On Wednesday 08 March 2006 21:49, "Kumar Golap" <tizan.moris@...> 
wrote about 'Re: [gentoo-user] equery, make.conf USE flag mismatch on 
amd64':
> Apologies for not having done my research properly....

No problem, it happens.  Truth be told it's probably more of a problem with 
people being unable to /find/ the manual than being unwilling to /read/ 
it.

Besides, the age-old man command, and it's younger upstart info, are 
quickly being deprecated in favor of simply pointing someone to a web 
page.  I find this unfortunate, at best.

BTW, if you don't like consoles or fixed-width fonts make you itch, you can 
always use a man:/ or info:/ URL in konqueror.  (Not sure what the 
Gnome/FB/BB/OB/ION/WMII/RP/other people use...)

> > In this /specific/ case, you don't have to because the ebuilds and gcc
> > know that x86_64 CHOST means that mmx etc. ARE supported and they will
> > hard-enable them (you may not turn them off).
>
> Do you mean that, say, xawtv would have been built with mmx for an
> amd64 arch...despite that "equery uses" say its not ? Because that
> what confused me....

Yes.  It will.  The ebuild controls which arguments are passed to 
configure/make so it can decide on the combination of you USE flags and 
profile.  I'm not sure if it is portage magic (the portage 'use' command 
available in ebuilds doing some check on CHOST) or just ebuild maintainers 
explicitly checking for an x86_64 CHOST, but you will get mmx/sse 
optimizations without any special USE flags.

You probably /should/ set your -march flag (or at least -mcpu) in CFLAGS, 
so that gcc will optimize to your particular processor, including extended 
instruction sets.

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh
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