User`s guide

System Initialization and Acceptance Testing (Normal Operation)
4.7 Operating System Bootstrap
Note that it is not necessary that the boot image actually resides 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 the KA52/53/54, 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 KA52/53/54 supports 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$V_DIAG bit or the RPB$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 15-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 KA52/53/54 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 4–3 and Table 4–4.
4–28 System Initialization and Acceptance Testing (Normal Operation)