diff options
| author | Simon Glass <sjg@chromium.org> | 2024-03-29 16:28:36 +1300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2024-04-12 15:48:32 +0100 |
| commit | 7a23b027ec17b2eb9c8ad9b09006502f3fa38215 (patch) | |
| tree | 2c89a64c6a0e0af436462b38a2718e558004defe /Documentation/process | |
| parent | 0dc1670bd0cef948ce782d6b3902af9bf8604beb (diff) | |
arm64: boot: Support Flat Image Tree
Add a script which produces a Flat Image Tree (FIT), a single file
containing the built kernel and associated devicetree files.
Compression defaults to gzip which gives a good balance of size and
performance.
The files compress from about 86MB to 24MB using this approach.
The FIT can be used by bootloaders which support it, such as U-Boot
and Linuxboot. It permits automatic selection of the correct
devicetree, matching the compatible string of the running board with
the closest compatible string in the FIT. There is no need for
filenames or other workarounds.
Add a 'make image.fit' build target for arm64, as well.
The FIT can be examined using 'dumpimage -l'.
This uses the 'dtbs-list' file but processes only .dtb files, ignoring
the overlay .dtbo files.
This features requires pylibfdt (use 'pip install libfdt'). It also
requires compression utilities for the algorithm being used. Supported
compression options are the same as the Image.xxx files. Use
FIT_COMPRESSION to select an algorithm other than gzip.
While FIT supports a ramdisk / initrd, no attempt is made to support
this here, since it must be built separately from the Linux build.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240329032836.141899-3-sjg@chromium.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Documentation/process')
| -rw-r--r-- | Documentation/process/changes.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst index 7ef8de58f7f8..3a39395bd9d3 100644 --- a/Documentation/process/changes.rst +++ b/Documentation/process/changes.rst @@ -62,6 +62,7 @@ Sphinx\ [#f1]_ 2.4.4 sphinx-build --version cpio any cpio --version GNU tar 1.28 tar --version gtags (optional) 6.6.5 gtags --version +mkimage (optional) 2017.01 mkimage --version ====================== =============== ======================================== .. [#f1] Sphinx is needed only to build the Kernel documentation @@ -189,6 +190,14 @@ The kernel build requires GNU GLOBAL version 6.6.5 or later to generate tag files through ``make gtags``. This is due to its use of the gtags ``-C (--directory)`` flag. +mkimage +------- + +This tool is used when building a Flat Image Tree (FIT), commonly used on ARM +platforms. The tool is available via the ``u-boot-tools`` package or can be +built from the U-Boot source code. See the instructions at +https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux + System utilities **************** |