Re: [tip:x86/debug] x86/kdump: No need to disable ioapic/ lapic incrash path

From: Don Zickus
Date: Fri Feb 17 2012 - 14:55:01 EST


On Fri, Feb 17, 2012 at 04:41:01AM -0800, Eric W. Biederman wrote:
>
> The fix with a guarantee of no more scope creep is to just disable the
> nmi watchdog on the kexec on panic path.
>
> Don if you have time please figure out is needed to ignore nmi's and
> possible record and/or report them while we boot, otherwise please cook
> up a patch that just disables the nmi watchdog wherever we are sending
> it from (the local apic or the ioapic).

Can I keep things even simpler? The original problem was the deadlock
with the ioapic lock. We fixed that by removing the call to
disable_IO_APIC(). Can we just leave the disable_local_APIC calls in
there for now? Is there any real harm?

All this rewrite is going to take time which will delay fixing a current
problem with kexec on panic, the ioapic deadlock.

Thoughts?

Cheers,
Don
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