+SPDX-License-Identifier: GPL-2.0+
/*
* 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
+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
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.
+ store the kernel(or FIT image) 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
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
+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
specified in a different way
kernel <path> - if this label is chosen, use tftp to retrieve the kernel
- at <path>. it will be stored at the address indicated in
- the kernel_addr_r environment variable, and that address
- will be passed to bootm to boot this kernel.
+ (or FIT image) at <path>. it will be stored at the address
+ indicated in the kernel_addr_r environment variable, and
+ that address will be passed to bootm to boot this kernel.
+ For FIT image, The configuration specification can be
+ appended to the file name, with the format:
+ <path>#<conf>[#<extra-conf[#...]]
+ It will passed to bootm with that address.
+ (see: doc/uImage.FIT/command_syntax_extensions.txt)
+ It useful for overlay selection in pxe file
+ (see: doc/uImage.FIT/overlay-fdt-boot.txt)
append <string> - use <string> as the kernel command line when booting this
label.
the fdt_addr_r environment variable, and that address will
be passed to bootm.
+fdtdir <path> - if this label is chosen, use tftp to retrieve a fdt blob
+ relative to <path>. If the fdtfile environment variable
+ is set, <path>/<fdtfile> is retrieved. Otherwise, the
+ filename is generated from the soc and board environment
+ variables, i.e. <path>/<soc>-<board>.dtb is retrieved.
+ If the fdt command is specified, fdtdir is ignored.
+
localboot <flag> - Run the command defined by "localcmd" in the environment.
<flag> is ignored and is only here to match the syntax of
PXELINUX config files.
-------
Here's a couple of example files to show how this works.
-------------/tftpboot/pxelinux.cfg/menus/linux.list----------
+------------/tftpboot/pxelinux.cfg/menus/base.menu-----------
menu title Linux selections
# This is the default label
Differences with PXELINUX
=========================
-The biggest difference between U-boot's pxe and PXELINUX is that since
-U-boot's pxe support is written entirely in C, it can run on any platform
-with network support in U-boot. Here are some other differences between
-PXELINUX and U-boot's pxe support.
+The biggest difference between U-Boot's pxe and PXELINUX is that since
+U-Boot's pxe support is written entirely in C, it can run on any platform
+with network support in U-Boot. Here are some other differences between
+PXELINUX and U-Boot's pxe support.
-- U-boot's pxe does not support the PXELINUX DHCP option codes specified
+- U-Boot's pxe does not support the PXELINUX DHCP option codes specified
in RFC 5071, but could be extended to do so.
-- when U-boot's pxe fails to boot, it will return control to U-boot,
- allowing another command to run, other U-boot command, instead of resetting
+- when U-Boot's pxe fails to boot, it will return control to U-Boot,
+ allowing another command to run, other U-Boot command, instead of resetting
the machine like PXELINUX.
-- U-boot's pxe doesn't rely on or provide an UNDI/PXE stack in memory, it
- only uses U-boot.
+- U-Boot's pxe doesn't rely on or provide an UNDI/PXE stack in memory, it
+ only uses U-Boot.
-- U-boot's pxe doesn't provide the full menu implementation that PXELINUX
+- U-Boot's pxe doesn't provide the full menu implementation that PXELINUX
does, only a simple text based menu using the commands described in
this README. With PXELINUX, it's possible to have a graphical boot
- menu, submenus, passwords, etc. U-boot's pxe could be extended to support
+ menu, submenus, passwords, etc. U-Boot's pxe could be extended to support
a more robust menuing system like that of PXELINUX's.
-- U-boot's pxe expects U-boot uimg's as kernels. Anything that would work
- with the 'bootm' command in U-boot could work with the 'pxe boot' command.
+- U-Boot's pxe expects U-Boot uimg's as kernels. Anything that would work
+ with the 'bootm' command in U-Boot could work with the 'pxe boot' command.
-- U-boot's pxe only recognizes a single file on the initrd command line. It
+- U-Boot's pxe only recognizes a single file on the initrd command line. It
could be extended to support multiple.
-- in U-boot's pxe, the localboot command doesn't necessarily cause a local
+- in U-Boot's pxe, the localboot command doesn't necessarily cause a local
disk boot - it will do whatever is defined in the 'localcmd' env
variable. And since it doesn't support a full UNDI/PXE stack, the
type field is ignored.
-- the interactive prompt in U-boot's pxe only allows you to choose a label
+- the interactive prompt in U-Boot's pxe only allows you to choose a label
from the menu. If you want to boot something not listed, you can ctrl+c
- out of 'pxe boot' and use existing U-boot commands to accomplish it.
+ out of 'pxe boot' and use existing U-Boot commands to accomplish it.
projects / oweals / u-boot.git / blobdiff