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30 .Nd Preboot Execution Environment (PXE) bootloader
34 bootloader is a modified version of the system third-stage bootstrap
36 configured to run under Intel's Preboot Execution Environment (PXE) system.
37 PXE is a form of smart boot ROM, built into Ethernet cards, and
38 Ethernet-equipped motherboards.
39 PXE supports DHCP configuration and provides low-level NIC access services.
42 bootloader retrieves the kernel, modules,
43 and other files either via NFS over UDP or by TFTP,
44 selectable through DHCP options.
48 binary is loaded just like any other boot file,
49 by specifying it in the DHCP server's configuration file.
50 Below is a sample configuration for the ISC DHCP v2 server:
51 .Bd -literal -offset indent
52 option domain-name "example.com";
53 option routers 10.0.0.1;
54 option subnet-mask 255.255.255.0;
55 option broadcast-address 10.0.0.255;
56 option domain-name-servers 10.0.0.1;
57 server-name "DHCPserver";
58 server-identifier 10.0.0.1;
60 default-lease-time 120;
63 subnet 10.0.0.0 netmask 255.255.255.0 {
65 range 10.0.0.10 10.0.0.254;
75 directives as the server and path to NFS mount for file requests,
76 respectively, or the server to make TFTP requests to.
81 from the specified server before loading any other files.
84 defaults to a conservative 1024 byte NFS data packet size.
85 This may be changed by setting the
88 .Pa /boot/loader.conf .
89 Valid values range from 1024 to 16384 bytes.
92 chooses NFS or TFTP based on the value of
94 variable provided by the DHCP server.
96 defaults to use NFS if the
99 .Qq Pa ip-address Ns :/ Ns Pa path
100 form, otherwise TFTP is used.
102 TFTP block size can be controlled by setting the
105 .Pa /boot/loader.conf .
106 Valid values range from 8 to 9008 bytes.
108 In all other respects,
113 For further information on Intel's PXE specifications and Wired for
114 Management (WfM) systems, see
115 .Li http://www.intel.com/design/archives/wfm/ .