xref: /freebsd/stand/i386/pxeldr/pxeboot.8 (revision 8a0a413e)
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25.\" $FreeBSD$
26.\"
27.Dd May 27, 2017
28.Dt PXEBOOT 8
29.Os
30.Sh NAME
31.Nm pxeboot
32.Nd Preboot Execution Environment (PXE) bootloader
33.Sh DESCRIPTION
34The
35.Nm
36bootloader is a modified version of the system third-stage bootstrap
37.Xr loader 8
38configured to run under Intel's Preboot Execution Environment (PXE) system.
39PXE is a form of smart boot ROM, built into Intel EtherExpress Pro/100 and
403Com 3c905c Ethernet cards, and Ethernet-equipped Intel motherboards.
41PXE supports DHCP configuration and provides low-level NIC access services.
42.Pp
43The DHCP client will set a DHCP user class named
44.Va FreeBSD
45to allow flexible configuration of the DHCP server.
46.Pp
47The
48.Nm
49bootloader retrieves the kernel, modules,
50and other files either via NFS over UDP or by TFTP,
51selectable through compile-time options.
52In combination with a memory file system image or NFS-mounted root file system,
53.Nm
54allows for easy,
55EEPROM-burner free construction of diskless machines.
56.Pp
57The
58.Nm
59binary is loaded just like any other boot file,
60by specifying it in the DHCP server's configuration file.
61Below is a sample configuration for the ISC DHCP v2 server:
62.Bd -literal -offset indent
63option domain-name "example.com";
64option routers 10.0.0.1;
65option subnet-mask 255.255.255.0;
66option broadcast-address 10.0.0.255;
67option domain-name-servers 10.0.0.1;
68server-name "DHCPserver";
69server-identifier 10.0.0.1;
70
71default-lease-time 120;
72max-lease-time 120;
73
74subnet 10.0.0.0 netmask 255.255.255.0 {
75       filename "pxeboot";
76       range 10.0.0.10 10.0.0.254;
77       if exists user-class and option user-class = "FreeBSD" {
78            option root-path "tftp://10.0.0.1/FreeBSD";
79       }
80}
81
82.Ed
83.Nm
84recognizes
85.Va next-server
86and
87.Va option root-path
88directives as the server and path to NFS mount for file requests,
89respectively, or the server to make TFTP requests to.
90Note that
91.Nm
92expects to fetch
93.Pa /boot/loader.rc
94from the specified server before loading any other files.
95.Pp
96Valid
97.Va option root-path
98Syntax is the following
99.Bl -tag -width <scheme>://ip/path indent
100.It /path
101path to the root filesystem on the NFS server
102.It ip:/path
103path to the root filesystem on the NFS server
104.Ar ip
105.It nfs:/path
106path to the root filesystem on the NFS server
107.It nfs://ip/path
108path to the root filesystem on the NFS server
109.Ar ip
110.It tftp:/path
111path to the root filesystem on the TFTP server
112.It tftp://ip/path
113path to the root filesystem on the TFTP server
114.Ar ip
115.El
116.Pp
117.Nm
118defaults to a conservative 1024 byte NFS data packet size.
119This may be changed by setting the
120.Va nfs.read_size
121variable in
122.Pa /boot/loader.conf .
123Valid values range from 1024 to 16384 bytes.
124.Pp
125In all other respects,
126.Nm
127acts just like
128.Xr loader 8 .
129.Pp
130As PXE is still in its infancy, some firmware versions may not work
131properly.
132The
133.Nm
134bootloader has been extensively tested on version 0.99 of Intel firmware;
135pre-release versions of the newer 2.0 firmware are known to have
136problems.
137Check with the device's manufacturer for their latest stable release.
138.Pp
139For further information on Intel's PXE specifications and Wired for
140Management (WfM) systems, see
141.Li http://www.intel.com/design/archives/wfm/ .
142.Sh SEE ALSO
143.Xr loader 8
144.Sh HISTORY
145The
146.Nm
147bootloader first appeared in
148.Fx 4.1 .
149.Sh AUTHORS
150.An -nosplit
151The
152.Nm
153bootloader was written by
154.An John Baldwin Aq jhb@FreeBSD.org
155and
156.An Paul Saab Aq ps@FreeBSD.org .
157This manual page was written by
158.An Doug White Aq dwhite@FreeBSD.org .
159