On 7/15/24 12:13, Simon Glass wrote:
Add documentation for the pxe bootmeth.Signed-off-by: Simon Glass <s...@chromium.org> --- doc/develop/bootstd/index.rst | 1 + doc/develop/bootstd/overview.rst | 2 +- doc/develop/bootstd/pxelinux.rst | 27 +++++++++++++++++++++++++++ 3 files changed, 29 insertions(+), 1 deletion(-) create mode 100644 doc/develop/bootstd/pxelinux.rst diff --git a/doc/develop/bootstd/index.rst b/doc/develop/bootstd/index.rst index 5bbb3d633a3..5052afe448f 100644 --- a/doc/develop/bootstd/index.rst +++ b/doc/develop/bootstd/index.rst @@ -8,3 +8,4 @@ Standard Boot overview extlinux + pxelinux diff --git a/doc/develop/bootstd/overview.rst b/doc/develop/bootstd/overview.rst index 086a0b1281d..fd0692daf0d 100644 --- a/doc/develop/bootstd/overview.rst +++ b/doc/develop/bootstd/overview.rst @@ -413,7 +413,7 @@ Available bootmeth drivers Bootmeth drivers are provided for: - :doc:`extlinux / syslinux <extlinux>` boot from a disk - - extlinux boot from a network (PXE) + - :doc:`extlinux / syslinux <extlinux>` boot from a network (PXE) - U-Boot scripts from disk, network or SPI flash - EFI boot using bootefi from disk - VBE diff --git a/doc/develop/bootstd/pxelinux.rst b/doc/develop/bootstd/pxelinux.rst new file mode 100644 index 00000000000..08ba67e09c5 --- /dev/null +++ b/doc/develop/bootstd/pxelinux.rst @@ -0,0 +1,27 @@ +.. SPDX-License-Identifier: GPL-2.0+: + +PXE Bootmeth +============ + +PXE (Preboot eXecution-Environment) provides a way to boot an Operating System
%s/Operating System/operating system/
+over a network interface. The PXE bootmeth supports PXELINUX and allows U-Boot to
%s/bootmeth/boot method/
+provide a menu of possible Operating Systems from which the user can choose.
PXELINUX is a binary. Does U-Boot really provide a menu when the PXELINUX binary is downloaded and executed?
+ +U-Boot includes a parser for the `extlinux.conf` file described +`here <https://uapi-group.org/specifications/specs/boot_loader_specification>`_. +It consists primarily of a list of named OSes along with the kernel, initial +ramdisk and other settings. The file is retrieved from a network server using +tftpboot.
Does this paragraph relate to PXELINUX? tftpboot is a command and not a protocol. Shouldn't boot methods work when the command line interface is disabled? I guess you want to replace %s/tftpboot/the TFTP protocol/
+ +When invoked on a bootdev, this bootmeth searches for the file and creates a
%s/bootdev/boot device/ %s/bootmeth/boot method/
+bootflow if found. See
%s/bootflow/boot flow/
+`PXELINUX <https://wiki.syslinux.org/wiki/index.php?title=PXELINUX>`_ for +a full description of the search procedure. + +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 OS or provide a list of options to the user, perhaps with a timeout. + +The compatible string "u-boot,extlinux-pxe" is used for the driver. The driver +is automatically instantiated if there are no bootmeth drivers in the +devicetree.
Device-trees contain compatible strings for drivers, not the drivers themselves. If every configured boot method is enabled if there is no compatible string for boot methods in the device-tree, why don't we mention this in the overview instead of repeating ourselves? Please, mention the relevant configuration option. Best regards Heinrich
