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Old 12-31-2003, 12:21 AM   #1
Spaz17
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mcpu vs march


im installing gentoo and am to the point where i edit /etc/make.conf

i want to change the flags (-mcpu and -march) of my processor to make it run more efficiently, but i dont know if i can use both ot them at the same time, because of how they deal differently with compatability with other processors

my question is this:
can i use both flags at the same time?
and if not: then which should i use?

looking around, some people use both, some only use march, and i have no idea

help?

Last edited by Spaz17; 12-31-2003 at 12:23 AM.
 
Old 12-31-2003, 12:36 AM   #2
synaptical
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well, what processor do you have?
 
Old 12-31-2003, 12:43 AM   #3
Spaz17
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athlon xp
1700+
 
Old 12-31-2003, 12:46 AM   #4
slakmagik
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I think -mcpu and -march are exclusive because -mcpu limits optimization to the point of retaining compatibility with others while -march breaks it. So -march would max it out. Or -march would override -mcpu, anyway.

Could be totally wrong, of course, but I think that's the deal. *g*
 
Old 12-31-2003, 12:50 AM   #5
Spaz17
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digiot: so youre saying that march will cancel out mcpu, therefore dont use -mcpu=athlon-xp, and use -march=athlon-xp ?
 
Old 12-31-2003, 01:02 AM   #6
slakmagik
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If you want maximum optimization, I believe so, yes. -march=athlon-xp should be sufficient. But be sure that you know your processor type. And, while I hate to say it, you might do better to post at (or search) the Gentoo forums for this particular issue to be absolutely certain. This is just my understanding.
 
Old 12-31-2003, 01:28 AM   #7
Demonbane
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check out this article:
http://freshmeat.net/articles/view/730
 
  


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