Re: o32 != n32

James Cowgill <[email protected]> Thu, 07 May 2015 10:41:35 +0100
Newsgroups	gmane.linux.debian.ports.mips
Message-ID	<[email protected]>
On Thu, 2015-05-07 at 11:25 +0200, Mathieu Malaterre wrote:
> On Thu, May 7, 2015 at 10:57 AM, James Cowgill <[email protected]> wrote:
> > On Thu, 2015-05-07 at 09:27 +0200, Mathieu Malaterre wrote:
> >> Hello MIPS gurus,
> >>
> >> Could someone please let me know if this is possible to have a
> >> dual-ABI system (eg: n32 & o32) on MIPS. On my x86-64 system I can run
> >> a multi-arch system (x86 & x86-64), thanks to the recent multi-arch
> >> effort.
> >>
> >> Is it possible on MIPS ? Does it make sense ?
> >
> > If you have a 64-bit kernel then that should completely work (all Debian
> > kernels except for 4kc are 64-bit).
> >
> > If you then install gcc-multilib you should be able to pass -mabi=n32 to
> > gcc to get n32 binaries (or -mabi=64 for n64 binaries). I haven't done a
> > huge amount of testing with it, but you should also be able to add the
> > mips64el debian repo which contains everything recompiled with n64. Then
> > you should be able to do proper multiarch.
> >
> > See: http://mipsdebian.imgtec.com/
> 
> I haven't received my Creator CI20 board yet, but I still fail to
> understand how that's possible. On my x86-64 there is a *single* ABI,
> and thus I can have a single `/usr/lib/x86_64-linux-gnu/libpthread.so`
> installed from libc6-dev:amd64 which wont conflict with
> `/usr/lib/i386-linux-gnu/libpthread.so` installed from libc6-dev:i386.

The processor in the CI20 is 32-bit only so you won't be able to do any
of this on that unfortunately.

If you use mipsel / mips64el multiarch, the setup use on amd64 is
identical on mips. Multilib places libraries in /lib32 or /lib64 just
link it does on x86.

> I may sound dumb, but I fail to understand how multi-abi can be
> handled when directories are setup to handle (single) per-arch object
> files.

The directories *are* setup to handle multiple ABIs. 'i386-linux-gnu' is
the ABI used on i386 and it is completely different to the
'x86_64-linux-gnu' ABI (you can't link amd64 and i386 objects together).

Thanks,
James
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