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Date: Fri, 05 Sep 2008 13:06:06 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Ingo Molnar <mingo@elte.hu>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
       Jan Beulich <jbeulich@novell.com>, linux@sandersweb.net,
       Andi Kleen <andi-suse@firstfloor.org>,
       Arjan van de Ven <arjan@infradead.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] x86 kenel won't boot under Virtual PC
References: <200808311422.12525.linux@sandersweb.net> <20080831122751.72afafb5@infradead.org> <alpine.LFD.1.10.0808311237290.12958@nehalem.linux-foundation.org> <200809051138.20615.linux@sandersweb.net> <48C17754.76E4.0078.0@novell.com> <alpine.LFD.1.10.0809050931340.3117@nehalem.linux-foundation.org> <20080905184353.GA29496@elte.hu>
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Ingo Molnar wrote:
> * Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
>>  - Move the optimized nop definitions (K7_NOPx etc) to the only place that 
>>    cares - asm/x86/kernel/alternative.c. When we do things _dynamically_, 
>>    it can actually make sense to pick a nop more precisely, but for this 
>>    whole static thing it's just a pain.
>>
>> IOW, if it actually _worked_ reasonably, I wouldn't care. But clearly 
>> it doesn't. And once it's not working reasonably, it should be fixed.
> 
> yes - we had 3-4 tries already and while it looked worthwile initially 
> it's clearly not showing signs of getting more robust and whatever 
> benefits there might be slightly better NOPs is dwarved by all these 
> robustness problems. Peter?

There is already a fix for this based on a first-principles test in tip.

	-hpa