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DragonFly users List (threaded) for 2005-03
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Re: stable GCC 3.4 configurations

From: Andreas Hauser <andy@xxxxxxxxxxxxxxx>
Date: 16 Mar 2005 19:50:55 -0000

dragonflybsd wrote @ Wed, 16 Mar 2005 19:02:11 +0100:
> Hi all,
> I've just built a DragonFly_Stable system with gcc 3.4 using CPUTYPE=p4 
> and -O2 optimization. The resulting kernel still bootet, but the overall 
> system was very unstable and therefore unusable.

Should be stable without CPUTYPE.

> Are there any flags that are reasonable save for 'make buildworld' and 
> 'make buildkernel' with gcc 3.4?
> Should different optimizations be used for buildworld and buildkernel to 
> achieve best performance without sacrificing stability?

For the kernel just use the defaults, there is not much to optimize!
(At least for stuff i tested.)

Usually anything besides -O2 or -Os is not worth the trouble.

If you have a special app you that you want to optimize:

-fno-stack-protector	you sacrifice buffer overflow protection

-fomit-frame-pointer	you sacrifice debugging

-O3	will usually not yield much more if not less than -O2
	and is more dangerous

-march=$arch	not always is the correct arch the best

-msse -msse2 -mfpmath=sse 	especially for some floating point weak cpus


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