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List:       linux-kernel
Subject:    Re: [patch]K6-2/K-III compile option
From:       Jeff Garzik <jgarzik () pobox ! com>
Date:       1999-09-30 23:38:37
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Michael Cummins wrote:
> Maybe I'm mixed up but I thought the K6 didn't have anything like mmx,

K6, K6-2, and K6-III all support MMX.


> But the 3DNow instructions set in the -2 and -3 version was AMD's
> alternative to mmx.

MMX is integer math, 3Dnow is floating point.


> I think I can guess that what you actually mean is that gcc only has two
> AMD style options.
> -march=k6 means k6 without any mmx-stlye instructions
> -march=k7 means Athlon with mmx and SIMD style instruction

The recently-merged new_ia32_branch of gcc supports -march=k6.  There is
no '-march=k7' currently.


> Shame there's not a -march=mmx alternative which covers both
> pentium MMX, K6-2, and K6-3.  Though I suppose the instructions
> sets are different so this would cause a problem.
> 
> What about -march=3dnow???  Would that be more plausible?

There is no MMX or 3Dnow support currently in gcc.  Three separate
patches exist which add minimal MMX support to gcc, but none have been
integrated into the mainline.

Regards,

	Jeff



-- 
Custom driver development	|    Never worry about theory as long
Open source programming		|    as the machinery does what it's
				|    supposed to do.  -- R. A. Heinlein

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