3dnow, mmx, k6-2 optimizing?

Erik Trulsson ertr1013 at student.uu.se
Mon Sep 13 10:30:32 PDT 2004

On Mon, Sep 13, 2004 at 12:23:18PM -0500, Puna Tannehill wrote:
> I've been looking for possible flags, optimizations, really anything 
> that would help me setup my laptop to use mmx and 3dnow.  I've updated 
> /etc/make.conf to -march to the drum of a k6-2, but I'm not even sure 
> if mmx and 3dnow are being taken into consideration for compiling and 
> such, especially for Xorg.
> I did some googling and found people who used CFLAGS like -mmmx and 
> -m3dnow, but when I run with those options, they fail and said to be 
> invalid.  they don't appear in 'man gcc' which should have been the 
> first place i looked.  I'm not finding anything in terms of compiling 
> or configuring Xorg to use 3dnow or mmx, or even how to check to see 
> if they are automatically detected and used.
> Any thoughts?

You do not say which version of FreeBSD or GCC you are using.
Gcc 2.95 (which is what FreeBSD 4.x ships with) do not know about MMX
or 3Dnow, and will not take advantage of them.
Gcc 3.4 (which is what FreeBSD 5.x comes with) does know about MMX and
3DNow and will take advantage of them when invoked correctly.
The switches you mention (-mmx and -m3dnow) are valid for gcc 3.4 but
not for gcc 2.95.

You can look at the GCC documentation found at
http://gcc.gnu.org/onlinedocs/ to find out what options are supported
by which versions of GCC.

<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se

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