ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Debug Registers Reference
The generation of Breakpoint debug events is UNPREDICTABLE if:
BRPn is linked to BRPm but is not configured for Linked IVA match or Linked IVA mismatch
WRPn is linked to BRPm but is not configured to enable linking
WRPn or BRPn is linked to BRPm and either:
— BRPm does not support Linked Context ID matching
— BRPm is not configured for Linked Context ID matching.
C10.5.3 Watchpoint Value Registers (DBGWVR)
A Watchpoint Value Register, DBGWVR, holds a Data Virtual Address (DVA) value for use in watchpoint
matching. Each DBGWVR is associated with a DBGWCR to form a Watchpoint Register Pair (WRP).
DBGWVRn is associated with DBGWCRn to form WRPn, where n takes the values from 0 to 15. A debug
event is generated when the WRP is matched. For more information, see Watchpoint debug events on
page C3-15.
A watchpoint can be set on either:
a DVA match
a DVA match occurring with a Context ID match.
For the second case:
a WRP and a BRP with Context ID comparison capability have to be linked, see Watchpoint Control
Registers (DBGWCR) on page C10-61 and Linked comparisons on page C10-59.
a debug event is generated when, on the same instruction, both:
— the DVA matches
— the Context ID matches.
See Memory addresses on page C3-23 for a definition of the DVA used to program a DBGWVR.
The DBGWVRs are:
debug registers 96-111, at offsets 0x180-0x1BC
read/write registers
when the Security Extensions are implemented, Common registers.
The format of a DBGWVR is:
31 2 1 0
Watchpoint Address[31:2]
Bits [31:2] Bits [31:2] of the value for comparison, DVA[31:2].
Bits [1:0] Reserved. UNK/SBZP.
The debug logic reset value of a DBGWVR is UNKNOWN.
UNK/
SBZP
C10-60 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B