Add documentation for the extlinux bootmeth.
Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Quentin Schulz quentin.schulz@cherry.de Reviewed-by: Mattijs Korpershoek mkorpershoek@baylibre.com ---
Changes in v3: - Use quoting on list and function names
Changes in v2: - Adjustments from Heinrich's comments
doc/develop/bootstd/extlinux.rst | 28 ++++++++++++++++++++++++++++ doc/develop/bootstd/index.rst | 1 + doc/develop/bootstd/overview.rst | 4 ++-- 3 files changed, 31 insertions(+), 2 deletions(-) create mode 100644 doc/develop/bootstd/extlinux.rst
diff --git a/doc/develop/bootstd/extlinux.rst b/doc/develop/bootstd/extlinux.rst new file mode 100644 index 00000000000..46e9ad9eea1 --- /dev/null +++ b/doc/develop/bootstd/extlinux.rst @@ -0,0 +1,28 @@ +.. SPDX-License-Identifier: GPL-2.0+: + +Extlinux Bootmeth +================= + +`Extlinux https://uapi-group.org/specifications/specs/boot_loader_specification`_ +(sometimes called syslinux) allows U-Boot to provide a menu of available +operating systems from which the user can choose. + +U-Boot includes a parser for the `extlinux.conf` file. It consists primarily of +a list of named operating systems along with the kernel, initial ramdisk and +other settings. The file is stored in the `extlinux/` subdirectory, possibly +under the `boot/` subdirectory. This list of prefixes (``{"/", "/boot"}`` by +default) can be selected with the `filename-prefixes` property in the bootstd +device. + +Note that the PXE bootmeth uses the same file format, but in a network context. + +When invoked on a bootdev, this bootmeth searches for the file and creates a +bootflow if found. + +When the bootflow is booted, the bootmeth calls ``pxe_setup_ctx()`` to set up +the context, then ``pxe_process()`` to process the file. Depending on the +contents, this may boot an operating system or provide a list of options to +the user, perhaps with a timeout. + +The compatible string "u-boot,extlinux" is used for the driver. It is present +if `CONFIG_BOOTMETH_EXTLINUX` is enabled. diff --git a/doc/develop/bootstd/index.rst b/doc/develop/bootstd/index.rst index f4f87c7787c..5bbb3d633a3 100644 --- a/doc/develop/bootstd/index.rst +++ b/doc/develop/bootstd/index.rst @@ -7,3 +7,4 @@ Standard Boot :maxdepth: 2
overview + extlinux diff --git a/doc/develop/bootstd/overview.rst b/doc/develop/bootstd/overview.rst index d5051e986bb..7af159b9ca8 100644 --- a/doc/develop/bootstd/overview.rst +++ b/doc/develop/bootstd/overview.rst @@ -410,9 +410,9 @@ a good selection of boot options is available. Available bootmeth drivers --------------------------
-Bootmeth drivers are provided for: +Bootmeth drivers are provided for booting from various media:
- - extlinux / syslinux boot from a disk + - :doc:`extlinux / syslinux <extlinux>` boot from a storage device - extlinux boot from a network (PXE) - U-Boot scripts from disk, network or SPI flash - EFI boot using bootefi from disk