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    SubjectRe: [PATCH 2/2] acpi: Disable IRQ 0 through I/O APIC for some HP systems
    Date
    On Monday, 7 of July 2008, Maciej W. Rozycki wrote:
    > On Mon, 7 Jul 2008, Ingo Molnar wrote:
    >
    > > > Please note two things:
    > > > (1) The whole acpi_dmi_table[] thing originally depended on __i386__, so it
    > > > wouldn't work on x86-64 no matter what. I removed that dependecy, but
    > > > I have no idea why it was there and so I'm not sure if that's correct.
    >
    > Well spottedd -- perhaps the x86-64 was though to be perfect. ;)
    >
    > > > (2) The clear_IO_APIC_pin(apic1, pin1) done if
    > > > disable_irq0_through_ioapic is true is absolutely essential. The
    > > > symptoms are 100% reproducible without it.
    > >
    > > thanks, applied to tip/x86, to give this some more testing.
    > >
    > > the clear_IO_APIC_pin() is the most worrisome aspect of the change - but
    > > since we are already in limited quirk mode, does it hurt? Maciej, any
    > > preferences?
    >
    > It makes absolutely no sense and should be harmful to call
    > clear_IO_APIC_pin(apic1, pin1) here, because both apic1 and pin1 should be
    > equal to -1 here. If it has to be called, then I suppose the DMI matching
    > did not work and the workaround has not been enabled.

    BTW, did you even to look at the code _as_ _is_ in linux-next?

    In fact, it is _impossible_ that either apic1 or pin1 are equal to -1 at this
    point, because of this part:

    /*
    * Some BIOS writers are clueless and report the ExtINTA
    * I/O APIC input from the cascaded 8259A as the timer
    * interrupt input. So just in case, if only one pin
    * was found above, try it both directly and through the
    * 8259A.
    */
    if (pin1 == -1) {
    pin1 = pin2;
    apic1 = apic2;
    no_pin1 = 1;
    } else if (pin2 == -1) {
    pin2 = pin1;
    apic2 = apic1;
    }

    that originates from your patch.

    End even without this part apic1 and pin1 are _not_ equal to -1 on this box
    (apic2 and pin2 are, but that's a different matter).

    Thanks,
    Rafael


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