Linux compilation opt-flag?

**BFlurie** · December 24th, 2002, 02:03 PM

A minor issue 'cause I can't see much difference with compiling opt-flags, but would a K6-3 w/on-board cache be best modeled as an i586, i686, or perhaps even an Athlon?

I use the K6 flag for the kernel, which works fine, but gcc-2.95 doesn't define the K6 flag for general program source compiling, so I have to choose something else.

**pbharris** · December 24th, 2002, 03:39 PM

hello,
for my k6 i use CFLAGS="-march=i586"

edit! forgot closing quote mark!

**BFlurie** · December 25th, 2002, 06:43 AM

I wonder if the i586, i686, k6, etc. flag in itself does anything or is only an identifier. Perhaps the only real "tweaks" are the flags like -- fomit-frame-pointer, pipe, preferred-stack-boundary=2, etc.

**Scott Tiger** · December 25th, 2002, 08:41 AM

Supposedly there's some preformance to be gained by compiling for you chip architecture but that's just what I've heard. This:

export CFLAGS="-O2 -march=i686 -fomit-frame-pointer -malign-functions=4 -mpreferred-stack-boundary=2"
export CXXFLAGS=$CFLAGS

Is what I've put into my .bash_profile so that when I compile it builds this way for all source packages.

Merry Christmas..

**BFlurie** · December 25th, 2002, 12:12 PM

Mine's similar. Whatcher CPU?

**storm2k** · December 27th, 2002, 03:15 AM

ok, i have an athlon xp... could i put into my profile -march=athlon and get this supposed speed increase?

i'd also LOVE to get rpm rebuilds to better work with that... they don't too well unfortunately...

**Praetorian** · December 27th, 2002, 04:22 AM

-march="i686" would be correct, I think.

**KraM** · December 27th, 2002, 04:55 AM

go here for people obsessed with compiler flags

**storm2k** · December 28th, 2002, 03:06 PM

see that's confusing me. have they depreciated the -march athlon thing nowadays?

where's otheos when you need him? :P he knows all about this stuff...