Local APIC operation in a Pentium 4

Local APIC operation in a Pentium 4

Does delivery mode 101 (INIT) work for the Performance Management Interrupt in the local APIC of a Pentium 4? (using the LVT entry at address FEE00340h).

Deliver modes 000 (Fixed) and 100 (NMI) work with my logic, but if I change the deliver mode to 101 and set the vector field to 0, the counter runs and overflows at the expected time but *no* INIT request is generated by the APIC. Furthermore, bit 16 of the LVT entry for the PMI does *not* transit from 0 to 1 at counter overflow time (contrary to the documentation), but bit 31 (OVF) in the CCCR for the counter does transit from 0 to 1 at this same time (in agreement with the documentation.) I am using the MSR_BPU_COUNTER0 counter with the global_power_events event to count clockticks when the processor is active.

I am developing my code using document 253668, "IA-32 Intel Architecture Software Developer's Manual, Volume 3, System Programming Guide", dated 2004, as the definitive reference for the APIC and the Performance Management counters, etc. Chapter 8 seems to indicate that the INIT delivery mode is available for the PMI. I cannot find any contraindications to using the INIT mode, either in this manual nor in the other manuals of the same series, nor in any specification updates or errata.

I have been developing and testing my logic on a Family F, Model 2, Stepping 7 processor, in real mode. My application requires the INIT delivery mode for a PMI, the other modes or interrupts will not provide the true watchdog timer I am trying to implement for my embedded code.

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We will forward your question to our engineering contacts and let you know how they respond.

Regards,

Lexi S.

IntelSoftware NetworkSupport

http://www.intel.com/software

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Message Edited by intel.software.network.support on 12-01-2005 07:05 PM

Our engineering team responded as follows:

Although the documentation implies certain things, that does not mean that your interpretation of the implication is correct. The only interrupt delivery mode actually supported for PMI is FIXED. Even if the interrupt was specified as INIT, the action that the processor will take is to default to a FIXED mode and vector to that address. If you desire more detailed information, please contact your local Intel sales representative.

Regards,

Lexi S.

IntelSoftware NetworkSupport

http://www.intel.com/software

Contact us

Message Edited by intel.software.network.support on 12-01-2005 07:06 PM

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