CPUID.0 returning different values each call. Pentium D 820

[eddo]

I'm experiencinginconsistent results from the CPUID.0 instruction.

When I call this function multiple times, it either returns 3 or 5 in EAX. This is supposed to return the max value supported by the CPUID function. But, sometimes it returns 3 and other times it returns 5.

Furthermore, I can verify the inconsistent behavior that it is returning different results by running your own CPUCount20.exe program found here:

http://www.intel.com/cd/ids/developer/asmo-na/eng/dc/threading/hyperthreading/19122.htm

Running this program over and over will yield inconsistent results as well.See the bottom for the results of two consecutive runs of CPUCount20.exethat shows different output .

I am running this on MS Windows Media Center 2005. Fully patched. My CPU is a 'Intel Pentium D CPU 2.80GHz' Family 15, Model 4, Stepping 4.

Is there something I can do to get consistent results from this processor?

Investigating further shows that I can get consistent results if I set the Processors Affinity before calling CPUID.0. If I set the affinity to 1,CPUID.0 returns 3, if I set the affinityto 2,CPUID.0 returns 5.

Is setting the affinity required for calling CPUID? Shouldn't each core return the same data? I don't see anywhere in your papers ormanuals that mention that.

Any help would be appreciated.

Eddie Fast

Institute for Creative Technologies

fast@ict.usc.edu

Output from 2 consecutive calls to CPUCount2.exe:

------------------------------------------------------------------------

c:EdCPUCount>CPUCount20.exe
CPU Counting Utility
Version 2.4
Copyright (C) 2001, 2005 Intel Corporation. All Rights Reserved

APIC_ID = 0
Physical ID = 0 Core ID = 0 Logical ID = 0

APIC_ID = 1
Physical ID = 0 Core ID = 0 Logical ID = 1

Hyper-Threading Technology: Enabled
System: Single Core
EM64T: Capable

Number of available logical processors per physical processor: 2
Number of available cores per physical processor: 1
Number of physical processors: 1

Press Enter To Continue

c:EdCPUCount>CPUCount20.exe
CPU Counting Utility
Version 2.4
Copyright (C) 2001, 2005 Intel Corporation. All Rights Reserved

APIC_ID = 0
Phy sical ID = 0 Core ID = 0 Logical ID = 0

APIC_ID = 1
Physical ID = 0 Core ID = 1 Logical ID = 0

Hyper-Threading Technology: Disabled
System: Multi-Core
EM64T: Capable

Number of available logical processors per physical processor: 2
Number of available cores per physical processor: 2
Number of physical processors: 1

Press Enter To Continue

[Intel_Software_Netw1]

Greetings from Intel Software Network Support. We also received your inquiry through email, and we escalated your question to the author of the cpucount20.exe article and to our engineering team. We'll let you know what we find out.

Regards,

Lexi S.
Intel Software Network Support
http://www.intel.com/software/
Contact us

*Other names and brands may be claimed as the property of others.

Message Edited by intel.software.network.support on 11-15-2005 11:16 PM

[Intel_Software_Netw1]

Greetings from Intel Software Network Support. We also received your inquiry through email, and we escalated your question to the author of the cpucount20.exe article and to our engineering team. Here is what we have found.

Before we try further testing on the processor or code,first make sure you are not toggling the Limit CPUID MAXVal bit. It is bit 22 in MSR 1A0h.

If after checking this you are still experiencing undesired results, please contact us for further testing.

Regards,

Jim A.
Intel Software Network Support
http://www.intel.com/software/
Contact us

*Other names and brands may be claimed as the property of others.

Message Edited by intel.software.network.support on 11-15-2005 11:16 PM

[kevin120bl]

I'm experiencing the exact same problem with CPUID. When executed on the first core, I get a maximum CPUID level of 3 and when executed on the second core, I get a maximum CPUID level of 5.

I was wondering if this might be a problem in the BIOS where it is only initializing IA32_MISC_ENABLES.BOOT_NT on one core, but that doesn't really make sense because the default is 0 (no restriction on CPUID level). So this still could be a bug in the CPU.

My system is a Dell, I think in the Dimension 9100 line but I don't have access to it at the moment to see the BIOS maker and version (if Dell even displays that).

[jim_dempsey]

I might not know jack about this but it seems like you have HT disabled on the 2nd core.

Jim

[eddo]

Great! I'm glad I'm not the only one experiencing this problem. My machine is also a Dell 9100, so I hope this problem isn't limited to that. Dell's BIOS is pretty restrictive, so there's not much hope in being able to configure anything.

I'm supposed to be contacted by someone from Intel who will help me. As soon as I have some more information, I will let you know.