PXELINUX - SYSLINUX for network boot
7 September 2006PXELINUX - SYSLINUX for network boot Page
{ How do I Configure PXELINUX? }
PXELINUX operates in many ways like SYSLINUX. If you are not familiar with SYSLINUX, read the SYSLINUX FAQ first, since this documentation only explains the differences.
On the TFTP server, create the directory “/tftpboot”, and copy pxelinux.0 from the SYSLINUX distribution and any kernel or initrd images that you want to boot.
Finally, create the directory “/tftpboot/pxelinux.cfg”. The configuration file equivalent of syslinux.cfg — see the SYSLINUX FAQ for the options here will live in this directory. Because more than one system may be booted from the same server, the configuration file name depends on the IP address of the booting machine. PXELINUX will search for its config file on the boot server in the following way:
First, it will search for the config file using the hardware type using its ARP type code and address, all in lower case hexadecimal with dash separators; for example, for an Ethernet ARP type 1 with address 88:99:AA:BB:CC:DD it would search for the filename 01-88-99-aa-bb-cc-dd.
Next, it will search for the config file using its own IP address in upper case hexadecimal, e.g. 192.0.2.91 -> C000025B you can use the included progam gethostip to compute the hexadecimal IP address for any host.
If that file is not found, it will remove one hex digit and try again. Ultimately, it will try looking for a file named default in lower case. As an example, if the boot file name is /mybootdir/pxelinux.0, the Ethernet MAC address is 88:99:AA:BB:CC:DD and the IP address 192.0.2.91, it will try:
/mybootdir/pxelinux.cfg/01-88-99-aa-bb-cc-dd
/mybootdir/pxelinux.cfg/C000025B
/mybootdir/pxelinux.cfg/C000025
/mybootdir/pxelinux.cfg/C00002
/mybootdir/pxelinux.cfg/C0000
/mybootdir/pxelinux.cfg/C000
/mybootdir/pxelinux.cfg/C00
/mybootdir/pxelinux.cfg/C0
/mybootdir/pxelinux.cfg/C
/mybootdir/pxelinux.cfg/default
… in that order.
Note that all filename references are relative to the directory pxelinux.0 lives in. PXELINUX generally requires that filenames including any relative path are 127 characters or shorter in length.
PXELINUX does not support MTFTP, and I have no immediate plans of doing so. It is of course possible to use MTFTP for the initial boot, if you have such a setup. MTFTP server setup is beyond the scope of this document.
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