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Date: Sun, 16 Dec 2012 21:39:13 +0100
From: Borislav Petkov <bp@alien8.de>
To: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Cc: Yinghai Lu <yinghai@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        linux-kernel@vger.kernel.org, Weidong Han <weidong.han@intel.com>,
        David Woodhouse <David.Woodhouse@intel.com>
Subject: Re: [regression] 3.7 ends in APIC panic
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On Sun, Dec 16, 2012 at 08:46:06PM +0100, Bernd Schubert wrote:
> Hmm, I read it the other way around - x2apic depends on interrupt
> remapping, but interrupt remapping can be used without x2apic.

Ok, you're right. X2APIC should depend on IRQ_REMAP:
https://lwn.net/Articles/289881/

> The help text of CONFIG_IRQ_REMAP also says "x2APIC enhancements or to
> support platforms with CPU's having > 8 bit APIC ID, say Y." I guess
> may CPU has the latter?

I think it is what Yinghai said - you obviously need x2apic kernel
support if you have IRQ_REMAP on.

> Can the kernel panic a bit improved to help user to understand what
> needs to be enabled?

Well, your kernel enables IRQ_REMAP properly:

[    0.031115] Enabled IRQ remapping in x2apic mode

I guess at that stage we could probably check for x2apic support and
scream loudly if it is not present... IMHO.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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