Warm Bootstrapping In A Uniprocessor Environment - DEC 4000 AXP Service Manual

7. If the bootstrap device list is empty, bootdef_dev or boot_dev are null, and
the action is implementation-specific. The console may remain in console I/O
mode or attempt to locate a bootstrap device in an implementation-specific
manner.
The boot_file and boot_osflags environment variables are used as default values
for the bootstrap filename and option flags. The console indicates the actual
bootstrap image filename (if any) and option flags for the current bootstrap
attempt in the booted_file and booted_osflags and environment variables. The
boot_file default bootstrap image filename is used whenever the bootstrap
requires a filename and either none was specified on the
bootstrap was initiated by the console as the result of a major state transition.
The console never interprets the bootstrap option flags, but simply passes them
between the console presentation layer and system software.

2.4.3 Warm Bootstrapping in a Uniprocessor Environment

The actions of the console on a warm bootstrap are a subset of those for a cold
bootstrap. A system bootstrap will be a warm bootstrap whenever the boot_
reset environment variable is set to ''Off'' (46 4E4F
permits.
The console program performs the following steps in the warm bootstrap
sequence.
1. Locates and validates the Hardware Reset Parameter Block (HWRPB)
2. Locates and loads the system software primary bootstrap image
3. Initializes processor state on all processors
4. Initializes bootstrap page tables and maps initial regions
5. Transfers control to the system software primary bootstrap image
At warm bootstrap, the console does not load PALcode, does not modify the
Memory Data Descriptor Table, and does not reinitialize any environment
variables. If the console cannot locate and validate the previously initialized
HWRPB, the console must initiate a cold bootstrap. Prior to beginning a
bootstrap, the console must clear any internally pended restarts to any processor.
2–36 Power-On Diagnostics and System LEDs
command or the
boot
) and console internal state
16