GCC 3.2.1 Optimizations and Via C3 Ezra CPU
cheeziologist at mail.isc.rit.edu
Sat Feb 14 19:29:51 PST 2004
On Sat, 14 Feb 2004 21:04:36 -0600, Bryan K. Walton <zxcvbnm at tds.net>
> I have a question regarding compiler optimizations for the Via
> C3 Ezra processor. I did a little searching around on the web and found
> CFLAGS="-march=i586 -m3dnow -O3 -pipe -fomit-frame-pointer"
> CXXFLAGS="-march=i586 -m3dnow -O3 -pipe -fomit-frame-pointer"
> Now, that makes sense to me. However, when I issue a "uname -m" on
> this box, it reports that it is a i686. And sure enough, when I
> compile gcc on this box, without any optimizations, it seems to be
> identifying the host as i686-pc-linux-gnu. Any ideas what might be
> going on here. Is gcc incorrectly identifying hardware on the box?
> I'm using GCC 3.2.1. Or can I specify i686 in those three
> optimization lines?
> Bryan Walton
IIRC the C3 processor is a 686 processor but it lacks the CMov instruction
that other 686 processors have. Thus default i686 instructions will call
CMOV and you will get an error stating an illegal instruction has been
called. I also seem to remember hearing that newer C3's didnt have this
problem. Take what I say with a grain of salt, as I'm trying to recall all
this from memory.
Registered LFS User 6929
Registered Linux User 298182
More information about the lfs-support