[Qemu-devel] Re: x86: PMTIMER calibration sometimes fails

[Thomas De Schampheleire]

Hi,

Can anyone help me with this?

Thanks,  Thomas

On Tue, Sep 21, 2010 at 8:58 AM, Thomas De Schampheleire
<address@hidden> wrote:
> Hi,
>
> I am running an x86 based Linux system under qemu. Linux boots up
> correctly in most cases, however sometimes the PMTIMER fails to
> calibrate correctly:
>
> [    0.000000] Fast TSC calibration failed
> [    0.000000] TSC: Unable to calibrate against PIT
> [    0.000000] TSC: HPET/PMTIMER calibration failed.
> [    0.000000] Marking TSC unstable due to could not calculate TSC khz
> [    0.010998] Calibrating delay loop... 1011.71 BogoMIPS (lpj=505856)
>
> while the following messages appears in a good situation:
>
> [    0.000000] Fast TSC calibration failed
> [    0.000000] TSC: Unable to calibrate against PIT
> [    0.000000] TSC: using PMTIMER reference calibration
> [    0.000000] Detected 2258.151 MHz processor.
> [    0.009099] Calibrating delay loop (skipped), value calculated
> using timer frequency.. 4516.30 BogoMIPS (lpj=2258151)
>
> HPET is deliberately disabled.
>
> Both situations occur with the same Linux kernel configuration, so I
> am assuming this is a qemu problem.
> I have the impression that in a bad situation, the boot messages
> scroll by slower, indicating a slower emulation than in the good case
> (as the timings seen by the kernel are approximately the same).
>
> Please find in attachment the full boot log of a good and bad
> situation, plus the kernel configuration.
>
> Have you seen this problem before? Do you have any idea how to fix it?
>
> Thanks,
> Thomas
>