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

Debug Registers Reference
Address range mask, bits [28:24], v7 Debug
In v7 Debug, whether address range masking is supported is IMPLEMENTATION DEFINED. If
it is not supported these bits are RAZ/WI.
If address range masking is supported, this field can be used to break on a range of addresses
by masking lower order address bits out of the breakpoint comparison. The value of this
field is the number of low order bits of the address that are masked off, except that values of
1 and 2 are reserved. Therefore, the meaning of Breakpoint address range mask values are:
0b00000 No mask
0b00001 Reserved
0b00010 Reserved
0b00011 0x00000007 mask for instruction address, three bits masked
0b00100 0x0000000F mask for instruction address, four bits masked
0b00101 0x0000001F mask for instruction address, five bits masked
. .
. .
. .
0b11111 0x7FFFFFFF mask for instruction address, 31 bits masked.
This field must be programmed to 0b00000 if either:
this BRP is programmed for Context ID comparison
the Byte address select field is programmed to a value other than 0b1111.
If this is not done, the generation of Breakpoint debug events is UNPREDICTABLE.
If this field is not zero, the DBGBVR bits that are not included in the comparison must be
zero, otherwise the generation of Breakpoint debug events is UNPREDICTABLE.
For more information about the use of this field see Breakpoint address range masking
behavior, v7 Debug on page C3-9.
Bits [28:24], v6 Debug and v6.1 Debug
Reserved, UNK/SBZP.
DBGBVR meaning, bits [22:20]
This field controls the behavior of Breakpoint debug event generation. This includes the
meaning of the value held in the associated DBGBVR, whether it is an IVA or a Context ID.
Each bit of this field has particular significance, and there can be restrictions on the values
of bits [22:21]:
Bit [22], Match or mismatch
This bit is set to 1 for a mismatch comparison.
This bit is not supported and is UNK/SBZP in v6 Debug.
For more information about IVA mismatching see Additional considerations for
IVA mismatch breakpoints on page C3-13.
The Debug architecture does not support Context ID mismatch comparisons.
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