USE variable in /etc/make.cong

lordalyc · Posted: Tue Dec 10, 2002 12:06 am Post subject: USE variable in /etc/make.cong

I have not actually yet understood the meaning of the USE variable in /etc/make.conf.
1) Is it kind of like selecting the packages that I want?
2) Or does it effect in the way each source is compiled?
3) And..for expample, if I didn't include "mysql" in USE variable before bootstrapping, can I add it later on after the installation? And if I didnt include "mysql" in USE, am i not able to install MySQL server on my gentoo machine?
4) and does USE have any effect if I use stage2 or stage3 tarball?

rac

mooman · Posted: Tue Dec 10, 2002 12:13 am Post subject:

Lots of programs can have different functionality compiled into them. That is, you can enable or disable certain interfaces, APIs, and so on based on settings you choose.

USE flags are a way of setting all that stuff in one place and picking values so that if you don't plan on using a given functionality (like gnome) then you can bascially tell the system that anytime you compile something, don't bother adding the extra bits for gnome, since you don't need it.

Adding flags to USE does not cause any packages to be built for you. It just controls what features are compiled into the packages that you *do* build.

You can change USE flags at any point. You may need to go recompile programs that need them, however. In general a USE flag like 'mysql' doesn't control whether or not MySQL can be used on the system, it controls whether the other apps that might be able to connect to or use MySQL will have those capabilities compiled into them...

Regarding stage 2 and stage 3: Given that you may end up recompiling your kernel and other major packages at any point, even if you didn't start from Stage 1, I think (and someone correct me if I'm wrong here) you still should set the USE flags based on your needs....
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Linux user off and on since circa 1995

lordalyc · Posted: Tue Dec 10, 2002 12:18 am Post subject:

but do the options in USE variable affect in any way the performance or size or whatever of my system? for example if i had more stuff in USE, would my system be slower?
and is it safe to add all the options possible to USE variable so it'd be sure that everything works fine when the installation is complete?

mooman · Posted: Tue Dec 10, 2002 12:22 am Post subject:

Well, technically, yes. Maybe not a lot, and maybe not even perceptably, but as I said before, you're having other interfaces and functions added into any programs you compile.

But I'm pretty sure it's probably more painful to deal with things that are broken because you chose too few USE flags and have a machine that is 0.02% faster, than to error on the side of caution and have flags in there that you really don't end up needing. So feel free to play it safe and use any USE flags that seem like you might use them at all ....

Did that answer your question?
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Linux user off and on since circa 1995

lordalyc · Posted: Tue Dec 10, 2002 12:22 am Post subject:

yes. thanks.

and one more thing, if i have Duron 1GHz then what should be the options in CFLAGS variable?
CFLAGS="-march=athlon-xp -03 -pipe" would be fine? since the newest duron should have Palomino architecture core.

mooman · Posted: Tue Dec 10, 2002 12:24 am Post subject:

There is a very thorough thread about CFLAGS at CFLAG Central

Skim through it and you should find lots of info..
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Linux user off and on since circa 1995

lordalyc · Posted: Tue Dec 10, 2002 12:25 am Post subject:

ok thanks.