[gentoo-mips] Re: On MIPS using the same CHOST for all multilib ABIs

[Joshua Kinard]

On 12/28/2013 5:58 PM, Michał Górny wrote:
> Hello, folks.
>
> I've noticed today that mips uses the same CHOST value for all three
> ABIs it supports:
>
> arch/mips/mips64/multilib/make.defaults:CHOST_o32="${CHOST}"
> arch/mips/mips64/multilib/make.defaults:CHOST_n32=${CHOST}
> arch/mips/mips64/multilib/make.defaults:CHOST_n64=${CHOST}
> arch/mips/mipsel/mips64el/multilib/make.defaults:CHOST_o32="${CHOST}"
> arch/mips/mipsel/mips64el/multilib/make.defaults:CHOST_n32="${CHOST}"
> arch/mips/mipsel/mips64el/multilib/make.defaults:CHOST_n64="${CHOST}"
>
> Long story short, this sucks and will cause trouble.
>
> In the multilib stuff, we're using CHOST for two purposes:
>
> 1. wrapped headers are put in /usr/include/$CHOST,
>
> 2. multilib executables are prefixed with $CHOST-.
>
> (1) here is not really a killer feature but I'd rather avoid changing
> this at this point. (2) is actually a killer feature, since the eclass
> sets CHOST properly and thanks to that AC_CHECK_TOOL and friends can
> find multilib *-config progs and stuff without any special hackery.
>
> And those are just the examples I can think of. I suspect that more stuff
> may actually expect CHOST to uniquely identify build, especially some
> tricky hidden features in autotools :).
>
> I'd suggest that you changed the CHOST values to uniquely identify ABI
> in use, at least in multilib profiles and preferably in all of them.

Matt can probably vouch for this better, but the only two ABIs affected by
this are n32 and n64.  mips[el]-unknown-linux-gnu implies a 32-bit
big/little endian CHOST, which means the o32 ABI.
mips64[el]-unknown-linux-gnu means either n32 or n64.  So no change should
be needed for o32-based installs.

According to this Debian wiki entry:
https://wiki.debian.org/Multiarch/Tuples

We would have to adopt mips64[el]-unknown-linux-gnuabin32 for n32 and
-gnuabin64 for n64.  Testing would be needed to watch for packages that
don't have updated config.sub/config.guess files and fail to recognize this
particular CHOST.

-- 
Joshua Kinard
Gentoo/MIPS
kumba@g.o
4096R/D25D95E3 2011-03-28

"The past tempts us, the present confuses us, the future frightens us.  And
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