support: CONFIG_LCD
993 Define this to enable LCD support (for output to LCD
994 display); also select one of the supported displays
995 by defining one of these:
999 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1001 CONFIG_NEC_NL6448AC33:
1003 NEC NL6448AC33-18. Active, color, single scan.
1005 CONFIG_NEC_NL6448BC20
1007 NEC NL6448BC20-08. 6.5", 640x480.
1008 Active, color, single scan.
1010 CONFIG_NEC_NL6448BC33_54
1012 NEC NL6448BC33-54. 10.4", 640x480.
1013 Active, color, single scan.
1017 Sharp 320x240. Active, color, single scan.
1018 It isn't 16x9, and I am not sure what it is.
1020 CONFIG_SHARP_LQ64D341
1022 Sharp LQ64D341 display, 640x480.
1023 Active, color, single scan.
1027 HLD1045 display, 640x480.
1028 Active, color, single scan.
1032 Optrex CBL50840-2 NF-FW 99 22 M5
1034 Hitachi LMG6912RPFC-00T
1038 320x240. Black & white.
1040 CONFIG_LCD_ALIGNMENT
1042 Normally the LCD is page-aligned (typically 4KB). If this is
1043 defined then the LCD will be aligned to this value instead.
1044 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1045 here, since it is cheaper to change data cache settings on
1046 a per-section basis.
1051 Sometimes, for example if the display is mounted in portrait
1052 mode or even if it's mounted landscape but rotated by 180degree,
1053 we need to rotate our content of the display relative to the
1054 framebuffer, so that user can read the messages which are
1056 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1057 initialized with a given rotation from "vl_rot" out of
1058 "vidinfo_t" which is provided by the board specific code.
1059 The value for vl_rot is coded as following (matching to
1060 fbcon=rotate:<n> linux-kernel commandline):
1061 0 = no rotation respectively 0 degree
1062 1 = 90 degree rotation
1063 2 = 180 degree rotation
1064 3 = 270 degree rotation
1066 If CONFIG_LCD_ROTATION is not defined, the console will be
1067 initialized with 0degree rotation.
1071 Support drawing of RLE8-compressed bitmaps on the LCD.
1074 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1076 The clock frequency of the MII bus
1078 CONFIG_PHY_CMD_DELAY (ppc4xx)
1080 Some PHY like Intel LXT971A need extra delay after
1081 command issued before MII status register can be read
1086 Define a default value for the IP address to use for
1087 the default Ethernet interface, in case this is not
1088 determined through e.g. bootp.
1089 (Environment variable "ipaddr")
1091 - Server IP address:
1094 Defines a default value for the IP address of a TFTP
1095 server to contact when using the "tftboot" command.
1096 (Environment variable "serverip")
1098 - Gateway IP address:
1101 Defines a default value for the IP address of the
1102 default router where packets to other networks are
1104 (Environment variable "gatewayip")
1109 Defines a default value for the subnet mask (or
1110 routing prefix) which is used to determine if an IP
1111 address belongs to the local subnet or needs to be
1112 forwarded through a router.
1113 (Environment variable "netmask")
1115 - BOOTP Recovery Mode:
1116 CONFIG_BOOTP_RANDOM_DELAY
1118 If you have many targets in a network that try to
1119 boot using BOOTP, you may want to avoid that all
1120 systems send out BOOTP requests at precisely the same
1121 moment (which would happen for instance at recovery
1122 from a power failure, when all systems will try to
1123 boot, thus flooding the BOOTP server. Defining
1124 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1125 inserted before sending out BOOTP requests. The
1126 following delays are inserted then:
1128 1st BOOTP request: delay 0 ... 1 sec
1129 2nd BOOTP request: delay 0 ... 2 sec
1130 3rd BOOTP request: delay 0 ... 4 sec
1132 BOOTP requests: delay 0 ... 8 sec
1134 CONFIG_BOOTP_ID_CACHE_SIZE
1136 BOOTP packets are uniquely identified using a 32-bit ID. The
1137 server will copy the ID from client requests to responses and
1138 U-Boot will use this to determine if it is the destination of
1139 an incoming response. Some servers will check that addresses
1140 aren't in use before handing them out (usually using an ARP
1141 ping) and therefore take up to a few hundred milliseconds to
1142 respond. Network congestion may also influence the time it
1143 takes for a response to make it back to the client. If that
1144 time is too long, U-Boot will retransmit requests. In order
1145 to allow earlier responses to still be accepted after these
1146 retransmissions, U-Boot's BOOTP client keeps a small cache of
1147 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1148 cache. The default is to keep IDs for up to four outstanding
1149 requests. Increasing this will allow U-Boot to accept offers
1150 from a BOOTP client in networks with unusually high latency.
1152 - DHCP Advanced Options:
1154 - Link-local IP address negotiation:
1155 Negotiate with other link-local clients on the local network
1156 for an address that doesn't require explicit configuration.
1157 This is especially useful if a DHCP server cannot be guaranteed
1158 to exist in all environments that the device must operate.
1160 See doc/README.link-local for more information.
1162 - MAC address from environment variables
1164 FDT_SEQ_MACADDR_FROM_ENV
1166 Fix-up device tree with MAC addresses fetched sequentially from
1167 environment variables. This config work on assumption that
1168 non-usable ethernet node of device-tree are either not present
1169 or their status has been marked as "disabled".
1172 CONFIG_CDP_DEVICE_ID
1174 The device id used in CDP trigger frames.
1176 CONFIG_CDP_DEVICE_ID_PREFIX
1178 A two character string which is prefixed to the MAC address
1183 A printf format string which contains the ascii name of
1184 the port. Normally is set to "eth%d" which sets
1185 eth0 for the first Ethernet, eth1 for the second etc.
1187 CONFIG_CDP_CAPABILITIES
1189 A 32bit integer which indicates the device capabilities;
1190 0x00000010 for a normal host which does not forwards.
1194 An ascii string containing the version of the software.
1198 An ascii string containing the name of the platform.
1202 A 32bit integer sent on the trigger.
1204 CONFIG_CDP_POWER_CONSUMPTION
1206 A 16bit integer containing the power consumption of the
1207 device in .1 of milliwatts.
1209 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1211 A byte containing the id of the VLAN.
1213 - Status LED: CONFIG_LED_STATUS
1215 Several configurations allow to display the current
1216 status using a LED. For instance, the LED will blink
1217 fast while running U-Boot code, stop blinking as
1218 soon as a reply to a BOOTP request was received, and
1219 start blinking slow once the Linux kernel is running
1220 (supported by a status LED driver in the Linux
1221 kernel). Defining CONFIG_LED_STATUS enables this
1226 CONFIG_LED_STATUS_GPIO
1227 The status LED can be connected to a GPIO pin.
1228 In such cases, the gpio_led driver can be used as a
1229 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1230 to include the gpio_led driver in the U-Boot binary.
1232 CONFIG_GPIO_LED_INVERTED_TABLE
1233 Some GPIO connected LEDs may have inverted polarity in which
1234 case the GPIO high value corresponds to LED off state and
1235 GPIO low value corresponds to LED on state.
1236 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1237 with a list of GPIO LEDs that have inverted polarity.
1240 CONFIG_SYS_NUM_I2C_BUSES
1241 Hold the number of i2c buses you want to use.
1243 CONFIG_SYS_I2C_DIRECT_BUS
1244 define this, if you don't use i2c muxes on your hardware.
1245 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1248 CONFIG_SYS_I2C_MAX_HOPS
1249 define how many muxes are maximal consecutively connected
1250 on one i2c bus. If you not use i2c muxes, omit this
1253 CONFIG_SYS_I2C_BUSES
1254 hold a list of buses you want to use, only used if
1255 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1256 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1257 CONFIG_SYS_NUM_I2C_BUSES = 9:
1259 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1260 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1261 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1262 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1263 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1264 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1265 {1, {I2C_NULL_HOP}}, \
1266 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1267 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1271 bus 0 on adapter 0 without a mux
1272 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1273 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1274 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1275 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1276 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1277 bus 6 on adapter 1 without a mux
1278 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1279 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1281 If you do not have i2c muxes on your board, omit this define.
1283 - Legacy I2C Support:
1284 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1285 then the following macros need to be defined (examples are
1286 from include/configs/lwmon.h):
1290 (Optional). Any commands necessary to enable the I2C
1291 controller or configure ports.
1293 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1297 The code necessary to make the I2C data line active
1298 (driven). If the data line is open collector, this
1301 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1305 The code necessary to make the I2C data line tri-stated
1306 (inactive). If the data line is open collector, this
1309 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1313 Code that returns true if the I2C data line is high,
1316 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1320 If <bit> is true, sets the I2C data line high. If it
1321 is false, it clears it (low).
1323 eg: #define I2C_SDA(bit) \
1324 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1325 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1329 If <bit> is true, sets the I2C clock line high. If it
1330 is false, it clears it (low).
1332 eg: #define I2C_SCL(bit) \
1333 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1334 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1338 This delay is invoked four times per clock cycle so this
1339 controls the rate of data transfer. The data rate thus
1340 is 1 / (I2C_DELAY * 4). Often defined to be something
1343 #define I2C_DELAY udelay(2)
1345 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1347 If your arch supports the generic GPIO framework (asm/gpio.h),
1348 then you may alternatively define the two GPIOs that are to be
1349 used as SCL / SDA. Any of the previous I2C_xxx macros will
1350 have GPIO-based defaults assigned to them as appropriate.
1352 You should define these to the GPIO value as given directly to
1353 the generic GPIO functions.
1355 CONFIG_SYS_I2C_INIT_BOARD
1357 When a board is reset during an i2c bus transfer
1358 chips might think that the current transfer is still
1359 in progress. On some boards it is possible to access
1360 the i2c SCLK line directly, either by using the
1361 processor pin as a GPIO or by having a second pin
1362 connected to the bus. If this option is defined a
1363 custom i2c_init_board() routine in boards/xxx/board.c
1364 is run early in the boot sequence.
1366 CONFIG_I2C_MULTI_BUS
1368 This option allows the use of multiple I2C buses, each of which
1369 must have a controller. At any point in time, only one bus is
1370 active. To switch to a different bus, use the 'i2c dev' command.
1371 Note that bus numbering is zero-based.
1373 CONFIG_SYS_I2C_NOPROBES
1375 This option specifies a list of I2C devices that will be skipped
1376 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1377 is set, specify a list of bus-device pairs. Otherwise, specify
1378 a 1D array of device addresses
1381 #undef CONFIG_I2C_MULTI_BUS
1382 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1384 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1386 #define CONFIG_I2C_MULTI_BUS
1387 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1389 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1391 CONFIG_SYS_SPD_BUS_NUM
1393 If defined, then this indicates the I2C bus number for DDR SPD.
1394 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1396 CONFIG_SYS_RTC_BUS_NUM
1398 If defined, then this indicates the I2C bus number for the RTC.
1399 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1401 CONFIG_SOFT_I2C_READ_REPEATED_START
1403 defining this will force the i2c_read() function in
1404 the soft_i2c driver to perform an I2C repeated start
1405 between writing the address pointer and reading the
1406 data. If this define is omitted the default behaviour
1407 of doing a stop-start sequence will be used. Most I2C
1408 devices can use either method, but some require one or
1411 - SPI Support: CONFIG_SPI
1413 Enables SPI driver (so far only tested with
1414 SPI EEPROM, also an instance works with Crystal A/D and
1415 D/As on the SACSng board)
1417 CONFIG_SYS_SPI_MXC_WAIT
1418 Timeout for waiting until spi transfer completed.
1419 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1421 - FPGA Support: CONFIG_FPGA
1423 Enables FPGA subsystem.
1425 CONFIG_FPGA_<vendor>
1427 Enables support for specific chip vendors.
1430 CONFIG_FPGA_<family>
1432 Enables support for FPGA family.
1433 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1437 Specify the number of FPGA devices to support.
1439 CONFIG_SYS_FPGA_PROG_FEEDBACK
1441 Enable printing of hash marks during FPGA configuration.
1443 CONFIG_SYS_FPGA_CHECK_BUSY
1445 Enable checks on FPGA configuration interface busy
1446 status by the configuration function. This option
1447 will require a board or device specific function to
1452 If defined, a function that provides delays in the FPGA
1453 configuration driver.
1455 CONFIG_SYS_FPGA_CHECK_CTRLC
1456 Allow Control-C to interrupt FPGA configuration
1458 CONFIG_SYS_FPGA_CHECK_ERROR
1460 Check for configuration errors during FPGA bitfile
1461 loading. For example, abort during Virtex II
1462 configuration if the INIT_B line goes low (which
1463 indicated a CRC error).
1465 CONFIG_SYS_FPGA_WAIT_INIT
1467 Maximum time to wait for the INIT_B line to de-assert
1468 after PROB_B has been de-asserted during a Virtex II
1469 FPGA configuration sequence. The default time is 500
1472 CONFIG_SYS_FPGA_WAIT_BUSY
1474 Maximum time to wait for BUSY to de-assert during
1475 Virtex II FPGA configuration. The default is 5 ms.
1477 CONFIG_SYS_FPGA_WAIT_CONFIG
1479 Time to wait after FPGA configuration. The default is
1482 - Vendor Parameter Protection:
1484 U-Boot considers the values of the environment
1485 variables "serial#" (Board Serial Number) and
1486 "ethaddr" (Ethernet Address) to be parameters that
1487 are set once by the board vendor / manufacturer, and
1488 protects these variables from casual modification by
1489 the user. Once set, these variables are read-only,
1490 and write or delete attempts are rejected. You can
1491 change this behaviour:
1493 If CONFIG_ENV_OVERWRITE is #defined in your config
1494 file, the write protection for vendor parameters is
1495 completely disabled. Anybody can change or delete
1498 Alternatively, if you define _both_ an ethaddr in the
1499 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1500 Ethernet address is installed in the environment,
1501 which can be changed exactly ONCE by the user. [The
1502 serial# is unaffected by this, i. e. it remains
1505 The same can be accomplished in a more flexible way
1506 for any variable by configuring the type of access
1507 to allow for those variables in the ".flags" variable
1508 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1513 Define this variable to enable the reservation of
1514 "protected RAM", i. e. RAM which is not overwritten
1515 by U-Boot. Define CONFIG_PRAM to hold the number of
1516 kB you want to reserve for pRAM. You can overwrite
1517 this default value by defining an environment
1518 variable "pram" to the number of kB you want to
1519 reserve. Note that the board info structure will
1520 still show the full amount of RAM. If pRAM is
1521 reserved, a new environment variable "mem" will
1522 automatically be defined to hold the amount of
1523 remaining RAM in a form that can be passed as boot
1524 argument to Linux, for instance like that:
1526 setenv bootargs ... mem=\${mem}
1529 This way you can tell Linux not to use this memory,
1530 either, which results in a memory region that will
1531 not be affected by reboots.
1533 *WARNING* If your board configuration uses automatic
1534 detection of the RAM size, you must make sure that
1535 this memory test is non-destructive. So far, the
1536 following board configurations are known to be
1539 IVMS8, IVML24, SPD8xx,
1540 HERMES, IP860, RPXlite, LWMON,
1546 In the current implementation, the local variables
1547 space and global environment variables space are
1548 separated. Local variables are those you define by
1549 simply typing `name=value'. To access a local
1550 variable later on, you have write `$name' or
1551 `${name}'; to execute the contents of a variable
1552 directly type `$name' at the command prompt.
1554 Global environment variables are those you use
1555 setenv/printenv to work with. To run a command stored
1556 in such a variable, you need to use the run command,
1557 and you must not use the '$' sign to access them.
1559 To store commands and special characters in a
1560 variable, please use double quotation marks
1561 surrounding the whole text of the variable, instead
1562 of the backslashes before semicolons and special
1565 - Command Line Editing and History:
1566 CONFIG_CMDLINE_PS_SUPPORT
1568 Enable support for changing the command prompt string
1569 at run-time. Only static string is supported so far.
1570 The string is obtained from environment variables PS1
1573 - Default Environment:
1574 CONFIG_EXTRA_ENV_SETTINGS
1576 Define this to contain any number of null terminated
1577 strings (variable = value pairs) that will be part of
1578 the default environment compiled into the boot image.
1580 For example, place something like this in your
1581 board's config file:
1583 #define CONFIG_EXTRA_ENV_SETTINGS \
1587 Warning: This method is based on knowledge about the
1588 internal format how the environment is stored by the
1589 U-Boot code. This is NOT an official, exported
1590 interface! Although it is unlikely that this format
1591 will change soon, there is no guarantee either.
1592 You better know what you are doing here.
1594 Note: overly (ab)use of the default environment is
1595 discouraged. Make sure to check other ways to preset
1596 the environment like the "source" command or the
1599 CONFIG_DELAY_ENVIRONMENT
1601 Normally the environment is loaded when the board is
1602 initialised so that it is available to U-Boot. This inhibits
1603 that so that the environment is not available until
1604 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1605 this is instead controlled by the value of
1606 /config/load-environment.
1608 CONFIG_STANDALONE_LOAD_ADDR
1610 This option defines a board specific value for the
1611 address where standalone program gets loaded, thus
1612 overwriting the architecture dependent default
1615 - Frame Buffer Address:
1618 Define CONFIG_FB_ADDR if you want to use specific
1619 address for frame buffer. This is typically the case
1620 when using a graphics controller has separate video
1621 memory. U-Boot will then place the frame buffer at
1622 the given address instead of dynamically reserving it
1623 in system RAM by calling lcd_setmem(), which grabs
1624 the memory for the frame buffer depending on the
1625 configured panel size.
1627 Please see board_init_f function.
1629 - Automatic software updates via TFTP server
1631 CONFIG_UPDATE_TFTP_CNT_MAX
1632 CONFIG_UPDATE_TFTP_MSEC_MAX
1634 These options enable and control the auto-update feature;
1635 for a more detailed description refer to doc/README.update.
1637 - MTD Support (mtdparts command, UBI support)
1638 CONFIG_MTD_UBI_WL_THRESHOLD
1639 This parameter defines the maximum difference between the highest
1640 erase counter value and the lowest erase counter value of eraseblocks
1641 of UBI devices. When this threshold is exceeded, UBI starts performing
1642 wear leveling by means of moving data from eraseblock with low erase
1643 counter to eraseblocks with high erase counter.
1645 The default value should be OK for SLC NAND flashes, NOR flashes and
1646 other flashes which have eraseblock life-cycle 100000 or more.
1647 However, in case of MLC NAND flashes which typically have eraseblock
1648 life-cycle less than 10000, the threshold should be lessened (e.g.,
1649 to 128 or 256, although it does not have to be power of 2).
1653 CONFIG_MTD_UBI_BEB_LIMIT
1654 This option specifies the maximum bad physical eraseblocks UBI
1655 expects on the MTD device (per 1024 eraseblocks). If the
1656 underlying flash does not admit of bad eraseblocks (e.g. NOR
1657 flash), this value is ignored.
1659 NAND datasheets often specify the minimum and maximum NVM
1660 (Number of Valid Blocks) for the flashes' endurance lifetime.
1661 The maximum expected bad eraseblocks per 1024 eraseblocks
1662 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1663 which gives 20 for most NANDs (MaxNVB is basically the total
1664 count of eraseblocks on the chip).
1666 To put it differently, if this value is 20, UBI will try to
1667 reserve about 1.9% of physical eraseblocks for bad blocks
1668 handling. And that will be 1.9% of eraseblocks on the entire
1669 NAND chip, not just the MTD partition UBI attaches. This means
1670 that if you have, say, a NAND flash chip admits maximum 40 bad
1671 eraseblocks, and it is split on two MTD partitions of the same
1672 size, UBI will reserve 40 eraseblocks when attaching a
1677 CONFIG_MTD_UBI_FASTMAP
1678 Fastmap is a mechanism which allows attaching an UBI device
1679 in nearly constant time. Instead of scanning the whole MTD device it
1680 only has to locate a checkpoint (called fastmap) on the device.
1681 The on-flash fastmap contains all information needed to attach
1682 the device. Using fastmap makes only sense on large devices where
1683 attaching by scanning takes long. UBI will not automatically install
1684 a fastmap on old images, but you can set the UBI parameter
1685 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1686 that fastmap-enabled images are still usable with UBI implementations
1687 without fastmap support. On typical flash devices the whole fastmap
1688 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1690 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1691 Set this parameter to enable fastmap automatically on images
1695 CONFIG_MTD_UBI_FM_DEBUG
1696 Enable UBI fastmap debug
1701 Enable building of SPL globally.
1703 CONFIG_SPL_MAX_FOOTPRINT
1704 Maximum size in memory allocated to the SPL, BSS included.
1705 When defined, the linker checks that the actual memory
1706 used by SPL from _start to __bss_end does not exceed it.
1707 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1708 must not be both defined at the same time.
1711 Maximum size of the SPL image (text, data, rodata, and
1712 linker lists sections), BSS excluded.
1713 When defined, the linker checks that the actual size does
1716 CONFIG_SPL_RELOC_TEXT_BASE
1717 Address to relocate to. If unspecified, this is equal to
1718 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1720 CONFIG_SPL_BSS_START_ADDR
1721 Link address for the BSS within the SPL binary.
1723 CONFIG_SPL_BSS_MAX_SIZE
1724 Maximum size in memory allocated to the SPL BSS.
1725 When defined, the linker checks that the actual memory used
1726 by SPL from __bss_start to __bss_end does not exceed it.
1727 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1728 must not be both defined at the same time.
1731 Adress of the start of the stack SPL will use
1733 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1734 When defined, SPL will panic() if the image it has
1735 loaded does not have a signature.
1736 Defining this is useful when code which loads images
1737 in SPL cannot guarantee that absolutely all read errors
1739 An example is the LPC32XX MLC NAND driver, which will
1740 consider that a completely unreadable NAND block is bad,
1741 and thus should be skipped silently.
1743 CONFIG_SPL_RELOC_STACK
1744 Adress of the start of the stack SPL will use after
1745 relocation. If unspecified, this is equal to
1748 CONFIG_SYS_SPL_MALLOC_START
1749 Starting address of the malloc pool used in SPL.
1750 When this option is set the full malloc is used in SPL and
1751 it is set up by spl_init() and before that, the simple malloc()
1752 can be used if CONFIG_SYS_MALLOC_F is defined.
1754 CONFIG_SYS_SPL_MALLOC_SIZE
1755 The size of the malloc pool used in SPL.
1757 CONFIG_SPL_DISPLAY_PRINT
1758 For ARM, enable an optional function to print more information
1759 about the running system.
1761 CONFIG_SPL_INIT_MINIMAL
1762 Arch init code should be built for a very small image
1764 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1765 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1766 Sector and number of sectors to load kernel argument
1767 parameters from when MMC is being used in raw mode
1770 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1771 Filename to read to load U-Boot when reading from filesystem
1773 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1774 Filename to read to load kernel uImage when reading
1775 from filesystem (for Falcon mode)
1777 CONFIG_SPL_FS_LOAD_ARGS_NAME
1778 Filename to read to load kernel argument parameters
1779 when reading from filesystem (for Falcon mode)
1781 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1782 Set this for NAND SPL on PPC mpc83xx targets, so that
1783 start.S waits for the rest of the SPL to load before
1784 continuing (the hardware starts execution after just
1785 loading the first page rather than the full 4K).
1787 CONFIG_SPL_SKIP_RELOCATE
1788 Avoid SPL relocation
1791 Support for a lightweight UBI (fastmap) scanner and
1794 CONFIG_SPL_NAND_RAW_ONLY
1795 Support to boot only raw u-boot.bin images. Use this only
1796 if you need to save space.
1798 CONFIG_SPL_COMMON_INIT_DDR
1799 Set for common ddr init with serial presence detect in
1802 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1803 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1804 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1805 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1806 CONFIG_SYS_NAND_ECCBYTES
1807 Defines the size and behavior of the NAND that SPL uses
1810 CONFIG_SYS_NAND_U_BOOT_DST
1811 Location in memory to load U-Boot to
1813 CONFIG_SYS_NAND_U_BOOT_SIZE
1814 Size of image to load
1816 CONFIG_SYS_NAND_U_BOOT_START
1817 Entry point in loaded image to jump to
1819 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1820 Define this if you need to first read the OOB and then the
1821 data. This is used, for example, on davinci platforms.
1823 CONFIG_SPL_RAM_DEVICE
1824 Support for running image already present in ram, in SPL binary
1827 Image offset to which the SPL should be padded before appending
1828 the SPL payload. By default, this is defined as
1829 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1830 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1831 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1834 Final target image containing SPL and payload. Some SPLs
1835 use an arch-specific makefile fragment instead, for
1836 example if more than one image needs to be produced.
1838 CONFIG_SPL_FIT_PRINT
1839 Printing information about a FIT image adds quite a bit of
1840 code to SPL. So this is normally disabled in SPL. Use this
1841 option to re-enable it. This will affect the output of the
1842 bootm command when booting a FIT image.
1846 Enable building of TPL globally.
1849 Image offset to which the TPL should be padded before appending
1850 the TPL payload. By default, this is defined as
1851 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1852 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1853 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1855 - Interrupt support (PPC):
1857 There are common interrupt_init() and timer_interrupt()
1858 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1859 for CPU specific initialization. interrupt_init_cpu()
1860 should set decrementer_count to appropriate value. If
1861 CPU resets decrementer automatically after interrupt
1862 (ppc4xx) it should set decrementer_count to zero.
1863 timer_interrupt() calls timer_interrupt_cpu() for CPU
1864 specific handling. If board has watchdog / status_led
1865 / other_activity_monitor it works automatically from
1866 general timer_interrupt().
1869 Board initialization settings:
1870 ------------------------------
1872 During Initialization u-boot calls a number of board specific functions
1873 to allow the preparation of board specific prerequisites, e.g. pin setup
1874 before drivers are initialized. To enable these callbacks the
1875 following configuration macros have to be defined. Currently this is
1876 architecture specific, so please check arch/your_architecture/lib/board.c
1877 typically in board_init_f() and board_init_r().
1879 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1880 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1881 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1883 Configuration Settings:
1884 -----------------------
1886 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1887 Optionally it can be defined to support 64-bit memory commands.
1889 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1890 undefine this when you're short of memory.
1892 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1893 width of the commands listed in the 'help' command output.
1895 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1896 prompt for user input.
1898 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
1900 - CONFIG_SYS_PBSIZE: Buffer size for Console output
1902 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
1904 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
1905 the application (usually a Linux kernel) when it is
1908 - CONFIG_SYS_BAUDRATE_TABLE:
1909 List of legal baudrate settings for this board.
1911 - CONFIG_SYS_MEM_RESERVE_SECURE
1912 Only implemented for ARMv8 for now.
1913 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1914 is substracted from total RAM and won't be reported to OS.
1915 This memory can be used as secure memory. A variable
1916 gd->arch.secure_ram is used to track the location. In systems
1917 the RAM base is not zero, or RAM is divided into banks,
1918 this variable needs to be recalcuated to get the address.
1920 - CONFIG_SYS_MEM_TOP_HIDE:
1921 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
1922 this specified memory area will get subtracted from the top
1923 (end) of RAM and won't get "touched" at all by U-Boot. By
1924 fixing up gd->ram_size the Linux kernel should gets passed
1925 the now "corrected" memory size and won't touch it either.
1926 This should work for arch/ppc and arch/powerpc. Only Linux
1927 board ports in arch/powerpc with bootwrapper support that
1928 recalculate the memory size from the SDRAM controller setup
1929 will have to get fixed in Linux additionally.
1931 This option can be used as a workaround for the 440EPx/GRx
1932 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
1935 WARNING: Please make sure that this value is a multiple of
1936 the Linux page size (normally 4k). If this is not the case,
1937 then the end address of the Linux memory will be located at a
1938 non page size aligned address and this could cause major
1941 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1942 Enable temporary baudrate change while serial download
1944 - CONFIG_SYS_SDRAM_BASE:
1945 Physical start address of SDRAM. _Must_ be 0 here.
1947 - CONFIG_SYS_FLASH_BASE:
1948 Physical start address of Flash memory.
1950 - CONFIG_SYS_MONITOR_BASE:
1951 Physical start address of boot monitor code (set by
1952 make config files to be same as the text base address
1953 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
1954 CONFIG_SYS_FLASH_BASE when booting from flash.
1956 - CONFIG_SYS_MONITOR_LEN:
1957 Size of memory reserved for monitor code, used to
1958 determine _at_compile_time_ (!) if the environment is
1959 embedded within the U-Boot image, or in a separate
1962 - CONFIG_SYS_MALLOC_LEN:
1963 Size of DRAM reserved for malloc() use.
1965 - CONFIG_SYS_MALLOC_F_LEN
1966 Size of the malloc() pool for use before relocation. If
1967 this is defined, then a very simple malloc() implementation
1968 will become available before relocation. The address is just
1969 below the global data, and the stack is moved down to make
1972 This feature allocates regions with increasing addresses
1973 within the region. calloc() is supported, but realloc()
1974 is not available. free() is supported but does nothing.
1975 The memory will be freed (or in fact just forgotten) when
1976 U-Boot relocates itself.
1978 - CONFIG_SYS_MALLOC_SIMPLE
1979 Provides a simple and small malloc() and calloc() for those
1980 boards which do not use the full malloc in SPL (which is
1981 enabled with CONFIG_SYS_SPL_MALLOC_START).
1983 - CONFIG_SYS_NONCACHED_MEMORY:
1984 Size of non-cached memory area. This area of memory will be
1985 typically located right below the malloc() area and mapped
1986 uncached in the MMU. This is useful for drivers that would
1987 otherwise require a lot of explicit cache maintenance. For
1988 some drivers it's also impossible to properly maintain the
1989 cache. For example if the regions that need to be flushed
1990 are not a multiple of the cache-line size, *and* padding
1991 cannot be allocated between the regions to align them (i.e.
1992 if the HW requires a contiguous array of regions, and the
1993 size of each region is not cache-aligned), then a flush of
1994 one region may result in overwriting data that hardware has
1995 written to another region in the same cache-line. This can
1996 happen for example in network drivers where descriptors for
1997 buffers are typically smaller than the CPU cache-line (e.g.
1998 16 bytes vs. 32 or 64 bytes).
2000 Non-cached memory is only supported on 32-bit ARM at present.
2002 - CONFIG_SYS_BOOTM_LEN:
2003 Normally compressed uImages are limited to an
2004 uncompressed size of 8 MBytes. If this is not enough,
2005 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2006 to adjust this setting to your needs.
2008 - CONFIG_SYS_BOOTMAPSZ:
2009 Maximum size of memory mapped by the startup code of
2010 the Linux kernel; all data that must be processed by
2011 the Linux kernel (bd_info, boot arguments, FDT blob if
2012 used) must be put below this limit, unless "bootm_low"
2013 environment variable is defined and non-zero. In such case
2014 all data for the Linux kernel must be between "bootm_low"
2015 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2016 variable "bootm_mapsize" will override the value of
2017 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2018 then the value in "bootm_size" will be used instead.
2020 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2021 Enable initrd_high functionality. If defined then the
2022 initrd_high feature is enabled and the bootm ramdisk subcommand
2025 - CONFIG_SYS_BOOT_GET_CMDLINE:
2026 Enables allocating and saving kernel cmdline in space between
2027 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2029 - CONFIG_SYS_BOOT_GET_KBD:
2030 Enables allocating and saving a kernel copy of the bd_info in
2031 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2033 - CONFIG_SYS_MAX_FLASH_SECT:
2034 Max number of sectors on a Flash chip
2036 - CONFIG_SYS_FLASH_ERASE_TOUT:
2037 Timeout for Flash erase operations (in ms)
2039 - CONFIG_SYS_FLASH_WRITE_TOUT:
2040 Timeout for Flash write operations (in ms)
2042 - CONFIG_SYS_FLASH_LOCK_TOUT
2043 Timeout for Flash set sector lock bit operation (in ms)
2045 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2046 Timeout for Flash clear lock bits operation (in ms)
2048 - CONFIG_SYS_FLASH_PROTECTION
2049 If defined, hardware flash sectors protection is used
2050 instead of U-Boot software protection.
2052 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2054 Enable TFTP transfers directly to flash memory;
2055 without this option such a download has to be
2056 performed in two steps: (1) download to RAM, and (2)
2057 copy from RAM to flash.
2059 The two-step approach is usually more reliable, since
2060 you can check if the download worked before you erase
2061 the flash, but in some situations (when system RAM is
2062 too limited to allow for a temporary copy of the
2063 downloaded image) this option may be very useful.
2065 - CONFIG_SYS_FLASH_CFI:
2066 Define if the flash driver uses extra elements in the
2067 common flash structure for storing flash geometry.
2069 - CONFIG_FLASH_CFI_DRIVER
2070 This option also enables the building of the cfi_flash driver
2071 in the drivers directory
2073 - CONFIG_FLASH_CFI_MTD
2074 This option enables the building of the cfi_mtd driver
2075 in the drivers directory. The driver exports CFI flash
2078 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2079 Use buffered writes to flash.
2081 - CONFIG_FLASH_SPANSION_S29WS_N
2082 s29ws-n MirrorBit flash has non-standard addresses for buffered
2085 - CONFIG_SYS_FLASH_QUIET_TEST
2086 If this option is defined, the common CFI flash doesn't
2087 print it's warning upon not recognized FLASH banks. This
2088 is useful, if some of the configured banks are only
2089 optionally available.
2091 - CONFIG_FLASH_SHOW_PROGRESS
2092 If defined (must be an integer), print out countdown
2093 digits and dots. Recommended value: 45 (9..1) for 80
2094 column displays, 15 (3..1) for 40 column displays.
2096 - CONFIG_FLASH_VERIFY
2097 If defined, the content of the flash (destination) is compared
2098 against the source after the write operation. An error message
2099 will be printed when the contents are not identical.
2100 Please note that this option is useless in nearly all cases,
2101 since such flash programming errors usually are detected earlier
2102 while unprotecting/erasing/programming. Please only enable
2103 this option if you really know what you are doing.
2105 - CONFIG_ENV_MAX_ENTRIES
2107 Maximum number of entries in the hash table that is used
2108 internally to store the environment settings. The default
2109 setting is supposed to be generous and should work in most
2110 cases. This setting can be used to tune behaviour; see
2111 lib/hashtable.c for details.
2113 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2114 - CONFIG_ENV_FLAGS_LIST_STATIC
2115 Enable validation of the values given to environment variables when
2116 calling env set. Variables can be restricted to only decimal,
2117 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2118 the variables can also be restricted to IP address or MAC address.
2120 The format of the list is:
2121 type_attribute = [s|d|x|b|i|m]
2122 access_attribute = [a|r|o|c]
2123 attributes = type_attribute[access_attribute]
2124 entry = variable_name[:attributes]
2127 The type attributes are:
2128 s - String (default)
2131 b - Boolean ([1yYtT|0nNfF])
2135 The access attributes are:
2141 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2142 Define this to a list (string) to define the ".flags"
2143 environment variable in the default or embedded environment.
2145 - CONFIG_ENV_FLAGS_LIST_STATIC
2146 Define this to a list (string) to define validation that
2147 should be done if an entry is not found in the ".flags"
2148 environment variable. To override a setting in the static
2149 list, simply add an entry for the same variable name to the
2152 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2153 regular expression. This allows multiple variables to define the same
2154 flags without explicitly listing them for each variable.
2156 The following definitions that deal with the placement and management
2157 of environment data (variable area); in general, we support the
2158 following configurations:
2160 - CONFIG_BUILD_ENVCRC:
2162 Builds up envcrc with the target environment so that external utils
2163 may easily extract it and embed it in final U-Boot images.
2165 BE CAREFUL! The first access to the environment happens quite early
2166 in U-Boot initialization (when we try to get the setting of for the
2167 console baudrate). You *MUST* have mapped your NVRAM area then, or
2170 Please note that even with NVRAM we still use a copy of the
2171 environment in RAM: we could work on NVRAM directly, but we want to
2172 keep settings there always unmodified except somebody uses "saveenv"
2173 to save the current settings.
2175 BE CAREFUL! For some special cases, the local device can not use
2176 "saveenv" command. For example, the local device will get the
2177 environment stored in a remote NOR flash by SRIO or PCIE link,
2178 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2180 - CONFIG_NAND_ENV_DST
2182 Defines address in RAM to which the nand_spl code should copy the
2183 environment. If redundant environment is used, it will be copied to
2184 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2186 Please note that the environment is read-only until the monitor
2187 has been relocated to RAM and a RAM copy of the environment has been
2188 created; also, when using EEPROM you will have to use env_get_f()
2189 until then to read environment variables.
2191 The environment is protected by a CRC32 checksum. Before the monitor
2192 is relocated into RAM, as a result of a bad CRC you will be working
2193 with the compiled-in default environment - *silently*!!! [This is
2194 necessary, because the first environment variable we need is the
2195 "baudrate" setting for the console - if we have a bad CRC, we don't
2196 have any device yet where we could complain.]
2198 Note: once the monitor has been relocated, then it will complain if
2199 the default environment is used; a new CRC is computed as soon as you
2200 use the "saveenv" command to store a valid environment.
2202 - CONFIG_SYS_FAULT_MII_ADDR:
2203 MII address of the PHY to check for the Ethernet link state.
2205 - CONFIG_NS16550_MIN_FUNCTIONS:
2206 Define this if you desire to only have use of the NS16550_init
2207 and NS16550_putc functions for the serial driver located at
2208 drivers/serial/ns16550.c. This option is useful for saving
2209 space for already greatly restricted images, including but not
2210 limited to NAND_SPL configurations.
2212 - CONFIG_DISPLAY_BOARDINFO
2213 Display information about the board that U-Boot is running on
2214 when U-Boot starts up. The board function checkboard() is called
2217 - CONFIG_DISPLAY_BOARDINFO_LATE
2218 Similar to the previous option, but display this information
2219 later, once stdio is running and output goes to the LCD, if
2222 - CONFIG_BOARD_SIZE_LIMIT:
2223 Maximum size of the U-Boot image. When defined, the
2224 build system checks that the actual size does not
2227 Low Level (hardware related) configuration options:
2228 ---------------------------------------------------
2230 - CONFIG_SYS_CACHELINE_SIZE:
2231 Cache Line Size of the CPU.
2233 - CONFIG_SYS_CCSRBAR_DEFAULT:
2234 Default (power-on reset) physical address of CCSR on Freescale
2237 - CONFIG_SYS_CCSRBAR:
2238 Virtual address of CCSR. On a 32-bit build, this is typically
2239 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2241 - CONFIG_SYS_CCSRBAR_PHYS:
2242 Physical address of CCSR. CCSR can be relocated to a new
2243 physical address, if desired. In this case, this macro should
2244 be set to that address. Otherwise, it should be set to the
2245 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2246 is typically relocated on 36-bit builds. It is recommended
2247 that this macro be defined via the _HIGH and _LOW macros:
2249 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2250 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2252 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2253 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2254 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2255 used in assembly code, so it must not contain typecasts or
2256 integer size suffixes (e.g. "ULL").
2258 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2259 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2260 used in assembly code, so it must not contain typecasts or
2261 integer size suffixes (e.g. "ULL").
2263 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2264 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2265 forced to a value that ensures that CCSR is not relocated.
2267 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2268 DO NOT CHANGE unless you know exactly what you're
2269 doing! (11-4) [MPC8xx systems only]
2271 - CONFIG_SYS_INIT_RAM_ADDR:
2273 Start address of memory area that can be used for
2274 initial data and stack; please note that this must be
2275 writable memory that is working WITHOUT special
2276 initialization, i. e. you CANNOT use normal RAM which
2277 will become available only after programming the
2278 memory controller and running certain initialization
2281 U-Boot uses the following memory types:
2282 - MPC8xx: IMMR (internal memory of the CPU)
2284 - CONFIG_SYS_GBL_DATA_OFFSET:
2286 Offset of the initial data structure in the memory
2287 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2288 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2289 data is located at the end of the available space
2290 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2291 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2292 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2293 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2296 On the MPC824X (or other systems that use the data
2297 cache for initial memory) the address chosen for
2298 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2299 point to an otherwise UNUSED address space between
2300 the top of RAM and the start of the PCI space.
2302 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2304 - CONFIG_SYS_OR_TIMING_SDRAM:
2307 - CONFIG_SYS_MAMR_PTA:
2308 periodic timer for refresh
2311 Chip has SRIO or not
2314 Board has SRIO 1 port available
2317 Board has SRIO 2 port available
2319 - CONFIG_SRIO_PCIE_BOOT_MASTER
2320 Board can support master function for Boot from SRIO and PCIE
2322 - CONFIG_SYS_SRIOn_MEM_VIRT:
2323 Virtual Address of SRIO port 'n' memory region
2325 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2326 Physical Address of SRIO port 'n' memory region
2328 - CONFIG_SYS_SRIOn_MEM_SIZE:
2329 Size of SRIO port 'n' memory region
2331 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2332 Defined to tell the NAND controller that the NAND chip is using
2334 Not all NAND drivers use this symbol.
2335 Example of drivers that use it:
2336 - drivers/mtd/nand/raw/ndfc.c
2337 - drivers/mtd/nand/raw/mxc_nand.c
2339 - CONFIG_SYS_NDFC_EBC0_CFG
2340 Sets the EBC0_CFG register for the NDFC. If not defined
2341 a default value will be used.
2344 Get DDR timing information from an I2C EEPROM. Common
2345 with pluggable memory modules such as SODIMMs
2348 I2C address of the SPD EEPROM
2350 - CONFIG_SYS_SPD_BUS_NUM
2351 If SPD EEPROM is on an I2C bus other than the first
2352 one, specify here. Note that the value must resolve
2353 to something your driver can deal with.
2355 - CONFIG_SYS_DDR_RAW_TIMING
2356 Get DDR timing information from other than SPD. Common with
2357 soldered DDR chips onboard without SPD. DDR raw timing
2358 parameters are extracted from datasheet and hard-coded into
2359 header files or board specific files.
2361 - CONFIG_FSL_DDR_INTERACTIVE
2362 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2364 - CONFIG_FSL_DDR_SYNC_REFRESH
2365 Enable sync of refresh for multiple controllers.
2367 - CONFIG_FSL_DDR_BIST
2368 Enable built-in memory test for Freescale DDR controllers.
2370 - CONFIG_SYS_83XX_DDR_USES_CS0
2371 Only for 83xx systems. If specified, then DDR should
2372 be configured using CS0 and CS1 instead of CS2 and CS3.
2375 Enable RMII mode for all FECs.
2376 Note that this is a global option, we can't
2377 have one FEC in standard MII mode and another in RMII mode.
2379 - CONFIG_CRC32_VERIFY
2380 Add a verify option to the crc32 command.
2383 => crc32 -v <address> <count> <crc32>
2385 Where address/count indicate a memory area
2386 and crc32 is the correct crc32 which the
2390 Add the "loopw" memory command. This only takes effect if
2391 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2393 - CONFIG_CMD_MX_CYCLIC
2394 Add the "mdc" and "mwc" memory commands. These are cyclic
2399 This command will print 4 bytes (10,11,12,13) each 500 ms.
2401 => mwc.l 100 12345678 10
2402 This command will write 12345678 to address 100 all 10 ms.
2404 This only takes effect if the memory commands are activated
2405 globally (CONFIG_CMD_MEMORY).
2408 Set when the currently-running compilation is for an artifact
2409 that will end up in the SPL (as opposed to the TPL or U-Boot
2410 proper). Code that needs stage-specific behavior should check
2414 Set when the currently-running compilation is for an artifact
2415 that will end up in the TPL (as opposed to the SPL or U-Boot
2416 proper). Code that needs stage-specific behavior should check
2419 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2420 Only for 85xx systems. If this variable is specified, the section
2421 .resetvec is not kept and the section .bootpg is placed in the
2422 previous 4k of the .text section.
2424 - CONFIG_ARCH_MAP_SYSMEM
2425 Generally U-Boot (and in particular the md command) uses
2426 effective address. It is therefore not necessary to regard
2427 U-Boot address as virtual addresses that need to be translated
2428 to physical addresses. However, sandbox requires this, since
2429 it maintains its own little RAM buffer which contains all
2430 addressable memory. This option causes some memory accesses
2431 to be mapped through map_sysmem() / unmap_sysmem().
2433 - CONFIG_X86_RESET_VECTOR
2434 If defined, the x86 reset vector code is included. This is not
2435 needed when U-Boot is running from Coreboot.
2437 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2438 Option to disable subpage write in NAND driver
2439 driver that uses this:
2440 drivers/mtd/nand/raw/davinci_nand.c
2442 Freescale QE/FMAN Firmware Support:
2443 -----------------------------------
2445 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2446 loading of "firmware", which is encoded in the QE firmware binary format.
2447 This firmware often needs to be loaded during U-Boot booting, so macros
2448 are used to identify the storage device (NOR flash, SPI, etc) and the address
2451 - CONFIG_SYS_FMAN_FW_ADDR
2452 The address in the storage device where the FMAN microcode is located. The
2453 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2456 - CONFIG_SYS_QE_FW_ADDR
2457 The address in the storage device where the QE microcode is located. The
2458 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2461 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2462 The maximum possible size of the firmware. The firmware binary format
2463 has a field that specifies the actual size of the firmware, but it
2464 might not be possible to read any part of the firmware unless some
2465 local storage is allocated to hold the entire firmware first.
2467 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2468 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2469 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2470 virtual address in NOR flash.
2472 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2473 Specifies that QE/FMAN firmware is located in NAND flash.
2474 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2476 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2477 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2478 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2480 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2481 Specifies that QE/FMAN firmware is located in the remote (master)
2482 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2483 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2484 window->master inbound window->master LAW->the ucode address in
2485 master's memory space.
2487 Freescale Layerscape Management Complex Firmware Support:
2488 ---------------------------------------------------------
2489 The Freescale Layerscape Management Complex (MC) supports the loading of
2491 This firmware often needs to be loaded during U-Boot booting, so macros
2492 are used to identify the storage device (NOR flash, SPI, etc) and the address
2495 - CONFIG_FSL_MC_ENET
2496 Enable the MC driver for Layerscape SoCs.
2498 Freescale Layerscape Debug Server Support:
2499 -------------------------------------------
2500 The Freescale Layerscape Debug Server Support supports the loading of
2501 "Debug Server firmware" and triggering SP boot-rom.
2502 This firmware often needs to be loaded during U-Boot booting.
2504 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2505 Define alignment of reserved memory MC requires
2510 In order to achieve reproducible builds, timestamps used in the U-Boot build
2511 process have to be set to a fixed value.
2513 This is done using the SOURCE_DATE_EPOCH environment variable.
2514 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2515 option for U-Boot or an environment variable in U-Boot.
2517 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2519 Building the Software:
2520 ======================
2522 Building U-Boot has been tested in several native build environments
2523 and in many different cross environments. Of course we cannot support
2524 all possibly existing versions of cross development tools in all
2525 (potentially obsolete) versions. In case of tool chain problems we
2526 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2527 which is extensively used to build and test U-Boot.
2529 If you are not using a native environment, it is assumed that you
2530 have GNU cross compiling tools available in your path. In this case,
2531 you must set the environment variable CROSS_COMPILE in your shell.
2532 Note that no changes to the Makefile or any other source files are
2533 necessary. For example using the ELDK on a 4xx CPU, please enter:
2535 $ CROSS_COMPILE=ppc_4xx-
2536 $ export CROSS_COMPILE
2538 U-Boot is intended to be simple to build. After installing the
2539 sources you must configure U-Boot for one specific board type. This
2544 where "NAME_defconfig" is the name of one of the existing configu-
2545 rations; see configs/*_defconfig for supported names.
2547 Note: for some boards special configuration names may exist; check if
2548 additional information is available from the board vendor; for
2549 instance, the TQM823L systems are available without (standard)
2550 or with LCD support. You can select such additional "features"
2551 when choosing the configuration, i. e.
2553 make TQM823L_defconfig
2554 - will configure for a plain TQM823L, i. e. no LCD support
2556 make TQM823L_LCD_defconfig
2557 - will configure for a TQM823L with U-Boot console on LCD
2562 Finally, type "make all", and you should get some working U-Boot
2563 images ready for download to / installation on your system:
2565 - "u-boot.bin" is a raw binary image
2566 - "u-boot" is an image in ELF binary format
2567 - "u-boot.srec" is in Motorola S-Record format
2569 By default the build is performed locally and the objects are saved
2570 in the source directory. One of the two methods can be used to change
2571 this behavior and build U-Boot to some external directory:
2573 1. Add O= to the make command line invocations:
2575 make O=/tmp/build distclean
2576 make O=/tmp/build NAME_defconfig
2577 make O=/tmp/build all
2579 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2581 export KBUILD_OUTPUT=/tmp/build
2586 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2589 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2590 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2591 For example to treat all compiler warnings as errors:
2593 make KCFLAGS=-Werror
2595 Please be aware that the Makefiles assume you are using GNU make, so
2596 for instance on NetBSD you might need to use "gmake" instead of
2600 If the system board that you have is not listed, then you will need
2601 to port U-Boot to your hardware platform. To do this, follow these
2604 1. Create a new directory to hold your board specific code. Add any
2605 files you need. In your board directory, you will need at least
2606 the "Makefile" and a "<board>.c".
2607 2. Create a new configuration file "include/configs/<board>.h" for
2609 3. If you're porting U-Boot to a new CPU, then also create a new
2610 directory to hold your CPU specific code. Add any files you need.
2611 4. Run "make <board>_defconfig" with your new name.
2612 5. Type "make", and you should get a working "u-boot.srec" file
2613 to be installed on your target system.
2614 6. Debug and solve any problems that might arise.
2615 [Of course, this last step is much harder than it sounds.]
2618 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2619 ==============================================================
2621 If you have modified U-Boot sources (for instance added a new board
2622 or support for new devices, a new CPU, etc.) you are expected to
2623 provide feedback to the other developers. The feedback normally takes
2624 the form of a "patch", i.e. a context diff against a certain (latest
2625 official or latest in the git repository) version of U-Boot sources.
2627 But before you submit such a patch, please verify that your modifi-
2628 cation did not break existing code. At least make sure that *ALL* of
2629 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2630 just run the buildman script (tools/buildman/buildman), which will
2631 configure and build U-Boot for ALL supported system. Be warned, this
2632 will take a while. Please see the buildman README, or run 'buildman -H'
2636 See also "U-Boot Porting Guide" below.
2639 Monitor Commands - Overview:
2640 ============================
2642 go - start application at address 'addr'
2643 run - run commands in an environment variable
2644 bootm - boot application image from memory
2645 bootp - boot image via network using BootP/TFTP protocol
2646 bootz - boot zImage from memory
2647 tftpboot- boot image via network using TFTP protocol
2648 and env variables "ipaddr" and "serverip"
2649 (and eventually "gatewayip")
2650 tftpput - upload a file via network using TFTP protocol
2651 rarpboot- boot image via network using RARP/TFTP protocol
2652 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2653 loads - load S-Record file over serial line
2654 loadb - load binary file over serial line (kermit mode)
2656 mm - memory modify (auto-incrementing)
2657 nm - memory modify (constant address)
2658 mw - memory write (fill)
2661 cmp - memory compare
2662 crc32 - checksum calculation
2663 i2c - I2C sub-system
2664 sspi - SPI utility commands
2665 base - print or set address offset
2666 printenv- print environment variables
2667 pwm - control pwm channels
2668 setenv - set environment variables
2669 saveenv - save environment variables to persistent storage
2670 protect - enable or disable FLASH write protection
2671 erase - erase FLASH memory
2672 flinfo - print FLASH memory information
2673 nand - NAND memory operations (see doc/README.nand)
2674 bdinfo - print Board Info structure
2675 iminfo - print header information for application image
2676 coninfo - print console devices and informations
2677 ide - IDE sub-system
2678 loop - infinite loop on address range
2679 loopw - infinite write loop on address range
2680 mtest - simple RAM test
2681 icache - enable or disable instruction cache
2682 dcache - enable or disable data cache
2683 reset - Perform RESET of the CPU
2684 echo - echo args to console
2685 version - print monitor version
2686 help - print online help
2687 ? - alias for 'help'
2690 Monitor Commands - Detailed Description:
2691 ========================================
2695 For now: just type "help <command>".
2698 Note for Redundant Ethernet Interfaces:
2699 =======================================
2701 Some boards come with redundant Ethernet interfaces; U-Boot supports
2702 such configurations and is capable of automatic selection of a
2703 "working" interface when needed. MAC assignment works as follows:
2705 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2706 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2707 "eth1addr" (=>eth1), "eth2addr", ...
2709 If the network interface stores some valid MAC address (for instance
2710 in SROM), this is used as default address if there is NO correspon-
2711 ding setting in the environment; if the corresponding environment
2712 variable is set, this overrides the settings in the card; that means:
2714 o If the SROM has a valid MAC address, and there is no address in the
2715 environment, the SROM's address is used.
2717 o If there is no valid address in the SROM, and a definition in the
2718 environment exists, then the value from the environment variable is
2721 o If both the SROM and the environment contain a MAC address, and
2722 both addresses are the same, this MAC address is used.
2724 o If both the SROM and the environment contain a MAC address, and the
2725 addresses differ, the value from the environment is used and a
2728 o If neither SROM nor the environment contain a MAC address, an error
2729 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2730 a random, locally-assigned MAC is used.
2732 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2733 will be programmed into hardware as part of the initialization process. This
2734 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2735 The naming convention is as follows:
2736 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2741 U-Boot is capable of booting (and performing other auxiliary operations on)
2742 images in two formats:
2744 New uImage format (FIT)
2745 -----------------------
2747 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2748 to Flattened Device Tree). It allows the use of images with multiple
2749 components (several kernels, ramdisks, etc.), with contents protected by
2750 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2756 Old image format is based on binary files which can be basically anything,
2757 preceded by a special header; see the definitions in include/image.h for
2758 details; basically, the header defines the following image properties:
2760 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2761 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2762 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2763 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2764 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2765 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2766 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2767 * Compression Type (uncompressed, gzip, bzip2)
2773 The header is marked by a special Magic Number, and both the header
2774 and the data portions of the image are secured against corruption by
2781 Although U-Boot should support any OS or standalone application
2782 easily, the main focus has always been on Linux during the design of
2785 U-Boot includes many features that so far have been part of some
2786 special "boot loader" code within the Linux kernel. Also, any
2787 "initrd" images to be used are no longer part of one big Linux image;
2788 instead, kernel and "initrd" are separate images. This implementation
2789 serves several purposes:
2791 - the same features can be used for other OS or standalone
2792 applications (for instance: using compressed images to reduce the
2793 Flash memory footprint)
2795 - it becomes much easier to port new Linux kernel versions because
2796 lots of low-level, hardware dependent stuff are done by U-Boot
2798 - the same Linux kernel image can now be used with different "initrd"
2799 images; of course this also means that different kernel images can
2800 be run with the same "initrd". This makes testing easier (you don't
2801 have to build a new "zImage.initrd" Linux image when you just
2802 change a file in your "initrd"). Also, a field-upgrade of the
2803 software is easier now.
2809 Porting Linux to U-Boot based systems:
2810 ---------------------------------------
2812 U-Boot cannot save you from doing all the necessary modifications to
2813 configure the Linux device drivers for use with your target hardware
2814 (no, we don't intend to provide a full virtual machine interface to
2817 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2819 Just make sure your machine specific header file (for instance
2820 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2821 Information structure as we define in include/asm-<arch>/u-boot.h,
2822 and make sure that your definition of IMAP_ADDR uses the same value
2823 as your U-Boot configuration in CONFIG_SYS_IMMR.
2825 Note that U-Boot now has a driver model, a unified model for drivers.
2826 If you are adding a new driver, plumb it into driver model. If there
2827 is no uclass available, you are encouraged to create one. See
2831 Configuring the Linux kernel:
2832 -----------------------------
2834 No specific requirements for U-Boot. Make sure you have some root
2835 device (initial ramdisk, NFS) for your target system.
2838 Building a Linux Image:
2839 -----------------------
2841 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2842 not used. If you use recent kernel source, a new build target
2843 "uImage" will exist which automatically builds an image usable by
2844 U-Boot. Most older kernels also have support for a "pImage" target,
2845 which was introduced for our predecessor project PPCBoot and uses a
2846 100% compatible format.
2850 make TQM850L_defconfig
2855 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2856 encapsulate a compressed Linux kernel image with header information,
2857 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2859 * build a standard "vmlinux" kernel image (in ELF binary format):
2861 * convert the kernel into a raw binary image:
2863 ${CROSS_COMPILE}-objcopy -O binary \
2864 -R .note -R .comment \
2865 -S vmlinux linux.bin
2867 * compress the binary image:
2871 * package compressed binary image for U-Boot:
2873 mkimage -A ppc -O linux -T kernel -C gzip \
2874 -a 0 -e 0 -n "Linux Kernel Image" \
2875 -d linux.bin.gz uImage
2878 The "mkimage" tool can also be used to create ramdisk images for use
2879 with U-Boot, either separated from the Linux kernel image, or
2880 combined into one file. "mkimage" encapsulates the images with a 64
2881 byte header containing information about target architecture,
2882 operating system, image type, compression method, entry points, time
2883 stamp, CRC32 checksums, etc.
2885 "mkimage" can be called in two ways: to verify existing images and
2886 print the header information, or to build new images.
2888 In the first form (with "-l" option) mkimage lists the information
2889 contained in the header of an existing U-Boot image; this includes
2890 checksum verification:
2892 tools/mkimage -l image
2893 -l ==> list image header information
2895 The second form (with "-d" option) is used to build a U-Boot image
2896 from a "data file" which is used as image payload:
2898 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2899 -n name -d data_file image
2900 -A ==> set architecture to 'arch'
2901 -O ==> set operating system to 'os'
2902 -T ==> set image type to 'type'
2903 -C ==> set compression type 'comp'
2904 -a ==> set load address to 'addr' (hex)
2905 -e ==> set entry point to 'ep' (hex)
2906 -n ==> set image name to 'name'
2907 -d ==> use image data from 'datafile'
2909 Right now, all Linux kernels for PowerPC systems use the same load
2910 address (0x00000000), but the entry point address depends on the
2913 - 2.2.x kernels have the entry point at 0x0000000C,
2914 - 2.3.x and later kernels have the entry point at 0x00000000.
2916 So a typical call to build a U-Boot image would read:
2918 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2919 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2920 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2921 > examples/uImage.TQM850L
2922 Image Name: 2.4.4 kernel for TQM850L
2923 Created: Wed Jul 19 02:34:59 2000
2924 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2925 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2926 Load Address: 0x00000000
2927 Entry Point: 0x00000000
2929 To verify the contents of the image (or check for corruption):
2931 -> tools/mkimage -l examples/uImage.TQM850L
2932 Image Name: 2.4.4 kernel for TQM850L
2933 Created: Wed Jul 19 02:34:59 2000
2934 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2935 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2936 Load Address: 0x00000000
2937 Entry Point: 0x00000000
2939 NOTE: for embedded systems where boot time is critical you can trade
2940 speed for memory and install an UNCOMPRESSED image instead: this
2941 needs more space in Flash, but boots much faster since it does not
2942 need to be uncompressed:
2944 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2945 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2946 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2947 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2948 > examples/uImage.TQM850L-uncompressed
2949 Image Name: 2.4.4 kernel for TQM850L
2950 Created: Wed Jul 19 02:34:59 2000
2951 Image Type: PowerPC Linux Kernel Image (uncompressed)
2952 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2953 Load Address: 0x00000000
2954 Entry Point: 0x00000000
2957 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2958 when your kernel is intended to use an initial ramdisk:
2960 -> tools/mkimage -n 'Simple Ramdisk Image' \
2961 > -A ppc -O linux -T ramdisk -C gzip \
2962 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2963 Image Name: Simple Ramdisk Image
2964 Created: Wed Jan 12 14:01:50 2000
2965 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2966 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2967 Load Address: 0x00000000
2968 Entry Point: 0x00000000
2970 The "dumpimage" tool can be used to disassemble or list the contents of images
2971 built by mkimage. See dumpimage's help output (-h) for details.
2973 Installing a Linux Image:
2974 -------------------------
2976 To downloading a U-Boot image over the serial (console) interface,
2977 you must convert the image to S-Record format:
2979 objcopy -I binary -O srec examples/image examples/image.srec
2981 The 'objcopy' does not understand the information in the U-Boot
2982 image header, so the resulting S-Record file will be relative to
2983 address 0x00000000. To load it to a given address, you need to
2984 specify the target address as 'offset' parameter with the 'loads'
2987 Example: install the image to address 0x40100000 (which on the
2988 TQM8xxL is in the first Flash bank):
2990 => erase 40100000 401FFFFF
2996 ## Ready for S-Record download ...
2997 ~>examples/image.srec
2998 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3000 15989 15990 15991 15992
3001 [file transfer complete]
3003 ## Start Addr = 0x00000000
3006 You can check the success of the download using the 'iminfo' command;
3007 this includes a checksum verification so you can be sure no data
3008 corruption happened:
3012 ## Checking Image at 40100000 ...
3013 Image Name: 2.2.13 for initrd on TQM850L
3014 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3015 Data Size: 335725 Bytes = 327 kB = 0 MB
3016 Load Address: 00000000
3017 Entry Point: 0000000c
3018 Verifying Checksum ... OK
3024 The "bootm" command is used to boot an application that is stored in
3025 memory (RAM or Flash). In case of a Linux kernel image, the contents
3026 of the "bootargs" environment variable is passed to the kernel as
3027 parameters. You can check and modify this variable using the
3028 "printenv" and "setenv" commands:
3031 => printenv bootargs
3032 bootargs=root=/dev/ram
3034 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3036 => printenv bootargs
3037 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3040 ## Booting Linux kernel at 40020000 ...
3041 Image Name: 2.2.13 for NFS on TQM850L
3042 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3043 Data Size: 381681 Bytes = 372 kB = 0 MB
3044 Load Address: 00000000
3045 Entry Point: 0000000c
3046 Verifying Checksum ... OK
3047 Uncompressing Kernel Image ... OK
3048 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
3049 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3050 time_init: decrementer frequency = 187500000/60
3051 Calibrating delay loop... 49.77 BogoMIPS
3052 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3055 If you want to boot a Linux kernel with initial RAM disk, you pass
3056 the memory addresses of both the kernel and the initrd image (PPBCOOT
3057 format!) to the "bootm" command:
3059 => imi 40100000 40200000
3061 ## Checking Image at 40100000 ...
3062 Image Name: 2.2.13 for initrd on TQM850L
3063 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3064 Data Size: 335725 Bytes = 327 kB = 0 MB
3065 Load Address: 00000000
3066 Entry Point: 0000000c
3067 Verifying Checksum ... OK
3069 ## Checking Image at 40200000 ...
3070 Image Name: Simple Ramdisk Image
3071 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3072 Data Size: 566530 Bytes = 553 kB = 0 MB
3073 Load Address: 00000000
3074 Entry Point: 00000000
3075 Verifying Checksum ... OK
3077 => bootm 40100000 40200000
3078 ## Booting Linux kernel at 40100000 ...
3079 Image Name: 2.2.13 for initrd on TQM850L
3080 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3081 Data Size: 335725 Bytes = 327 kB = 0 MB
3082 Load Address: 00000000
3083 Entry Point: 0000000c
3084 Verifying Checksum ... OK
3085 Uncompressing Kernel Image ... OK
3086 ## Loading RAMDisk Image at 40200000 ...
3087 Image Name: Simple Ramdisk Image
3088 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3089 Data Size: 566530 Bytes = 553 kB = 0 MB
3090 Load Address: 00000000
3091 Entry Point: 00000000
3092 Verifying Checksum ... OK
3093 Loading Ramdisk ... OK
3094 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
3095 Boot arguments: root=/dev/ram
3096 time_init: decrementer frequency = 187500000/60
3097 Calibrating delay loop... 49.77 BogoMIPS
3099 RAMDISK: Compressed image found at block 0
3100 VFS: Mounted root (ext2 filesystem).
3104 Boot Linux and pass a flat device tree:
3107 First, U-Boot must be compiled with the appropriate defines. See the section
3108 titled "Linux Kernel Interface" above for a more in depth explanation. The
3109 following is an example of how to start a kernel and pass an updated
3115 oft=oftrees/mpc8540ads.dtb
3116 => tftp $oftaddr $oft
3117 Speed: 1000, full duplex
3119 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3120 Filename 'oftrees/mpc8540ads.dtb'.
3121 Load address: 0x300000
3124 Bytes transferred = 4106 (100a hex)
3125 => tftp $loadaddr $bootfile
3126 Speed: 1000, full duplex
3128 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3130 Load address: 0x200000
3131 Loading:############
3133 Bytes transferred = 1029407 (fb51f hex)
3138 => bootm $loadaddr - $oftaddr
3139 ## Booting image at 00200000 ...
3140 Image Name: Linux-2.6.17-dirty
3141 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3142 Data Size: 1029343 Bytes = 1005.2 kB
3143 Load Address: 00000000
3144 Entry Point: 00000000
3145 Verifying Checksum ... OK
3146 Uncompressing Kernel Image ... OK
3147 Booting using flat device tree at 0x300000
3148 Using MPC85xx ADS machine description
3149 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3153 More About U-Boot Image Types:
3154 ------------------------------
3156 U-Boot supports the following image types:
3158 "Standalone Programs" are directly runnable in the environment
3159 provided by U-Boot; it is expected that (if they behave
3160 well) you can continue to work in U-Boot after return from
3161 the Standalone Program.
3162 "OS Kernel Images" are usually images of some Embedded OS which
3163 will take over control completely. Usually these programs
3164 will install their own set of exception handlers, device
3165 drivers, set up the MMU, etc. - this means, that you cannot
3166 expect to re-enter U-Boot except by resetting the CPU.
3167 "RAMDisk Images" are more or less just data blocks, and their
3168 parameters (address, size) are passed to an OS kernel that is
3170 "Multi-File Images" contain several images, typically an OS
3171 (Linux) kernel image and one or more data images like
3172 RAMDisks. This construct is useful for instance when you want
3173 to boot over the network using BOOTP etc., where the boot
3174 server provides just a single image file, but you want to get
3175 for instance an OS kernel and a RAMDisk image.
3177 "Multi-File Images" start with a list of image sizes, each
3178 image size (in bytes) specified by an "uint32_t" in network
3179 byte order. This list is terminated by an "(uint32_t)0".
3180 Immediately after the terminating 0 follow the images, one by
3181 one, all aligned on "uint32_t" boundaries (size rounded up to
3182 a multiple of 4 bytes).
3184 "Firmware Images" are binary images containing firmware (like
3185 U-Boot or FPGA images) which usually will be programmed to
3188 "Script files" are command sequences that will be executed by
3189 U-Boot's command interpreter; this feature is especially
3190 useful when you configure U-Boot to use a real shell (hush)
3191 as command interpreter.
3193 Booting the Linux zImage:
3194 -------------------------
3196 On some platforms, it's possible to boot Linux zImage. This is done
3197 using the "bootz" command. The syntax of "bootz" command is the same
3198 as the syntax of "bootm" command.
3200 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3201 kernel with raw initrd images. The syntax is slightly different, the
3202 address of the initrd must be augmented by it's size, in the following
3203 format: "<initrd addres>:<initrd size>".
3209 One of the features of U-Boot is that you can dynamically load and
3210 run "standalone" applications, which can use some resources of
3211 U-Boot like console I/O functions or interrupt services.
3213 Two simple examples are included with the sources:
3218 'examples/hello_world.c' contains a small "Hello World" Demo
3219 application; it is automatically compiled when you build U-Boot.
3220 It's configured to run at address 0x00040004, so you can play with it
3224 ## Ready for S-Record download ...
3225 ~>examples/hello_world.srec
3226 1 2 3 4 5 6 7 8 9 10 11 ...
3227 [file transfer complete]
3229 ## Start Addr = 0x00040004
3231 => go 40004 Hello World! This is a test.
3232 ## Starting application at 0x00040004 ...
3243 Hit any key to exit ...
3245 ## Application terminated, rc = 0x0
3247 Another example, which demonstrates how to register a CPM interrupt
3248 handler with the U-Boot code, can be found in 'examples/timer.c'.
3249 Here, a CPM timer is set up to generate an interrupt every second.
3250 The interrupt service routine is trivial, just printing a '.'
3251 character, but this is just a demo program. The application can be
3252 controlled by the following keys:
3254 ? - print current values og the CPM Timer registers
3255 b - enable interrupts and start timer
3256 e - stop timer and disable interrupts
3257 q - quit application
3260 ## Ready for S-Record download ...
3261 ~>examples/timer.srec
3262 1 2 3 4 5 6 7 8 9 10 11 ...
3263 [file transfer complete]
3265 ## Start Addr = 0x00040004
3268 ## Starting application at 0x00040004 ...
3271 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3274 [q, b, e, ?] Set interval 1000000 us
3277 [q, b, e, ?] ........
3278 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3281 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3284 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3287 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3289 [q, b, e, ?] ...Stopping timer
3291 [q, b, e, ?] ## Application terminated, rc = 0x0
3297 Over time, many people have reported problems when trying to use the
3298 "minicom" terminal emulation program for serial download. I (wd)
3299 consider minicom to be broken, and recommend not to use it. Under
3300 Unix, I recommend to use C-Kermit for general purpose use (and
3301 especially for kermit binary protocol download ("loadb" command), and
3302 use "cu" for S-Record download ("loads" command). See
3303 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3304 for help with kermit.
3307 Nevertheless, if you absolutely want to use it try adding this
3308 configuration to your "File transfer protocols" section:
3310 Name Program Name U/D FullScr IO-Red. Multi
3311 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3312 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3318 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3319 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3321 Building requires a cross environment; it is known to work on
3322 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3323 need gmake since the Makefiles are not compatible with BSD make).
3324 Note that the cross-powerpc package does not install include files;
3325 attempting to build U-Boot will fail because <machine/ansi.h> is
3326 missing. This file has to be installed and patched manually:
3328 # cd /usr/pkg/cross/powerpc-netbsd/include
3330 # ln -s powerpc machine
3331 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3332 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3334 Native builds *don't* work due to incompatibilities between native
3335 and U-Boot include files.
3337 Booting assumes that (the first part of) the image booted is a
3338 stage-2 loader which in turn loads and then invokes the kernel
3339 proper. Loader sources will eventually appear in the NetBSD source
3340 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3341 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3344 Implementation Internals:
3345 =========================
3347 The following is not intended to be a complete description of every
3348 implementation detail. However, it should help to understand the
3349 inner workings of U-Boot and make it easier to port it to custom
3353 Initial Stack, Global Data:
3354 ---------------------------
3356 The implementation of U-Boot is complicated by the fact that U-Boot
3357 starts running out of ROM (flash memory), usually without access to
3358 system RAM (because the memory controller is not initialized yet).
3359 This means that we don't have writable Data or BSS segments, and BSS
3360 is not initialized as zero. To be able to get a C environment working
3361 at all, we have to allocate at least a minimal stack. Implementation
3362 options for this are defined and restricted by the CPU used: Some CPU
3363 models provide on-chip memory (like the IMMR area on MPC8xx and
3364 MPC826x processors), on others (parts of) the data cache can be
3365 locked as (mis-) used as memory, etc.
3367 Chris Hallinan posted a good summary of these issues to the
3368 U-Boot mailing list:
3370 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3371 From: "Chris Hallinan" <clh@net1plus.com>
3372 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3375 Correct me if I'm wrong, folks, but the way I understand it
3376 is this: Using DCACHE as initial RAM for Stack, etc, does not
3377 require any physical RAM backing up the cache. The cleverness
3378 is that the cache is being used as a temporary supply of
3379 necessary storage before the SDRAM controller is setup. It's
3380 beyond the scope of this list to explain the details, but you
3381 can see how this works by studying the cache architecture and
3382 operation in the architecture and processor-specific manuals.
3384 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3385 is another option for the system designer to use as an
3386 initial stack/RAM area prior to SDRAM being available. Either
3387 option should work for you. Using CS 4 should be fine if your
3388 board designers haven't used it for something that would
3389 cause you grief during the initial boot! It is frequently not
3392 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3393 with your processor/board/system design. The default value
3394 you will find in any recent u-boot distribution in
3395 walnut.h should work for you. I'd set it to a value larger
3396 than your SDRAM module. If you have a 64MB SDRAM module, set
3397 it above 400_0000. Just make sure your board has no resources
3398 that are supposed to respond to that address! That code in
3399 start.S has been around a while and should work as is when
3400 you get the config right.
3405 It is essential to remember this, since it has some impact on the C
3406 code for the initialization procedures:
3408 * Initialized global data (data segment) is read-only. Do not attempt
3411 * Do not use any uninitialized global data (or implicitly initialized
3412 as zero data - BSS segment) at all - this is undefined, initiali-
3413 zation is performed later (when relocating to RAM).
3415 * Stack space is very limited. Avoid big data buffers or things like
3418 Having only the stack as writable memory limits means we cannot use
3419 normal global data to share information between the code. But it
3420 turned out that the implementation of U-Boot can be greatly
3421 simplified by making a global data structure (gd_t) available to all
3422 functions. We could pass a pointer to this data as argument to _all_
3423 functions, but this would bloat the code. Instead we use a feature of
3424 the GCC compiler (Global Register Variables) to share the data: we
3425 place a pointer (gd) to the global data into a register which we
3426 reserve for this purpose.
3428 When choosing a register for such a purpose we are restricted by the
3429 relevant (E)ABI specifications for the current architecture, and by
3430 GCC's implementation.
3432 For PowerPC, the following registers have specific use:
3434 R2: reserved for system use
3435 R3-R4: parameter passing and return values
3436 R5-R10: parameter passing
3437 R13: small data area pointer
3441 (U-Boot also uses R12 as internal GOT pointer. r12
3442 is a volatile register so r12 needs to be reset when
3443 going back and forth between asm and C)
3445 ==> U-Boot will use R2 to hold a pointer to the global data
3447 Note: on PPC, we could use a static initializer (since the
3448 address of the global data structure is known at compile time),
3449 but it turned out that reserving a register results in somewhat
3450 smaller code - although the code savings are not that big (on
3451 average for all boards 752 bytes for the whole U-Boot image,
3452 624 text + 127 data).
3454 On ARM, the following registers are used:
3456 R0: function argument word/integer result
3457 R1-R3: function argument word
3458 R9: platform specific
3459 R10: stack limit (used only if stack checking is enabled)
3460 R11: argument (frame) pointer
3461 R12: temporary workspace
3464 R15: program counter
3466 ==> U-Boot will use R9 to hold a pointer to the global data
3468 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3470 On Nios II, the ABI is documented here:
3471 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3473 ==> U-Boot will use gp to hold a pointer to the global data
3475 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3476 to access small data sections, so gp is free.
3478 On NDS32, the following registers are used:
3480 R0-R1: argument/return
3482 R15: temporary register for assembler
3483 R16: trampoline register
3484 R28: frame pointer (FP)
3485 R29: global pointer (GP)
3486 R30: link register (LP)
3487 R31: stack pointer (SP)
3488 PC: program counter (PC)
3490 ==> U-Boot will use R10 to hold a pointer to the global data
3492 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3493 or current versions of GCC may "optimize" the code too much.
3495 On RISC-V, the following registers are used:
3497 x0: hard-wired zero (zero)
3498 x1: return address (ra)
3499 x2: stack pointer (sp)
3500 x3: global pointer (gp)
3501 x4: thread pointer (tp)
3502 x5: link register (t0)
3503 x8: frame pointer (fp)
3504 x10-x11: arguments/return values (a0-1)
3505 x12-x17: arguments (a2-7)
3506 x28-31: temporaries (t3-6)
3507 pc: program counter (pc)
3509 ==> U-Boot will use gp to hold a pointer to the global data
3514 U-Boot runs in system state and uses physical addresses, i.e. the
3515 MMU is not used either for address mapping nor for memory protection.
3517 The available memory is mapped to fixed addresses using the memory
3518 controller. In this process, a contiguous block is formed for each
3519 memory type (Flash, SDRAM, SRAM), even when it consists of several
3520 physical memory banks.
3522 U-Boot is installed in the first 128 kB of the first Flash bank (on
3523 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3524 booting and sizing and initializing DRAM, the code relocates itself
3525 to the upper end of DRAM. Immediately below the U-Boot code some
3526 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3527 configuration setting]. Below that, a structure with global Board
3528 Info data is placed, followed by the stack (growing downward).
3530 Additionally, some exception handler code is copied to the low 8 kB
3531 of DRAM (0x00000000 ... 0x00001FFF).
3533 So a typical memory configuration with 16 MB of DRAM could look like
3536 0x0000 0000 Exception Vector code
3539 0x0000 2000 Free for Application Use
3545 0x00FB FF20 Monitor Stack (Growing downward)
3546 0x00FB FFAC Board Info Data and permanent copy of global data
3547 0x00FC 0000 Malloc Arena
3550 0x00FE 0000 RAM Copy of Monitor Code
3551 ... eventually: LCD or video framebuffer
3552 ... eventually: pRAM (Protected RAM - unchanged by reset)
3553 0x00FF FFFF [End of RAM]
3556 System Initialization:
3557 ----------------------
3559 In the reset configuration, U-Boot starts at the reset entry point
3560 (on most PowerPC systems at address 0x00000100). Because of the reset
3561 configuration for CS0# this is a mirror of the on board Flash memory.
3562 To be able to re-map memory U-Boot then jumps to its link address.
3563 To be able to implement the initialization code in C, a (small!)
3564 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3565 which provide such a feature like), or in a locked part of the data
3566 cache. After that, U-Boot initializes the CPU core, the caches and
3569 Next, all (potentially) available memory banks are mapped using a
3570 preliminary mapping. For example, we put them on 512 MB boundaries
3571 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3572 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3573 programmed for SDRAM access. Using the temporary configuration, a
3574 simple memory test is run that determines the size of the SDRAM
3577 When there is more than one SDRAM bank, and the banks are of
3578 different size, the largest is mapped first. For equal size, the first
3579 bank (CS2#) is mapped first. The first mapping is always for address
3580 0x00000000, with any additional banks following immediately to create
3581 contiguous memory starting from 0.
3583 Then, the monitor installs itself at the upper end of the SDRAM area
3584 and allocates memory for use by malloc() and for the global Board
3585 Info data; also, the exception vector code is copied to the low RAM
3586 pages, and the final stack is set up.
3588 Only after this relocation will you have a "normal" C environment;
3589 until that you are restricted in several ways, mostly because you are
3590 running from ROM, and because the code will have to be relocated to a
3594 U-Boot Porting Guide:
3595 ----------------------
3597 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3601 int main(int argc, char *argv[])
3603 sighandler_t no_more_time;
3605 signal(SIGALRM, no_more_time);
3606 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3608 if (available_money > available_manpower) {
3609 Pay consultant to port U-Boot;
3613 Download latest U-Boot source;
3615 Subscribe to u-boot mailing list;
3618 email("Hi, I am new to U-Boot, how do I get started?");
3621 Read the README file in the top level directory;
3622 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3623 Read applicable doc/README.*;
3624 Read the source, Luke;
3625 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3628 if (available_money > toLocalCurrency ($2500))
3631 Add a lot of aggravation and time;
3633 if (a similar board exists) { /* hopefully... */
3634 cp -a board/<similar> board/<myboard>
3635 cp include/configs/<similar>.h include/configs/<myboard>.h
3637 Create your own board support subdirectory;
3638 Create your own board include/configs/<myboard>.h file;
3640 Edit new board/<myboard> files
3641 Edit new include/configs/<myboard>.h
3646 Add / modify source code;
3650 email("Hi, I am having problems...");
3652 Send patch file to the U-Boot email list;
3653 if (reasonable critiques)
3654 Incorporate improvements from email list code review;
3656 Defend code as written;
3662 void no_more_time (int sig)
3671 All contributions to U-Boot should conform to the Linux kernel
3672 coding style; see the kernel coding style guide at
3673 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3674 script "scripts/Lindent" in your Linux kernel source directory.
3676 Source files originating from a different project (for example the
3677 MTD subsystem) are generally exempt from these guidelines and are not
3678 reformatted to ease subsequent migration to newer versions of those
3681 Please note that U-Boot is implemented in C (and to some small parts in
3682 Assembler); no C++ is used, so please do not use C++ style comments (//)
3685 Please also stick to the following formatting rules:
3686 - remove any trailing white space
3687 - use TAB characters for indentation and vertical alignment, not spaces
3688 - make sure NOT to use DOS '\r\n' line feeds
3689 - do not add more than 2 consecutive empty lines to source files
3690 - do not add trailing empty lines to source files
3692 Submissions which do not conform to the standards may be returned
3693 with a request to reformat the changes.
3699 Since the number of patches for U-Boot is growing, we need to
3700 establish some rules. Submissions which do not conform to these rules
3701 may be rejected, even when they contain important and valuable stuff.
3703 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3705 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3706 see https://lists.denx.de/listinfo/u-boot
3708 When you send a patch, please include the following information with
3711 * For bug fixes: a description of the bug and how your patch fixes
3712 this bug. Please try to include a way of demonstrating that the
3713 patch actually fixes something.
3715 * For new features: a description of the feature and your
3718 * For major contributions, add a MAINTAINERS file with your
3719 information and associated file and directory references.
3721 * When you add support for a new board, don't forget to add a
3722 maintainer e-mail address to the boards.cfg file, too.
3724 * If your patch adds new configuration options, don't forget to
3725 document these in the README file.
3727 * The patch itself. If you are using git (which is *strongly*
3728 recommended) you can easily generate the patch using the
3729 "git format-patch". If you then use "git send-email" to send it to
3730 the U-Boot mailing list, you will avoid most of the common problems
3731 with some other mail clients.
3733 If you cannot use git, use "diff -purN OLD NEW". If your version of
3734 diff does not support these options, then get the latest version of
3737 The current directory when running this command shall be the parent
3738 directory of the U-Boot source tree (i. e. please make sure that
3739 your patch includes sufficient directory information for the
3742 We prefer patches as plain text. MIME attachments are discouraged,
3743 and compressed attachments must not be used.
3745 * If one logical set of modifications affects or creates several
3746 files, all these changes shall be submitted in a SINGLE patch file.
3748 * Changesets that contain different, unrelated modifications shall be
3749 submitted as SEPARATE patches, one patch per changeset.
3754 * Before sending the patch, run the buildman script on your patched
3755 source tree and make sure that no errors or warnings are reported
3756 for any of the boards.
3758 * Keep your modifications to the necessary minimum: A patch
3759 containing several unrelated changes or arbitrary reformats will be
3760 returned with a request to re-formatting / split it.
3762 * If you modify existing code, make sure that your new code does not
3763 add to the memory footprint of the code ;-) Small is beautiful!
3764 When adding new features, these should compile conditionally only
3765 (using #ifdef), and the resulting code with the new feature
3766 disabled must not need more memory than the old code without your
3769 * Remember that there is a size limit of 100 kB per message on the
3770 u-boot mailing list. Bigger patches will be moderated. If they are
3771 reasonable and not too big, they will be acknowledged. But patches
3772 bigger than the size limit should be avoided.