/* * Copyright 2010-2011 Calxeda, Inc. * * SPDX-License-Identifier: GPL-2.0+ */ The 'pxe' commands provide a near subset of the functionality provided by the PXELINUX boot loader. This allows U-boot based systems to be controlled remotely using the same PXE based techniques that many non U-boot based servers use. Commands ======== pxe get ------- syntax: pxe get follows PXELINUX's rules for retrieving configuration files from a tftp server, and supports a subset of PXELINUX's config file syntax. Environment ----------- 'pxe get' requires two environment variables to be set: pxefile_addr_r - should be set to a location in RAM large enough to hold pxe files while they're being processed. Up to 16 config files may be held in memory at once. The exact number and size of the files varies with how the system is being used. A typical config file is a few hundred bytes long. bootfile,serverip - these two are typically set in the DHCP response handler, and correspond to fields in the DHCP response. 'pxe get' optionally supports these two environment variables being set: ethaddr - this is the standard MAC address for the ethernet adapter in use. 'pxe get' uses it to look for a configuration file specific to a system's MAC address. pxeuuid - this is a UUID in standard form using lower case hexadecimal digits, for example, 550e8400-e29b-41d4-a716-446655440000. 'pxe get' uses it to look for a configuration file based on the system's UUID. File Paths ---------- 'pxe get' repeatedly tries to download config files until it either successfully downloads one or runs out of paths to try. The order and contents of paths it tries mirrors exactly that of PXELINUX - you can read in more detail about it at: http://syslinux.zytor.com/wiki/index.php/Doc/pxelinux pxe boot -------- syntax: pxe boot [pxefile_addr_r] Interprets a pxe file stored in memory. pxefile_addr_r is an optional argument giving the location of the pxe file. The file must be terminated with a NUL byte. Environment ----------- There are some environment variables that may need to be set, depending on conditions. pxefile_addr_r - if the optional argument pxefile_addr_r is not supplied, an environment variable named pxefile_addr_r must be supplied. This is typically the same value as is used for the 'pxe get' command. bootfile - typically set in the DHCP response handler based on the same field in the DHCP respone, this path is used to generate the base directory that all other paths to files retrieved by 'pxe boot' will use. If no bootfile is specified, paths used in pxe files will be used as is. serverip - typically set in the DHCP response handler, this is the IP address of the tftp server from which other files will be retrieved. kernel_addr_r, initrd_addr_r - locations in RAM at which 'pxe boot' will store the kernel and initrd it retrieves from tftp. These locations will be passed to the bootm command to boot the kernel. These environment variables are required to be set. fdt_addr_r - location in RAM at which 'pxe boot' will store the fdt blob it retrieves from tftp. The retrieval is possible if 'fdt' label is defined in pxe file and 'fdt_addr_r' is set. If retrieval is possible, 'fdt_addr_r' will be passed to bootm command to boot the kernel. fdt_addr - the location of a fdt blob. 'fdt_addr' will be passed to bootm command if it is set and 'fdt_addr_r' is not passed to bootm command. pxe file format =============== The pxe file format is nearly a subset of the PXELINUX file format; see http://syslinux.zytor.com/wiki/index.php/PXELINUX. It's composed of one line commands - global commands, and commands specific to labels. Lines begining with # are treated as comments. White space between and at the beginning of lines is ignored. The size of pxe files and the number of labels is only limited by the amount of RAM available to U-boot. Memory for labels is dynamically allocated as they're parsed, and memory for pxe files is statically allocated, and its location is given by the pxefile_addr_r environment variable. The pxe code is not aware of the size of the pxefile memory and will outgrow it if pxe files are too large. Supported global commands ------------------------- Unrecognized commands are ignored. default