multilib: what is it? And how do I use it?

lincoder · n00b Joined: 10 Dec 2006 Posts: 4

I mean, how do i use it to compile 32-bit progs. My system is as follows:

Linux localhost 2.6.18-gentoo-r3 #7 SMP PREEMPT Sat Dec 9 17:45:55 GMT 2006 x86_64 AMD Athlon(tm) 64 X2 Dual Core Processor 4200+ AuthenticAMD GNU/Linux

If I was to compile a 32 bit program, do I just do:

USE="multilib" emerge mozilla-firefox..... // or whatever (e.g. for flash purposes)

Also, what is this nptl flag I keep hearing about (especially in regard to cedega et.al )?

When the program has been compiled will it be 32 bit? Will it be called something like firefox32? Will I then do something like USE="multilib" emerge flash to then get the 32 bit flash plugin?

Must I first append multilib (and nptl) to the USE variable list in make.conf and recompile glibc before there is even the facility to compile 32 bit programs?

Thanks, and sorry for all the questions :-)
Lincoder

thedude0001 · Arch/Herd Tester Joined: 16 Jan 2005 Posts: 69

First of all: Forget the multilib USE flag, it isn't used for anything and only present for löegacy reasons. What you're looking for is a "native" multilib support where you can compile packages as either 32 or 64 bit versions. That is under development, but as of now it isn't available. For now "multilib" means we have binary packages to install 32bit libraries if you emerge a (binary) package that needs them (openoffice-bin or mplayer-bin come to mind, also programs like Google earth or various games).

NPTL is a threading library with relatively low overhead and therefor much more efficient when used in multithreading environments. Unless you have a specific reason not to you should add "nptl nptlonly" to your make.conf. For glibc-2.4 this is mandatory.
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lincoder · n00b Joined: 10 Dec 2006 Posts: 4

Thanks, much appreciated :-)

Lincoder

reteo · Posted: Wed Dec 13, 2006 1:27 pm Post subject:

Multilib will allow you to run 32-bit compiled programs, but it won't compile them. However, if you can establish an x86 chroot, you can use it to do the compiling.

You can find the explanation in This thread.
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Lampros Liontos (aka. Reteo Varala)

The Penguin Producer - Tips, tricks, and techniques for producing various forms of media with Linux tools.

thedude0001 · Arch/Herd Tester Joined: 16 Jan 2005 Posts: 69

Slippery Jim · Apprentice Joined: 08 Jan 2005 Posts: 264

reteo · Posted: Thu Jan 18, 2007 3:06 pm Post subject:

spielc · Guru Joined: 20 Apr 2004 Posts: 452

Umm I always thought that glibc was already multilib-compatible? From what i can remember it is compiled twice once to get the 64-bit-version and the second time to get the 32-bit version? Other libs are not yet ready (as far as i can remember) that's why we have the emul-linux-x86-packages... But from what i've read the aim is to make such libraries compile twice to get both 64- and 32-bit version of the corresponding packages when you are running a multilib-environment

reteo · Posted: Sat Jan 20, 2007 11:51 pm Post subject:

I agree. However, as of yet, I've not encountered such a layout; the 'multilib' flag used to multiply-compile the toolchain, but has since ceased to be the case. Supposedly, the ABI environment variable should be set to the bit level of packages to be compiled, but as of right now, it still only seems to compile in the 64-bit environment, hence my use of the chroot to do 32-bit compiles.
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Lampros Liontos (aka. Reteo Varala)

The Penguin Producer - Tips, tricks, and techniques for producing various forms of media with Linux tools.

Slippery Jim · Apprentice Joined: 08 Jan 2005 Posts: 264