PXEBOOT(8) BSD System Manager's Manual PXEBOOT(8)NAMEpxeboot — Preboot Execution Environment (PXE) bootloader
DESCRIPTION
The pxeboot bootloader is a modified version of the system third-stage
bootstrap loader(8) configured to run under Intel's Preboot Execution
Environment (PXE) system. PXE is a form of smart boot ROM, built into
Intel EtherExpress Pro/100 and 3Com 3c905c Ethernet cards, and Ethernet-
equipped Intel motherboards. PXE supports DHCP configuration and pro‐
vides low-level NIC access services. The pxeboot bootloader retrieves
the kernel, modules, and other files either via NFS over UDP. In combi‐
nation with a NFS-mounted root file system, pxeboot allows for easy, EEP‐
ROM-burner free construction of diskless machines.
The pxeboot binary is loaded just like any other boot file, by specifying
it in the DHCP server's configuration file. Below is a sample configura‐
tion for the ISC DHCP v2 server:
option domain-name "example.com";
option routers 10.0.0.1;
option subnet-mask 255.255.255.0;
option broadcast-address 10.0.0.255;
option domain-name-servers 10.0.0.1;
server-name "DHCPserver";
server-identifier 10.0.0.1;
default-lease-time 120;
max-lease-time 120;
subnet 10.0.0.0 netmask 255.255.255.0 {
filename "boot/pxeboot";
range 10.0.0.10 10.0.0.254;
option root-path "10.0.0.1:/netbootroot";
}
pxeboot recognizes next-server and option root-path directives as the
server and path to NFS mount for file requests, respectively, or the
server to make TFTP requests to. Note that pxeboot expects to fetch
/boot/dloader.rc from the specified server before loading any other
files.
pxeboot uses /boot/kernel.BOOTP and /boot/loader-bootp.conf and
nextboot-bootp.conf instead of /boot/kernel and /boot/loader.conf. Note
that the TFTP version pxeboot_tftp(8) uses the standard boot loader
files. The NFS version uses different files to allow BOOTP boots via NFS
to be overloaded onto the same directory structure as a normal boot,
though many other changes would have to be made to actually make that
work. However, this is more for historical reasons. Current day PXE
boot code can handle complex root-path specifications allowing the root
image to be contained in a sub-directory of the NFS export.
In all other respects, pxeboot acts just like loader(8).
As PXE is still in its infancy, some firmware versions may not work prop‐
erly. The pxeboot bootloader has been extensively tested on version 0.99
of Intel firmware; pre-release versions of the newer 2.0 firmware are
known to have problems. Check with the device's manufacturer for their
latest stable release.
For further information on Intel's PXE specifications and Wired for Man‐
agement (WfM) systems, see http://developer.intel.com/ial/wfm/.
FILES
/boot/kernel.BOOTP Default kernel for pxeboot.
/boot/defaults/loader-bootp.conf pxeboot configuration file -- do not
change this file.
/boot/loader-bootp.conf pxeboot configuration file.
SEE ALSOdhcpd(8) (pkgsrc/net/isc-dhcpd4), diskless(8), loader(8), nfsd(8),
pxeboot_tftp(8), tftpd(8)HISTORY
The pxeboot bootloader first appeared in FreeBSD 4.1.
AUTHORS
The pxeboot bootloader was written by John Baldwin ⟨jhb@FreeBSD.org⟩ and
Paul Saab ⟨ps@FreeBSD.org⟩. This manual page was written by Doug White
⟨dwhite@FreeBSD.org⟩.
BSD October 6, 2010 BSD
