Timer interrupt lost on some x86_64 systems

Neil Horman nhorman at redhat.com
Wed Nov 14 06:51:32 EST 2007

On Wed, Nov 14, 2007 at 12:09:39PM +0530, Vivek Goyal wrote:
> 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().

I see the call to it in machine_crash_shutdown, but for whatever reason, it
doesn't seem to be having the desired effect in this case....hmmmmm...


> Thanks
> Vivek

 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman at redhat.com
 *gpg keyid: 1024D / 0x92A74FA1

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