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Re: [Sheflug] CFLAGS and USE Question
Wonkey Donkey wrote:
Im doing some compiling on my laptop, which is a P4M 2.4 processor.
I've found stacks of recommendations on various sites for the CFLAGS
setting, which is all beginning to get rather confusing.
What I've come up with now is:
-march=pentium4 -O2 -fomit-frame-pointer -mmmx -msse -mfpmath=sse
Is there anybody who knows enough about it to see if the above is reasonable
or even good for the CPU I have ?
That looks quite reasonable to me. I don't have a P4 (went for AMD64),
but -O2 seems to be the best all round option for most applications etc.
I think -march=pentium4 turns on '-mmmx -msse -mfpmath=sse' (at least
the first two) but it won't hurt for you to put it in too as far as I am
aware.
-fomit-frame-pointer seems to work well for most people, although it does make debugging virtually impossible. This isn't usually a problem unless you are trying to report bugs on a particular application.
Is there anything you would add to, or remove from, the line above ?
The first one I tried is:
-march=pentium4 -O3 -pipe -fomit-frame-pointer -fforce-addr -falign-function
s=4 -mmmx -msse -msse2 -mfpmath=sse -fprefetch-loop-arrays
But this seemed to barf a lot of the time.
Those flags are very aggressive, and many seem to believe -O3 does
little or nothing to improve speed (in some cases it seems to make it
worse) and it increases both executable size and compile time significantly.
The USE setting is currently :
acpi alsa avi cdr cups dvd encoder gnome gphoto2 gpm gtk gtk2 java jpeg kde
mmx mozilla mpeg png qt sse ssl tcltk tetex truetype usb X xosd xml xml2
xmms xv zlib x86
I *think* this one is quite reasonable, as I want to build it up to a fully
featured system with a good all round spread of applications.
That looks reasonable to me.
Any help much appreciated!
(This is for a new Gentoo install BTW).
You should be OK with what you have selected. I have an AMD64 install
with similar CFLAGS (although 64 bit compiled and a 32 bit chroot) and
it works fine. Also had a PIII with very similar that worked great until
it stopped posting :(
Give it a try - you should be fine. There is lots of help available on
the Gentoo forums and mailing lists too if you need it. They are a great
source of help and information.
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