AMD K manual Single Step Across I/O SMI Skips One Debug Trap

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Preliminary Information

23614K— October 2003

AMD Athlon™ Processor Model 4 Revision Guide

23 Single Step Across I/O SMI Skips One Debug Trap

Products Affected. A4, A5, A6, A7, A9

Normal Specified Operation. When single stepping (with EFLAGS.TF) across an IN or OUT instruction that detects an SMI, the processor correctly defers taking the debug trap and instead enters SMM. Upon RSM (without I/O restart), the processor should immediately enter the debug trap handler.

Non-conformance.Under this scenario, the processor does not enter the debug trap handler but instead returns to the instruction following the I/O instruction.

Potential Effect on System. When using the single step debug mode, following an I/O operation that detects an SMI, one instruction may appear to be skipped.

Suggested Workaround. None required as this is a debug limitation only. If a workaround is desired, modify the SMM handler to detect this case and enter the debug handler directly.

Resolution Status. No fix planned.

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Contents Revision Guide Advanced Micro Devices, Inc AMD Athlon Processor Model 4 Revision Guide Revision HistoryRevision Guide Policy AMD Athlon Processor Model Revision GuideProduct Errata Products Affected. A4, A5, A6, A7, A9 Resolution Status. No fix plannedProducts Affected. A4, A5 Resistance Value of the ZN and ZP PinsPotential Effect on System. The system hangs Suggested Workaround. None Instruction Execution DeadlockProducts Affected. A4, A5, A6, A7 Potential Effect on System. The system will hang Products Affected. A9 Preliminary Information Resolution Status. No fix planned Preliminary Information Preliminary Information Potential Effect on System. System failure Single Step Across I/O SMI Skips One Debug Trap Kernel Workaround Software Prefetches May Report a Page FaultPreliminary Information Revision Determination Technical and Documentation Support