System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-265
ID021414
Non-Confidential
Table 4-238
shows the RMR bit assignments.
To access the RMR:
MRC p15,0,<Rt>,c12,c0,2 ; Read RMR into Rt
MCR p15,0,<Rt>,c12,c0,2 ; Write Rt to RMR
Register access is encoded as follows:
4.5.72
Interrupt Status Register
The ISR characteristics are:
Purpose
Shows whether an IRQ, FIQ, or external abort is pending. An indicated
pending abort might be a physical abort or a virtual abort.
Usage constraints
This register is accessible as follows:
Configurations
ISR is architecturally mapped to AArch64 register ISR_EL1. See
Interrupt Status Register
on page 4-123
.
There is one copy of this register that is used in both Secure and
Non-secure states.
Attributes
ISR is a 32-bit register.
Figure 4-137 on page 4-266
shows the ISR bit assignments.
Table 4-238 RMR bit assignments
Bits
Name
Function
[31:2]
-
Reserved,
RES
0.
[1]
RR
Reset Request. The possible values are:
0
This is the reset value.
1
Requests a warm reset. This bit is set to 0 by either a cold or warm reset.
The bit is strictly a request.
The RR bit drives the
WARMRSTREQ
output signal.
[0]
AA64
a
Determines which execution state the processor boots into after a warm reset. The possible values are:
0
AArch32 Execution state.
1
AArch64 Execution state.
The reset vector address on reset takes a choice between two values, depending on the value in the AA64 bit. This
ensures that even with reprogramming of the AA64 bit, it is not possible to change the reset vector to go to a
different location.
a. The cold reset value depends on the
AA64nAA32
signal.
Table 4-239 ISR access encoding
coproc
opc1
CRn
CRm
opc2
1111
000
1100
0000
010
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RO
RO
RO
RO
RO