Re: [gentoo-user] gcc 4.2.4 fails to build

[Steffen Loos]

Roger Mason schrieb:
> Hello,
>
> I need to build gcc 4.2 on a core 2 duo system.  The only 4.2.x version
> is 4.2.4, which is masked by ~.  When I try to build it fails:
>
> ...
> /var/tmp/portage/sys-devel/gcc-4.2.4-r1/work/build/./gcc/xgcc -B/var/tmp/portage/sys-devel/gcc-4.2.4-r1/work/build/./gcc/ -B/usr/x86_64-pc-linux-gnu/bin/ -B/usr/x86_64-pc-linux-gnu/lib/ -isystem /usr/x86_64-pc-linux-gnu/include -isystem /usr/x86_64-pc-linux-gnu/sys-include -O2  -O2 -O2 -march=core2 -pipe  -DIN_GCC    -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition  -isystem ./include  -fPIC -g -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED  -msse -c \
> 		/var/tmp/portage/sys-devel/gcc-4.2.4-r1/work/gcc-4.2.4/gcc/config/i386/crtfastmath.c \
> 		-o crtfastmath.o
> /var/tmp/portage/sys-devel/gcc-4.2.4-r1/work/gcc-4.2.4/gcc/config/i386/crtfastmath.c:1: error: bad value (core2) for -march= switch
> /var/tmp/portage/sys-devel/gcc-4.2.4-r1/work/gcc-4.2.4/gcc/config/i386/crtfastmath.c:1:
> error: bad value (core2) for -mtune= switch
>
> I do indeed have -march=core2 in /etc/make.conf.  I suppose I could
> change -march= to something else and try again - but what should I
> change it to?  gcc-4.2.4 would only be used for non-portage compiling
> so, am I right in thinking that after it is built it would be safe to
> revert to -march=core2?

You can try "march=native".

Maybe it is a good choice for make.conf too?! 

And yes, you can switch back to core2 after emerge gcc-4.2.4. It's only used from emerge processes.

Steffen