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Subject: Re: Noob question. Why is the for-pentium4 kernel built
	with	-march=i686 ?
From: Kerin Millar <kerframil@gmail.com>
To: ivan@yosifov.net
Cc: linux-kernel@vger.kernel.org
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Date: Wed, 20 Jul 2005 10:44:02 +0100
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On Wed, 2005-07-20 at 11:23 +0300, Ivan Yosifov wrote:
> On Wed, 2005-07-20 at 09:03 +0100, Kerin Millar wrote:
> > On Tue, 19 Jul 2005 21:35:51 +0300, Ivan Yosifov wrote:
> > 

<snip>

> > Also, I believe that the -march=pentium4 option /was/ actually used up
> > until kernel 2.6.10 where it was dropped because of a risk that some
> > versions of gcc would cause the kernel to use SSE registers for data
> > movement (which is a no-no).
> > 
> 
> You seem right. I fetched a 2.6.9 tarball and it is really built with
> -march=pentium4. Do you know which are versions of gcc in question ?
> 

No, I'm afraid not. I only know that the advice came from Richard
Henderson who (I think) is one of the core glibc hackers. You can see
the point at which it was introduced by Linus in the ChangeLog (2nd
message from last):

http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.10

Cheers,

--Kerin Millar