Privileged Instructions - ARM ARM926EJ-S Technical Reference Manual

8.5

Privileged instructions

Coprocessor pipeline
CLK
CPINSTR[31:0]
nCPMREQ
nCPTRANS
CPPASS
CPLATECANCEL
CHSDE[1:0]
CHSEX[1:0]
ARM DDI0198D
The coprocessor might restrict certain instructions for use in privileged modes only. To
do this, the coprocessor has to track the nCPTRANS output.
Figure 8-7 shows how nCPTRANS changes after a mode change.
Fetch Decode
CPRT
Old mode
Ignored
Copyright © 2001-2003 ARM Limited. All rights reserved.
Decode Decode Execute
New mode
Ignored LAST
Coprocessor Interface
Instruction
Memory
aborted
Ignored
Figure 8-7 Privileged instructions
8-9