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 /nios2 Files generic to Altera NIOS2 architecture
138 /powerpc Files generic to PowerPC architecture
139 /riscv Files generic to RISC-V architecture
140 /sandbox Files generic to HW-independent "sandbox"
141 /sh Files generic to SH architecture
142 /x86 Files generic to x86 architecture
143 /xtensa Files generic to Xtensa architecture
144 /api Machine/arch-independent API for external apps
145 /board Board-dependent files
146 /boot Support for images and booting
147 /cmd U-Boot commands functions
148 /common Misc architecture-independent functions
149 /configs Board default configuration files
150 /disk Code for disk drive partition handling
151 /doc Documentation (a mix of ReST and READMEs)
152 /drivers Device drivers
153 /dts Makefile for building internal U-Boot fdt.
154 /env Environment support
155 /examples Example code for standalone applications, etc.
156 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
157 /include Header Files
158 /lib Library routines generic to all architectures
159 /Licenses Various license files
161 /post Power On Self Test
162 /scripts Various build scripts and Makefiles
163 /test Various unit test files
164 /tools Tools to build and sign FIT images, etc.
166 Software Configuration:
167 =======================
169 Configuration is usually done using C preprocessor defines; the
170 rationale behind that is to avoid dead code whenever possible.
172 There are two classes of configuration variables:
174 * Configuration _OPTIONS_:
175 These are selectable by the user and have names beginning with
178 * Configuration _SETTINGS_:
179 These depend on the hardware etc. and should not be meddled with if
180 you don't know what you're doing; they have names beginning with
183 Previously, all configuration was done by hand, which involved creating
184 symbolic links and editing configuration files manually. More recently,
185 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
186 allowing you to use the "make menuconfig" command to configure your
190 Selection of Processor Architecture and Board Type:
191 ---------------------------------------------------
193 For all supported boards there are ready-to-use default
194 configurations available; just type "make <board_name>_defconfig".
196 Example: For a TQM823L module type:
199 make TQM823L_defconfig
201 Note: If you're looking for the default configuration file for a board
202 you're sure used to be there but is now missing, check the file
203 doc/README.scrapyard for a list of no longer supported boards.
208 U-Boot can be built natively to run on a Linux host using the 'sandbox'
209 board. This allows feature development which is not board- or architecture-
210 specific to be undertaken on a native platform. The sandbox is also used to
211 run some of U-Boot's tests.
213 See doc/arch/sandbox.rst for more details.
216 Board Initialisation Flow:
217 --------------------------
219 This is the intended start-up flow for boards. This should apply for both
220 SPL and U-Boot proper (i.e. they both follow the same rules).
222 Note: "SPL" stands for "Secondary Program Loader," which is explained in
223 more detail later in this file.
225 At present, SPL mostly uses a separate code path, but the function names
226 and roles of each function are the same. Some boards or architectures
227 may not conform to this. At least most ARM boards which use
228 CONFIG_SPL_FRAMEWORK conform to this.
230 Execution typically starts with an architecture-specific (and possibly
231 CPU-specific) start.S file, such as:
233 - arch/arm/cpu/armv7/start.S
234 - arch/powerpc/cpu/mpc83xx/start.S
235 - arch/mips/cpu/start.S
237 and so on. From there, three functions are called; the purpose and
238 limitations of each of these functions are described below.
241 - purpose: essential init to permit execution to reach board_init_f()
242 - no global_data or BSS
243 - there is no stack (ARMv7 may have one but it will soon be removed)
244 - must not set up SDRAM or use console
245 - must only do the bare minimum to allow execution to continue to
247 - this is almost never needed
248 - return normally from this function
251 - purpose: set up the machine ready for running board_init_r():
252 i.e. SDRAM and serial UART
253 - global_data is available
255 - BSS is not available, so you cannot use global/static variables,
256 only stack variables and global_data
258 Non-SPL-specific notes:
259 - dram_init() is called to set up DRAM. If already done in SPL this
263 - you can override the entire board_init_f() function with your own
265 - preloader_console_init() can be called here in extremis
266 - should set up SDRAM, and anything needed to make the UART work
267 - there is no need to clear BSS, it will be done by crt0.S
268 - for specific scenarios on certain architectures an early BSS *can*
269 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
270 of BSS prior to entering board_init_f()) but doing so is discouraged.
271 Instead it is strongly recommended to architect any code changes
272 or additions such to not depend on the availability of BSS during
273 board_init_f() as indicated in other sections of this README to
274 maintain compatibility and consistency across the entire code base.
275 - must return normally from this function (don't call board_init_r()
278 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
279 this point the stack and global_data are relocated to below
280 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
284 - purpose: main execution, common code
285 - global_data is available
287 - BSS is available, all static/global variables can be used
288 - execution eventually continues to main_loop()
290 Non-SPL-specific notes:
291 - U-Boot is relocated to the top of memory and is now running from
295 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
296 CONFIG_SYS_FSL_HAS_CCI400
298 Defined For SoC that has cache coherent interconnect
301 CONFIG_SYS_FSL_HAS_CCN504
303 Defined for SoC that has cache coherent interconnect CCN-504
305 The following options need to be configured:
307 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
309 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
314 Specifies that the core is a 64-bit PowerPC implementation (implements
315 the "64" category of the Power ISA). This is necessary for ePAPR
316 compliance, among other possible reasons.
318 CONFIG_SYS_FSL_TBCLK_DIV
320 Defines the core time base clock divider ratio compared to the
321 system clock. On most PQ3 devices this is 8, on newer QorIQ
322 devices it can be 16 or 32. The ratio varies from SoC to Soc.
324 CONFIG_SYS_FSL_PCIE_COMPAT
326 Defines the string to utilize when trying to match PCIe device
327 tree nodes for the given platform.
329 CONFIG_SYS_FSL_ERRATUM_A004510
331 Enables a workaround for erratum A004510. If set,
332 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
333 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
335 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
336 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
338 Defines one or two SoC revisions (low 8 bits of SVR)
339 for which the A004510 workaround should be applied.
341 The rest of SVR is either not relevant to the decision
342 of whether the erratum is present (e.g. p2040 versus
343 p2041) or is implied by the build target, which controls
344 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
346 See Freescale App Note 4493 for more information about
349 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
351 This is the value to write into CCSR offset 0x18600
352 according to the A004510 workaround.
354 CONFIG_SYS_FSL_DSP_DDR_ADDR
355 This value denotes start offset of DDR memory which is
356 connected exclusively to the DSP cores.
358 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
359 This value denotes start offset of M2 memory
360 which is directly connected to the DSP core.
362 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
363 This value denotes start offset of M3 memory which is directly
364 connected to the DSP core.
366 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
367 This value denotes start offset of DSP CCSR space.
369 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
370 Single Source Clock is clocking mode present in some of FSL SoC's.
371 In this mode, a single differential clock is used to supply
372 clocks to the sysclock, ddrclock and usbclock.
374 CONFIG_SYS_CPC_REINIT_F
375 This CONFIG is defined when the CPC is configured as SRAM at the
376 time of U-Boot entry and is required to be re-initialized.
378 - Generic CPU options:
379 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
381 Defines the endianess of the CPU. Implementation of those
382 values is arch specific.
385 Freescale DDR driver in use. This type of DDR controller is
386 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
388 CONFIG_SYS_FSL_DDR_ADDR
389 Freescale DDR memory-mapped register base.
391 CONFIG_SYS_FSL_DDRC_GEN1
392 Freescale DDR1 controller.
394 CONFIG_SYS_FSL_DDRC_GEN2
395 Freescale DDR2 controller.
397 CONFIG_SYS_FSL_DDRC_GEN3
398 Freescale DDR3 controller.
400 CONFIG_SYS_FSL_DDRC_GEN4
401 Freescale DDR4 controller.
403 CONFIG_SYS_FSL_DDRC_ARM_GEN3
404 Freescale DDR3 controller for ARM-based SoCs.
407 Board config to use DDR1. It can be enabled for SoCs with
408 Freescale DDR1 or DDR2 controllers, depending on the board
412 Board config to use DDR2. It can be enabled for SoCs with
413 Freescale DDR2 or DDR3 controllers, depending on the board
417 Board config to use DDR3. It can be enabled for SoCs with
418 Freescale DDR3 or DDR3L controllers.
421 Board config to use DDR3L. It can be enabled for SoCs with
424 CONFIG_SYS_FSL_IFC_BE
425 Defines the IFC controller register space as Big Endian
427 CONFIG_SYS_FSL_IFC_LE
428 Defines the IFC controller register space as Little Endian
430 CONFIG_SYS_FSL_IFC_CLK_DIV
431 Defines divider of platform clock(clock input to IFC controller).
433 CONFIG_SYS_FSL_LBC_CLK_DIV
434 Defines divider of platform clock(clock input to eLBC controller).
436 CONFIG_SYS_FSL_DDR_BE
437 Defines the DDR controller register space as Big Endian
439 CONFIG_SYS_FSL_DDR_LE
440 Defines the DDR controller register space as Little Endian
442 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
443 Physical address from the view of DDR controllers. It is the
444 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
445 it could be different for ARM SoCs.
447 CONFIG_SYS_FSL_DDR_INTLV_256B
448 DDR controller interleaving on 256-byte. This is a special
449 interleaving mode, handled by Dickens for Freescale layerscape
452 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
453 Number of controllers used as main memory.
455 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
456 Number of controllers used for other than main memory.
458 CONFIG_SYS_FSL_SEC_BE
459 Defines the SEC controller register space as Big Endian
461 CONFIG_SYS_FSL_SEC_LE
462 Defines the SEC controller register space as Little Endian
465 CONFIG_XWAY_SWAP_BYTES
467 Enable compilation of tools/xway-swap-bytes needed for Lantiq
468 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
469 be swapped if a flash programmer is used.
472 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
474 Select high exception vectors of the ARM core, e.g., do not
475 clear the V bit of the c1 register of CP15.
478 Generic timer clock source frequency.
480 COUNTER_FREQUENCY_REAL
481 Generic timer clock source frequency if the real clock is
482 different from COUNTER_FREQUENCY, and can only be determined
486 CONFIG_TEGRA_SUPPORT_NON_SECURE
488 Support executing U-Boot in non-secure (NS) mode. Certain
489 impossible actions will be skipped if the CPU is in NS mode,
490 such as ARM architectural timer initialization.
492 - Linux Kernel Interface:
493 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
495 When transferring memsize parameter to Linux, some versions
496 expect it to be in bytes, others in MB.
497 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
501 New kernel versions are expecting firmware settings to be
502 passed using flattened device trees (based on open firmware
506 * New libfdt-based support
507 * Adds the "fdt" command
508 * The bootm command automatically updates the fdt
510 OF_TBCLK - The timebase frequency.
512 boards with QUICC Engines require OF_QE to set UCC MAC
517 U-Boot can detect if an IDE device is present or not.
518 If not, and this new config option is activated, U-Boot
519 removes the ATA node from the DTS before booting Linux,
520 so the Linux IDE driver does not probe the device and
521 crash. This is needed for buggy hardware (uc101) where
522 no pull down resistor is connected to the signal IDE5V_DD7.
524 - vxWorks boot parameters:
526 bootvx constructs a valid bootline using the following
527 environments variables: bootdev, bootfile, ipaddr, netmask,
528 serverip, gatewayip, hostname, othbootargs.
529 It loads the vxWorks image pointed bootfile.
531 Note: If a "bootargs" environment is defined, it will override
532 the defaults discussed just above.
534 - Cache Configuration for ARM:
535 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
537 CONFIG_SYS_PL310_BASE - Physical base address of PL310
538 controller register space
543 If you have Amba PrimeCell PL011 UARTs, set this variable to
544 the clock speed of the UARTs.
548 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
549 define this to a list of base addresses for each (supported)
550 port. See e.g. include/configs/versatile.h
552 CONFIG_SERIAL_HW_FLOW_CONTROL
554 Define this variable to enable hw flow control in serial driver.
555 Current user of this option is drivers/serial/nsl16550.c driver
557 - Serial Download Echo Mode:
559 If defined to 1, all characters received during a
560 serial download (using the "loads" command) are
561 echoed back. This might be needed by some terminal
562 emulations (like "cu"), but may as well just take
563 time on others. This setting #define's the initial
564 value of the "loads_echo" environment variable.
566 - Removal of commands
567 If no commands are needed to boot, you can disable
568 CONFIG_CMDLINE to remove them. In this case, the command line
569 will not be available, and when U-Boot wants to execute the
570 boot command (on start-up) it will call board_run_command()
571 instead. This can reduce image size significantly for very
572 simple boot procedures.
574 - Regular expression support:
576 If this variable is defined, U-Boot is linked against
577 the SLRE (Super Light Regular Expression) library,
578 which adds regex support to some commands, as for
579 example "env grep" and "setexpr".
582 CONFIG_SYS_WATCHDOG_FREQ
583 Some platforms automatically call WATCHDOG_RESET()
584 from the timer interrupt handler every
585 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
586 board configuration file, a default of CONFIG_SYS_HZ/2
587 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
588 to 0 disables calling WATCHDOG_RESET() from the timer
593 When CONFIG_CMD_DATE is selected, the type of the RTC
594 has to be selected, too. Define exactly one of the
597 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
598 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
599 CONFIG_RTC_MC146818 - use MC146818 RTC
600 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
601 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
602 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
603 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
604 CONFIG_RTC_DS164x - use Dallas DS164x RTC
605 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
606 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
607 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
608 CONFIG_SYS_RV3029_TCR - enable trickle charger on
611 Note that if the RTC uses I2C, then the I2C interface
612 must also be configured. See I2C Support, below.
615 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
617 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
618 chip-ngpio pairs that tell the PCA953X driver the number of
619 pins supported by a particular chip.
621 Note that if the GPIO device uses I2C, then the I2C interface
622 must also be configured. See I2C Support, below.
625 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
626 accesses and can checksum them or write a list of them out
627 to memory. See the 'iotrace' command for details. This is
628 useful for testing device drivers since it can confirm that
629 the driver behaves the same way before and after a code
630 change. Currently this is supported on sandbox and arm. To
631 add support for your architecture, add '#include <iotrace.h>'
632 to the bottom of arch/<arch>/include/asm/io.h and test.
634 Example output from the 'iotrace stats' command is below.
635 Note that if the trace buffer is exhausted, the checksum will
636 still continue to operate.
639 Start: 10000000 (buffer start address)
640 Size: 00010000 (buffer size)
641 Offset: 00000120 (current buffer offset)
642 Output: 10000120 (start + offset)
643 Count: 00000018 (number of trace records)
644 CRC32: 9526fb66 (CRC32 of all trace records)
648 When CONFIG_TIMESTAMP is selected, the timestamp
649 (date and time) of an image is printed by image
650 commands like bootm or iminfo. This option is
651 automatically enabled when you select CONFIG_CMD_DATE .
653 - Partition Labels (disklabels) Supported:
654 Zero or more of the following:
655 CONFIG_MAC_PARTITION Apple's MacOS partition table.
656 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
657 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
658 bootloader. Note 2TB partition limit; see
660 CONFIG_SCSI) you must configure support for at
661 least one non-MTD partition type as well.
663 - NETWORK Support (PCI):
665 Utility code for direct access to the SPI bus on Intel 8257x.
666 This does not do anything useful unless you set at least one
667 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
670 Support for National dp83815 chips.
673 Support for National dp8382[01] gigabit chips.
675 - NETWORK Support (other):
677 Support for the Calxeda XGMAC device
680 Support for SMSC's LAN91C96 chips.
682 CONFIG_LAN91C96_USE_32_BIT
683 Define this to enable 32 bit addressing
686 Support for SMSC's LAN91C111 chip
689 Define this to hold the physical address
690 of the device (I/O space)
692 CONFIG_SMC_USE_32_BIT
693 Define this if data bus is 32 bits
695 CONFIG_SMC_USE_IOFUNCS
696 Define this to use i/o functions instead of macros
697 (some hardware wont work with macros)
699 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
700 Define this if you have more then 3 PHYs.
703 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
705 CONFIG_FTGMAC100_EGIGA
706 Define this to use GE link update with gigabit PHY.
707 Define this if FTGMAC100 is connected to gigabit PHY.
708 If your system has 10/100 PHY only, it might not occur
709 wrong behavior. Because PHY usually return timeout or
710 useless data when polling gigabit status and gigabit
711 control registers. This behavior won't affect the
712 correctnessof 10/100 link speed update.
715 Support for Renesas on-chip Ethernet controller
717 CONFIG_SH_ETHER_USE_PORT
718 Define the number of ports to be used
720 CONFIG_SH_ETHER_PHY_ADDR
721 Define the ETH PHY's address
723 CONFIG_SH_ETHER_CACHE_WRITEBACK
724 If this option is set, the driver enables cache flush.
730 CONFIG_TPM_TIS_INFINEON
731 Support for Infineon i2c bus TPM devices. Only one device
732 per system is supported at this time.
734 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
735 Define the burst count bytes upper limit
738 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
740 CONFIG_TPM_ST33ZP24_I2C
741 Support for STMicroelectronics ST33ZP24 I2C devices.
742 Requires TPM_ST33ZP24 and I2C.
744 CONFIG_TPM_ST33ZP24_SPI
745 Support for STMicroelectronics ST33ZP24 SPI devices.
746 Requires TPM_ST33ZP24 and SPI.
749 Support for Atmel TWI TPM device. Requires I2C support.
752 Support for generic parallel port TPM devices. Only one device
753 per system is supported at this time.
755 CONFIG_TPM_TIS_BASE_ADDRESS
756 Base address where the generic TPM device is mapped
757 to. Contemporary x86 systems usually map it at
761 Define this to enable the TPM support library which provides
762 functional interfaces to some TPM commands.
763 Requires support for a TPM device.
765 CONFIG_TPM_AUTH_SESSIONS
766 Define this to enable authorized functions in the TPM library.
767 Requires CONFIG_TPM and CONFIG_SHA1.
770 At the moment only the UHCI host controller is
771 supported (PIP405, MIP405); define
772 CONFIG_USB_UHCI to enable it.
773 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
774 and define CONFIG_USB_STORAGE to enable the USB
777 Supported are USB Keyboards and USB Floppy drives
780 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
784 Define the below if you wish to use the USB console.
785 Once firmware is rebuilt from a serial console issue the
786 command "setenv stdin usbtty; setenv stdout usbtty" and
787 attach your USB cable. The Unix command "dmesg" should print
788 it has found a new device. The environment variable usbtty
789 can be set to gserial or cdc_acm to enable your device to
790 appear to a USB host as a Linux gserial device or a
791 Common Device Class Abstract Control Model serial device.
792 If you select usbtty = gserial you should be able to enumerate
794 # modprobe usbserial vendor=0xVendorID product=0xProductID
795 else if using cdc_acm, simply setting the environment
796 variable usbtty to be cdc_acm should suffice. The following
797 might be defined in YourBoardName.h
800 Define this to build a UDC device
803 Define this to have a tty type of device available to
804 talk to the UDC device
807 Define this to enable the high speed support for usb
808 device and usbtty. If this feature is enabled, a routine
809 int is_usbd_high_speed(void)
810 also needs to be defined by the driver to dynamically poll
811 whether the enumeration has succeded at high speed or full
814 If you have a USB-IF assigned VendorID then you may wish to
815 define your own vendor specific values either in BoardName.h
816 or directly in usbd_vendor_info.h. If you don't define
817 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
818 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
819 should pretend to be a Linux device to it's target host.
821 CONFIG_USBD_MANUFACTURER
822 Define this string as the name of your company for
823 - CONFIG_USBD_MANUFACTURER "my company"
825 CONFIG_USBD_PRODUCT_NAME
826 Define this string as the name of your product
827 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
830 Define this as your assigned Vendor ID from the USB
831 Implementors Forum. This *must* be a genuine Vendor ID
832 to avoid polluting the USB namespace.
833 - CONFIG_USBD_VENDORID 0xFFFF
835 CONFIG_USBD_PRODUCTID
836 Define this as the unique Product ID
838 - CONFIG_USBD_PRODUCTID 0xFFFF
840 - ULPI Layer Support:
841 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
842 the generic ULPI layer. The generic layer accesses the ULPI PHY
843 via the platform viewport, so you need both the genric layer and
844 the viewport enabled. Currently only Chipidea/ARC based
845 viewport is supported.
846 To enable the ULPI layer support, define CONFIG_USB_ULPI and
847 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
848 If your ULPI phy needs a different reference clock than the
849 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
850 the appropriate value in Hz.
853 The MMC controller on the Intel PXA is supported. To
854 enable this define CONFIG_MMC. The MMC can be
855 accessed from the boot prompt by mapping the device
856 to physical memory similar to flash. Command line is
857 enabled with CONFIG_CMD_MMC. The MMC driver also works with
858 the FAT fs. This is enabled with CONFIG_CMD_FAT.
861 Support for Renesas on-chip MMCIF controller
864 Define the base address of MMCIF registers
867 Define the clock frequency for MMCIF
869 - USB Device Firmware Update (DFU) class support:
871 This enables the USB portion of the DFU USB class
874 This enables support for exposing NAND devices via DFU.
877 This enables support for exposing RAM via DFU.
878 Note: DFU spec refer to non-volatile memory usage, but
879 allow usages beyond the scope of spec - here RAM usage,
880 one that would help mostly the developer.
882 CONFIG_SYS_DFU_DATA_BUF_SIZE
883 Dfu transfer uses a buffer before writing data to the
884 raw storage device. Make the size (in bytes) of this buffer
885 configurable. The size of this buffer is also configurable
886 through the "dfu_bufsiz" environment variable.
888 CONFIG_SYS_DFU_MAX_FILE_SIZE
889 When updating files rather than the raw storage device,
890 we use a static buffer to copy the file into and then write
891 the buffer once we've been given the whole file. Define
892 this to the maximum filesize (in bytes) for the buffer.
893 Default is 4 MiB if undefined.
895 DFU_DEFAULT_POLL_TIMEOUT
896 Poll timeout [ms], is the timeout a device can send to the
897 host. The host must wait for this timeout before sending
898 a subsequent DFU_GET_STATUS request to the device.
900 DFU_MANIFEST_POLL_TIMEOUT
901 Poll timeout [ms], which the device sends to the host when
902 entering dfuMANIFEST state. Host waits this timeout, before
903 sending again an USB request to the device.
905 - Journaling Flash filesystem support:
906 CONFIG_SYS_JFFS2_FIRST_SECTOR,
907 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
908 Define these for a default partition on a NOR device
911 See Kconfig help for available keyboard drivers.
913 - LCD Support: CONFIG_LCD
915 Define this to enable LCD support (for output to LCD
916 display); also select one of the supported displays
917 by defining one of these:
919 CONFIG_NEC_NL6448AC33:
921 NEC NL6448AC33-18. Active, color, single scan.
923 CONFIG_NEC_NL6448BC20
925 NEC NL6448BC20-08. 6.5", 640x480.
926 Active, color, single scan.
928 CONFIG_NEC_NL6448BC33_54
930 NEC NL6448BC33-54. 10.4", 640x480.
931 Active, color, single scan.
935 Sharp 320x240. Active, color, single scan.
936 It isn't 16x9, and I am not sure what it is.
938 CONFIG_SHARP_LQ64D341
940 Sharp LQ64D341 display, 640x480.
941 Active, color, single scan.
945 HLD1045 display, 640x480.
946 Active, color, single scan.
950 Optrex CBL50840-2 NF-FW 99 22 M5
952 Hitachi LMG6912RPFC-00T
956 320x240. Black & white.
960 Normally the LCD is page-aligned (typically 4KB). If this is
961 defined then the LCD will be aligned to this value instead.
962 For ARM it is sometimes useful to use MMU_SECTION_SIZE
963 here, since it is cheaper to change data cache settings on
969 Sometimes, for example if the display is mounted in portrait
970 mode or even if it's mounted landscape but rotated by 180degree,
971 we need to rotate our content of the display relative to the
972 framebuffer, so that user can read the messages which are
974 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
975 initialized with a given rotation from "vl_rot" out of
976 "vidinfo_t" which is provided by the board specific code.
977 The value for vl_rot is coded as following (matching to
978 fbcon=rotate:<n> linux-kernel commandline):
979 0 = no rotation respectively 0 degree
980 1 = 90 degree rotation
981 2 = 180 degree rotation
982 3 = 270 degree rotation
984 If CONFIG_LCD_ROTATION is not defined, the console will be
985 initialized with 0degree rotation.
988 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
990 The clock frequency of the MII bus
992 CONFIG_PHY_CMD_DELAY (ppc4xx)
994 Some PHY like Intel LXT971A need extra delay after
995 command issued before MII status register can be read
1000 Define a default value for the IP address to use for
1001 the default Ethernet interface, in case this is not
1002 determined through e.g. bootp.
1003 (Environment variable "ipaddr")
1005 - Server IP address:
1008 Defines a default value for the IP address of a TFTP
1009 server to contact when using the "tftboot" command.
1010 (Environment variable "serverip")
1012 - Gateway IP address:
1015 Defines a default value for the IP address of the
1016 default router where packets to other networks are
1018 (Environment variable "gatewayip")
1023 Defines a default value for the subnet mask (or
1024 routing prefix) which is used to determine if an IP
1025 address belongs to the local subnet or needs to be
1026 forwarded through a router.
1027 (Environment variable "netmask")
1029 - BOOTP Recovery Mode:
1030 CONFIG_BOOTP_RANDOM_DELAY
1032 If you have many targets in a network that try to
1033 boot using BOOTP, you may want to avoid that all
1034 systems send out BOOTP requests at precisely the same
1035 moment (which would happen for instance at recovery
1036 from a power failure, when all systems will try to
1037 boot, thus flooding the BOOTP server. Defining
1038 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1039 inserted before sending out BOOTP requests. The
1040 following delays are inserted then:
1042 1st BOOTP request: delay 0 ... 1 sec
1043 2nd BOOTP request: delay 0 ... 2 sec
1044 3rd BOOTP request: delay 0 ... 4 sec
1046 BOOTP requests: delay 0 ... 8 sec
1048 CONFIG_BOOTP_ID_CACHE_SIZE
1050 BOOTP packets are uniquely identified using a 32-bit ID. The
1051 server will copy the ID from client requests to responses and
1052 U-Boot will use this to determine if it is the destination of
1053 an incoming response. Some servers will check that addresses
1054 aren't in use before handing them out (usually using an ARP
1055 ping) and therefore take up to a few hundred milliseconds to
1056 respond. Network congestion may also influence the time it
1057 takes for a response to make it back to the client. If that
1058 time is too long, U-Boot will retransmit requests. In order
1059 to allow earlier responses to still be accepted after these
1060 retransmissions, U-Boot's BOOTP client keeps a small cache of
1061 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1062 cache. The default is to keep IDs for up to four outstanding
1063 requests. Increasing this will allow U-Boot to accept offers
1064 from a BOOTP client in networks with unusually high latency.
1066 - DHCP Advanced Options:
1068 - Link-local IP address negotiation:
1069 Negotiate with other link-local clients on the local network
1070 for an address that doesn't require explicit configuration.
1071 This is especially useful if a DHCP server cannot be guaranteed
1072 to exist in all environments that the device must operate.
1074 See doc/README.link-local for more information.
1076 - MAC address from environment variables
1078 FDT_SEQ_MACADDR_FROM_ENV
1080 Fix-up device tree with MAC addresses fetched sequentially from
1081 environment variables. This config work on assumption that
1082 non-usable ethernet node of device-tree are either not present
1083 or their status has been marked as "disabled".
1086 CONFIG_CDP_DEVICE_ID
1088 The device id used in CDP trigger frames.
1090 CONFIG_CDP_DEVICE_ID_PREFIX
1092 A two character string which is prefixed to the MAC address
1097 A printf format string which contains the ascii name of
1098 the port. Normally is set to "eth%d" which sets
1099 eth0 for the first Ethernet, eth1 for the second etc.
1101 CONFIG_CDP_CAPABILITIES
1103 A 32bit integer which indicates the device capabilities;
1104 0x00000010 for a normal host which does not forwards.
1108 An ascii string containing the version of the software.
1112 An ascii string containing the name of the platform.
1116 A 32bit integer sent on the trigger.
1118 CONFIG_CDP_POWER_CONSUMPTION
1120 A 16bit integer containing the power consumption of the
1121 device in .1 of milliwatts.
1123 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1125 A byte containing the id of the VLAN.
1127 - Status LED: CONFIG_LED_STATUS
1129 Several configurations allow to display the current
1130 status using a LED. For instance, the LED will blink
1131 fast while running U-Boot code, stop blinking as
1132 soon as a reply to a BOOTP request was received, and
1133 start blinking slow once the Linux kernel is running
1134 (supported by a status LED driver in the Linux
1135 kernel). Defining CONFIG_LED_STATUS enables this
1140 CONFIG_LED_STATUS_GPIO
1141 The status LED can be connected to a GPIO pin.
1142 In such cases, the gpio_led driver can be used as a
1143 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1144 to include the gpio_led driver in the U-Boot binary.
1146 CONFIG_GPIO_LED_INVERTED_TABLE
1147 Some GPIO connected LEDs may have inverted polarity in which
1148 case the GPIO high value corresponds to LED off state and
1149 GPIO low value corresponds to LED on state.
1150 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1151 with a list of GPIO LEDs that have inverted polarity.
1154 CONFIG_SYS_NUM_I2C_BUSES
1155 Hold the number of i2c buses you want to use.
1157 CONFIG_SYS_I2C_DIRECT_BUS
1158 define this, if you don't use i2c muxes on your hardware.
1159 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1162 CONFIG_SYS_I2C_MAX_HOPS
1163 define how many muxes are maximal consecutively connected
1164 on one i2c bus. If you not use i2c muxes, omit this
1167 CONFIG_SYS_I2C_BUSES
1168 hold a list of buses you want to use, only used if
1169 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1170 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1171 CONFIG_SYS_NUM_I2C_BUSES = 9:
1173 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1174 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1175 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1176 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1177 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1178 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1179 {1, {I2C_NULL_HOP}}, \
1180 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1181 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1185 bus 0 on adapter 0 without a mux
1186 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1187 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1188 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1189 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1190 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1191 bus 6 on adapter 1 without a mux
1192 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1193 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1195 If you do not have i2c muxes on your board, omit this define.
1197 - Legacy I2C Support:
1198 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1199 then the following macros need to be defined (examples are
1200 from include/configs/lwmon.h):
1204 (Optional). Any commands necessary to enable the I2C
1205 controller or configure ports.
1207 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1211 The code necessary to make the I2C data line active
1212 (driven). If the data line is open collector, this
1215 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1219 The code necessary to make the I2C data line tri-stated
1220 (inactive). If the data line is open collector, this
1223 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1227 Code that returns true if the I2C data line is high,
1230 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1234 If <bit> is true, sets the I2C data line high. If it
1235 is false, it clears it (low).
1237 eg: #define I2C_SDA(bit) \
1238 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1239 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1243 If <bit> is true, sets the I2C clock line high. If it
1244 is false, it clears it (low).
1246 eg: #define I2C_SCL(bit) \
1247 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1248 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1252 This delay is invoked four times per clock cycle so this
1253 controls the rate of data transfer. The data rate thus
1254 is 1 / (I2C_DELAY * 4). Often defined to be something
1257 #define I2C_DELAY udelay(2)
1259 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1261 If your arch supports the generic GPIO framework (asm/gpio.h),
1262 then you may alternatively define the two GPIOs that are to be
1263 used as SCL / SDA. Any of the previous I2C_xxx macros will
1264 have GPIO-based defaults assigned to them as appropriate.
1266 You should define these to the GPIO value as given directly to
1267 the generic GPIO functions.
1269 CONFIG_SYS_I2C_INIT_BOARD
1271 When a board is reset during an i2c bus transfer
1272 chips might think that the current transfer is still
1273 in progress. On some boards it is possible to access
1274 the i2c SCLK line directly, either by using the
1275 processor pin as a GPIO or by having a second pin
1276 connected to the bus. If this option is defined a
1277 custom i2c_init_board() routine in boards/xxx/board.c
1278 is run early in the boot sequence.
1280 CONFIG_I2C_MULTI_BUS
1282 This option allows the use of multiple I2C buses, each of which
1283 must have a controller. At any point in time, only one bus is
1284 active. To switch to a different bus, use the 'i2c dev' command.
1285 Note that bus numbering is zero-based.
1287 CONFIG_SYS_I2C_NOPROBES
1289 This option specifies a list of I2C devices that will be skipped
1290 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1291 is set, specify a list of bus-device pairs. Otherwise, specify
1292 a 1D array of device addresses
1295 #undef CONFIG_I2C_MULTI_BUS
1296 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1298 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1300 #define CONFIG_I2C_MULTI_BUS
1301 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1303 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1305 CONFIG_SYS_RTC_BUS_NUM
1307 If defined, then this indicates the I2C bus number for the RTC.
1308 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1310 CONFIG_SOFT_I2C_READ_REPEATED_START
1312 defining this will force the i2c_read() function in
1313 the soft_i2c driver to perform an I2C repeated start
1314 between writing the address pointer and reading the
1315 data. If this define is omitted the default behaviour
1316 of doing a stop-start sequence will be used. Most I2C
1317 devices can use either method, but some require one or
1320 - SPI Support: CONFIG_SPI
1322 Enables SPI driver (so far only tested with
1323 SPI EEPROM, also an instance works with Crystal A/D and
1324 D/As on the SACSng board)
1326 CONFIG_SYS_SPI_MXC_WAIT
1327 Timeout for waiting until spi transfer completed.
1328 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1330 - FPGA Support: CONFIG_FPGA
1332 Enables FPGA subsystem.
1334 CONFIG_FPGA_<vendor>
1336 Enables support for specific chip vendors.
1339 CONFIG_FPGA_<family>
1341 Enables support for FPGA family.
1342 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1344 CONFIG_SYS_FPGA_PROG_FEEDBACK
1346 Enable printing of hash marks during FPGA configuration.
1348 CONFIG_SYS_FPGA_CHECK_BUSY
1350 Enable checks on FPGA configuration interface busy
1351 status by the configuration function. This option
1352 will require a board or device specific function to
1357 If defined, a function that provides delays in the FPGA
1358 configuration driver.
1360 CONFIG_SYS_FPGA_CHECK_CTRLC
1361 Allow Control-C to interrupt FPGA configuration
1363 CONFIG_SYS_FPGA_CHECK_ERROR
1365 Check for configuration errors during FPGA bitfile
1366 loading. For example, abort during Virtex II
1367 configuration if the INIT_B line goes low (which
1368 indicated a CRC error).
1370 CONFIG_SYS_FPGA_WAIT_INIT
1372 Maximum time to wait for the INIT_B line to de-assert
1373 after PROB_B has been de-asserted during a Virtex II
1374 FPGA configuration sequence. The default time is 500
1377 CONFIG_SYS_FPGA_WAIT_BUSY
1379 Maximum time to wait for BUSY to de-assert during
1380 Virtex II FPGA configuration. The default is 5 ms.
1382 CONFIG_SYS_FPGA_WAIT_CONFIG
1384 Time to wait after FPGA configuration. The default is
1387 - Vendor Parameter Protection:
1389 U-Boot considers the values of the environment
1390 variables "serial#" (Board Serial Number) and
1391 "ethaddr" (Ethernet Address) to be parameters that
1392 are set once by the board vendor / manufacturer, and
1393 protects these variables from casual modification by
1394 the user. Once set, these variables are read-only,
1395 and write or delete attempts are rejected. You can
1396 change this behaviour:
1398 If CONFIG_ENV_OVERWRITE is #defined in your config
1399 file, the write protection for vendor parameters is
1400 completely disabled. Anybody can change or delete
1403 Alternatively, if you define _both_ an ethaddr in the
1404 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1405 Ethernet address is installed in the environment,
1406 which can be changed exactly ONCE by the user. [The
1407 serial# is unaffected by this, i. e. it remains
1410 The same can be accomplished in a more flexible way
1411 for any variable by configuring the type of access
1412 to allow for those variables in the ".flags" variable
1413 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1418 Define this variable to enable the reservation of
1419 "protected RAM", i. e. RAM which is not overwritten
1420 by U-Boot. Define CONFIG_PRAM to hold the number of
1421 kB you want to reserve for pRAM. You can overwrite
1422 this default value by defining an environment
1423 variable "pram" to the number of kB you want to
1424 reserve. Note that the board info structure will
1425 still show the full amount of RAM. If pRAM is
1426 reserved, a new environment variable "mem" will
1427 automatically be defined to hold the amount of
1428 remaining RAM in a form that can be passed as boot
1429 argument to Linux, for instance like that:
1431 setenv bootargs ... mem=\${mem}
1434 This way you can tell Linux not to use this memory,
1435 either, which results in a memory region that will
1436 not be affected by reboots.
1438 *WARNING* If your board configuration uses automatic
1439 detection of the RAM size, you must make sure that
1440 this memory test is non-destructive. So far, the
1441 following board configurations are known to be
1444 IVMS8, IVML24, SPD8xx,
1445 HERMES, IP860, RPXlite, LWMON,
1451 In the current implementation, the local variables
1452 space and global environment variables space are
1453 separated. Local variables are those you define by
1454 simply typing `name=value'. To access a local
1455 variable later on, you have write `$name' or
1456 `${name}'; to execute the contents of a variable
1457 directly type `$name' at the command prompt.
1459 Global environment variables are those you use
1460 setenv/printenv to work with. To run a command stored
1461 in such a variable, you need to use the run command,
1462 and you must not use the '$' sign to access them.
1464 To store commands and special characters in a
1465 variable, please use double quotation marks
1466 surrounding the whole text of the variable, instead
1467 of the backslashes before semicolons and special
1470 - Default Environment:
1471 CONFIG_EXTRA_ENV_SETTINGS
1473 Define this to contain any number of null terminated
1474 strings (variable = value pairs) that will be part of
1475 the default environment compiled into the boot image.
1477 For example, place something like this in your
1478 board's config file:
1480 #define CONFIG_EXTRA_ENV_SETTINGS \
1484 Warning: This method is based on knowledge about the
1485 internal format how the environment is stored by the
1486 U-Boot code. This is NOT an official, exported
1487 interface! Although it is unlikely that this format
1488 will change soon, there is no guarantee either.
1489 You better know what you are doing here.
1491 Note: overly (ab)use of the default environment is
1492 discouraged. Make sure to check other ways to preset
1493 the environment like the "source" command or the
1496 CONFIG_DELAY_ENVIRONMENT
1498 Normally the environment is loaded when the board is
1499 initialised so that it is available to U-Boot. This inhibits
1500 that so that the environment is not available until
1501 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1502 this is instead controlled by the value of
1503 /config/load-environment.
1505 CONFIG_STANDALONE_LOAD_ADDR
1507 This option defines a board specific value for the
1508 address where standalone program gets loaded, thus
1509 overwriting the architecture dependent default
1512 - Automatic software updates via TFTP server
1514 CONFIG_UPDATE_TFTP_CNT_MAX
1515 CONFIG_UPDATE_TFTP_MSEC_MAX
1517 These options enable and control the auto-update feature;
1518 for a more detailed description refer to doc/README.update.
1520 - MTD Support (mtdparts command, UBI support)
1521 CONFIG_MTD_UBI_WL_THRESHOLD
1522 This parameter defines the maximum difference between the highest
1523 erase counter value and the lowest erase counter value of eraseblocks
1524 of UBI devices. When this threshold is exceeded, UBI starts performing
1525 wear leveling by means of moving data from eraseblock with low erase
1526 counter to eraseblocks with high erase counter.
1528 The default value should be OK for SLC NAND flashes, NOR flashes and
1529 other flashes which have eraseblock life-cycle 100000 or more.
1530 However, in case of MLC NAND flashes which typically have eraseblock
1531 life-cycle less than 10000, the threshold should be lessened (e.g.,
1532 to 128 or 256, although it does not have to be power of 2).
1536 CONFIG_MTD_UBI_BEB_LIMIT
1537 This option specifies the maximum bad physical eraseblocks UBI
1538 expects on the MTD device (per 1024 eraseblocks). If the
1539 underlying flash does not admit of bad eraseblocks (e.g. NOR
1540 flash), this value is ignored.
1542 NAND datasheets often specify the minimum and maximum NVM
1543 (Number of Valid Blocks) for the flashes' endurance lifetime.
1544 The maximum expected bad eraseblocks per 1024 eraseblocks
1545 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1546 which gives 20 for most NANDs (MaxNVB is basically the total
1547 count of eraseblocks on the chip).
1549 To put it differently, if this value is 20, UBI will try to
1550 reserve about 1.9% of physical eraseblocks for bad blocks
1551 handling. And that will be 1.9% of eraseblocks on the entire
1552 NAND chip, not just the MTD partition UBI attaches. This means
1553 that if you have, say, a NAND flash chip admits maximum 40 bad
1554 eraseblocks, and it is split on two MTD partitions of the same
1555 size, UBI will reserve 40 eraseblocks when attaching a
1560 CONFIG_MTD_UBI_FASTMAP
1561 Fastmap is a mechanism which allows attaching an UBI device
1562 in nearly constant time. Instead of scanning the whole MTD device it
1563 only has to locate a checkpoint (called fastmap) on the device.
1564 The on-flash fastmap contains all information needed to attach
1565 the device. Using fastmap makes only sense on large devices where
1566 attaching by scanning takes long. UBI will not automatically install
1567 a fastmap on old images, but you can set the UBI parameter
1568 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1569 that fastmap-enabled images are still usable with UBI implementations
1570 without fastmap support. On typical flash devices the whole fastmap
1571 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1573 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1574 Set this parameter to enable fastmap automatically on images
1578 CONFIG_MTD_UBI_FM_DEBUG
1579 Enable UBI fastmap debug
1584 Enable building of SPL globally.
1586 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1587 When defined, SPL will panic() if the image it has
1588 loaded does not have a signature.
1589 Defining this is useful when code which loads images
1590 in SPL cannot guarantee that absolutely all read errors
1592 An example is the LPC32XX MLC NAND driver, which will
1593 consider that a completely unreadable NAND block is bad,
1594 and thus should be skipped silently.
1596 CONFIG_SPL_DISPLAY_PRINT
1597 For ARM, enable an optional function to print more information
1598 about the running system.
1600 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1601 Set this for NAND SPL on PPC mpc83xx targets, so that
1602 start.S waits for the rest of the SPL to load before
1603 continuing (the hardware starts execution after just
1604 loading the first page rather than the full 4K).
1607 Support for a lightweight UBI (fastmap) scanner and
1610 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1611 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1612 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1613 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1614 CONFIG_SYS_NAND_ECCBYTES
1615 Defines the size and behavior of the NAND that SPL uses
1618 CONFIG_SYS_NAND_U_BOOT_DST
1619 Location in memory to load U-Boot to
1621 CONFIG_SYS_NAND_U_BOOT_SIZE
1622 Size of image to load
1624 CONFIG_SYS_NAND_U_BOOT_START
1625 Entry point in loaded image to jump to
1627 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1628 Define this if you need to first read the OOB and then the
1629 data. This is used, for example, on davinci platforms.
1631 CONFIG_SPL_RAM_DEVICE
1632 Support for running image already present in ram, in SPL binary
1634 CONFIG_SPL_FIT_PRINT
1635 Printing information about a FIT image adds quite a bit of
1636 code to SPL. So this is normally disabled in SPL. Use this
1637 option to re-enable it. This will affect the output of the
1638 bootm command when booting a FIT image.
1640 - Interrupt support (PPC):
1642 There are common interrupt_init() and timer_interrupt()
1643 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1644 for CPU specific initialization. interrupt_init_cpu()
1645 should set decrementer_count to appropriate value. If
1646 CPU resets decrementer automatically after interrupt
1647 (ppc4xx) it should set decrementer_count to zero.
1648 timer_interrupt() calls timer_interrupt_cpu() for CPU
1649 specific handling. If board has watchdog / status_led
1650 / other_activity_monitor it works automatically from
1651 general timer_interrupt().
1654 Board initialization settings:
1655 ------------------------------
1657 During Initialization u-boot calls a number of board specific functions
1658 to allow the preparation of board specific prerequisites, e.g. pin setup
1659 before drivers are initialized. To enable these callbacks the
1660 following configuration macros have to be defined. Currently this is
1661 architecture specific, so please check arch/your_architecture/lib/board.c
1662 typically in board_init_f() and board_init_r().
1664 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1665 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1666 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1668 Configuration Settings:
1669 -----------------------
1671 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1672 Optionally it can be defined to support 64-bit memory commands.
1674 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1675 undefine this when you're short of memory.
1677 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1678 width of the commands listed in the 'help' command output.
1680 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1681 prompt for user input.
1683 - CONFIG_SYS_BAUDRATE_TABLE:
1684 List of legal baudrate settings for this board.
1686 - CONFIG_SYS_MEM_RESERVE_SECURE
1687 Only implemented for ARMv8 for now.
1688 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1689 is substracted from total RAM and won't be reported to OS.
1690 This memory can be used as secure memory. A variable
1691 gd->arch.secure_ram is used to track the location. In systems
1692 the RAM base is not zero, or RAM is divided into banks,
1693 this variable needs to be recalcuated to get the address.
1695 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1696 Enable temporary baudrate change while serial download
1698 - CONFIG_SYS_SDRAM_BASE:
1699 Physical start address of SDRAM. _Must_ be 0 here.
1701 - CONFIG_SYS_FLASH_BASE:
1702 Physical start address of Flash memory.
1704 - CONFIG_SYS_MONITOR_LEN:
1705 Size of memory reserved for monitor code, used to
1706 determine _at_compile_time_ (!) if the environment is
1707 embedded within the U-Boot image, or in a separate
1710 - CONFIG_SYS_MALLOC_LEN:
1711 Size of DRAM reserved for malloc() use.
1713 - CONFIG_SYS_MALLOC_F_LEN
1714 Size of the malloc() pool for use before relocation. If
1715 this is defined, then a very simple malloc() implementation
1716 will become available before relocation. The address is just
1717 below the global data, and the stack is moved down to make
1720 This feature allocates regions with increasing addresses
1721 within the region. calloc() is supported, but realloc()
1722 is not available. free() is supported but does nothing.
1723 The memory will be freed (or in fact just forgotten) when
1724 U-Boot relocates itself.
1726 - CONFIG_SYS_MALLOC_SIMPLE
1727 Provides a simple and small malloc() and calloc() for those
1728 boards which do not use the full malloc in SPL (which is
1729 enabled with CONFIG_SYS_SPL_MALLOC).
1731 - CONFIG_SYS_NONCACHED_MEMORY:
1732 Size of non-cached memory area. This area of memory will be
1733 typically located right below the malloc() area and mapped
1734 uncached in the MMU. This is useful for drivers that would
1735 otherwise require a lot of explicit cache maintenance. For
1736 some drivers it's also impossible to properly maintain the
1737 cache. For example if the regions that need to be flushed
1738 are not a multiple of the cache-line size, *and* padding
1739 cannot be allocated between the regions to align them (i.e.
1740 if the HW requires a contiguous array of regions, and the
1741 size of each region is not cache-aligned), then a flush of
1742 one region may result in overwriting data that hardware has
1743 written to another region in the same cache-line. This can
1744 happen for example in network drivers where descriptors for
1745 buffers are typically smaller than the CPU cache-line (e.g.
1746 16 bytes vs. 32 or 64 bytes).
1748 Non-cached memory is only supported on 32-bit ARM at present.
1750 - CONFIG_SYS_BOOTM_LEN:
1751 Normally compressed uImages are limited to an
1752 uncompressed size of 8 MBytes. If this is not enough,
1753 you can define CONFIG_SYS_BOOTM_LEN in your board config file
1754 to adjust this setting to your needs.
1756 - CONFIG_SYS_BOOTMAPSZ:
1757 Maximum size of memory mapped by the startup code of
1758 the Linux kernel; all data that must be processed by
1759 the Linux kernel (bd_info, boot arguments, FDT blob if
1760 used) must be put below this limit, unless "bootm_low"
1761 environment variable is defined and non-zero. In such case
1762 all data for the Linux kernel must be between "bootm_low"
1763 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1764 variable "bootm_mapsize" will override the value of
1765 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1766 then the value in "bootm_size" will be used instead.
1768 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
1769 Enable initrd_high functionality. If defined then the
1770 initrd_high feature is enabled and the bootm ramdisk subcommand
1773 - CONFIG_SYS_BOOT_GET_CMDLINE:
1774 Enables allocating and saving kernel cmdline in space between
1775 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1777 - CONFIG_SYS_BOOT_GET_KBD:
1778 Enables allocating and saving a kernel copy of the bd_info in
1779 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1781 - CONFIG_SYS_MAX_FLASH_SECT:
1782 Max number of sectors on a Flash chip
1784 - CONFIG_SYS_FLASH_ERASE_TOUT:
1785 Timeout for Flash erase operations (in ms)
1787 - CONFIG_SYS_FLASH_WRITE_TOUT:
1788 Timeout for Flash write operations (in ms)
1790 - CONFIG_SYS_FLASH_LOCK_TOUT
1791 Timeout for Flash set sector lock bit operation (in ms)
1793 - CONFIG_SYS_FLASH_UNLOCK_TOUT
1794 Timeout for Flash clear lock bits operation (in ms)
1796 - CONFIG_SYS_FLASH_PROTECTION
1797 If defined, hardware flash sectors protection is used
1798 instead of U-Boot software protection.
1800 - CONFIG_SYS_DIRECT_FLASH_TFTP:
1802 Enable TFTP transfers directly to flash memory;
1803 without this option such a download has to be
1804 performed in two steps: (1) download to RAM, and (2)
1805 copy from RAM to flash.
1807 The two-step approach is usually more reliable, since
1808 you can check if the download worked before you erase
1809 the flash, but in some situations (when system RAM is
1810 too limited to allow for a temporary copy of the
1811 downloaded image) this option may be very useful.
1813 - CONFIG_SYS_FLASH_CFI:
1814 Define if the flash driver uses extra elements in the
1815 common flash structure for storing flash geometry.
1817 - CONFIG_FLASH_CFI_DRIVER
1818 This option also enables the building of the cfi_flash driver
1819 in the drivers directory
1821 - CONFIG_FLASH_CFI_MTD
1822 This option enables the building of the cfi_mtd driver
1823 in the drivers directory. The driver exports CFI flash
1826 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1827 Use buffered writes to flash.
1829 - CONFIG_FLASH_SPANSION_S29WS_N
1830 s29ws-n MirrorBit flash has non-standard addresses for buffered
1833 - CONFIG_SYS_FLASH_QUIET_TEST
1834 If this option is defined, the common CFI flash doesn't
1835 print it's warning upon not recognized FLASH banks. This
1836 is useful, if some of the configured banks are only
1837 optionally available.
1839 - CONFIG_FLASH_SHOW_PROGRESS
1840 If defined (must be an integer), print out countdown
1841 digits and dots. Recommended value: 45 (9..1) for 80
1842 column displays, 15 (3..1) for 40 column displays.
1844 - CONFIG_FLASH_VERIFY
1845 If defined, the content of the flash (destination) is compared
1846 against the source after the write operation. An error message
1847 will be printed when the contents are not identical.
1848 Please note that this option is useless in nearly all cases,
1849 since such flash programming errors usually are detected earlier
1850 while unprotecting/erasing/programming. Please only enable
1851 this option if you really know what you are doing.
1853 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1854 - CONFIG_ENV_FLAGS_LIST_STATIC
1855 Enable validation of the values given to environment variables when
1856 calling env set. Variables can be restricted to only decimal,
1857 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1858 the variables can also be restricted to IP address or MAC address.
1860 The format of the list is:
1861 type_attribute = [s|d|x|b|i|m]
1862 access_attribute = [a|r|o|c]
1863 attributes = type_attribute[access_attribute]
1864 entry = variable_name[:attributes]
1867 The type attributes are:
1868 s - String (default)
1871 b - Boolean ([1yYtT|0nNfF])
1875 The access attributes are:
1881 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1882 Define this to a list (string) to define the ".flags"
1883 environment variable in the default or embedded environment.
1885 - CONFIG_ENV_FLAGS_LIST_STATIC
1886 Define this to a list (string) to define validation that
1887 should be done if an entry is not found in the ".flags"
1888 environment variable. To override a setting in the static
1889 list, simply add an entry for the same variable name to the
1892 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1893 regular expression. This allows multiple variables to define the same
1894 flags without explicitly listing them for each variable.
1896 The following definitions that deal with the placement and management
1897 of environment data (variable area); in general, we support the
1898 following configurations:
1900 - CONFIG_BUILD_ENVCRC:
1902 Builds up envcrc with the target environment so that external utils
1903 may easily extract it and embed it in final U-Boot images.
1905 BE CAREFUL! The first access to the environment happens quite early
1906 in U-Boot initialization (when we try to get the setting of for the
1907 console baudrate). You *MUST* have mapped your NVRAM area then, or
1910 Please note that even with NVRAM we still use a copy of the
1911 environment in RAM: we could work on NVRAM directly, but we want to
1912 keep settings there always unmodified except somebody uses "saveenv"
1913 to save the current settings.
1915 BE CAREFUL! For some special cases, the local device can not use
1916 "saveenv" command. For example, the local device will get the
1917 environment stored in a remote NOR flash by SRIO or PCIE link,
1918 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1920 - CONFIG_NAND_ENV_DST
1922 Defines address in RAM to which the nand_spl code should copy the
1923 environment. If redundant environment is used, it will be copied to
1924 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1926 Please note that the environment is read-only until the monitor
1927 has been relocated to RAM and a RAM copy of the environment has been
1928 created; also, when using EEPROM you will have to use env_get_f()
1929 until then to read environment variables.
1931 The environment is protected by a CRC32 checksum. Before the monitor
1932 is relocated into RAM, as a result of a bad CRC you will be working
1933 with the compiled-in default environment - *silently*!!! [This is
1934 necessary, because the first environment variable we need is the
1935 "baudrate" setting for the console - if we have a bad CRC, we don't
1936 have any device yet where we could complain.]
1938 Note: once the monitor has been relocated, then it will complain if
1939 the default environment is used; a new CRC is computed as soon as you
1940 use the "saveenv" command to store a valid environment.
1942 - CONFIG_SYS_FAULT_MII_ADDR:
1943 MII address of the PHY to check for the Ethernet link state.
1945 - CONFIG_NS16550_MIN_FUNCTIONS:
1946 Define this if you desire to only have use of the NS16550_init
1947 and NS16550_putc functions for the serial driver located at
1948 drivers/serial/ns16550.c. This option is useful for saving
1949 space for already greatly restricted images, including but not
1950 limited to NAND_SPL configurations.
1952 - CONFIG_DISPLAY_BOARDINFO
1953 Display information about the board that U-Boot is running on
1954 when U-Boot starts up. The board function checkboard() is called
1957 - CONFIG_DISPLAY_BOARDINFO_LATE
1958 Similar to the previous option, but display this information
1959 later, once stdio is running and output goes to the LCD, if
1962 Low Level (hardware related) configuration options:
1963 ---------------------------------------------------
1965 - CONFIG_SYS_CACHELINE_SIZE:
1966 Cache Line Size of the CPU.
1968 - CONFIG_SYS_CCSRBAR_DEFAULT:
1969 Default (power-on reset) physical address of CCSR on Freescale
1972 - CONFIG_SYS_CCSRBAR:
1973 Virtual address of CCSR. On a 32-bit build, this is typically
1974 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
1976 - CONFIG_SYS_CCSRBAR_PHYS:
1977 Physical address of CCSR. CCSR can be relocated to a new
1978 physical address, if desired. In this case, this macro should
1979 be set to that address. Otherwise, it should be set to the
1980 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
1981 is typically relocated on 36-bit builds. It is recommended
1982 that this macro be defined via the _HIGH and _LOW macros:
1984 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
1985 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
1987 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
1988 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
1989 either 0 (32-bit build) or 0xF (36-bit build). This macro is
1990 used in assembly code, so it must not contain typecasts or
1991 integer size suffixes (e.g. "ULL").
1993 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
1994 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
1995 used in assembly code, so it must not contain typecasts or
1996 integer size suffixes (e.g. "ULL").
1998 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
1999 DO NOT CHANGE unless you know exactly what you're
2000 doing! (11-4) [MPC8xx systems only]
2002 - CONFIG_SYS_INIT_RAM_ADDR:
2004 Start address of memory area that can be used for
2005 initial data and stack; please note that this must be
2006 writable memory that is working WITHOUT special
2007 initialization, i. e. you CANNOT use normal RAM which
2008 will become available only after programming the
2009 memory controller and running certain initialization
2012 U-Boot uses the following memory types:
2013 - MPC8xx: IMMR (internal memory of the CPU)
2015 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2017 - CONFIG_SYS_OR_TIMING_SDRAM:
2020 - CONFIG_SYS_MAMR_PTA:
2021 periodic timer for refresh
2024 Chip has SRIO or not
2027 Board has SRIO 1 port available
2030 Board has SRIO 2 port available
2032 - CONFIG_SRIO_PCIE_BOOT_MASTER
2033 Board can support master function for Boot from SRIO and PCIE
2035 - CONFIG_SYS_SRIOn_MEM_VIRT:
2036 Virtual Address of SRIO port 'n' memory region
2038 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2039 Physical Address of SRIO port 'n' memory region
2041 - CONFIG_SYS_SRIOn_MEM_SIZE:
2042 Size of SRIO port 'n' memory region
2044 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2045 Defined to tell the NAND controller that the NAND chip is using
2047 Not all NAND drivers use this symbol.
2048 Example of drivers that use it:
2049 - drivers/mtd/nand/raw/ndfc.c
2050 - drivers/mtd/nand/raw/mxc_nand.c
2052 - CONFIG_SYS_NDFC_EBC0_CFG
2053 Sets the EBC0_CFG register for the NDFC. If not defined
2054 a default value will be used.
2057 Get DDR timing information from an I2C EEPROM. Common
2058 with pluggable memory modules such as SODIMMs
2061 I2C address of the SPD EEPROM
2063 - CONFIG_SYS_SPD_BUS_NUM
2064 If SPD EEPROM is on an I2C bus other than the first
2065 one, specify here. Note that the value must resolve
2066 to something your driver can deal with.
2068 - CONFIG_FSL_DDR_INTERACTIVE
2069 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2071 - CONFIG_FSL_DDR_SYNC_REFRESH
2072 Enable sync of refresh for multiple controllers.
2074 - CONFIG_FSL_DDR_BIST
2075 Enable built-in memory test for Freescale DDR controllers.
2078 Enable RMII mode for all FECs.
2079 Note that this is a global option, we can't
2080 have one FEC in standard MII mode and another in RMII mode.
2082 - CONFIG_CRC32_VERIFY
2083 Add a verify option to the crc32 command.
2086 => crc32 -v <address> <count> <crc32>
2088 Where address/count indicate a memory area
2089 and crc32 is the correct crc32 which the
2093 Add the "loopw" memory command. This only takes effect if
2094 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2096 - CONFIG_CMD_MX_CYCLIC
2097 Add the "mdc" and "mwc" memory commands. These are cyclic
2102 This command will print 4 bytes (10,11,12,13) each 500 ms.
2104 => mwc.l 100 12345678 10
2105 This command will write 12345678 to address 100 all 10 ms.
2107 This only takes effect if the memory commands are activated
2108 globally (CONFIG_CMD_MEMORY).
2111 Set when the currently-running compilation is for an artifact
2112 that will end up in the SPL (as opposed to the TPL or U-Boot
2113 proper). Code that needs stage-specific behavior should check
2117 Set when the currently-running compilation is for an artifact
2118 that will end up in the TPL (as opposed to the SPL or U-Boot
2119 proper). Code that needs stage-specific behavior should check
2122 - CONFIG_ARCH_MAP_SYSMEM
2123 Generally U-Boot (and in particular the md command) uses
2124 effective address. It is therefore not necessary to regard
2125 U-Boot address as virtual addresses that need to be translated
2126 to physical addresses. However, sandbox requires this, since
2127 it maintains its own little RAM buffer which contains all
2128 addressable memory. This option causes some memory accesses
2129 to be mapped through map_sysmem() / unmap_sysmem().
2131 - CONFIG_X86_RESET_VECTOR
2132 If defined, the x86 reset vector code is included. This is not
2133 needed when U-Boot is running from Coreboot.
2135 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2136 Option to disable subpage write in NAND driver
2137 driver that uses this:
2138 drivers/mtd/nand/raw/davinci_nand.c
2140 Freescale QE/FMAN Firmware Support:
2141 -----------------------------------
2143 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2144 loading of "firmware", which is encoded in the QE firmware binary format.
2145 This firmware often needs to be loaded during U-Boot booting, so macros
2146 are used to identify the storage device (NOR flash, SPI, etc) and the address
2149 - CONFIG_SYS_FMAN_FW_ADDR
2150 The address in the storage device where the FMAN microcode is located. The
2151 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2154 - CONFIG_SYS_QE_FW_ADDR
2155 The address in the storage device where the QE microcode is located. The
2156 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2159 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2160 The maximum possible size of the firmware. The firmware binary format
2161 has a field that specifies the actual size of the firmware, but it
2162 might not be possible to read any part of the firmware unless some
2163 local storage is allocated to hold the entire firmware first.
2165 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2166 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2167 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2168 virtual address in NOR flash.
2170 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2171 Specifies that QE/FMAN firmware is located in NAND flash.
2172 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2174 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2175 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2176 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2178 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2179 Specifies that QE/FMAN firmware is located in the remote (master)
2180 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2181 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2182 window->master inbound window->master LAW->the ucode address in
2183 master's memory space.
2185 Freescale Layerscape Management Complex Firmware Support:
2186 ---------------------------------------------------------
2187 The Freescale Layerscape Management Complex (MC) supports the loading of
2189 This firmware often needs to be loaded during U-Boot booting, so macros
2190 are used to identify the storage device (NOR flash, SPI, etc) and the address
2193 - CONFIG_FSL_MC_ENET
2194 Enable the MC driver for Layerscape SoCs.
2196 Freescale Layerscape Debug Server Support:
2197 -------------------------------------------
2198 The Freescale Layerscape Debug Server Support supports the loading of
2199 "Debug Server firmware" and triggering SP boot-rom.
2200 This firmware often needs to be loaded during U-Boot booting.
2202 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2203 Define alignment of reserved memory MC requires
2208 In order to achieve reproducible builds, timestamps used in the U-Boot build
2209 process have to be set to a fixed value.
2211 This is done using the SOURCE_DATE_EPOCH environment variable.
2212 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2213 option for U-Boot or an environment variable in U-Boot.
2215 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2217 Building the Software:
2218 ======================
2220 Building U-Boot has been tested in several native build environments
2221 and in many different cross environments. Of course we cannot support
2222 all possibly existing versions of cross development tools in all
2223 (potentially obsolete) versions. In case of tool chain problems we
2224 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2225 which is extensively used to build and test U-Boot.
2227 If you are not using a native environment, it is assumed that you
2228 have GNU cross compiling tools available in your path. In this case,
2229 you must set the environment variable CROSS_COMPILE in your shell.
2230 Note that no changes to the Makefile or any other source files are
2231 necessary. For example using the ELDK on a 4xx CPU, please enter:
2233 $ CROSS_COMPILE=ppc_4xx-
2234 $ export CROSS_COMPILE
2236 U-Boot is intended to be simple to build. After installing the
2237 sources you must configure U-Boot for one specific board type. This
2242 where "NAME_defconfig" is the name of one of the existing configu-
2243 rations; see configs/*_defconfig for supported names.
2245 Note: for some boards special configuration names may exist; check if
2246 additional information is available from the board vendor; for
2247 instance, the TQM823L systems are available without (standard)
2248 or with LCD support. You can select such additional "features"
2249 when choosing the configuration, i. e.
2251 make TQM823L_defconfig
2252 - will configure for a plain TQM823L, i. e. no LCD support
2254 make TQM823L_LCD_defconfig
2255 - will configure for a TQM823L with U-Boot console on LCD
2260 Finally, type "make all", and you should get some working U-Boot
2261 images ready for download to / installation on your system:
2263 - "u-boot.bin" is a raw binary image
2264 - "u-boot" is an image in ELF binary format
2265 - "u-boot.srec" is in Motorola S-Record format
2267 By default the build is performed locally and the objects are saved
2268 in the source directory. One of the two methods can be used to change
2269 this behavior and build U-Boot to some external directory:
2271 1. Add O= to the make command line invocations:
2273 make O=/tmp/build distclean
2274 make O=/tmp/build NAME_defconfig
2275 make O=/tmp/build all
2277 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2279 export KBUILD_OUTPUT=/tmp/build
2284 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2287 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2288 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2289 For example to treat all compiler warnings as errors:
2291 make KCFLAGS=-Werror
2293 Please be aware that the Makefiles assume you are using GNU make, so
2294 for instance on NetBSD you might need to use "gmake" instead of
2298 If the system board that you have is not listed, then you will need
2299 to port U-Boot to your hardware platform. To do this, follow these
2302 1. Create a new directory to hold your board specific code. Add any
2303 files you need. In your board directory, you will need at least
2304 the "Makefile" and a "<board>.c".
2305 2. Create a new configuration file "include/configs/<board>.h" for
2307 3. If you're porting U-Boot to a new CPU, then also create a new
2308 directory to hold your CPU specific code. Add any files you need.
2309 4. Run "make <board>_defconfig" with your new name.
2310 5. Type "make", and you should get a working "u-boot.srec" file
2311 to be installed on your target system.
2312 6. Debug and solve any problems that might arise.
2313 [Of course, this last step is much harder than it sounds.]
2316 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2317 ==============================================================
2319 If you have modified U-Boot sources (for instance added a new board
2320 or support for new devices, a new CPU, etc.) you are expected to
2321 provide feedback to the other developers. The feedback normally takes
2322 the form of a "patch", i.e. a context diff against a certain (latest
2323 official or latest in the git repository) version of U-Boot sources.
2325 But before you submit such a patch, please verify that your modifi-
2326 cation did not break existing code. At least make sure that *ALL* of
2327 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2328 just run the buildman script (tools/buildman/buildman), which will
2329 configure and build U-Boot for ALL supported system. Be warned, this
2330 will take a while. Please see the buildman README, or run 'buildman -H'
2334 See also "U-Boot Porting Guide" below.
2337 Monitor Commands - Overview:
2338 ============================
2340 go - start application at address 'addr'
2341 run - run commands in an environment variable
2342 bootm - boot application image from memory
2343 bootp - boot image via network using BootP/TFTP protocol
2344 bootz - boot zImage from memory
2345 tftpboot- boot image via network using TFTP protocol
2346 and env variables "ipaddr" and "serverip"
2347 (and eventually "gatewayip")
2348 tftpput - upload a file via network using TFTP protocol
2349 rarpboot- boot image via network using RARP/TFTP protocol
2350 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2351 loads - load S-Record file over serial line
2352 loadb - load binary file over serial line (kermit mode)
2353 loadm - load binary blob from source address to destination address
2355 mm - memory modify (auto-incrementing)
2356 nm - memory modify (constant address)
2357 mw - memory write (fill)
2360 cmp - memory compare
2361 crc32 - checksum calculation
2362 i2c - I2C sub-system
2363 sspi - SPI utility commands
2364 base - print or set address offset
2365 printenv- print environment variables
2366 pwm - control pwm channels
2367 setenv - set environment variables
2368 saveenv - save environment variables to persistent storage
2369 protect - enable or disable FLASH write protection
2370 erase - erase FLASH memory
2371 flinfo - print FLASH memory information
2372 nand - NAND memory operations (see doc/README.nand)
2373 bdinfo - print Board Info structure
2374 iminfo - print header information for application image
2375 coninfo - print console devices and informations
2376 ide - IDE sub-system
2377 loop - infinite loop on address range
2378 loopw - infinite write loop on address range
2379 mtest - simple RAM test
2380 icache - enable or disable instruction cache
2381 dcache - enable or disable data cache
2382 reset - Perform RESET of the CPU
2383 echo - echo args to console
2384 version - print monitor version
2385 help - print online help
2386 ? - alias for 'help'
2389 Monitor Commands - Detailed Description:
2390 ========================================
2394 For now: just type "help <command>".
2397 Note for Redundant Ethernet Interfaces:
2398 =======================================
2400 Some boards come with redundant Ethernet interfaces; U-Boot supports
2401 such configurations and is capable of automatic selection of a
2402 "working" interface when needed. MAC assignment works as follows:
2404 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2405 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2406 "eth1addr" (=>eth1), "eth2addr", ...
2408 If the network interface stores some valid MAC address (for instance
2409 in SROM), this is used as default address if there is NO correspon-
2410 ding setting in the environment; if the corresponding environment
2411 variable is set, this overrides the settings in the card; that means:
2413 o If the SROM has a valid MAC address, and there is no address in the
2414 environment, the SROM's address is used.
2416 o If there is no valid address in the SROM, and a definition in the
2417 environment exists, then the value from the environment variable is
2420 o If both the SROM and the environment contain a MAC address, and
2421 both addresses are the same, this MAC address is used.
2423 o If both the SROM and the environment contain a MAC address, and the
2424 addresses differ, the value from the environment is used and a
2427 o If neither SROM nor the environment contain a MAC address, an error
2428 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2429 a random, locally-assigned MAC is used.
2431 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2432 will be programmed into hardware as part of the initialization process. This
2433 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2434 The naming convention is as follows:
2435 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2440 U-Boot is capable of booting (and performing other auxiliary operations on)
2441 images in two formats:
2443 New uImage format (FIT)
2444 -----------------------
2446 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2447 to Flattened Device Tree). It allows the use of images with multiple
2448 components (several kernels, ramdisks, etc.), with contents protected by
2449 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2455 Old image format is based on binary files which can be basically anything,
2456 preceded by a special header; see the definitions in include/image.h for
2457 details; basically, the header defines the following image properties:
2459 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2460 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2461 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2462 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2463 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2464 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2465 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2466 * Compression Type (uncompressed, gzip, bzip2)
2472 The header is marked by a special Magic Number, and both the header
2473 and the data portions of the image are secured against corruption by
2480 Although U-Boot should support any OS or standalone application
2481 easily, the main focus has always been on Linux during the design of
2484 U-Boot includes many features that so far have been part of some
2485 special "boot loader" code within the Linux kernel. Also, any
2486 "initrd" images to be used are no longer part of one big Linux image;
2487 instead, kernel and "initrd" are separate images. This implementation
2488 serves several purposes:
2490 - the same features can be used for other OS or standalone
2491 applications (for instance: using compressed images to reduce the
2492 Flash memory footprint)
2494 - it becomes much easier to port new Linux kernel versions because
2495 lots of low-level, hardware dependent stuff are done by U-Boot
2497 - the same Linux kernel image can now be used with different "initrd"
2498 images; of course this also means that different kernel images can
2499 be run with the same "initrd". This makes testing easier (you don't
2500 have to build a new "zImage.initrd" Linux image when you just
2501 change a file in your "initrd"). Also, a field-upgrade of the
2502 software is easier now.
2508 Porting Linux to U-Boot based systems:
2509 ---------------------------------------
2511 U-Boot cannot save you from doing all the necessary modifications to
2512 configure the Linux device drivers for use with your target hardware
2513 (no, we don't intend to provide a full virtual machine interface to
2516 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2518 Just make sure your machine specific header file (for instance
2519 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2520 Information structure as we define in include/asm-<arch>/u-boot.h,
2521 and make sure that your definition of IMAP_ADDR uses the same value
2522 as your U-Boot configuration in CONFIG_SYS_IMMR.
2524 Note that U-Boot now has a driver model, a unified model for drivers.
2525 If you are adding a new driver, plumb it into driver model. If there
2526 is no uclass available, you are encouraged to create one. See
2530 Configuring the Linux kernel:
2531 -----------------------------
2533 No specific requirements for U-Boot. Make sure you have some root
2534 device (initial ramdisk, NFS) for your target system.
2537 Building a Linux Image:
2538 -----------------------
2540 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2541 not used. If you use recent kernel source, a new build target
2542 "uImage" will exist which automatically builds an image usable by
2543 U-Boot. Most older kernels also have support for a "pImage" target,
2544 which was introduced for our predecessor project PPCBoot and uses a
2545 100% compatible format.
2549 make TQM850L_defconfig
2554 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2555 encapsulate a compressed Linux kernel image with header information,
2556 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2558 * build a standard "vmlinux" kernel image (in ELF binary format):
2560 * convert the kernel into a raw binary image:
2562 ${CROSS_COMPILE}-objcopy -O binary \
2563 -R .note -R .comment \
2564 -S vmlinux linux.bin
2566 * compress the binary image:
2570 * package compressed binary image for U-Boot:
2572 mkimage -A ppc -O linux -T kernel -C gzip \
2573 -a 0 -e 0 -n "Linux Kernel Image" \
2574 -d linux.bin.gz uImage
2577 The "mkimage" tool can also be used to create ramdisk images for use
2578 with U-Boot, either separated from the Linux kernel image, or
2579 combined into one file. "mkimage" encapsulates the images with a 64
2580 byte header containing information about target architecture,
2581 operating system, image type, compression method, entry points, time
2582 stamp, CRC32 checksums, etc.
2584 "mkimage" can be called in two ways: to verify existing images and
2585 print the header information, or to build new images.
2587 In the first form (with "-l" option) mkimage lists the information
2588 contained in the header of an existing U-Boot image; this includes
2589 checksum verification:
2591 tools/mkimage -l image
2592 -l ==> list image header information
2594 The second form (with "-d" option) is used to build a U-Boot image
2595 from a "data file" which is used as image payload:
2597 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2598 -n name -d data_file image
2599 -A ==> set architecture to 'arch'
2600 -O ==> set operating system to 'os'
2601 -T ==> set image type to 'type'
2602 -C ==> set compression type 'comp'
2603 -a ==> set load address to 'addr' (hex)
2604 -e ==> set entry point to 'ep' (hex)
2605 -n ==> set image name to 'name'
2606 -d ==> use image data from 'datafile'
2608 Right now, all Linux kernels for PowerPC systems use the same load
2609 address (0x00000000), but the entry point address depends on the
2612 - 2.2.x kernels have the entry point at 0x0000000C,
2613 - 2.3.x and later kernels have the entry point at 0x00000000.
2615 So a typical call to build a U-Boot image would read:
2617 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2618 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2619 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2620 > examples/uImage.TQM850L
2621 Image Name: 2.4.4 kernel for TQM850L
2622 Created: Wed Jul 19 02:34:59 2000
2623 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2624 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2625 Load Address: 0x00000000
2626 Entry Point: 0x00000000
2628 To verify the contents of the image (or check for corruption):
2630 -> tools/mkimage -l examples/uImage.TQM850L
2631 Image Name: 2.4.4 kernel for TQM850L
2632 Created: Wed Jul 19 02:34:59 2000
2633 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2634 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2635 Load Address: 0x00000000
2636 Entry Point: 0x00000000
2638 NOTE: for embedded systems where boot time is critical you can trade
2639 speed for memory and install an UNCOMPRESSED image instead: this
2640 needs more space in Flash, but boots much faster since it does not
2641 need to be uncompressed:
2643 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2644 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2645 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2646 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2647 > examples/uImage.TQM850L-uncompressed
2648 Image Name: 2.4.4 kernel for TQM850L
2649 Created: Wed Jul 19 02:34:59 2000
2650 Image Type: PowerPC Linux Kernel Image (uncompressed)
2651 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2652 Load Address: 0x00000000
2653 Entry Point: 0x00000000
2656 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2657 when your kernel is intended to use an initial ramdisk:
2659 -> tools/mkimage -n 'Simple Ramdisk Image' \
2660 > -A ppc -O linux -T ramdisk -C gzip \
2661 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2662 Image Name: Simple Ramdisk Image
2663 Created: Wed Jan 12 14:01:50 2000
2664 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2665 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2666 Load Address: 0x00000000
2667 Entry Point: 0x00000000
2669 The "dumpimage" tool can be used to disassemble or list the contents of images
2670 built by mkimage. See dumpimage's help output (-h) for details.
2672 Installing a Linux Image:
2673 -------------------------
2675 To downloading a U-Boot image over the serial (console) interface,
2676 you must convert the image to S-Record format:
2678 objcopy -I binary -O srec examples/image examples/image.srec
2680 The 'objcopy' does not understand the information in the U-Boot
2681 image header, so the resulting S-Record file will be relative to
2682 address 0x00000000. To load it to a given address, you need to
2683 specify the target address as 'offset' parameter with the 'loads'
2686 Example: install the image to address 0x40100000 (which on the
2687 TQM8xxL is in the first Flash bank):
2689 => erase 40100000 401FFFFF
2695 ## Ready for S-Record download ...
2696 ~>examples/image.srec
2697 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2699 15989 15990 15991 15992
2700 [file transfer complete]
2702 ## Start Addr = 0x00000000
2705 You can check the success of the download using the 'iminfo' command;
2706 this includes a checksum verification so you can be sure no data
2707 corruption happened:
2711 ## Checking Image at 40100000 ...
2712 Image Name: 2.2.13 for initrd on TQM850L
2713 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2714 Data Size: 335725 Bytes = 327 kB = 0 MB
2715 Load Address: 00000000
2716 Entry Point: 0000000c
2717 Verifying Checksum ... OK
2723 The "bootm" command is used to boot an application that is stored in
2724 memory (RAM or Flash). In case of a Linux kernel image, the contents
2725 of the "bootargs" environment variable is passed to the kernel as
2726 parameters. You can check and modify this variable using the
2727 "printenv" and "setenv" commands:
2730 => printenv bootargs
2731 bootargs=root=/dev/ram
2733 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2735 => printenv bootargs
2736 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2739 ## Booting Linux kernel at 40020000 ...
2740 Image Name: 2.2.13 for NFS on TQM850L
2741 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2742 Data Size: 381681 Bytes = 372 kB = 0 MB
2743 Load Address: 00000000
2744 Entry Point: 0000000c
2745 Verifying Checksum ... OK
2746 Uncompressing Kernel Image ... OK
2747 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
2748 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2749 time_init: decrementer frequency = 187500000/60
2750 Calibrating delay loop... 49.77 BogoMIPS
2751 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2754 If you want to boot a Linux kernel with initial RAM disk, you pass
2755 the memory addresses of both the kernel and the initrd image (PPBCOOT
2756 format!) to the "bootm" command:
2758 => imi 40100000 40200000
2760 ## Checking Image at 40100000 ...
2761 Image Name: 2.2.13 for initrd on TQM850L
2762 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2763 Data Size: 335725 Bytes = 327 kB = 0 MB
2764 Load Address: 00000000
2765 Entry Point: 0000000c
2766 Verifying Checksum ... OK
2768 ## Checking Image at 40200000 ...
2769 Image Name: Simple Ramdisk Image
2770 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2771 Data Size: 566530 Bytes = 553 kB = 0 MB
2772 Load Address: 00000000
2773 Entry Point: 00000000
2774 Verifying Checksum ... OK
2776 => bootm 40100000 40200000
2777 ## Booting Linux kernel at 40100000 ...
2778 Image Name: 2.2.13 for initrd on TQM850L
2779 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2780 Data Size: 335725 Bytes = 327 kB = 0 MB
2781 Load Address: 00000000
2782 Entry Point: 0000000c
2783 Verifying Checksum ... OK
2784 Uncompressing Kernel Image ... OK
2785 ## Loading RAMDisk Image at 40200000 ...
2786 Image Name: Simple Ramdisk Image
2787 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2788 Data Size: 566530 Bytes = 553 kB = 0 MB
2789 Load Address: 00000000
2790 Entry Point: 00000000
2791 Verifying Checksum ... OK
2792 Loading Ramdisk ... OK
2793 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
2794 Boot arguments: root=/dev/ram
2795 time_init: decrementer frequency = 187500000/60
2796 Calibrating delay loop... 49.77 BogoMIPS
2798 RAMDISK: Compressed image found at block 0
2799 VFS: Mounted root (ext2 filesystem).
2803 Boot Linux and pass a flat device tree:
2806 First, U-Boot must be compiled with the appropriate defines. See the section
2807 titled "Linux Kernel Interface" above for a more in depth explanation. The
2808 following is an example of how to start a kernel and pass an updated
2814 oft=oftrees/mpc8540ads.dtb
2815 => tftp $oftaddr $oft
2816 Speed: 1000, full duplex
2818 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2819 Filename 'oftrees/mpc8540ads.dtb'.
2820 Load address: 0x300000
2823 Bytes transferred = 4106 (100a hex)
2824 => tftp $loadaddr $bootfile
2825 Speed: 1000, full duplex
2827 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2829 Load address: 0x200000
2830 Loading:############
2832 Bytes transferred = 1029407 (fb51f hex)
2837 => bootm $loadaddr - $oftaddr
2838 ## Booting image at 00200000 ...
2839 Image Name: Linux-2.6.17-dirty
2840 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2841 Data Size: 1029343 Bytes = 1005.2 kB
2842 Load Address: 00000000
2843 Entry Point: 00000000
2844 Verifying Checksum ... OK
2845 Uncompressing Kernel Image ... OK
2846 Booting using flat device tree at 0x300000
2847 Using MPC85xx ADS machine description
2848 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2852 More About U-Boot Image Types:
2853 ------------------------------
2855 U-Boot supports the following image types:
2857 "Standalone Programs" are directly runnable in the environment
2858 provided by U-Boot; it is expected that (if they behave
2859 well) you can continue to work in U-Boot after return from
2860 the Standalone Program.
2861 "OS Kernel Images" are usually images of some Embedded OS which
2862 will take over control completely. Usually these programs
2863 will install their own set of exception handlers, device
2864 drivers, set up the MMU, etc. - this means, that you cannot
2865 expect to re-enter U-Boot except by resetting the CPU.
2866 "RAMDisk Images" are more or less just data blocks, and their
2867 parameters (address, size) are passed to an OS kernel that is
2869 "Multi-File Images" contain several images, typically an OS
2870 (Linux) kernel image and one or more data images like
2871 RAMDisks. This construct is useful for instance when you want
2872 to boot over the network using BOOTP etc., where the boot
2873 server provides just a single image file, but you want to get
2874 for instance an OS kernel and a RAMDisk image.
2876 "Multi-File Images" start with a list of image sizes, each
2877 image size (in bytes) specified by an "uint32_t" in network
2878 byte order. This list is terminated by an "(uint32_t)0".
2879 Immediately after the terminating 0 follow the images, one by
2880 one, all aligned on "uint32_t" boundaries (size rounded up to
2881 a multiple of 4 bytes).
2883 "Firmware Images" are binary images containing firmware (like
2884 U-Boot or FPGA images) which usually will be programmed to
2887 "Script files" are command sequences that will be executed by
2888 U-Boot's command interpreter; this feature is especially
2889 useful when you configure U-Boot to use a real shell (hush)
2890 as command interpreter.
2892 Booting the Linux zImage:
2893 -------------------------
2895 On some platforms, it's possible to boot Linux zImage. This is done
2896 using the "bootz" command. The syntax of "bootz" command is the same
2897 as the syntax of "bootm" command.
2899 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2900 kernel with raw initrd images. The syntax is slightly different, the
2901 address of the initrd must be augmented by it's size, in the following
2902 format: "<initrd addres>:<initrd size>".
2908 One of the features of U-Boot is that you can dynamically load and
2909 run "standalone" applications, which can use some resources of
2910 U-Boot like console I/O functions or interrupt services.
2912 Two simple examples are included with the sources:
2917 'examples/hello_world.c' contains a small "Hello World" Demo
2918 application; it is automatically compiled when you build U-Boot.
2919 It's configured to run at address 0x00040004, so you can play with it
2923 ## Ready for S-Record download ...
2924 ~>examples/hello_world.srec
2925 1 2 3 4 5 6 7 8 9 10 11 ...
2926 [file transfer complete]
2928 ## Start Addr = 0x00040004
2930 => go 40004 Hello World! This is a test.
2931 ## Starting application at 0x00040004 ...
2942 Hit any key to exit ...
2944 ## Application terminated, rc = 0x0
2946 Another example, which demonstrates how to register a CPM interrupt
2947 handler with the U-Boot code, can be found in 'examples/timer.c'.
2948 Here, a CPM timer is set up to generate an interrupt every second.
2949 The interrupt service routine is trivial, just printing a '.'
2950 character, but this is just a demo program. The application can be
2951 controlled by the following keys:
2953 ? - print current values og the CPM Timer registers
2954 b - enable interrupts and start timer
2955 e - stop timer and disable interrupts
2956 q - quit application
2959 ## Ready for S-Record download ...
2960 ~>examples/timer.srec
2961 1 2 3 4 5 6 7 8 9 10 11 ...
2962 [file transfer complete]
2964 ## Start Addr = 0x00040004
2967 ## Starting application at 0x00040004 ...
2970 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2973 [q, b, e, ?] Set interval 1000000 us
2976 [q, b, e, ?] ........
2977 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2980 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2983 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2986 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2988 [q, b, e, ?] ...Stopping timer
2990 [q, b, e, ?] ## Application terminated, rc = 0x0
2996 Over time, many people have reported problems when trying to use the
2997 "minicom" terminal emulation program for serial download. I (wd)
2998 consider minicom to be broken, and recommend not to use it. Under
2999 Unix, I recommend to use C-Kermit for general purpose use (and
3000 especially for kermit binary protocol download ("loadb" command), and
3001 use "cu" for S-Record download ("loads" command). See
3002 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3003 for help with kermit.
3006 Nevertheless, if you absolutely want to use it try adding this
3007 configuration to your "File transfer protocols" section:
3009 Name Program Name U/D FullScr IO-Red. Multi
3010 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3011 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3017 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3018 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3020 Building requires a cross environment; it is known to work on
3021 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3022 need gmake since the Makefiles are not compatible with BSD make).
3023 Note that the cross-powerpc package does not install include files;
3024 attempting to build U-Boot will fail because <machine/ansi.h> is
3025 missing. This file has to be installed and patched manually:
3027 # cd /usr/pkg/cross/powerpc-netbsd/include
3029 # ln -s powerpc machine
3030 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3031 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3033 Native builds *don't* work due to incompatibilities between native
3034 and U-Boot include files.
3036 Booting assumes that (the first part of) the image booted is a
3037 stage-2 loader which in turn loads and then invokes the kernel
3038 proper. Loader sources will eventually appear in the NetBSD source
3039 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3040 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3043 Implementation Internals:
3044 =========================
3046 The following is not intended to be a complete description of every
3047 implementation detail. However, it should help to understand the
3048 inner workings of U-Boot and make it easier to port it to custom
3052 Initial Stack, Global Data:
3053 ---------------------------
3055 The implementation of U-Boot is complicated by the fact that U-Boot
3056 starts running out of ROM (flash memory), usually without access to
3057 system RAM (because the memory controller is not initialized yet).
3058 This means that we don't have writable Data or BSS segments, and BSS
3059 is not initialized as zero. To be able to get a C environment working
3060 at all, we have to allocate at least a minimal stack. Implementation
3061 options for this are defined and restricted by the CPU used: Some CPU
3062 models provide on-chip memory (like the IMMR area on MPC8xx and
3063 MPC826x processors), on others (parts of) the data cache can be
3064 locked as (mis-) used as memory, etc.
3066 Chris Hallinan posted a good summary of these issues to the
3067 U-Boot mailing list:
3069 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3070 From: "Chris Hallinan" <clh@net1plus.com>
3071 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3074 Correct me if I'm wrong, folks, but the way I understand it
3075 is this: Using DCACHE as initial RAM for Stack, etc, does not
3076 require any physical RAM backing up the cache. The cleverness
3077 is that the cache is being used as a temporary supply of
3078 necessary storage before the SDRAM controller is setup. It's
3079 beyond the scope of this list to explain the details, but you
3080 can see how this works by studying the cache architecture and
3081 operation in the architecture and processor-specific manuals.
3083 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3084 is another option for the system designer to use as an
3085 initial stack/RAM area prior to SDRAM being available. Either
3086 option should work for you. Using CS 4 should be fine if your
3087 board designers haven't used it for something that would
3088 cause you grief during the initial boot! It is frequently not
3091 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3092 with your processor/board/system design. The default value
3093 you will find in any recent u-boot distribution in
3094 walnut.h should work for you. I'd set it to a value larger
3095 than your SDRAM module. If you have a 64MB SDRAM module, set
3096 it above 400_0000. Just make sure your board has no resources
3097 that are supposed to respond to that address! That code in
3098 start.S has been around a while and should work as is when
3099 you get the config right.
3104 It is essential to remember this, since it has some impact on the C
3105 code for the initialization procedures:
3107 * Initialized global data (data segment) is read-only. Do not attempt
3110 * Do not use any uninitialized global data (or implicitly initialized
3111 as zero data - BSS segment) at all - this is undefined, initiali-
3112 zation is performed later (when relocating to RAM).
3114 * Stack space is very limited. Avoid big data buffers or things like
3117 Having only the stack as writable memory limits means we cannot use
3118 normal global data to share information between the code. But it
3119 turned out that the implementation of U-Boot can be greatly
3120 simplified by making a global data structure (gd_t) available to all
3121 functions. We could pass a pointer to this data as argument to _all_
3122 functions, but this would bloat the code. Instead we use a feature of
3123 the GCC compiler (Global Register Variables) to share the data: we
3124 place a pointer (gd) to the global data into a register which we
3125 reserve for this purpose.
3127 When choosing a register for such a purpose we are restricted by the
3128 relevant (E)ABI specifications for the current architecture, and by
3129 GCC's implementation.
3131 For PowerPC, the following registers have specific use:
3133 R2: reserved for system use
3134 R3-R4: parameter passing and return values
3135 R5-R10: parameter passing
3136 R13: small data area pointer
3140 (U-Boot also uses R12 as internal GOT pointer. r12
3141 is a volatile register so r12 needs to be reset when
3142 going back and forth between asm and C)
3144 ==> U-Boot will use R2 to hold a pointer to the global data
3146 Note: on PPC, we could use a static initializer (since the
3147 address of the global data structure is known at compile time),
3148 but it turned out that reserving a register results in somewhat
3149 smaller code - although the code savings are not that big (on
3150 average for all boards 752 bytes for the whole U-Boot image,
3151 624 text + 127 data).
3153 On ARM, the following registers are used:
3155 R0: function argument word/integer result
3156 R1-R3: function argument word
3157 R9: platform specific
3158 R10: stack limit (used only if stack checking is enabled)
3159 R11: argument (frame) pointer
3160 R12: temporary workspace
3163 R15: program counter
3165 ==> U-Boot will use R9 to hold a pointer to the global data
3167 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3169 On Nios II, the ABI is documented here:
3170 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3172 ==> U-Boot will use gp to hold a pointer to the global data
3174 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3175 to access small data sections, so gp is free.
3177 On RISC-V, the following registers are used:
3179 x0: hard-wired zero (zero)
3180 x1: return address (ra)
3181 x2: stack pointer (sp)
3182 x3: global pointer (gp)
3183 x4: thread pointer (tp)
3184 x5: link register (t0)
3185 x8: frame pointer (fp)
3186 x10-x11: arguments/return values (a0-1)
3187 x12-x17: arguments (a2-7)
3188 x28-31: temporaries (t3-6)
3189 pc: program counter (pc)
3191 ==> U-Boot will use gp to hold a pointer to the global data
3196 U-Boot runs in system state and uses physical addresses, i.e. the
3197 MMU is not used either for address mapping nor for memory protection.
3199 The available memory is mapped to fixed addresses using the memory
3200 controller. In this process, a contiguous block is formed for each
3201 memory type (Flash, SDRAM, SRAM), even when it consists of several
3202 physical memory banks.
3204 U-Boot is installed in the first 128 kB of the first Flash bank (on
3205 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3206 booting and sizing and initializing DRAM, the code relocates itself
3207 to the upper end of DRAM. Immediately below the U-Boot code some
3208 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3209 configuration setting]. Below that, a structure with global Board
3210 Info data is placed, followed by the stack (growing downward).
3212 Additionally, some exception handler code is copied to the low 8 kB
3213 of DRAM (0x00000000 ... 0x00001FFF).
3215 So a typical memory configuration with 16 MB of DRAM could look like
3218 0x0000 0000 Exception Vector code
3221 0x0000 2000 Free for Application Use
3227 0x00FB FF20 Monitor Stack (Growing downward)
3228 0x00FB FFAC Board Info Data and permanent copy of global data
3229 0x00FC 0000 Malloc Arena
3232 0x00FE 0000 RAM Copy of Monitor Code
3233 ... eventually: LCD or video framebuffer
3234 ... eventually: pRAM (Protected RAM - unchanged by reset)
3235 0x00FF FFFF [End of RAM]
3238 System Initialization:
3239 ----------------------
3241 In the reset configuration, U-Boot starts at the reset entry point
3242 (on most PowerPC systems at address 0x00000100). Because of the reset
3243 configuration for CS0# this is a mirror of the on board Flash memory.
3244 To be able to re-map memory U-Boot then jumps to its link address.
3245 To be able to implement the initialization code in C, a (small!)
3246 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3247 which provide such a feature like), or in a locked part of the data
3248 cache. After that, U-Boot initializes the CPU core, the caches and
3251 Next, all (potentially) available memory banks are mapped using a
3252 preliminary mapping. For example, we put them on 512 MB boundaries
3253 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3254 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3255 programmed for SDRAM access. Using the temporary configuration, a
3256 simple memory test is run that determines the size of the SDRAM
3259 When there is more than one SDRAM bank, and the banks are of
3260 different size, the largest is mapped first. For equal size, the first
3261 bank (CS2#) is mapped first. The first mapping is always for address
3262 0x00000000, with any additional banks following immediately to create
3263 contiguous memory starting from 0.
3265 Then, the monitor installs itself at the upper end of the SDRAM area
3266 and allocates memory for use by malloc() and for the global Board
3267 Info data; also, the exception vector code is copied to the low RAM
3268 pages, and the final stack is set up.
3270 Only after this relocation will you have a "normal" C environment;
3271 until that you are restricted in several ways, mostly because you are
3272 running from ROM, and because the code will have to be relocated to a
3276 U-Boot Porting Guide:
3277 ----------------------
3279 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3283 int main(int argc, char *argv[])
3285 sighandler_t no_more_time;
3287 signal(SIGALRM, no_more_time);
3288 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3290 if (available_money > available_manpower) {
3291 Pay consultant to port U-Boot;
3295 Download latest U-Boot source;
3297 Subscribe to u-boot mailing list;
3300 email("Hi, I am new to U-Boot, how do I get started?");
3303 Read the README file in the top level directory;
3304 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3305 Read applicable doc/README.*;
3306 Read the source, Luke;
3307 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3310 if (available_money > toLocalCurrency ($2500))
3313 Add a lot of aggravation and time;
3315 if (a similar board exists) { /* hopefully... */
3316 cp -a board/<similar> board/<myboard>
3317 cp include/configs/<similar>.h include/configs/<myboard>.h
3319 Create your own board support subdirectory;
3320 Create your own board include/configs/<myboard>.h file;
3322 Edit new board/<myboard> files
3323 Edit new include/configs/<myboard>.h
3328 Add / modify source code;
3332 email("Hi, I am having problems...");
3334 Send patch file to the U-Boot email list;
3335 if (reasonable critiques)
3336 Incorporate improvements from email list code review;
3338 Defend code as written;
3344 void no_more_time (int sig)
3353 All contributions to U-Boot should conform to the Linux kernel
3354 coding style; see the kernel coding style guide at
3355 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3356 script "scripts/Lindent" in your Linux kernel source directory.
3358 Source files originating from a different project (for example the
3359 MTD subsystem) are generally exempt from these guidelines and are not
3360 reformatted to ease subsequent migration to newer versions of those
3363 Please note that U-Boot is implemented in C (and to some small parts in
3364 Assembler); no C++ is used, so please do not use C++ style comments (//)
3367 Please also stick to the following formatting rules:
3368 - remove any trailing white space
3369 - use TAB characters for indentation and vertical alignment, not spaces
3370 - make sure NOT to use DOS '\r\n' line feeds
3371 - do not add more than 2 consecutive empty lines to source files
3372 - do not add trailing empty lines to source files
3374 Submissions which do not conform to the standards may be returned
3375 with a request to reformat the changes.
3381 Since the number of patches for U-Boot is growing, we need to
3382 establish some rules. Submissions which do not conform to these rules
3383 may be rejected, even when they contain important and valuable stuff.
3385 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3387 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3388 see https://lists.denx.de/listinfo/u-boot
3390 When you send a patch, please include the following information with
3393 * For bug fixes: a description of the bug and how your patch fixes
3394 this bug. Please try to include a way of demonstrating that the
3395 patch actually fixes something.
3397 * For new features: a description of the feature and your
3400 * For major contributions, add a MAINTAINERS file with your
3401 information and associated file and directory references.
3403 * When you add support for a new board, don't forget to add a
3404 maintainer e-mail address to the boards.cfg file, too.
3406 * If your patch adds new configuration options, don't forget to
3407 document these in the README file.
3409 * The patch itself. If you are using git (which is *strongly*
3410 recommended) you can easily generate the patch using the
3411 "git format-patch". If you then use "git send-email" to send it to
3412 the U-Boot mailing list, you will avoid most of the common problems
3413 with some other mail clients.
3415 If you cannot use git, use "diff -purN OLD NEW". If your version of
3416 diff does not support these options, then get the latest version of
3419 The current directory when running this command shall be the parent
3420 directory of the U-Boot source tree (i. e. please make sure that
3421 your patch includes sufficient directory information for the
3424 We prefer patches as plain text. MIME attachments are discouraged,
3425 and compressed attachments must not be used.
3427 * If one logical set of modifications affects or creates several
3428 files, all these changes shall be submitted in a SINGLE patch file.
3430 * Changesets that contain different, unrelated modifications shall be
3431 submitted as SEPARATE patches, one patch per changeset.
3436 * Before sending the patch, run the buildman script on your patched
3437 source tree and make sure that no errors or warnings are reported
3438 for any of the boards.
3440 * Keep your modifications to the necessary minimum: A patch
3441 containing several unrelated changes or arbitrary reformats will be
3442 returned with a request to re-formatting / split it.
3444 * If you modify existing code, make sure that your new code does not
3445 add to the memory footprint of the code ;-) Small is beautiful!
3446 When adding new features, these should compile conditionally only
3447 (using #ifdef), and the resulting code with the new feature
3448 disabled must not need more memory than the old code without your
3451 * Remember that there is a size limit of 100 kB per message on the
3452 u-boot mailing list. Bigger patches will be moderated. If they are
3453 reasonable and not too big, they will be acknowledged. But patches
3454 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob