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    SubjectRe: [BUG] 2.6.21-rc1,2,3 regressions on my system that I found so far
    Date
    On Saturday 17 March 2007 03:32:53 Len Brown wrote:
    > On Friday 16 March 2007 19:44, Thomas Gleixner wrote:
    > > Maxim,
    > >
    > > On Fri, 2007-03-16 at 12:30 +0200, Maxim Levitsky wrote:
    > > > 3) Sometimes I get this (once in three boots or so)
    > > >
    > > > [ 36.217405] ENABLING IO-APIC IRQs
    > > > [ 36.217587] ..TIMER: vector=0x31 apic1=0 pin1=2 apic2=-1 pin2=-1
    > > > [ 36.433917] APIC timer disabled due to verification failure.
    > > >
    > > > And NO_HZ is disabled due to that (I get 1000/s timer's interrupts)
    > > > I haven't investigated that yet.
    > > > It looks like another new test that my hardware fails to perform...
    > >
    > > Yes, this is probably caused by SMM code trying to emulate a PS/2
    > > keyboard from a (maybe connected or not) USB keyboard. Unfortunately we
    > > have no way to disable this BIOS misfeature in the early boot process.
    > > Arjan, Len ?????
    >
    > Nope. By definition, SMM is invisible to the OS -- we don't even
    > get a bit that said it occurred (though we'd like one -- it would
    > be really helpful to diagnose issues like this one)
    >
    > So go into BIOS SETUP and see if there is a USB Legacy Emulation
    > feature that you can disable. Sometimes there is not, but disabling
    > onboard USB altogether may help at least prove the issue is in that area.
    >
    > > I built in this test to rule out bogus LAPIC timer calibration values
    > > which are sometimes off by factor 2-10.
    > >
    > > But I also built in a calibration against the PM-Timer, which turned out
    > > to be quite reliable and I think the additional verification step is
    > > only necessary for sytems without PM-Timer.
    > >
    > > That was a bit over cautious from my side. I send a patch to avoid this
    > > when PM-Timer is available in a separate mail.
    >
    > PM-Timer was invented to work-around the issue that the TSC became unreliable
    > in the face of power management on laptops. In particular, to be able
    > to time duration of OS idle where TSC stopped.
    >
    > While it is not fine grain, and it is not low-latency, is should
    > be very reliable. My understanding is that it is implemented as
    > a simple divider right off the system 14MHz clock -- the signal
    > which most motherboard clocks are PLL multiplied up from --
    > including the 100MHz front-side bus which drives the LAPIC timer.
    >
    > But that said, I don't understand why calibrating the LAPIC timer
    > using the PM-timer is going to be more reliable -- exactly how
    > and why did the previous calibration scheme fail?
    > Maybe I could follow the new logic in apic.c if I saw the "apic=debug"
    > output for this box.
    >
    > cheers,
    > -Len
    >
    >
    >

    Hi,

    Yes, usb emulation is enabled, but I need it. I will test without usb emulation, but since it shows only sometimes,
    I don't know yet whenever usb legacy affects it.

    Regards,
    Maxim Levitsky
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