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IDT EJTAG System
Hardware Breakpoints
79RC32438 User Reference Manual
20 - 47
November 4, 2002
Notes
Data Breakpoint Registers
This section describes the data breakpoint registers for MIPS32 and MIPS64 processors, and other R4k
privileged environment implementations of 32-bit and 64-bit processors. These registers provide status and
control for the data breakpoints. All registers are in drseg. The 1 to 15 implemented breakpoints are
numbered 0 to 14, respectively, for registers and breakpoints. The specific breakpoint number is indicated
by “n”. The registers and their respective addresses offsets are shown in Table 20.34.
Data Breakpoint Status (DBS) Register
Compliance Level
: Required if any data breakpoints are implemented, optional otherwise.
The Data Breakpoint Status (DBS) register holds implementation and status information about the data
breakpoints. It is located at drseg offset 0x2000. The ASIDsup, NoSVmatch, and NoLVmatch fields apply to
all data breakpoints. Figure 20.14 shows the format of the DBS register and Table 20.35 describes the DBS
register fields
Figure 20.14 DBS Register Format
Offset in
drseg
Register
Mnemonic
Register Name and Description
0x2000
DBS
Data Breakpoint Status
0x2100 + 0x100*n
DBAn
Data Breakpoint Address n
0x2108 + 0x100*n
DBMn
Data Breakpoint Address Mask n
0x2110 + 0x100*n
DBASIDn
Data Breakpoint ASID n
0x2118 + 0x100*n
DBCn
Data Breakpoint Control n
0x2120 + 0x100*n
DBVn
Data Breakpoint Value n
Table 20.34 Data Breakpoint Register Mapping
31
0
30
29
28
27
24 23
15 14
0
ASID
sup
NoSV
match
NoLV-
match
BCN
0
BS[14:0]
Fields
Description
Read/
Write
Reset
State
Compli-
ance
Name
Bit
ASIDsup
30
Indicates if ASID compare is supported in
data breakpoints:
0:
No ASID compare
1:
ASID compare (DBASIDn register
implemented)
ASID support indication does not guaran-
tee a TLB-type MMU, because the same
breakpoint implementation can be used
with processors having all different types of
MMUs.
R
Preset
Required
Table 20.35 DBS Register Field Description (Part 1 of 2)