Palcode Exception Entry Points; Palcode Exception Entry Locations - Compaq 21264 Hardware Reference Manual

Each CALL_PAL instruction includes a function field that is used to calculate the PC of
its associated PALcode entry point. The PALcode OPCDEC exception flow will be
invoked if the CALL_PAL function field satisfies any of the following requirements:
•
Is in the range of 40
•
Is greater than BF
•
Is between 00
mode value 0
If none of the conditions above are met, the PALcode entry point PC is as follows:
•
PC[63:15] = PAL_BASE[63:15]
•
PC[14] = 0
•
PC[13] = 1
•
PC[12] = CALL_PAL function field [7]
•
PC[11:6] = CALL_PAL function field [5:0]
•
PC[5:1] = 0
•
PC[0] = 1 (PALmode)

6.8.2 PALcode Exception Entry Points

When hardware encounters an exception, Ibox execution jumps to a PALcode entry
point at a PC determined by the type of exception. The return PC of the instruction that
triggered the exception is placed in the EXC_ADDR register and onto the return predic-
tion stack.
Table 6–8 shows the PALcode exception entry locations and their offset from the
PAL_BASE IPR.
Table 6–8 PALcode Exception Entry Locations
Entry Name Type
DTBM_DOUBLE_3 Fault
DTBM_DOUBLE_4 Fault
FEN Fault
UNALIGN Fault
DTBM_SINGLE Fault
DFAULT Fault
OPCDEC Fault
IACV Fault
Alpha 21264/EV67 Hardware Reference Manual
to 7F inclusive
16 16
16
and 3F inclusive, and IER_CM[CM] is not equal to the kernel
16 16
Offset Description
16
100 Dstream TB miss on virtual page table entry fetch. Use three-
level flow.
180 Dstream TB miss on virtual page table entry fetch. Use four-
level flow.
200 Floating point disabled.
280 Unaligned Dstream reference.
300 Dstream TB miss.
380 Dstream fault or virtual address sign check error.
400 Illegal opcode or function field:
• Opcode 1, 2, 3, 4, 5, 6 or 7
• Opcode 19
not I_CTL[HWE]
• Extended precision IEEE format
• Unimplemented function field of opcodes 14
480 Istream access violation or virtual address sign check error.
PALcode Entry Points
, 1B , 1D , 1E or 1F
16 16 16 16 16
Privileged Architecture Library Code
, not PALmode or
or 1C
16 16
6–13