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Date: Sat, 3 May 2008 21:54:48 +0200
From: Ingo Molnar <mingo@elte.hu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Mikael Pettersson <mikpe@it.uu.se>,
       jamal <hadi@cyberus.ca>, Suresh Siddha <suresh.b.siddha@intel.com>,
       Arjan van de Ven <arjan@linux.intel.com>,
       LKML <linux-kernel@vger.kernel.org>, Jan Beulich <jbeulich@novell.com>
Subject: Re: i387/FPU init issues...
Message-ID: <20080503195448.GE25097@elte.hu>
References: <1209810775.6972.37.camel@localhost> <alpine.LFD.1.10.0805031650120.6003@apollo.tec.linutronix.de> <481CA40A.7040906@zytor.com> <alpine.LFD.1.10.0805032017290.6003@apollo.tec.linutronix.de> <18460.46554.826031.184323@harpo.it.uu.se> <481CB82D.60404@zytor.com> <alpine.LFD.1.10.0805032115330.6003@apollo.tec.linutronix.de> <481CBBF2.4090501@zytor.com>
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* H. Peter Anvin <hpa@zytor.com> wrote:

>> This might also be caused by a calibration error. We've seen enough 
>> of them already.
>
> No doubt.  However, there is *something* ugly going on.

i think a vital clue can be found in the original report:

|  I am able to reproduce the issue consistently on my laptop using qemu 
|  (which helped speed debugging a bit). I have also narrowed it down to 
|  include/asm-x86/i387.h::__save_init_fpu in (32 bit version) - it dies 
|  somewhere in calling the following line:

so it might just be incorrect Qemu emulation of a PII's NOP instruction?

(which btw. probably proves that Linux is the first OS to make 
intelligent use of those instructions?)

	Ingo