[PATCH 04/13] doc: Add a description for bootmeth_pxe

[Simon Glass]

Add documentation for the pxe bootmeth.

Signed-off-by: Simon Glass <sjg at 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
+over a network interface. The PXE bootmeth supports PXELINUX and allows U-Boot to
+provide a menu of possible Operating Systems from which the user can choose.
+
+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.
+
+When invoked on a bootdev, this bootmeth searches for the file and creates a
+bootflow if found. See
+`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.
-- 
2.34.1