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IDT EJTAG System
Hardware Breakpoints
79RC32438 User Reference Manual
20 - 43
November 4, 2002
Notes
Data breakpoints with imprecise matches generate imprecise triggers when enabled by the TE bit. Note
that trigger indications by BS may be set based on compare with UNPREDICTABLE data. A triggerpoint
match can be indicated on an optional internal signal or chip pin.
Instruction Breakpoint Registers
This section describes the instruction 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 instruction breakpoints. All registers are in drseg. The 1 to 15 implemented break-
points 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 20.28.
Instruction Breakpoint Status (IBS) Register
Compliance Level
: Required if any instruction breakpoints are implemented, optional otherwise.
The Instruction Breakpoint Status (IBS) register holds implementation and status information about the
instruction breakpoints. It is located at drseg offset 0x1000. The ASIDsup bit applies to all instruction break-
points. Figure 20.9 shows the format of the IBS register and Table 20.29 describes the IBS register fields.
Instruction
With/Without
Value Compare
BS Bits Update for Triggerpoint
Load / Store
Without value compare
BS bit set if no exception with higher priority than
the Debug Data Break Load/Store exception, with
address match only, occurred on the instruction.
Load
With value compare
BS bit set if no exception with higher priority than
the Debug Data Break Load exception, with
address and data value match, occurred on the
instruction.
Store
With value compare
BS bit is set if no exception occurred on the instruc-
tion, and is optional to be if an exception with equal
or lower priority than the Debug Data Break Store
exception, with address match only, occurred on
the instruction, with the requirement that either all
the relevant BS bits are set, or none are changed.
Table 20.27 Rules for Update of BS Bits on Data Triggerpoints
Offset in drseg
Register
Mnemonic
Register Name and Description
0x1000
IBS
Instruction Breakpoint Status
0x1100 + 0x100*n
IBAn
Instruction Breakpoint Address n
0x1108 + 0x100*n
IBMn
Instruction Breakpoint Address Mask n
0x1110 + 0x100*n
IBASIDn
Instruction Breakpoint ASID n
0x1118 + 0x100*n
IBCn
Instruction Breakpoint Control n
Table 20.28 Instruction Breakpoint Register Mapping