System Initialization and Acceptance Testing (Normal Operation)
4.7 Operating System Bootstrap
Note that it is not necessary that the boot image actually reside in PROM. Any
boot image in Q22–bus memory space with a valid signature block on a 16 KB
boundary is a candidate. Indeed, auxiliary bootstrap assumes that the image
is in shared memory.
The PROM image is copied into main memory in 127 page "chunks" until the
entire PROM is moved. All destination pages beyond the primary 128 KB
block are verified to make sure they are marked good in the PFN bitmap. The
PROM must be copied contiguously and if all required pages cannot fit into the
memory immediately following the VMB image, the boot fails.
4.7.3.3 MOP Ethernet Functions and Network Bootstrap Procedure
Whenever a network bootstrap is selected on KA681/KA691/KA692/KA694, the
VMB code makes continuous attempts to boot from the network. VMB uses
the DNA Maintenance Operations Protocol (MOP) as the transport protocol
for network bootstraps and other network operations. Once a network boot
has been invoked, VMB turns on the designated network link and repeats load
attempt, until either a successful boot occurs, a fatal controller error occurs, or
VMB is halted from the operator console.
The KA681/KA691/KA692/KA694 support the load of a standard operating
system, a diagnostic image, or a user-designated program via network
bootstraps. The default image is the standard operating system, however,
a user may select an alternate image by setting either the RPB$V_DIAG bit
or in the RPB$V_SOLICT bit in the boot flag longword R5. Note that the
RPB$V_SOLICT bit has precedence over the RPB$V_DIAG bit. Hence, if both
bits are set, then the solicited file is requested.
Note
VMB accepts a maximum 39 characters for a file specification for
solicited boots. However, MOP V3 only supports a 16-character file
name. If the network server is running the OpenVMS operating
system, the following defaults apply to the file specification: the
directory MOM$LOAD:, and the extension .SYS. Therefore, the file
specification need only consist of the filename if the default directory
and extension attributes are used.
The KA681/KA691/KA692/KA694 VMB uses the MOP program load sequence
for bootstrapping the module and the MOP "dump/load" protocol type for load
related message exchanges. The types of MOP message used in the exchange
are listed in Table 4–5 and Table 4–6.
4–32 System Initialization and Acceptance Testing (Normal Operation)