Re: [gentoo-cluster] Tips for multilib compiles for 64-bit head node

[Donnie Berkholz]

Andrew D. Fant wrote:
> Afternoon all,
>     After some amount of wrangling, I have been given a new head node for our
> cluster of 32-bit xeons.  It's one of the new multicore EMT64 Intel systems, and
> part of the reason I got to have it is that we have some users who need to run
> large-memory processes. Hence, I will need to compile it for 64 bits.  There are
> some 32 bit applications I will need to run there as well to support our extant
> cluster, which leads to my question.
>      Does anyone have any tips about configuring and building the amd64
> environment with multilib/32 bit support?  The FAQ makes it sound like it's
> mostly taken care of within various ebuilds, which is fine when everything is in
> portage, but there's enough commercial code we have been running that I want to
> get this nailed down early.

So, the basic idea is that lib64 is used for 64-bit code and lib32 for
32-bit code. I think right now, lib symlinks to lib64, but I wouldn't
install anything directly to lib unless it's architecture-independent.
Ensure that your stuff installs to the proper locations and you should
be fine.

There are a bunch of packages in app-emulation/emul-linux-x86-* to
provide 32-bit versions of stuff because portage doesn't properly
support installing the same ebuild twice, once for 32-bit ABI and once
for 64-bit ABI.

http://www.gentoo.org/doc/en/gentoo-amd64-faq.xml will probably answer
many of your questions.

Thanks,
Donnie