Debug Reset; Debug Timer Freeze; Debug Registers - IBM PPC440X5 CPU Core User Manual

User's Manual
PPC440x5 CPU Core
Table 8-3. Debug Event Summary (continued)
External Debug
Debug Wait
Mode Mode
Disabled Disabled
Disabled Disabled
Table Notes
1. IRPT debug events may only occur for non-critical class interrupts when operating in internal debug mode with
external debug mode and debug wait mode both disabled.
2. IAC debug events may not occur in internal debug mode with MSR[DE] = 0 and with external debug mode
and debug wait mode both disabled, and the IAC mode set to range inclusive or range exclusive. They may
occur if the IAC mode is set to exact.
3. RET debug events may not occur for rfci or rfmci instructions when operating in internal debug mode with
MSR[DE] = 0 and with external debug mode and debug wait mode both disabled. They may only occur in this
mode for the rfi instruction.
4. ICMP debug events are not permitted when operating in trace debug mode. Software must not enable ICMP
debug events unless one of the other debug modes is enabled.

8.4 Debug Reset

Software can initiate an immediate reset operation by setting DBCR0[RST] to a non-zero value. The results of
a reset operation within the PPC440x5 core are described in Initialization on page 85. The results of a reset
operation on the rest of the chip and/or system is dependent on the particular type of reset operation (core,
chip, or system reset), and on the particular chip and system implementation. See the chip user's manual for
details.

8.5 Debug Timer Freeze

In order to maintain the semblance of "real time" operation while a system is being debugged, DBCR0[FT]
can be set to 1, which will cause all of the timers within the PPC440x5 core to stop incrementing or decre-
menting for as long as a debug event bit is set in the DBSR, or until DBCR0[FT] is set to 0. See Timer Facili-
ties on page 209 for more information on the operation of the PPC440x5 core timers.

8.6 Debug Registers

Various Special Purpose Registers (SPRs) are used to enable the debug modes, to configure and record
debug events, and to communicate with debug tool hardware and software. These debug registers may be
accessed either through software running on the processor or through the JTAG debug port of the
PPC440x5.
Programming Note: It is the responsibility of software to synchronize the context of any
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Internal
MSR
Debug
DE
IAC
Mode
Enabled 0 Note 2
Disabled — Yes
changes to the debug facility registers. Specifically, when changing the
contents of any of the debug facility registers, software must execute an
isync instruction both before and after the changes to these registers, to
ensure that all preceding instructions use the old values of the registers,
and that all succeeding instructions use the new values. In addition, when
Debug Events
DAC DVC BRT TRAP
Yes Yes No Yes
Yes Yes Yes Yes
Preliminary
RET ICMP IRPT
Note 3 No Note 1
Yes Note 4 yes
debug.fm.
September 12, 2002
UDE
Yes
Yes