.\" Copyright (c) 1999 Doug White
.\" All rights reserved.
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.\" $FreeBSD: src/sys/boot/i386/pxeldr/pxeboot.8,v 1.7 2002/12/12 17:25:59 ru Exp $
.\"
.Dd October 6, 2010
.Dt PXEBOOT 8
.Os
.Sh NAME
.Nm pxeboot
.Nd Preboot Execution Environment (PXE) bootloader
.Sh DESCRIPTION
The
.Nm
bootloader is a modified version of the system third-stage bootstrap
.Xr 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 provides low-level NIC access services.
The
.Nm
bootloader retrieves the kernel, modules,
and other files either via NFS over UDP.
In combination with a NFS-mounted root file system,
.Nm
allows for easy,
EEPROM-burner free construction of diskless machines.
.Pp
The
.Nm
binary is loaded just like any other boot file,
by specifying it in the DHCP server's configuration file.
Below is a sample configuration for the ISC DHCP v2 server:
.Bd -literal -offset indent
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";
}

.Ed
.Nm
recognizes
.Va next-server
and
.Va 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
.Nm
expects to fetch
.Pa /boot/dloader.rc
from the specified server before loading any other files.
.Pp
.Nm
uses
.Pa /boot/kernel.BOOTP
and
.Pa /boot/loader-bootp.conf
and
.Pa nextboot-bootp.conf
instead of
.Pa /boot/kernel
and
.Pa /boot/loader.conf .
Note that the TFTP version
.Xr 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.
.Pp
In all other respects,
.Nm
acts just like
.Xr loader 8 .
.Pp
As PXE is still in its infancy, some firmware versions may not work
properly.
The
.Nm
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.
.Pp
For further information on Intel's PXE specifications and Wired for
Management (WfM) systems, see
.Pa http://developer.intel.com/ial/wfm/ .
.Sh FILES
.Bl -tag -width ".Pa /boot/defaults/loader-bootp.conf" -compact
.It Pa /boot/kernel.BOOTP
Default kernel for
.Nm .
.It Pa /boot/defaults/loader-bootp.conf
.Nm
configuration file -- do not change this file.
.It Pa /boot/loader-bootp.conf
.Nm
configuration file.
.El
.Sh SEE ALSO
.Xr dhcpd 8 Pq Pa net/isc-dhcp42-server ,
.Xr diskless 8 ,
.Xr loader 8 ,
.Xr nfsd 8 ,
.Xr pxeboot_tftp 8 ,
.Xr tftpd 8
.Sh HISTORY
The
.Nm
bootloader first appeared in
.Fx 4.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
bootloader was written by
.An John Baldwin Aq Mt jhb@FreeBSD.org
and
.An Paul Saab Aq Mt ps@FreeBSD.org .
This manual page was written by
.An Doug White Aq Mt dwhite@FreeBSD.org .