| .. 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 operating systems along with the |
| kernel, initial ramdisk and other settings. The file is retrieved from a network |
| server using the TFTP protocol. |
| |
| 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 Operating System 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. It is |
| present if `CONFIG_BOOTMETH_EXTLINUX_PXE` is enabled. |