Re: [gentoo-dev] Replacing cpu-feature USE flags

["Diego 'Flameeyes' Pettenò" <flameeyes@gentoo.org>]

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On Thursday 06 July 2006 14:49, Ciaran McCreesh wrote:
> Well, you're assuming that
Properly listing, what an arcane science.

> a) everyone's using a C compiler,
No, I assume that everyone is using a compiler. You cannot have a C++ compiler 
without a C compiler. The first person I see that sets CXXFLAGS but not 
CFLAGS I'm personally going to give him the "doesn't have a clue" prize.

> b) that gcc has the slightest clue what it's doing,
No, I assume that gcc has a big clue about which capabilities are available to 
the -march switch. I might be assuming that users have a clue on what they 
are doing, but that's an assumption I do have to do, or I shouldn't be 
working on Gentoo but on Debian, which seems pretty good at optimising for 
i386 still.

> c) that the user has no problem using nasty hacks to regain control,
Where "regain control" is "doing something that could have done before but 
made actually no sense to do before. And the bashrc thing is not a big nasty 
hack, works quite well for me.

> d) that this information is only needed at compile time,
Well of course use flags are available at runtime for the packages built to 
know, this is perfectly logic of you.

You really was getting out of arguments, don't you?

If I have to enable a configure switch I need it only at buildtime. If it has 
to be known at runtime there's the cpuid function!

> e) that various gcc internal definitions won't change... 
It's like assuming that gcc will always output the correct hello world for

int main() {
	printf("Hello, world!\n");
	return 0;
}

If it does change those values, it's going to be a killer for way more than 
just Portage.

> You're adding a lot of complexity, and thus 
> room for very weird breakages, to something that doesn't need it.
You're not exposing any of such breakages, I find it to reduce complexity to 
users that cannot try to enable SSE3 on an Athlon-TBird system.

-- 
Diego "Flameeyes" Pettenò - http://farragut.flameeyes.is-a-geek.org/
Gentoo/Alt lead, Gentoo/FreeBSD, Video, AMD64, Sound, PAM, KDE

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