Timer interrupt lost on some x86_64 systems

Vivek Goyal vgoyal at in.ibm.com
Wed Nov 14 01:39:39 EST 2007

On Tue, Nov 13, 2007 at 09:33:30AM -0500, Neil Horman wrote:

> > In the past I have found issues with interrupt routing on IOPAPIC and
> > interrupt lockup on LAPIC. But these issues are already solved. I would
> > also think of priting LAPIC and IOAPIC entries to see how timer interrupt
> > routing changes from first kernel to second.
> > 
> I recently read the ioapic section in the opteron processor guide and noted the
> ioapic routing field in the config registers, so I'll be looking at that.  We
> also not that in the failing case on the systems in question the boot cpu is
> _not_ the cpu that boots the kdump kernel, and its APIC ID is 1 not 0, IIRC

Failing on non-boot cpu should not be an issue. I had fixed an issue in the
past where non-boot cpu was not receiving the timer interrupts because of
IOAPIC settings where timer interrupts were always routed to boot cpu (cpu0).

Now it has been modified and while going down we determine which cpu we
are crashing on and setup IOAPIC entry accordingly. See disable_IO_APIC().


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