29 September 1997 – Subject To Change
Privileged Architecture Library Code
6–1
6
Privileged Architecture Library Code
This chapter describes the 21164PC privileged architecture library code (PALcode).
The chapter is organized as follows:
•
PALcode description
•
PALmode environment
•
Invoking PALcode
•
PALcode entry points
•
Required PALcode function codes
•
21164PC implementation of the architecturally reserved opcodes
6.1 PALcode Description
Privileged architecture library code (PALcode) is macrocode that provides an archi-
tecturally defined operating-system-specific programming interface that is common
across all Alpha microprocessors. The actual implementation of PALcode differs for
each operating system.
PALcode runs with privileges enabled, instruction stream mapping disabled, and
interrupts disabled. PALcode has privilege to use five special opcodes that allow
functions such as physical data stream references and internal processor register
(IPR) manipulation.
PALcode can be invoked by the following events:
•
Reset
•
System hardware exceptions (MCHK, ARITH)
•
Memory-management exceptions
•
Interrupts