Sam Ravnborg wrote:
> On Thu, Jul 24, 2003 at 09:16:17AM +0200, Michal Semler wrote:
>
>>Hello,
>>
>>I use gcc-3.3 and I would like compile my kernel with flags:
>>
>>-O4 -march=pentium3 -mcpu=pentium3
-mcpu is taken care of by -march in gcc3
-O4 does nothing, -O3 is the highest gcc3 goes, and -O3 does cause
problems with certain code.
I'd suggest also -ftracer as it is supposed to help your standard -O2
level optimizations do their jobs. How well, probably not very noticable
in real life, but then neither is -march=pentium3 over i686.
>>Is there any way to do this?
>
> Only way to specify -O4 is to manually edit top-level Makefile.
> Change the assignment to CFLAGS (not hOSTCFLAGS as someone suggested).
>
> The -m options are set in arch/i386/Makefile.
> The best way to set them is to select the correct processor type.
>
> Sam
>
basically, makefiles are supposed to add the value of CFLAGS to their
flag variable. CXXFLAGS for c++ arguments. But i understand why the
kernel doesn't do this since it needs strict management over the build.
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