.\" Copyright (c) 1999 Doug White
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.\" $FreeBSD$
.\"
.Dd November 25, 2018
.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.
.Pp
The DHCP client will set a DHCP user class named
.Va FreeBSD
to allow flexible configuration of the DHCP server.
.Pp
The
.Nm
bootloader retrieves the kernel, modules,
and other files either via NFS over UDP or by TFTP,
selectable through compile-time options.
In combination with a memory file system image or 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 v3 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;
next-server 10.0.0.1;

default-lease-time 120;
max-lease-time 120;

subnet 10.0.0.0 netmask 255.255.255.0 {
       filename "pxeboot";
       range 10.0.0.10 10.0.0.254;
       if exists user-class and option user-class = "FreeBSD" {
            option root-path "tftp://10.0.0.1/FreeBSD";
       }
}

.Ed
.Va next-server
is the IP address of the next server in the bootstrap process, i.e.
your TFTP server or NFS server.
.Nm
recognizes
.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/loader.rc
from the specified server before loading any other files.
.Pp
Valid
.Va option root-path
Syntax is the following
.Bl -tag -width <scheme>://ip/path indent
.It /path
path to the root filesystem on the NFS server
.It ip:/path
path to the root filesystem on the NFS server
.Ar ip
.It nfs:/path
path to the root filesystem on the NFS server
.It nfs://ip/path
path to the root filesystem on the NFS server
.Ar ip
.It tftp:/path
path to the root filesystem on the TFTP server
.It tftp://ip/path
path to the root filesystem on the TFTP server
.Ar ip
.El
.Pp
.Nm
defaults to a conservative 1024 byte NFS data packet size.
This may be changed by setting the
.Va nfs.read_size
variable in
.Pa /boot/loader.conf .
Valid values range from 1024 to 16384 bytes.
.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
.Li http://www.intel.com/design/archives/wfm/ .
.Sh SEE ALSO
.Xr loader 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 jhb@FreeBSD.org
and
.An Paul Saab Aq ps@FreeBSD.org .
This manual page was written by
.An Doug White Aq dwhite@FreeBSD.org .