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

device and optional filename information specified either on the command line or
in appropriate environment variables.
There are only three conditions under which the boot processor attempts to
bootstrap the operating system:
1. The boot command is typed on the console terminal.
2. The system is reset or powered up and AUTO_ACTION is set to boot (and the
halt switch is not set to halt).
3. An operating system restart is attempted and fails.
The firmware's function in a bootstrap is to load a program into memory and
begin its execution. This program may be a primary bootstrap program, such as
Alpha Primary Boot (APB), Ultrixboot, or any other applicable program specified
by the user or residing in the boot block, MOP server, or TCP/IP server.

2.4.1 Cold Bootstrapping in a Uniprocessor Environment

This section describes a cold bootstrap in a uniprocessor environment. A system
bootstrap will be a cold bootstrap when any of the follow occur:
• Power is first applied to the system
• A console
initialize
variable is set to ''Boot.''
• The boot_reset environment variable is set to ''On.''
• A cold bootstrap is requested by system software.
The console must perform the following steps in the cold bootstrap sequence:
1. Perform a system initialization
2. Size memory
3. Test sufficient memory for bootstrapping
4. Load PALcode
5. Build a valid Hardware Restart Parameter Block (HWRPB)
6. Build a valid Memory Data Descriptor Table in the HWRPB
7. Initialize bootstrap page tables and map initial regions
8. Locate and load the system software primary bootstrap image
9. Initialize processor state on all processors
10. Transfer control to the system software primary bootstrap image
2–34 Power-On Diagnostics and System LEDs
command is issued and the auto_action environment