
MOTOROLA
Chapter 37. System Development and Debugging
37-5
Part VI. Debug and Test
37.1.4.2 Program Trace When In Debug Mode
When entering debug mode an interrupt/exception taken is reported on the VF pins (VF =
0b100) and a cycle marked with the program trace cycle is made externally visible. When
the core is in debug mode, VF = 0b000 and VFLS = 0b11. For more information on debug
mode, see Section 37.3, ÒDevelopment System Interface.Ó
If TECR[VSYNC] is set or cleared while the core is in debug mode, this information is
reported when the Þrst VF pins report as the core returns to regular mode. If VSYNC was
not changed while in debug mode, the Þrst VF pins report will be encoded as VF = 0b101
(indirect branch) due to the rÞ instruction that is being issued. In both cases, the Þrst
instruction fetch after debug mode is marked with the program trace cycle attribute and is
externally visible.
37.1.4.3 Sequential Instructions Marked as Indirect Branch
There are instances where non-branch (sequential) instructions can affect the machine in a
manner similar to indirect branch instructions. These instructions include rÞ, mtmsr, isync,
and mtspr to registers CMPAÐCMPF, ICTRL, ICR, and DER.
The core marks these instructions are marked as indirect branch instructions (VF = 0b101).
The next instruction address is marked with the program trace cycle attribute, as if it were
an indirect branch target. Therefore, when one of these special instructions is detected in
the core, the address of the next instruction is externally visible. The reconstructing
software can now correctly evaluate the effect of these instructions.
37.1.5 Reconstructing Program Trace
When program trace is needed, external hardware must sample the status pins (VF and
VFLS) of every clock and mark the address of all cycles with the program trace cycle
attribute. Although program trace can be used in various ways, the following describes only
back trace and window trace.
37.1.5.1 Back Trace
Back trace is useful when a record of the program trace before an event occurred is needed.
An example of such an event is a system failure. If back trace is needed, external hardware
should start sampling VF and VFLS and the address of all cycles marked with the program
trace cycle attribute immediately after reset is negated.
At reset, cycles marked with the program trace cycle attribute are visible on the external bus
(that is, the instruction fetch show cycle/core serialize control Þeld (ICTRL[ISCT_SER])
is cleared at reset). To avoid this slower default mode, it is recommended that the user enters
VSYNC state as described in Section 37.1.1, ÒProgram Trace Functional Description.Ó To
exit VSYNC state after a particular event, either trap in debug mode and trigger the freeze
indication or follow the method described in Section 37.1.1, ÒProgram Trace Functional
Description.Ó After exiting VSYNC state, the trace buffer holds the trace of the program
executed before the pertinent event occurred.
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 394: ...14 42 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 748: ...27 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 846: ...31 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 914: ...35 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1086: ...Glossary 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA ...
Page 1106: ......