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Re: [Xen-devel] Re: [PATCH] x86: fix the potential of encountering panic

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] x86: fix the potential of encountering panic "IO-APIC + timer doesn't work! ..."
From: Ingo Molnar <mingo@xxxxxxx>
Date: Fri, 12 Dec 2008 10:24:41 +0100
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* Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:

> On 12/12/2008 09:13, "Ingo Molnar" <mingo@xxxxxxx> wrote:
> >>> From all I can tell, the below reproduced full description of the
> >> original Linux patch applies to Xen, too - at least in the watchdog
> >> enabled case IRQs can be enabled when entering setup_IO_APIC(). My
> >> attention to this change really got caught just by the fact that it got
> >> added to our (2.6.16-based) SLE10 kernel pretty recently.
> > 
> > note that we had to revert that eventually. The real solution is an 
> > array of fixes from Maciej spread out over many months.
> Does it do more harm than good on some systems, or is it simply not a 
> comprehensive fix?

more harm than good - fixes some, breaks others. Have a look at the 
latest upstream io_apic.c, that has it all settled down reasonably well.


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