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Date: Mon, 30 Mar 2009 22:29:41 +0100
From: Dave Korn <dave DOT korn DOT cygwin AT googlemail DOT com>
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Subject: Re: gcc4: missing atomic builtins?
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Corinna Vinschen wrote:

> The last i586 was built in 1999 and had a 300 MHz clock rate.  The i686
> has been introduced in 1995 and in 1999 the P3 had a minimum clock rate
> of 450 MHz.
> 
> I don't think we really need a default compiler and a default installation
> sticking to the old i586 design any longer.  And, btw, is there any
> Linux distro still using a i586 compiler?
> 
> If there are really still i586 users out there, hey, it's all available
> in sources.


  Right.  I'll set i686 as the default arch.  If anyone really does want to
run Cygwin on an i586, they will be SOL, as it's entirely possible they won't
be able to run the DLL or anything because everything in the distro will use
instructions that their CPU doesn't handle; they'll have to stick with 1.5, or
cross-boostrap the entire distro themselves starting from scratch.

  To Andy's previous post: I think the documentation suggests we want to use
-mtune=generic for the best results across the broadest range of CPUs.  At the
moment, generic and i686 are basically the same, but since -march sets the
*minimum* level CPU whereas mtune is aimed at the *typical* CPU (since it will
only pessimise, not break anything if incorrct) I think it makes sense to
anchor -march and let -mtune float.

    cheers,
      DaveK

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