What implications does the new x32 abi hold for gentoo?

civilian · Tux's lil' helper Joined: 23 Jan 2007 Posts: 78

This is about to hit the world (next kernel I believe). How will portage have to change to take advantage of this? I'm guessing that my system will end up with libx32 directories in conjunction with the lib32 and lib64 directories.

genstorm · Advocate Joined: 05 Apr 2007 Posts: 2241 Location: Austria

No change I think. glibc will need to address that.
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Hu · Watchman Joined: 06 Mar 2007 Posts: 7610

No change is required for Portage to continue to work as it does today. Some changes are required if you want to have Portage build/install x32 code.

Ant P. · Veteran Joined: 18 Apr 2009 Posts: 1920 Location: UK

Portage currently doesn't have real multilib at all so there'll be no change for Gentoo.

civilian · Tux's lil' helper Joined: 23 Jan 2007 Posts: 78

Can glibc actually take care of it? The way I understood it, x32 programs will effectively require a new set of x32 libraries.
If this is the case then it can be added via a third abi flag to the multilib overlay, yes?

i92guboj · Posted: Sun Apr 15, 2012 9:36 pm Post subject:

Well, I know that IA32 is not quite the same, but... it's been there for years. There's no support for it in portage (though you can get it mostly working using the multilib overlay), so I advice that you don't hold your breath to get yet-another-64/32-mix in Gentoo.

This is far from a simple change, since it requires to decouple support for both bitnesses in every single package, and handle the dependencies for that. If you want, let's say, 32 bits fvwm in a 64 bits gentoo, you need to install 32 bits X, drivers, librsvg, libpng, etc. etc. and so on. But you also need the 64 bits version of those libs, for the rest of your 64 bits software.

The multilib overlay does exactly that, but I have no idea if they are working in the x32 thing or not. It might "just work" just like with IA32, so if you are truly interested research on that.
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Martin.Jansa · n00b Joined: 09 Mar 2004 Posts: 55 Location: Prague

srcshelton · n00b Joined: 10 Apr 2004 Posts: 12 Location: Cambridge

Now that Kernel 3.4 (with x32 ABI support) has been released, it's finally possible to try this out.

One question I have is how the filesystem will end up being laid out. I do like the SGI(/MIPS?) approach of having:

/lib -> o32/straight 32-bit shared-objects;
/lib32 -> n32/64-bit with 32-bit pointers shared-objects;
/lib64 -> 64-bit shared-objects.

... which is clean, obvious, but clashes with what's already used as standard in Gentoo

Currently, /lib is a symlink to /lib64, /lib64 contains 64-bit shared-objects, and /lib32 contains 32-bit shared-objects. Not all distros are the same: Ubuntu/Debian use /lib and /lib64, leaving /lib32 free for use. /libx32 is an option... but I'd argue a messy and easily-confused one.

Does portage have the capability to use different mappings for ABI=x32? Are there yet any definitive plans for how this issue will be addressed/resolved?

steveL · Posted: Wed May 23, 2012 6:23 pm Post subject:

I'd prefer /lib32x as it contrasts with /lib32 better than /libx32, especially for tired eyes in a terminal. Then again libx32 will tab at the same point as lib, lib64 and lib32, and x is easier to select at that point, if it's relevant.

There's obviously no point on a 64-bit install in /lib pointing to /lib32, but /lib symlinked to /lib32x might be a nice default option, since few apps apart from things like database servers, really require a 64bit address space.

(For /lib* /usr/lib* also applies, of course. Bikeshedding ftw. ;)
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