Wrong /proc/cpuinfo information with Q9550 Intel Core 2 CPU

[Christian Hudon]

Just installed hardy on a new machine (which has a recent cpu: Intel Core 2 Q9550... required a BIOS upgrade for a motherboard which was a year old). When I look at the /proc/cpuinfo for that machine, it reports 1 core with 4 siblings when the CPU is a quad-core with no hyperthreading (so should be 4 cores). An identical machine even with an older CPU (Intel Q6600) returns the correct number of cores in /proc/cpuinfo.

As said, I just updated the BIOS for the Q9550 machine to the latest version, so that shouldn't be the problem (but any hints on how to dump the ACPI data and confirm it is correct would be appreciated).

We're running 8.04.3 LTS, with kernel 2.6.24-24-server

[C. Brayton (cbrayton-boizebueditorial)]

This has been bedeviling me for quite some time now as well: cpufreq-info presents incorrect information about my T2500 Intel Core 2 CPU (attached).

SysRescueCD, Puppy Linux, and other live CDs detect the correct MHz for both cores: 1997.xx

I can't help but believe this problem is related to my problem with CPU frequency scaling. On logging into Gnome, the ondemand governor steps the two cores between 1.0GHz and 2.0GHz, as I wish, and as confirmed by cpufreq-info. A short time later, the processors are set to the lowest frequency, and cpufreq-info has the governor scaling between 1000Mhz and 1000Mhz.

I know from googling forums that this is a very, very common problem. I thought I had found a solution with a combination of boot options set in GRUB and selected by brute-force testing of one combination after another among boot options recommended in the fora -- "noapm, acpi=noirq, pnpacpi=off"

This may have been broken by the last update of 10.04 Lucid. Just a wild guess.

uname -a = macunaimachine 2.6.32-10-generic #14-Ubuntu SMP Thu Jan 7 17:38:40 UTC 2010 i686 GNU/Linux

[C. Brayton (cbrayton-boizebueditorial)]

Note: This problem first showed up in 9.10, I guess after the kernel developers compiled acpi-cpufreq into the kernel instead of leaving it as a module. I have been really been racking my brains about how to get more information about the problem. What process changes these settings?

I came across a thread discussion among Level 10 kernel mages in which such issues were discussed in depth using output from a kernel compiled with CPUFREQ_DEBUG=y ... Could that be baked into in-development kernels in the future? Again, I feel sure there are many, many laptop users with this problem.

[Jeremy Foshee (jeremyfoshee)]

Hi Christian,

Please be sure to confirm this issue exists with the latest development release of Ubuntu. ISO CD images are available from http://cdimage.ubuntu.com/releases/ . If the issue remains, please run the following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux 410043

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

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[Christian Hudon (chrish)]

I've tested using the Ubuntu 10.04 LTS beta 2 desktop CD (32 bits), and the number of cores in the CPU gets reported correctly with that kernel. Is testing with a (2.6.24) mainline kernel still useful?

[Jeremy Foshee (jeremyfoshee)]

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu development release http://cdimage.ubuntu.com/daily-live/current/ . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]