Re: [gentoo-dev] Move x86/amd64 CPU extensions USE flags to a new USE_EXPAND variable

[ross smith]

On Sat, Dec 11, 2010 at 14:03, Dirkjan Ochtman <djc@g.o> wrote:

> On Sat, Dec 11, 2010 at 20:01, Matt Turner <mattst88@g.o> wrote:
> > I agree that this could be better. To me, most of the problems with
> > this are due to users not knowing which of these should be set for
> > their particular CPU.
> >
> > Instead of having defaults set by a profile, I'd like to figure out a
> > way we can have these flags set by default dependent on the user's
> > CPU. This might require some additional logic in portage; I don't
> > know.
>
> Yeah, I think setting the best possible default is important here.
>

+1 to good defaults.

Perhaps  something along the lines of: If CPU_FLAGS is empty or not defined,
set flags based on the -march and -mtune variables.  If CPU_FLAGS is set,
respect what has been set there and ignore the other logic for defaults.

This would allow the average user, and the users building for multiple
machines to continue like nothing changed, and users that want to
selectively want to enable processor flags can in an easy way.

Best,

Ross

>
> Cheers,
>
> Dirkjan
>
>