| 1 |
On 9/26/06, Daniel Iliev <danny@××××××××.com> wrote: |
| 2 |
> Hello, everyone! |
| 3 |
|
| 4 |
Hi :) |
| 5 |
|
| 6 |
> 1) I use CFLAGS="-march=athlon64 -mfpmath=sse -msse -msse2 -msse3 |
| 7 |
> -m3dnow -mmmx -O3 -fomit-frame-pointer -pipe -fpic". Portage complains |
| 8 |
> with *red letters* about the fpic flag. Every time I emerge something it |
| 9 |
> says that "fpic breaks things", but I haven't met a single breakage so |
| 10 |
> far. Is that a bug? Actually there was an ebuild which could not be |
| 11 |
> compiled if mysql was compiled w/o "fpic". I'm not 100% sure but AFAIR |
| 12 |
> it was dev-perl/DBD-mysql. |
| 13 |
|
| 14 |
It is not necessary to tell gcc to use special instruction sets for |
| 15 |
your processor. When you specify -march gcc automatically knows |
| 16 |
exactly what instructions your processor is capable of utilizing most |
| 17 |
effectively. |
| 18 |
|
| 19 |
I am not familiar with PIC, but if portage gives a big red warning |
| 20 |
about explicitly enabling it in your CFLAGS I'm sure that there have |
| 21 |
been problems with it. If a package requires the flag then it should |
| 22 |
enable it in its own local CFLAGS. |
| 23 |
|
| 24 |
> 2) I see too many flags that are disabled by the profile - the kind with |
| 25 |
> the parenthesis around them, like "(-3dnow)". Why? As I mentioned above |
| 26 |
> I enable some of these through my CFLAGS - e.g. (-mmx), (-mmxext), |
| 27 |
> (-sse) and (-sse2) and everything works perfect. |
| 28 |
|
| 29 |
A 3dnow instruction path isn't always the best optimization for every |
| 30 |
user and every package. Also, AMD's Athlon and Opteron processors are |
| 31 |
not the only ones supported under the amd64 arch, there are also |
| 32 |
Intel's x86-64 processors to consider. While I imagine that Intel |
| 33 |
processors can execute 3dnow instructions I also imagine that SSE |
| 34 |
would be faster. |
| 35 |
-- |
| 36 |
gentoo-amd64@g.o mailing list |
Archives