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    SubjectRe: [patch] 2.4.0, 2.4.0-ac12: APIC lock-ups
    Manfred Spraul wrote:
    > But I think we can change the bug description:
    > If an io apic io redirection entry is unmasked while the irq pin is
    > active, then the io apic sends out the interrupt as edge triggered, but
    > nevertheless sets the IRR bit.

    I found another workaround:
    8390.c currently calls

    outb_p(ENISR_ALL, e8390_base + EN0_IMR);

    and locks up after ~ 100 packets flood ping.

    If I reorder these calls to

    outb_p(ENISR_ALL, e8390_base + EN0_IMR);
    (and the correct spin_lock()'s)

    the lockup disappears.

    But I have no idea how io_apic.c could prevent lockups.

    Playing with the trigger mode is not 100% reliable - I assume it kicks
    the io apic only after several changes of the trigger mode bit. Maciej's
    patch switches that bit twice during every start_tx operation and thus
    doesn't lock up, my patch touches the redirection entry exactly once and
    reliably locks up - even if I change trigger mode, polarity, delivery
    mode and vector during enable_level_irq().

    Any ideas?

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      Last update: 2005-03-22 12:52    [W:4.409 / U:0.020 seconds]
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