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Add documentation for the pxe bootmeth. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de> Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
27 lines
1.2 KiB
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27 lines
1.2 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+:
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PXE Bootmeth
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============
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PXE (Preboot eXecution-Environment) provides a way to boot an operating system
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over a network interface. The PXE bootmeth supports PXELINUX and allows U-Boot to
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provide a menu of possible Operating Systems from which the user can choose.
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U-Boot includes a parser for the `extlinux.conf` file described
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`here <https://uapi-group.org/specifications/specs/boot_loader_specification>`_.
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It consists primarily of a list of named operating systems along with the
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kernel, initial ramdisk and other settings. The file is retrieved from a network
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server using the TFTP protocol.
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When invoked on a bootdev, this bootmeth searches for the file and creates a
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bootflow if found. See
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`PXELINUX <https://wiki.syslinux.org/wiki/index.php?title=PXELINUX>`_ for
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a full description of the search procedure.
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When the bootflow is booted, the bootmeth calls ``pxe_setup_ctx()`` to set up
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the context, then ``pxe_process()`` to process the file. Depending on the
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contents, this may boot an Operating System or provide a list of options to the
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user, perhaps with a timeout.
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The compatible string "u-boot,extlinux-pxe" is used for the driver. It is
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present if `CONFIG_BOOTMETH_EXTLINUX_PXE` is enabled.
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