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March 2002 Release
547
Virtex-II Pro™ Platform FPGA Documentation
1-800-255-7778
R
When TDE events are enabled, execution of a trap instruction
does not
cause a
program exception if any of the following conditions are true:
•
Internal-debug mode is enabled and debug exceptions are enabled.
•
External-debug mode is enabled.
•
Debug wait-mode is enabled.
A program exception does occur when TDE events are enabled and internal-
debug mode is enabled, but debug interrupts are disabled. In this case, the
processor records an imprecise-debug exception by setting DBSR[IDE]
=
1.
If debug interrupts are enabled, the SRR2 register is loaded with the effective
address of the trap instruction that caused the TDE event.
Unconditional Debug Event
An unconditional (UDE) debug event occurs immediately if either of the
following two conditions are true:
•
An external debugger attached to the JTAG port causes the event.
•
The external unconditional-debug-event signal is asserted.
There is no enable bit for this event. The processor reports a UDE event by
setting the UDE bit in the debug-status register (DBSR[UDE]) to 1. After a
UDE event is recorded by a debugger, the status bit should be cleared to
prevent ambiguity when recording future debug events.
If debug interrupts are enabled, the SRR2 register is loaded with the effective
address of the instruction that would have executed had the UDE event not
occurred.
Instruction Address-Compare Debug Event
An instruction address-compare (IAC) debug event occurs immediately
before
executing an instruction. The effective address of the instruction must match
the value contained in one of the four IAC
n
registers. The IAC event is
controlled by conditions specified in the DBCR0 register. Three IAC
conditions can be specified:
•
Check for an exact instruction-address match.
•
Check for an instruction-address match within a range of addresses.
•
Check for an instruction-address match outside a range of addresses.
If debug interrupts are enabled, the SRR2 register is loaded with the effective
address of the instruction that caused the IAC event.
IAC Exact-Address Match
An IAC exact-address match causes a debug event when the effective address
in the specified IAC
n
register exactly matches the effective address of the
executing instruction. IAC
n
register comparisons are enabled by setting the
appropriate IA
n
enable bits in the DBCR0 register to 1. If a match occurs, the
corresponding status bit in DBSR is set to 1.
shows the control bits used to enable the IAC exact-address-match
debug events, the IAC
n
register used in the comparison, and the debug-status
register bit set when the event occurs. Any number of the IAC exact-address-
match conditions can be enabled simultaneously. IAC address-range
comparisons must be disabled as follows:
•
DBCR0[IA12]
=
0 for IAC1 and IAC2 exact-match comparisons.
•
DBCR0[IA34]
=
0 for IAC3 and IAC4 exact-match comparisons.
Содержание Virtex-II Pro PPC405
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