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From: David Sanders <linux@sandersweb.net>
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To: linux-kernel@vger.kernel.org
Subject: Re: [BUG] x86 kenel won't boot under Virtual PC
Date: Mon, 8 Sep 2008 12:26:35 -0400
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Cc: "H. Peter Anvin" <hpa@kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andi Kleen <andi@firstfloor.org>,
       the arch/x86 maintainers <x86@kernel.org>,
       Andi Kleen <andi-suse@firstfloor.org>
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On Monday 08 September 2008 12:15, H. Peter Anvin wrote:
> H. Peter Anvin wrote:
> > The issue at hand is that at least with the current toolchain, we need
> > to pass -march=generic in order for these instructions to be generated.
> >  We have an option for this, CONFIG_X86_GENERIC, which distributions
> > really *should* be using anyway.
>
> That should have been "-mtune=generic".  Sorry.
>
> > And yes, it should be the default.  The patch I have makes it
> > "default y" as well as change the help text.
> >
> > Would it make you happier if this option was forced enabled unless
> > CONFIG_EMBEDDED was on?
>
> I guess the other option is to create a new option for selecting the
> dangerous -mtune= variants, and possibly lock *that* option to
> CONFIG_EMBEDDED.
>
> 	-hpa

The option that works best for users is for the kernel to not use NOPLs on 
32-bit cpu's.  That is what Linus's patch accomplishes.  I am not having any 
issues with gcc or gas generating NOPLs.  The kernel should work out of the 
box for PentiumPro or later cpu's running in 32-bit mode.  I think you are 
trying to over-engineer the issue.  Just apply the patch and move on.
David