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From: Andi Kleen <andi@firstfloor.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux@sandersweb.net, linux-kernel@vger.kernel.org,
	the arch/x86 maintainers <x86@kernel.org>,
	Andi Kleen <andi-suse@firstfloor.org>
Subject: Re: [BUG] x86 kenel won't boot under Virtual PC
Date: Mon, 8 Sep 2008 19:18:58 +0200	[thread overview]
Message-ID: <20080908171858.GQ26079@one.firstfloor.org> (raw)
In-Reply-To: <alpine.LFD.1.10.0809081000490.3117@nehalem.linux-foundation.org>

> Btw, I do think that the whole NOPL issue is separate from all the other 
> issues. There can be _other_ cases where it really is worth doing some 
> "generic" optimizations or being more "specific", and my argument really 
> is that NOPL is _not_ one of those cases.
> 
> So I'm still not sure that X86_GENERIC is necessarily the answer. The 

FWIW I personally think Linux should always use very conservative nops. 
Unconditionally. This issue already cost far too much developer time
and it's unlikely to be worth it.

> Peter - does gcc actually use NOPL in _32-bit_ code too? It really seems 

gcc just uses .p2align, so it comes down to binutils

Yes there seems to be a pretty scary ISA selection code in there.

Line 565 of

http://www.google.com/codesearch?hl=en&q=i386_align_code+show:pxieOi43ptA:OXGjJbna8V8:zfd_fdPYgEI&sa=N&cd=1&ct=rc&cs_p=http://gentoo.osuosl.org/distfiles/binutils-2.17.50.0.13.tar.bz2&cs_f=binutils-2.17.50.0.13/gas/config/tc-i386.c

I haven't decoded it completely, but I suspect it does the wrong thing.

-Andi

      parent reply	other threads:[~2008-09-08 17:15 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-31 18:22 [BUG] x86 kenel won't boot under Virtual PC David Sanders
2008-08-31 18:47 ` Linus Torvalds
2008-08-31 19:27   ` Arjan van de Ven
2008-08-31 19:39     ` Linus Torvalds
2008-09-05 15:38       ` David Sanders
2008-09-05 16:15         ` Jan Beulich
2008-09-05 16:39           ` Linus Torvalds
2008-09-05 18:43             ` Ingo Molnar
2008-09-05 20:06               ` H. Peter Anvin
2008-09-05 19:08             ` Jeremy Fitzhardinge
2008-09-05 20:12           ` H. Peter Anvin
2008-09-05 16:30         ` Linus Torvalds
2008-09-05 17:55           ` Andi Kleen
2008-08-31 20:03   ` David Sanders
2008-09-01 20:23     ` David Sanders
2008-09-01 22:22       ` Linus Torvalds
2008-09-02 12:08         ` David Sanders
2008-09-02 18:12           ` Linus Torvalds
2008-09-02 18:44             ` David Sanders
2008-09-03 11:09               ` Peter Zijlstra
2008-09-03 11:20                 ` David Sanders
     [not found] ` <48C1C156.9080003@zytor.com>
2008-09-07 20:07   ` David Sanders
2008-09-07 23:22     ` David Sanders
2008-09-08  1:48       ` H. Peter Anvin
2008-09-08  2:49         ` David Sanders
2008-09-08  4:04           ` H. Peter Anvin
2008-09-08  9:42             ` Andi Kleen
2008-09-08 13:25             ` David Sanders
2008-09-08 15:09             ` Linus Torvalds
2008-09-08 15:23               ` Ingo Molnar
2008-09-08 15:36                 ` H. Peter Anvin
2008-09-08 15:38                 ` David Sanders
2008-09-08 15:38                 ` H. Peter Anvin
2008-09-08 15:45               ` Andi Kleen
2008-09-08 15:43                 ` H. Peter Anvin
2008-09-08 15:50                   ` H. Peter Anvin
2008-09-08 15:50                   ` Andi Kleen
2008-09-08 15:50                     ` H. Peter Anvin
2008-09-08 15:57                       ` Andi Kleen
2008-09-08 15:54                         ` H. Peter Anvin
2008-09-08 16:07                   ` Linus Torvalds
2008-09-08 16:13                     ` H. Peter Anvin
2008-09-08 16:15                       ` H. Peter Anvin
2008-09-08 16:26                         ` David Sanders
2008-09-08 16:20                       ` Linus Torvalds
2008-09-08 16:32                         ` H. Peter Anvin
2008-09-08 17:02                           ` Ingo Molnar
2008-09-08 16:34                         ` david
2008-09-08 16:42                           ` H. Peter Anvin
2008-09-08 18:51                             ` david
2008-09-08 16:59                           ` Linus Torvalds
2008-09-08 17:00                         ` Andi Kleen
2008-09-08 17:04                           ` Linus Torvalds
2008-09-08 17:08                             ` H. Peter Anvin
2008-09-08 17:12                               ` H. Peter Anvin
2008-09-08 17:41                                 ` Linus Torvalds
2008-09-08 17:38                               ` Linus Torvalds
2008-09-08 17:59                                 ` H. Peter Anvin
2008-09-08 19:09                                 ` H. Peter Anvin
2008-09-08 22:42                                   ` Linus Torvalds
2008-09-08 17:18                             ` Andi Kleen [this message]

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