Error Logs 4-53
4.5
Double Error Halts and Machine Checks While
in PAL Mode
Two error cases require special attention. Neither double error halts or
machine checks while the machine is in PAL mode result in error log entries.
Nevertheless, information is available that can help determine what error
occurred.
4.5.1
PALcode Overview
PALcode, privileged architecture library code, is used to implement a number of
functions at the machine level without the use of microcode. This allows operating
systems to make common calls to PALcode routines without knowing the hardware
specifics of each system the operating system is running on. PALcode routines
handle:
•
Instructions that require complex sequencing, such as atomic operations
•
Instructions that require VAX-style interlocked memory access
•
Privileged instructions
•
Memory management
•
Context swapping
•
Interrupt and exception dispatching
•
Power-up initialization and booting
•
Console functions
•
Emulation of instructions with no hardware support
