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The DBGWCR<n>_EL1 characteristics are:
Holds control information for a watchpoint. Forms watchpoint n together with value register DBGWVR<n>_EL1.
External register DBGWCR<n>_EL1 bits [31:0] are architecturally mapped to AArch64 System register DBGWCR<n>_EL1[31:0].
External register DBGWCR<n>_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGWCR<n>[31:0].
DBGWCR<n>_EL1 is in the Core power domain.
If watchpoint n is not implemented then accesses to this register are:
DBGWCR<n>_EL1 is a 32-bit register.
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
LBNX | RES0 | MASK | RES0 | WT | LBN | SSC | HMC | BAS | LSC | PAC | E |
When the E field is zero, all the other fields in the register are ignored.
Linked Breakpoint Number.
For Linked data address watchpoints, with DBGWCR<n>_EL1.LBN, specifies the index of the breakpoint linked to.
For all other watchpoint types, this field is ignored and reads of the register return an UNKNOWN value.
This field extends DBGWCR<n>_EL1.LBN to support up to 64 implemented breakpoints.
The reset behavior of this field is:
Reserved, RES0.
Reserved, RES0.
Address Mask.mask. Only objects up to 2GB can be watched using a single mask.
MASK | Meaning |
---|---|
0b00000 | No mask. |
0b00001 | Reserved. |
0b00010 | Reserved. |
If programmed with a reserved value, a watchpoint must behave as if either:
Software must not rely on this property because the behavior of reserved values might change in a future revision of the architecture.
Other values mask the corresponding number of address bits, from 0b00011 masking 3 address bits (0x00000007 mask for address) to 0b11111 masking 31 address bits (0x7FFFFFFF mask for address).
The reset behavior of this field is:
Reserved, RES0.
Watchpoint type. Possible values are:
WT | Meaning |
---|---|
0b0 | Unlinked data address match. |
0b1 | Linked data address match. |
The reset behavior of this field is:
Linked Breakpointbreakpoint Number.number. For Linked data address watchpoints, this specifies the index of the Context-matching breakpoint linked to.
For Linked data address watchpoints, with DBGWCR<n>_EL1.LBNX when implemented, specifies the index of the breakpoint linked to.
For all other watchpoint types, this field is ignored and reads of the register return an UNKNOWN value.
The reset behavior of this field is:
Security state control. Determines the Security states under which a Watchpoint debug event for watchpoint n is generated. This field must be interpreted along with the HMC and PAC fields.
For more information on the operation of the SSC, HMC, and PAC fields, see 'Execution conditions for which a watchpoint generates Watchpoint exceptions'.
The reset behavior of this field is:
Higher mode control. Determines the debug perspective for deciding when a Watchpoint debug event for watchpoint n is generated. This field must be interpreted along with the SSC and PAC fields.
For more information on the operation of the SSC, HMC, and PAC fields, see 'Execution conditions for which a watchpoint generates Watchpoint exceptions'.
The reset behavior of this field is:
Byte address select. Each bit of this field selects whether a byte from within the word or double-word addressed by DBGWVR<n>_EL1 is being watched.
BAS | Description |
---|---|
xxxxxxx1 | Match byte at DBGWVR<n>_EL1 |
xxxxxx1x | Match byte at DBGWVR<n>_EL1 + 1 |
xxxxx1xx | Match byte at DBGWVR<n>_EL1 + 2 |
xxxx1xxx | Match byte at DBGWVR<n>_EL1 + 3 |
In cases where DBGWVR<n>_EL1 addresses a double-word:
BAS | Description, if DBGWVR<n>_EL1[2] == 0 |
---|---|
xxx1xxxx | Match byte at DBGWVR<n>_EL1 + 4 |
xx1xxxxx | Match byte at DBGWVR<n>_EL1 + 5 |
x1xxxxxx | Match byte at DBGWVR<n>_EL1 + 6 |
1xxxxxxx | Match byte at DBGWVR<n>_EL1 + 7 |
If DBGWVR<n>_EL1[2] == 1, only BAS[3:0] is used. Arm deprecates setting DBGWVR<n>_EL1[2] == 1.
The valid values for BAS are non-zero binary number all of whose set bits are contiguous. All other values are reserved and must not be used by software. See 'Reserved DBGWCR<n>.BAS values'.
The reset behavior of this field is:
Load/store control. This field enables watchpoint matching on the type of access being made. Possible values of this field are:
LSC | Meaning |
---|---|
0b01 | Match instructions that load from a watchpointed address. |
0b10 | Match instructions that store to a watchpointed address. |
0b11 | Match instructions that load from or store to a watchpointed address. |
All other values are reserved, but must behave as if the watchpoint is disabled. Software must not rely on this property as the behavior of reserved values might change in a future revision of the architecture.
The reset behavior of this field is:
Privilege of access control. Determines the Exception level or levels at which a Watchpoint debug event for watchpoint n is generated. This field must be interpreted along with the SSC and HMC fields.
For more information on the operation of the SSC, HMC, and PAC fields, see 'Execution conditions for which a watchpoint generates Watchpoint exceptions'.
The reset behavior of this field is:
Enable watchpoint n. Possible values are:
E | Meaning |
---|---|
0b0 | Watchpoint n disabled. |
0b1 | Watchpoint n enabled. |
This bit is ignored by the PE and treated as zero when all of the following are true:
The reset behavior of this field is:
SoftwareLockStatus() depends on the type of access attempted and AllowExternalDebugAccess() has a new definition from Armv8.4. Refer to the Pseudocode definitions for more information.
Component | Offset | Instance |
---|---|---|
Debug | 0x808 + (16 * n) | DBGWCR<n>_EL1 |
This interface is accessible as follows:
3005/0907/2022 1517:5807; 21c5a6dd0fdaf10a712e2f2d6fffbdbd66d4d96fb0421fa9a8865165f9b91af9b4a566111f866305
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