# athlon xp 64 march flag



## lesho (Jan 7, 2010)

hi, 
i have following im my /etc/make.conf:


```
CPUTYPE?=k8 # CPUTYPE=k8 ## this doesn't work too
CFLAGS= -O2 -fno-strict-aliasing -pipe -fomit-frame-pointer -funroll-loops
```

is there any limitations for this architecture according to program compilation with gcc in freebsd?
why compiler sets "-march=athlon-mp" instead of "-march=k8", or, how can i fix it?


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## SirDice (Jan 7, 2010)

You're better off not using them. The gains are marginal at best and when you run into problems first thing anyone will suggest is to remove them.


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## mk (Jan 7, 2010)

there was a time that i wanted too, to do such optimization, esecialy when i was building kernel/world and watching thous 3dnow support bla bla.. flashing. make some research and first - such optimization flags as 3dnow, mmx etc.. for kernel/world are not desireable. second for userland.. too much effort to gain little. if someone doesnt make optimization whilie he is writing the code, then no reason to try optimize bad code. plus there is time when you cant optimize your problem ( let say spaning on more than two cores .. ) 

P.S. bad english as usual but to much beer in cold room - body worm - finghers not


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