Re: enabling IOAPIC on C3 processor? (how to investigate hangs without nmi watchdog)

[jerome lacoste]

On Tue, 15 Mar 2005 13:34:55 +0100, Mikael Pettersson <mikpe@xxxxxxxxx> 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.
>  > (http://www.via.com.tw/en/products/processors/c3/specs.jsp)
>  >
>  > 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?

Cheers,

Jerome

[2] http://www.via.com.tw/en/downloads/datasheets/processors/c3_nehemiah.zip
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