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ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 11-27
ID013010 Non-Confidential, Unrestricted Access
Figure 11-11 Watchpoint Control Registers format
Table 11-20 shows how the bit values correspond with the Watchpoint Control Registers
functions.
Reserved
Linked BRP Byte address select L/S P W
Reserved
Watchpoint
address mask
31
21
20 19 16 15 5 3 2 1
E
L/S
S
24
40
14 13
29 28
23
Secure state access control
12
Reserved
Table 11-20 Watchpoint Control Registers functions
Bits Field Function
[31:29] Reserved Do not modify on writes. On reads, the value returns zero.
[28:24] Watchpoint
address
mask
This field watches a range of addresses by masking lower order address bits out of the
watchpoint comparison.
b00000 = no mask
b00001 = Reserved
b00010 = Reserved
b00011 =
0x00000007
mask for data address
b00100 =
0x0000000F
mask for data address
b00101 =
0x0000001F
mask for data address
...
b11111 =
0x7FFFFFFF
mask for data address.
Note
• If WCR[28:24] is not set to b00000, then WCR[12:5] must be set to b11111111.
Otherwise the behavior is Unpredictable.
• If WCR[28:24] is not set to b00000, then the corresponding WVR bits that are not being
included in the comparison Should Be Zero. Otherwise the behavior is Unpredictable.
• To watch for a write to any byte in an 8-byte aligned object of size 8 bytes, ARM
recommends that a debugger sets WCR[28:24] to b00111, and WCR[12:5] to b11111111.
This is compatible with both ARMv7 debug compliant implementations that have an
8-bit WCR[12:5] and with those that have a 4-bit WCR[8:5] byte address select field.
[23:21] Reserved Do not modify on writes. On reads, the value returns zero.
[20] E Enable linking bit:
0 = linking disabled
1 = linking enabled.
When this bit is set, this watchpoint is linked with the context ID holding BRP selected by the
linked BRP field.
[19:16] Linked
BRP
Linked BRP number. The binary number encoded here indicates a context ID holding BRP to
link this WRP with. If this WRP is linked to a BRP that is not configured for linked context ID
matching, it is Unpredictable whether a watchpoint debug event is generated.
[15:14] Secure state
access
control
RAZ or SBZP.
[13] Reserved Appear as zero when read. Do not modify on writes.