linux-kernel - Re: [rfc patch] x86,apic: fix DEBUG_PREEMPT gripe when booting with threadirqs=1

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Message-ID: <1309091594.11217.18.camel@marge.simson.net>
Date:	Sun, 26 Jun 2011 14:33:14 +0200
From:	Mike Galbraith <mgalbraith@...e.de>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [rfc patch] x86,apic: fix DEBUG_PREEMPT gripe when booting
 with threadirqs=1

On Sun, 2011-06-26 at 12:45 +0200, Ingo Molnar wrote:
> * Mike Galbraith <mgalbraith@...e.de> wrote:
> 
> > x86,apic: fix DEBUG_PREEMPT gripe when booting with threadirqs=1
> > 
> > If CONFIG_PREEMPT and CONFIG_INTR_REMAP are both set, and a box is
> > booted with threadirqs, the gripe below is emitted.  It was suggested
> > that native_smp_prepare_cpus() shouldn't need to be run with preemption
> > disabled, and indeed, box boots with no hint of trouble.  Remove it.
> 
> Would also require a careful review of the code we take out of 
> preempt protection now - have you done that by any chance? (if not, 
> mind doing it?)

No, I haven't, I have only empirical evidence of having yet to see any
nastiness with an RT kernel.

I'll crawl through it once I get a couple PCI configuration space
thingies sorted.  I'm rather expecting to then find out why
INTR_REMAP/DMAR + X2APIC is disabled.. the head-on collision way.

	-Mike

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