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    SubjectRe: [RESEND] Fast TSC calibration fails with v3.14-rc1 and later
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    On Mon, 2014-03-10 at 11:04 +0100, Julian Wollrath wrote:
    > on a Thinkpad x121e (AMD E-450 APU) with version 3.13.5 and earlier of
    > the kernel I get:
    > [...]
    > [ 0.000000] tsc: Fast TSC calibration using PIT
    > [ 0.001000] tsc: Detected 1646.619 MHz processor
    > [ 0.000004] Calibrating delay loop (skipped), value calculated using
    > timer frequency.. 3293.23 BogoMIPS (lpj=1646619)
    > [...]
    >
    >
    > but starting with v3.14-rc1 the fast TSC calibration fails:
    > [...]
    > [ 0.000000] tsc: Fast TSC calibration failed
    > [ 0.000000] tsc: PIT calibration matches HPET. 1 loops
    > [ 0.000000] tsc: Detected 1646.490 MHz processor
    > [...]
    >
    > If you need more information, please do not hesitate to ask.

    I submitted a patch to downgrade the "Fast TSC calibration failed"
    message to KERN_INFO level, see https://lkml.org/lkml/2012/9/26/131 .
    That patch was basically ignored. I've carried it locally ever since.

    So the error need not be v3.14-rc1 specific. But perhaps something
    changed in v3.14-rc1 that makes it easier to trigger that error. I
    haven't checked.

    (I wrote some notes on this issue in
    https://lkml.org/lkml/2012/9/24/221 , perhaps they might be of help.)


    Paul Bolle



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