406 lines
14 KiB
Plaintext
406 lines
14 KiB
Plaintext
How to use images in the new image format
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=========================================
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Author: Bartlomiej Sieka <tur@semihalf.com>
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Overview
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--------
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The new uImage format allows more flexibility in handling images of various
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types (kernel, ramdisk, etc.), it also enhances integrity protection of images
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with sha1 and md5 checksums.
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Two auxiliary tools are needed on the development host system in order to
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create an uImage in the new format: mkimage and dtc, although only one
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(mkimage) is invoked directly. dtc is called from within mkimage and operates
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behind the scenes, but needs to be present in the $PATH nevertheless. It is
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important that the dtc used has support for binary includes -- refer to
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git://git.kernel.org/pub/scm/utils/dtc/dtc.git
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for its latest version. mkimage (together with dtc) takes as input
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an image source file, which describes the contents of the image and defines
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its various properties used during booting. By convention, image source file
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has the ".its" extension, also, the details of its format are given in
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doc/uImage.FIT/source_file_format.txt. The actual data that is to be included in
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the uImage (kernel, ramdisk, etc.) is specified in the image source file in the
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form of paths to appropriate data files. The outcome of the image creation
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process is a binary file (by convention with the ".itb" extension) that
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contains all the referenced data (kernel, ramdisk, etc.) and other information
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needed by U-Boot to handle the uImage properly. The uImage file is then
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transferred to the target (e.g., via tftp) and booted using the bootm command.
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To summarize the prerequisites needed for new uImage creation:
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- mkimage
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- dtc (with support for binary includes)
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- image source file (*.its)
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- image data file(s)
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Here's a graphical overview of the image creation and booting process:
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image source file mkimage + dtc transfer to target
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+ ---------------> image file --------------------> bootm
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image data file(s)
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SPL usage
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---------
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The SPL can make use of the new image format as well, this traditionally
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is used to ship multiple device tree files within one image. Code in the SPL
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will choose the one matching the current board and append this to the
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U-Boot proper binary to be automatically used up by it.
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Aside from U-Boot proper and one device tree blob the SPL can load multiple,
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arbitrary image files as well. These binaries should be specified in their
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own subnode under the /images node, which should then be referenced from one or
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multiple /configurations subnodes. The required images must be enumerated in
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the "loadables" property as a list of strings.
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If a platform specific image source file (.its) is shipped with the U-Boot
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source, it can be specified using the CONFIG_SPL_FIT_SOURCE Kconfig symbol.
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In this case it will be automatically used by U-Boot's Makefile to generate
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the image.
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If a static source file is not flexible enough, CONFIG_SPL_FIT_GENERATOR
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can point to a script which generates this image source file during
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the build process. It gets passed a list of device tree files (taken from the
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CONFIG_OF_LIST symbol).
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The SPL also records to a DT all additional images (called loadables) which are
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loaded. The information about loadables locations is passed via the DT node with
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fit-images name.
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Loadables Example
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-----------------
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Consider the following case for an ARM64 platform where U-Boot runs in EL2
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started by ATF where SPL is loading U-Boot (as loadables) and ATF (as firmware).
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/dts-v1/;
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/ {
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description = "Configuration to load ATF before U-Boot";
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images {
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uboot {
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description = "U-Boot (64-bit)";
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data = /incbin/("u-boot-nodtb.bin");
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type = "firmware";
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os = "u-boot";
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arch = "arm64";
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compression = "none";
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load = <0x8 0x8000000>;
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entry = <0x8 0x8000000>;
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hash {
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algo = "md5";
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};
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};
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atf {
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description = "ARM Trusted Firmware";
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data = /incbin/("bl31.bin");
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type = "firmware";
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os = "arm-trusted-firmware";
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arch = "arm64";
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compression = "none";
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load = <0xfffea000>;
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entry = <0xfffea000>;
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hash {
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algo = "md5";
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};
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};
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fdt_1 {
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description = "zynqmp-zcu102-revA";
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data = /incbin/("arch/arm/dts/zynqmp-zcu102-revA.dtb");
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type = "flat_dt";
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arch = "arm64";
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compression = "none";
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load = <0x100000>;
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hash {
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algo = "md5";
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};
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};
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};
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configurations {
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default = "config_1";
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config_1 {
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description = "zynqmp-zcu102-revA";
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firmware = "atf";
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loadables = "uboot";
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fdt = "fdt_1";
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};
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};
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};
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In this case the SPL records via fit-images DT node the information about
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loadables U-Boot image.
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ZynqMP> fdt addr $fdtcontroladdr
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ZynqMP> fdt print /fit-images
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fit-images {
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uboot {
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os = "u-boot";
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type = "firmware";
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size = <0x001017c8>;
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entry = <0x00000008 0x08000000>;
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load = <0x00000008 0x08000000>;
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};
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};
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As you can see entry and load properties are 64bit wide to support loading
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images above 4GB (in past entry and load properties where just 32bit).
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Example 1 -- old-style (non-FDT) kernel booting
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-----------------------------------------------
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Consider a simple scenario, where a PPC Linux kernel built from sources on the
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development host is to be booted old-style (non-FDT) by U-Boot on an embedded
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target. Assume that the outcome of the build is vmlinux.bin.gz, a file which
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contains a gzip-compressed PPC Linux kernel (the only data file in this case).
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The uImage can be produced using the image source file
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doc/uImage.FIT/kernel.its (note that kernel.its assumes that vmlinux.bin.gz is
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in the current working directory; if desired, an alternative path can be
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specified in the kernel.its file). Here's how to create the image and inspect
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its contents:
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[on the host system]
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$ mkimage -f kernel.its kernel.itb
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DTC: dts->dtb on file "kernel.its"
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$
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$ mkimage -l kernel.itb
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FIT description: Simple image with single Linux kernel
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Created: Tue Mar 11 17:26:15 2008
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Image 0 (kernel)
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Size: 943347 Bytes = 921.24 kB = 0.90 MB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2ae2bb40
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Hash algo: sha1
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Hash value: 3c200f34e2c226ddc789240cca0c59fc54a67cf4
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Default Configuration: 'config-1'
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Configuration 0 (config-1)
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Description: Boot Linux kernel
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Kernel: kernel
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The resulting image file kernel.itb can be now transferred to the target,
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inspected and booted (note that first three U-Boot commands below are shown
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for completeness -- they are part of the standard booting procedure and not
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specific to the new image format).
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[on the target system]
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=> print nfsargs
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nfsargs=setenv bootargs root=/dev/nfs rw nfsroot=${serverip}:${rootpath}
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=> print addip
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addip=setenv bootargs ${bootargs} ip=${ipaddr}:${serverip}:${gatewayip}:${netmask}:${hostname}:${netdev}:off panic=1
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=> run nfsargs addip
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=> tftp 900000 /path/to/tftp/location/kernel.itb
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Using FEC device
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TFTP from server 192.168.1.1; our IP address is 192.168.160.5
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Filename '/path/to/tftp/location/kernel.itb'.
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Load address: 0x900000
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Loading: #################################################################
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done
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Bytes transferred = 944464 (e6950 hex)
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=> iminfo
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## Checking Image at 00900000 ...
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FIT image found
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FIT description: Simple image with single Linux kernel
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Created: 2008-03-11 16:26:15 UTC
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Image 0 (kernel)
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Start: 0x009000e0
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Data Size: 943347 Bytes = 921.2 kB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2ae2bb40
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Hash algo: sha1
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Hash value: 3c200f34e2c226ddc789240cca0c59fc54a67cf4
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Default Configuration: 'config-1'
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Configuration 0 (config-1)
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Description: Boot Linux kernel
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Kernel: kernel
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=> bootm
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## Booting kernel from FIT Image at 00900000 ...
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Using 'config-1' configuration
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Trying 'kernel' kernel subimage
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Start: 0x009000e0
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Data Size: 943347 Bytes = 921.2 kB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2ae2bb40
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Hash algo: sha1
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Hash value: 3c200f34e2c226ddc789240cca0c59fc54a67cf4
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Verifying Hash Integrity ... crc32+ sha1+ OK
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Uncompressing Kernel Image ... OK
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Memory BAT mapping: BAT2=256Mb, BAT3=0Mb, residual: 0Mb
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Linux version 2.4.25 (m8@hekate) (gcc version 4.0.0 (DENX ELDK 4.0 4.0.0)) #2 czw lip 5 17:56:18 CEST 2007
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On node 0 totalpages: 65536
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zone(0): 65536 pages.
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zone(1): 0 pages.
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zone(2): 0 pages.
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Kernel command line: root=/dev/nfs rw nfsroot=192.168.1.1:/opt/eldk-4.1/ppc_6xx ip=192.168.160.5:192.168.1.1::255.255.0.0:lite5200b:eth0:off panic=1
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Calibrating delay loop... 307.20 BogoMIPS
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Example 2 -- new-style (FDT) kernel booting
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-------------------------------------------
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Consider another simple scenario, where a PPC Linux kernel is to be booted
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new-style, i.e., with a FDT blob. In this case there are two prerequisite data
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files: vmlinux.bin.gz (Linux kernel) and target.dtb (FDT blob). The uImage can
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be produced using image source file doc/uImage.FIT/kernel_fdt.its like this
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(note again, that both prerequisite data files are assumed to be present in
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the current working directory -- image source file kernel_fdt.its can be
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modified to take the files from some other location if needed):
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[on the host system]
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$ mkimage -f kernel_fdt.its kernel_fdt.itb
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DTC: dts->dtb on file "kernel_fdt.its"
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$
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$ mkimage -l kernel_fdt.itb
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FIT description: Simple image with single Linux kernel and FDT blob
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Created: Tue Mar 11 16:29:22 2008
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Image 0 (kernel)
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Size: 1092037 Bytes = 1066.44 kB = 1.04 MB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2c0cc807
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Hash algo: sha1
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Hash value: 264b59935470e42c418744f83935d44cdf59a3bb
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Image 1 (fdt-1)
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Description: Flattened Device Tree blob
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Type: Flat Device Tree
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Compression: uncompressed
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Data Size: 16384 Bytes = 16.00 kB = 0.02 MB
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Architecture: PowerPC
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Hash algo: crc32
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Hash value: 0d655d71
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Hash algo: sha1
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Hash value: 25ab4e15cd4b8a5144610394560d9c318ce52def
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Default Configuration: 'conf-1'
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Configuration 0 (conf-1)
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Description: Boot Linux kernel with FDT blob
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Kernel: kernel
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FDT: fdt-1
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The resulting image file kernel_fdt.itb can be now transferred to the target,
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inspected and booted:
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[on the target system]
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=> tftp 900000 /path/to/tftp/location/kernel_fdt.itb
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Using FEC device
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TFTP from server 192.168.1.1; our IP address is 192.168.160.5
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Filename '/path/to/tftp/location/kernel_fdt.itb'.
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Load address: 0x900000
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Loading: #################################################################
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###########
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done
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Bytes transferred = 1109776 (10ef10 hex)
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=> iminfo
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## Checking Image at 00900000 ...
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FIT image found
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FIT description: Simple image with single Linux kernel and FDT blob
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Created: 2008-03-11 15:29:22 UTC
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Image 0 (kernel)
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Start: 0x009000ec
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Data Size: 1092037 Bytes = 1 MB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2c0cc807
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Hash algo: sha1
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Hash value: 264b59935470e42c418744f83935d44cdf59a3bb
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Image 1 (fdt-1)
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Description: Flattened Device Tree blob
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Type: Flat Device Tree
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Compression: uncompressed
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Data Start: 0x00a0abdc
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Data Size: 16384 Bytes = 16 kB
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Architecture: PowerPC
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Hash algo: crc32
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Hash value: 0d655d71
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Hash algo: sha1
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Hash value: 25ab4e15cd4b8a5144610394560d9c318ce52def
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Default Configuration: 'conf-1'
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Configuration 0 (conf-1)
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Description: Boot Linux kernel with FDT blob
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Kernel: kernel
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FDT: fdt-1
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=> bootm
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## Booting kernel from FIT Image at 00900000 ...
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Using 'conf-1' configuration
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Trying 'kernel' kernel subimage
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Description: Vanilla Linux kernel
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Type: Kernel Image
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Compression: gzip compressed
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Data Start: 0x009000ec
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Data Size: 1092037 Bytes = 1 MB
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Architecture: PowerPC
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OS: Linux
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Load Address: 0x00000000
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Entry Point: 0x00000000
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Hash algo: crc32
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Hash value: 2c0cc807
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Hash algo: sha1
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Hash value: 264b59935470e42c418744f83935d44cdf59a3bb
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Verifying Hash Integrity ... crc32+ sha1+ OK
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Uncompressing Kernel Image ... OK
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## Flattened Device Tree from FIT Image at 00900000
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Using 'conf-1' configuration
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Trying 'fdt-1' FDT blob subimage
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Description: Flattened Device Tree blob
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Type: Flat Device Tree
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Compression: uncompressed
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Data Start: 0x00a0abdc
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Data Size: 16384 Bytes = 16 kB
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Architecture: PowerPC
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Hash algo: crc32
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Hash value: 0d655d71
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Hash algo: sha1
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Hash value: 25ab4e15cd4b8a5144610394560d9c318ce52def
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Verifying Hash Integrity ... crc32+ sha1+ OK
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Booting using the fdt blob at 0xa0abdc
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Loading Device Tree to 007fc000, end 007fffff ... OK
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[ 0.000000] Using lite5200 machine description
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[ 0.000000] Linux version 2.6.24-rc6-gaebecdfc (m8@hekate) (gcc version 4.0.0 (DENX ELDK 4.1 4.0.0)) #1 Sat Jan 12 15:38:48 CET 2008
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Example 3 -- advanced booting
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-----------------------------
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Refer to doc/uImage.FIT/multi.its for an image source file that allows more
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sophisticated booting scenarios (multiple kernels, ramdisks and fdt blobs).
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