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1 files changed, 95 insertions, 45 deletions
diff --git a/README b/README
index 30ff772..7e49a0c 100644
--- a/README
+++ b/README
@@ -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