Debug
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
11-12
ID021414
Non-Confidential
[20]
WT
Watchpoint Type. This bit is set to 1 to link the watchpoint to a breakpoint to create a linked watchpoint that
requires both data address matching and Context matching:
0
Unlinked data address match.
1
Linked data address match.
When this bit is set to 1 the linked BRP number field indicates the BRP that this WRP is linked. See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture profile
for more information.
[19:16]
LBN
Linked Breakpoint Number. If this watchpoint is programmed with the watchpoint type set to linked, then this
field must be programmed with the number of the breakpoint that defines the Context match to be combined with
data address comparison. Otherwise, this field must be programmed to
b0000
.
Reading this register returns an
UNKNOWN
value for this field, and the generation of Watchpoint debug events is
UNPREDICTABLE
, if either:
•
This watchpoint does not have linking enabled and this field is not programmed to
0x0
.
•
This watchpoint has linking enabled and the breakpoint indicated by this field does not support Context
matching, is not programmed for Context matching, or does not exist.
See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture profile
for more information.
[15:14]
SSC
Security State Control. This field enables the watchpoint to be conditional on the security state of the processor.
This field is used with the
Hyp Mode Control
(HMC) and
Privileged Access Control
(PAC) fields.
See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture profile
for possible values of
the fields, and the access modes and security states that can be tested.
[13]
HMC
Hyp Mode Control. This field is used with the
Security State Control
(SSC) and PAC fields. The value of
DBGWCR.PAC has no effect for accesses made in Hyp mode.
See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture profile
for possible values of
the fields, and the access modes and security states that can be tested.
[12:5]
BAS
Byte Address Select. The processor implements an 8-bit Byte address select field, DBGWCR[12:5].
A DBGWVR is programmed with a word-aligned address. This field enables the watchpoint to hit only if certain
bytes of the addressed word are accessed. The watchpoint hits if an access hits any byte being watched, even if:
•
The access size is larger than the size of the region being watched.
•
The access is unaligned, and the base address of the access is not in the same word of memory as the
address in the DBGWVR.
•
The access size is smaller than the size of region being watched.
See the
ARM
®
Architecture Reference Manual ARMv8, for ARMv8-A architecture profile
for more information.
Table 11-5 DBGWCR
n
_EL1 bit assignments (continued)
Bits
Name
Function