Re: [gentoo-dev] Support for multiple ABIs for amd64 (64bit,32bit) in multilib overlay

[Mike Frysinger]

On Monday 19 October 2009 17:02:50 Thomas Sachau wrote:
> Robin H. Johnson schrieb:
> > On Sun, Oct 18, 2009 at 10:26:37PM -0400, Mike Frysinger wrote:
> >> On Sunday 18 October 2009 14:49:09 Thomas Sachau wrote:
> >>> Robin H. Johnson schrieb:
> >>>> On Mon, Oct 12, 2009 at 04:50:23PM -0400, Mike Frysinger wrote:
> >>>>> what exactly does this "lib32" do ?  naming USE flags according to
> >>>>> specific ABI implementations is a bad idea.  you have to forget
> >>>>> special casing anything to "lib32 vs lib64".  amd64, while the most
> >>>>> common, is hardly extensible.  we must handle multiple ABIs which
> >>>>> easily might have the same bitsize.
> >>>>
> >>>> The canonical example for this does still remain MIPS I believe.
> >>>>
> >>>> The most common ABIs in MIPS are:
> >>>> o32, n32 - Both in Gentoo releases
> >>>> n64 - Was experimentally done in Gentoo
> >>>> (default-linux/mips/2007.1-dev/generic-be/n64) o64, eabi, meabi, nubi
> >>>> - Not sure if they were were ever released in any way.
> >>>>
> >>>> Crossdev DOES support the full swath of these last I checked it.
> >>>
> >>> There is a difference between creating a toolchain and supporting all
> >>>  packages for that arch and every possible ABI you can crosscompile.
> >>>
> >>> Currently i only support amd64 since thats the only ARCH i know and
> >>> have access to. If i get enough details to implement other ARCHes and
> >>> some way to test it there, i might try it for those other ARCHes too.
> >>
> >> we're not asking you to implement support for these ABIs, just to keep
> >> in mind that any implementation that does not scale and/or hardcodes to
> >> a single set of ABIs isnt a proper solution
> >
> > My main objection thusfar is hardcoding the names as lib64/lib32.
> >
> > Is there any specific reason you're using the content of the
> > LIBDIR_${ABI} variable? Maybe using the $ABI string as the USE flag
> > would be better, in some form of USE_EXPAND manner (cannot use them raw
> > as I believe we still have some code in the form of 'use $ARCH', which
> > might not behave sanely if say both amd64 and x86 were set.
> >
> > Egs:
> > multilib AMD64:
> > USE="abi_x86 abi_amd64"
> >
> > Multilib PPC64:
> > USE="abi_ppc abi_ppc64"
> >
> > Multilib MIPS (SGI hardware)
> > USE="abi_n32 abi_n64"
> >
> > Possible valid multilib sets on MIPS are:
> > [n32,n64] - at least one Gentoo system like this has been built.
> > [o32,o64]
> > [eabi,meabi] - docs fuzzy
> > [nubi]
>
> I dont mind using some other string here. So those USE flags would be fine
>  for me. They could be USE_EXPANDed to e.g. for multilib amd64 ABI="x86
>  amd64"
>
> Any other comment or suggestions on this part?

what Robin has proposed makes sense to me
-mike