mcpu vs march

Spaz17 · 12-30-2003, 11:21 PM

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?

synaptical · 12-30-2003, 11:36 PM

well, what processor do you have?

Spaz17 · 12-30-2003, 11:43 PM

athlon xp
1700+

slakmagik · 12-30-2003, 11:46 PM

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*

Spaz17 · 12-30-2003, 11:50 PM

digiot: so youre saying that march will cancel out mcpu, therefore dont use -mcpu=athlon-xp, and use -march=athlon-xp ?

slakmagik · 12-31-2003, 12:02 AM

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.

Demonbane · 12-31-2003, 12:28 AM

check out this article:
http://freshmeat.net/articles/view/730