PATCH/RFC: [kdump] fix APIC shutdown sequence

[Martin Wilck]

Eric W. Biederman wrote:

>> I think a lot would be gained if disable_IO_APIC() would just mask the IRQs
>> (like the function in my patch does), and perhaps fix the dest ID, instead of
>> totally clearing the registers.
> 
> Even masked we still won't see the EOI, because then we are in i8259
> mode.  So masked versus totally cleared really should make no
> difference.

You are talking about EOI sent in the kdump kernel, correct? With my patch
the EOI (sent in the "old" kernel) is seen.

> I guess right now I can see work put into cleaning things up a little
> or not having to call disable_IO_APIC() at all.  that was supposed
> to be a short term hack, until we fixed things properly.
> 
> So far no one has been brave enough to mess with the kernel apic
> initialization order so we can remove disable_IO_APIC.  If our
> goal isn't to fix things properly by removing the need for
> disable_IO_APIC I don't feel like putting much effort into this
> code path.

Who is working on this? Can you give a reference to a list of things that
would need to be done to do this right?

Martin

-- 
Martin Wilck
PRIMERGY System Software Engineer
FSC IP ESP DE6

Fujitsu Siemens Computers GmbH
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