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    SubjectRe: enabling IOAPIC on C3 processor? (how to investigate hangs without nmi watchdog)
    On Tue, 15 Mar 2005 13:34:55 +0100, Mikael Pettersson <> wrote:
    > jerome lacoste writes:
    > > I have a VIA Epia M10000 board that crashes very badly (and pretty
    > > often, especially when using DMA). I want to fix that.
    > >
    > > Serial console + magic SysRQ didn't help so I am going the nmi
    > > watchdog way. But in order to have nmi watchdog I need APIC, right?
    > >
    > > The C3 processor seems to support IOAPIC.
    > > (
    > >
    > > But:
    > > - I don't see anything in the BIOS related to APIC.
    > > - grep APIC /lib/modules/`uname -r`/build/.config shows me that all
    > > APIC options are 'y'.
    > > - dmesg | grep APIC tells me "no local APIC present or hardware disabled".
    > > - adding lapic kernel parameter doesn't change that.
    > > - and of course, nmi_watchdog=1 or 2 gives me NMI count 0 in /proc/interrupts.
    > >
    > > Did I miss something when it comes to enabling IOAPIC support on C3 processor?
    > Unless you have a pre-release engineering part for a future product,
    > then your C3 has no local APIC, and hence no I/O APIC functionality.
    > I know some C3 specs pages list I/O APIC support, but if you look in
    > the datasheets for current products you find zero APIC support.

    My board is 2 years old (May 2003).

    I've checked the specs [2] and they say (page 17 out of 83)
    "APIC will be available in future steppings." Yeah right...

    Mine is stepping 1 according to /proc/cpuinfo.

    So if I don't have APIC, that means I cannot use nmi_watchdog to
    investigate the problem, right?

    Do I have any alternative to investigate this hang or should I just
    give up and smash my board?



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