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Diffstat (limited to 'README')
| -rw-r--r-- | README | 140 |
1 files changed, 95 insertions, 45 deletions
@@ -24,13 +24,14 @@ Summary: ======== -This directory contains the source code for U-Boot, a monitor for -Embedded PowerPC boards, which can be installed in a boot ROM and -used to test the hardware or download and run application code. +This directory contains the source code for U-Boot, a boot loader for +Embedded boards based on PowerPC and ARM processors, which can be +installed in a boot ROM and used to initialize and test the hardware +or to download and run application code. The development of U-Boot is closely related to Linux: some parts of -the source code originate in the Linux source tree, we still have -some header files in common, and special provision has been made to +the source code originate in the Linux source tree, we have some +header files in common, and special provision has been made to support booting of Linux images. Some attention has been paid to make this software easily @@ -45,23 +46,20 @@ Status: ======= In general, all boards for which a configuration option exists in the -Makefile have been tested to some extent and can be considered +Makefile have been tested to some extent and can be considered "working". In fact, many of them are used in production systems. -In case of problems see the CHANGELOG and CREDITS files to find out +In case of problems see the CHANGELOG and CREDITS files to find out who contributed the specific port. -Exception from this rule: the port to the Sandpoint 8240 has not been -completed yet. - Where to get help: ================== -In case you have questions about, problems with or contributions for -U-Boot you should send a message to the U-Boot mailing list at -<u-boot-users@lists.sourceforge.net>. There is also an archive of -previous traffic on the mailing list - please search the archive +In case you have questions about, problems with or contributions for +U-Boot you should send a message to the U-Boot mailing list at +<u-boot-users@lists.sourceforge.net>. There is also an archive of +previous traffic on the mailing list - please search the archive before asking FAQ's. Please see http://lists.sourceforge.net/lists/listinfo/u-boot-users/ @@ -70,6 +68,7 @@ Where we come from: =================== - start from 8xxrom sources +- create PPCBoot project (http://sourceforge.net/projects/ppcboot) - clean up code - make it easier to add custom boards - make it possible to add other [PowerPC] CPUs @@ -78,7 +77,31 @@ Where we come from: * S-Record download * network boot * PCMCIA / CompactFLash / ATA disk / SCSI ... boot +- create ARMBoot project (http://sourceforge.net/projects/armboot) - add other CPU families (starting with ARM) +- create U-Boot project (http://sourceforge.net/projects/u-boot) + + +Names and Spelling: +=================== + +The "official" name of this project is "Das U-Boot". The spelling +"U-Boot" shall be used in all written text (documentation, comments +in source files etc.). Example: + + This is the README file for the U-Boot project. + +File names etc. shall be based on the string "u-boot". Examples: + + include/asm-ppc/u-boot.h + + #include <asm/u-boot.h> + +Variable names, preprocessor constants etc. shall be either based on +the string "u_boot" or on "U_BOOT". Example: + + U_BOOT_VERSION u_boot_logo + IH_OS_U_BOOT u_boot_hush_start Directory Hierarchy: @@ -1675,7 +1698,7 @@ Note: for some board special configuration names may exist; check if -Finally, type "make all", and you should get some working U-Boot +Finally, type "make all", and you should get some working U-Boot images ready for downlod to / installation on your system: - "u-boot.bin" is a raw binary image @@ -2013,28 +2036,55 @@ device (initial ramdisk, NFS) for your target system. Building a Linux Image: ----------------------- -No specific requirements for U-Boot. There is no need to add a -"ramdisk.image.gz" file when building the kernel, even when you -intend to run it with initial ramdisk. +With U-Boot, "normal" build targets like "zImage" or "bzImage" are +not used. If you use recent kernel source, a new build target +"uImage" will exist which automatically builds an image usable by +U-Boot. Most older kernels also have support for a "pImage" target, +which was introduced for our predecessor project PPCBoot and uses a +100% compatible format. Example: make TQM850L_config make oldconfig make dep - make zImage + make uImage + +The "uImage" build target uses a special tool (in 'tools/mkimage') to +encapsulate a compressed Linux kernel image with header information, +CRC32 checksum etc. for use with U-Boot. This is what we are doing: -However, we don't use the 'zImage' (= 'arch/ppc/mbxboot/zvmlinux') we -build this way. The 'zImage' includes the old boot loader code which -we don't ned any more. Instead, we use the raw (compressed) Linux -kernel image in 'arch/ppc/coffboot/vmlinux.gz'. +* build a standard "vmlinux" kernel image (in ELF binary format): -There is a special tool (in 'tools/mkimage') to encapsulate this -image with header information, CRC32 checksum etc. for use with -U-Boot: +* convert the kernel into a raw binary image: -In the first form (with "-l" option) mkimage lists the information -contained in the header of an existing U-Boot image; this includes + ${CROSS_COMPILE}-objcopy -O binary \ + -R .note -R .comment \ + -S vmlinux linux.bin + +* compress the binary image: + + gzip -9 linux.bin + +* package compressed binary image for U-Boot: + + mkimage -A ppc -O linux -T kernel -C gzip \ + -a 0 -e 0 -n "Linux Kernel Image" \ + -d linux.bin.gz uImage + + +The "mkimage" tool can also be used to create ramdisk images for use +with U-Boot, either separated from the Linux kernel image, or +combined into one file. "mkimage" encapsulates the images with a 64 +byte header containing information about target architecture, +operating system, image type, compression method, entry points, time +stamp, CRC32 checksums, etc. + +"mkimage" can be called in two ways: to verify existing images and +print the header information, or to build new images. + +In the first form (with "-l" option) mkimage lists the information +contained in the header of an existing U-Boot image; this includes checksum verification: tools/mkimage -l image @@ -2058,47 +2108,47 @@ Right now, all Linux kernels use the same load address (0x00000000), but the entry point address depends on the kernel version: - 2.2.x kernels have the entry point at 0x0000000C, -- 2.3.x and 2.4.x kernels have the entry point at 0x00000000. +- 2.3.x and later kernels have the entry point at 0x00000000. So a typical call to build a U-Boot image would read: - -> tools/mkimage -n '2.2.13 for initrd on TQM850L' \ - > -A ppc -O linux -T kernel -C gzip -a 00000000 -e 0000000C \ - > -d /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux.gz \ - > examples/image-2.2.13-initrd - Image Name: 2.2.13 for initrd on TQM850L + -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ + > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ + > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \ + > examples/uImage.TQM850L + Image Name: 2.4.4 kernel for TQM850L Created: Wed Jul 19 02:34:59 2000 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 335725 Bytes = 327.86 kB = 0.32 MB Load Address: 0x00000000 - Entry Point: 0x0000000c + Entry Point: 0x00000000 To verify the contents of the image (or check for corruption): - -> tools/mkimage -l examples/image-2.2.13-initrd - Image Name: 2.2.13 for initrd on TQM850L + -> tools/mkimage -l examples/uImage.TQM850L + Image Name: 2.4.4 kernel for TQM850L Created: Wed Jul 19 02:34:59 2000 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 335725 Bytes = 327.86 kB = 0.32 MB Load Address: 0x00000000 - Entry Point: 0x0000000c + Entry Point: 0x00000000 NOTE: for embedded systems where boot time is critical you can trade speed for memory and install an UNCOMPRESSED image instead: this needs more space in Flash, but boots much faster since it does not need to be uncompressed: - -> gunzip /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux.gz - -> tools/mkimage -n '2.2.13 for initrd on TQM850L' \ - > -A ppc -O linux -T kernel -C none -a 00000000 -e 0000000C \ - > -d /opt/mpc8xx/src/linux-2.2.13/arch/ppc/coffboot/vmlinux \ - > examples/image-2.2.13-initrd-uncompressed - Image Name: 2.2.13 for initrd on TQM850L + -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz + -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ + > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ + > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \ + > examples/uImage.TQM850L-uncompressed + Image Name: 2.4.4 kernel for TQM850L Created: Wed Jul 19 02:34:59 2000 Image Type: PowerPC Linux Kernel Image (uncompressed) Data Size: 792160 Bytes = 773.59 kB = 0.76 MB Load Address: 0x00000000 - Entry Point: 0x0000000c + Entry Point: 0x00000000 Similar you can build U-Boot images from a 'ramdisk.image.gz' file |