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Development Support
18-14
MPC801 USER’S MANUAL
MOTOROLA
18
Result: The event will be correctly detected if the compiler chooses a load/store instruction
with data size of half-word. If the compiler chooses load/store instructions with data size
greater than half-word (word, multiple), there might be some false detections.
These examples can only be ignored by the software that handles the breakpoints. The
following figure illustrates this partially supported scenario:
Figure 18-2. Partially Supported Watchpoints/Breakpoint Example
18.2.1.4 CONTEXT DEPENDENT FILTER.
recognize internal breakpoints when the MSR
recognize internal breakpoints (nonmasked mode). When it is programmed to recognize
internal breakpoints (when MSR
RI
=1), all parts of the code can be debugged, except when
registers SRR0 and SRR1, DAR, and DSISR are busy and MSR
epilogues of interrupt/exception handlers).
The core can only be programmed to
bit is set (masked mode) or to always
RI
RI
=0 (in the prologues and
When working in masked mode, all internal breakpoints detected when MSR
and detected watchpoints are not counted by the debug counters. Detected watchpoints are
always reported on the external pins, regardless of the value of the MSR
defaults to masked mode after reset. It is input in the nonmasked mode by setting the
BRKNOMSK bit in the LCTRL2 register.The BRKNOMSK bit controls all internal
breakpoints (I-breakpoints and L-breakpoints). See Table 18-14 for details.
RI
=0 are lost
RI
bit. The core
18.2.1.5 IGNORE FIRST MATCH OPTION.
and “go from x”, the ignore first match option is supported for the instruction breakpoints.
When an instruction breakpoint is first enabled, the first instruction will not cause an
instruction breakpoint if the IFM bit in the instruction support control (ICTRL) register is set.
This is used for “continue” utilities. When IFM is clear, every matched instruction can cause
an instruction breakpoint. This is used for “go from x”. The IFM bit is set by the software and
cleared by the hardware following the first instruction breakpoint, the match is ignored. Load/
store breakpoints and all counter-generated breakpoints (instruction and load/store) are
unaffected by this mode.
To facilitate the debugger utilities of “continue”
0X00000000
0X00000004
0X00000008
0X0000000C
0X00000010
POSSIBLE FALSE DETECT ON THESE HALF-WORDS WHEN USING WORD/MULTIPLE