Debug
ARM DDI 0363G Copyright © 2006-2011 ARM Limited. All rights reserved. 12-29
ID073015 Non-Confidential
Table 12-20 shows the DBGWCR bit assignments.
Table 12-20 DBGWCR Register bit assignments
Bits Name Function
[31:29] - 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.
• If DBGWCR[28:24] is not set to b00000, then DBGWCR[12:5] must be set to
b11111111. Otherwise the behavior is Unpredictable.
• If DBGWCR[28:24] is not set to b00000, then the corresponding DBGDSWVR 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 DBGWCR[28:24] to b00111, and DBGWCR[12:5] to
b11111111. This is compatible with both ARMv7 debug compliant implementations that
have an 8-bit DBGWCR[12:5] and with those that have a 4-bit DBGWCR[8:5] byte
address select field.
[23:21] - 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] - Appear as zero when read. Do not modify on writes.
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