DEC Digital Alpha VME 4/224 User Manual page 319

boot
Protocol Drivers
You normally use BOOTP and TFTP to bootstrap across a network. However,
you can invoke the protocols as protocol drivers. The BOOTP and TFTP protocols
must be followed by a network in the protocol tower.
When a BOOTP request is broadcast, the environment variable EWA0_BOOTP_
SERVER is copied into the sname field of the request packet and the variable
EWA0_BOOTP_FILE is copied into the file field of the request packet. The exact
interpretation of these fields depends on the BOOTP server. The sname field
must be the name of a specific host from which the local machine wants to boot.
If it does not matter which server answers, the variable EWA0_BOOTP_SERVER
must be left empty. The server must use the file field in the request to define
which boot file to specify in the response. For example, the client could supply
a generic name like UNIX or LAT, and the server would respond with the fully
qualified file path to be used with TFTP. If a machine always boots the same file,
EWA0_BOOTP_FILE can be left empty.
Use the TFTP protocol driver to read files across the network. TFTP accepts one
parameter, the host address concatenated to the file name of the remote file to be
read. Specify the host address in dotted decimal notation. Separate the address
from the file with a colon ( : ). A slash ( / ) in a file name must be doubled ( // ). The
following example displays the file /usr/foo/bar on a host with the address of
16.123.16.242:
>>> cat tftp:16.123.16.242://usr//foo//bar/ewa0
For convenience, you can save an address in an environment variable:
>>> set ktrose 16.123.16.242
>>> cat tftp:$ktrose://usr//foo//bar/ewa0
If you do not specify a parameter, TFTP uses the file name and server address
defined in EWA0_INETFILE and EWA0_SINETADDR.
When booting with TFTP, the boot command passes the contents of the
environment variable BOOT_FILE as the parameter for TFTP. If BOOT_FILE
does not have the correct format, TFTP fails. A common practice is to leave
BOOT_FILE undefined so that TFTP defaults to using EWA0_SINETADDR and
EWA0_INETFILE.
Syntax
boot [-file filename ] [-flags longword [, longword ]] [-protocols enet_protocol ] [-halt] [ boot_device ]
Console Commands 13–11