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Date: Wed, 05 Feb 2014 09:36:03 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>,
        Meelis Roos <mroos@linux.ee>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: 3.13: BUG: unable to handle kernel paging request at 00000000b4343e88
References: <alpine.SOC.1.00.1401211228410.25614@math.ut.ee> <20140121141037.f76dba61212c5597ff733207@linux-foundation.org> <alpine.SOC.1.00.1401221731150.3033@math.ut.ee> <52E26EF3.1090901@linux.vnet.ibm.com> <alpine.SOC.1.00.1401242249540.16252@math.ut.ee> <52E68111.6010005@linux.vnet.ibm.com> <alpine.SOC.1.00.1401280832500.5459@math.ut.ee> <52E918C9.7030408@linux.vnet.ibm.com> <alpine.SOC.1.00.1401292242390.12718@math.ut.ee> <52EBC65C.5020404@linux.vnet.ibm.com> <52F26E21.8000101@linux.vnet.ibm.com>
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On 02/05/2014 09:00 AM, Peter Oberparleiter wrote:
> 
> Could you give this patch a try? It is a variation of the approach
> proposed in the discussion mentioned earlier and fixes the problem
> on my system.
> 

I would rather suggest that we explicitly disable gcov etc. from these
kinds of small, magic primitives.  Honestly, you're just trying to put a
bandaid on a gaping wound.

The real thing here is that hweight.c is not a normal C file, and we
shouldn't treat is as such.  It is a constrained environment, and trying
to tack crap like gcov to it is bound to lose, simply because gcov
doesn't know the rules it has to play by.

Even with the below change, if gcov clobbers, say, %rdx we're still screwed.

	-hpa

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