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

[Thomas Sachau]

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?

-- 
Thomas Sachau

Gentoo Linux Developer