Re: [Distutils] Working toward Linux wheel support

On September 8, 2015 at 1:29:53 PM, Nate Coraor (n...@bx.psu.edu) wrote:
> On Mon, Sep 7, 2015 at 12:02 PM, Donald Stufft wrote:> > > On September 3, 2015 at 1:23:03 PM, Nate Coraor (n...@bx.psu.edu) wrote:> > > >>>> > > >>> I'll create PRs for this against wheel and pip shortly. I can also> > work> > > >>> on a PEP for the platform tag - I don't think it's going to need to> > be a> > > >>> big one. Are there any preferences as to whether this should be a> > new PEP> > > >>> or an update to 425?> > > >>>> >> > Coming back to this, I'm wondering if we should include the libc> > implementation/version in a less generic, but still generic linux wheel.> > Right> > now if you staticly link I think the only platform ABIs you need to worry> > about> > are libc and Python itself. Python itself is handled already but libc is> > not.> > The only thing I've seen so far is "build on an old enough version of glibc> > that it handles anything sane", but not all versions of Linux even use> > glibc at> > all.> > > This proposal makes a lot of sense to me. pip will need an update to do the> backwards compatibility, and it may be a little ugly to do this all on the> platform tag. For example, linux_x86_64_ubuntu_12_04 wheels should not be> installed on systems that identify as linux_x86_64_ubuntu_14_04, but> linux_x86_64_glibc_2_15 wheels can be installed on systems that identify as> linux_x86_64_glibc_2_19. pip would need to maintain a list of which tag> prefixes or patterns should be considered backward compatible, and which> should not. Granted, new libcs do not pop up overnight, so it's not exactly> a nightmare scenario.> > Wheel should be updated to generate the "libc-generic" wheels by default> when nothing other than libc is dynamically linked. It'll need libc> vendor/version detection.> > Alternatively, the platform tag could be split in two, in which case you> have a "generic" portion (which would probably be what it currently is,> distutils.util.get_platform()) and a "specific" portion (the distro or> libc), possibly prefixed with something to avoid having to maintain a list> of what's version compatible and what's not, (e.g. 'd_ubuntu_14_04' vs.> 'c_glibc_2_19')?> > I don't think there is a strong case to include the libc version in the> specific portion when a distro version will also be specified, because the> distro is supposed to define the ABI (at least in the case of distros with> stable ABIs), and that includes the libc compatibility. So for psycopg2> wheels you'd get a "distro" wheel (linux_x86_64-d_ubuntu_14_04) but for> SQLAlchemy, you'd get a "libc-generic" wheel (linux_x86_64-c_glibc_2_19).> > It's then up to PyPI project owners to build on whatever platforms they> wish to support.> 

I think it's reasonable to not include the libc when the wheel is distro
specific. I think the barrier to entry on adding new tags is far lower than
adding a whole new type of tag. Right now, I think our longest tag is for OSX
which is something like macosx_10_10_x86_64 at 19 chars, I don't think it's
much worse to have something like linux_glibc_2_19_x86_64 at 23 chars, or
linux_ubuntu_14_04_x86_64 at 25 chars. I don't think we need the special c or
d prefix, we can just treat it as ==, and special case glibc as >= like we're
currently special casing the macosx wheels to be >=.

-----------------
Donald Stufft
PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA


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