u-boot/doc/README.pxe

1 SPDX-License-Identifier: GPL-2.0+
3  * Copyright 2010-2011 Calxeda, Inc.
7 the PXELINUX boot loader. This allows U-Boot based systems to be controlled
8 remotely using the same PXE based techniques that many non U-Boot based servers
15 -------
22      -----------
25      pxefile_addr_r - should be set to a location in RAM large enough to hold
31      bootfile,serverip - these two are typically set in the DHCP response
36      ethaddr - this is the standard MAC address for the ethernet adapter in use.
40      pxeuuid - this is a UUID in standard form using lower case hexadecimal
41      digits, for example, 550e8400-e29b-41d4-a716-446655440000. 'pxe get' uses
45      ----------
48      contents of paths it tries mirrors exactly that of PXELINUX - you can
54 --------
63      -----------
67      pxefile_addr_r - if the optional argument pxefile_addr_r is not supplied,
71      bootfile - typically set in the DHCP response handler based on the
76      serverip - typically set in the DHCP response handler, this is the IP
79      kernel_addr_r, initrd_addr_r - locations in RAM at which 'pxe boot' will
84      fdt_addr_r - location in RAM at which 'pxe boot' will store the fdt blob it
89      fdt_addr - the location of a fdt blob. 'fdt_addr' will be passed to bootm
96 commands - global commands, and commands specific to labels. Lines begining
101 of RAM available to U-Boot. Memory for labels is dynamically allocated as
108 -------------------------
111 default <label>	    - the label named here is treated as the default and is
114 menu title <string> - sets a title for the menu of labels being displayed.
116 menu include <path> - use tftp to retrieve the pxe file at <path>, which
121 prompt <flag>	    - if 1, always prompt the user to enter a label to boot
124 timeout <num>	    - wait for user input for <num>/10 seconds before
125 		      auto-booting a node.
127 label <name>	    - begin a label definition. labels continue until
132 ------------------------
135 menu default	    - set this label as the default label to boot; this is
139 kernel <path>	    - if this label is chosen, use tftp to retrieve the kernel
145 		        <path>#<conf>[#<extra-conf[#...]]
149 		      (see: doc/uImage.FIT/overlay-fdt-boot.txt)
151 append <string>	    - use <string> as the kernel command line when booting this
154 initrd <path>	    - if this label is chosen, use tftp to retrieve the initrd
159 fdt <path>	    - if this label is chosen, use tftp to retrieve the fdt blob
164 fdtdir <path>	    - if this label is chosen, use tftp to retrieve a fdt blob
168 		      variables, i.e. <path>/<soc>-<board>.dtb is retrieved.
171 localboot <flag>    - Run the command defined by "localcmd" in the environment.
176 -------
179 ------------/tftpboot/pxelinux.cfg/menus/base.menu-----------
190 label linux-2.6.38
191 	kernel kernels/linux-2.6.38.bin
199 -------------------------------------------------------------
201 ------------/tftpboot/pxelinux.cfg/default-------------------
205 default linux-2.6.38
206 -------------------------------------------------------------
210 the linux-2.6.38 label, which will cause /tftpboot/kernels/linux-2.6.38.bin
215 The biggest difference between U-Boot's pxe and PXELINUX is that since
216 U-Boot's pxe support is written entirely in C, it can run on any platform
217 with network support in U-Boot. Here are some other differences between
218 PXELINUX and U-Boot's pxe support.
220 - U-Boot's pxe does not support the PXELINUX DHCP option codes specified
223 - when U-Boot's pxe fails to boot, it will return control to U-Boot,
224   allowing another command to run, other U-Boot command, instead of resetting
227 - U-Boot's pxe doesn't rely on or provide an UNDI/PXE stack in memory, it
228   only uses U-Boot.
230 - U-Boot's pxe doesn't provide the full menu implementation that PXELINUX
233   menu, submenus, passwords, etc. U-Boot's pxe could be extended to support
236 - U-Boot's pxe expects U-Boot uimg's as kernels.  Anything that would work
237   with the 'bootm' command in U-Boot could work with the 'pxe boot' command.
239 - U-Boot's pxe only recognizes a single file on the initrd command line.  It
242 - in U-Boot's pxe, the localboot command doesn't necessarily cause a local
243   disk boot - it will do whatever is defined in the 'localcmd' env
247 - the interactive prompt in U-Boot's pxe only allows you to choose a label
249   out of 'pxe boot' and use existing U-Boot commands to accomplish it.