Command Section
PXEBOOT(8)              FreeBSD System Manager's Manual             PXEBOOT(8)

     pxeboot - Preboot Execution Environment (PXE) bootloader

     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
     provides low-level NIC access services.  The pxeboot 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, pxeboot allows for
     easy, EEPROM-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
     configuration for the ISC DHCP v2 server:

           option domain-name "";
           option routers;
           option subnet-mask;
           option broadcast-address;
           option domain-name-servers;
           server-name "DHCPserver";

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

           subnet netmask {
                  filename "pxeboot";

     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/loader.rc from the specified server before loading any other files.

     pxeboot defaults to a conservative 1024 byte NFS data packet size.  This
     may be changed by setting the nfs.read_size variable in
     /boot/loader.conf.  Valid values range from 1024 to 4096 bytes.

     In all other respects, pxeboot acts just like loader(8).

     As PXE is still in its infancy, some firmware versions may not work
     properly.  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
     Management (WfM) systems, see


     The pxeboot bootloader first appeared in FreeBSD 4.1.

     The pxeboot bootloader was written by John Baldwin <[email protected]> and
     Paul Saab <[email protected]>.  This manual page was written by Doug White
     <[email protected]>.

FreeBSD 11.1-RELEASE-p4           May 1, 2000          FreeBSD 11.1-RELEASE-p4
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