Re: [Qemu-devel] [RFC] Require Python 3 for building QEMU

[Daniel P . Berrangé]

On Mon, Oct 15, 2018 at 11:02:03AM +0100, Peter Maydell wrote:
> On 15 October 2018 at 10:32, Daniel P. Berrangé <address@hidden> wrote:
> > On Sat, Oct 13, 2018 at 02:02:27AM -0300, Eduardo Habkost wrote:
> >> Signed-off-by: Eduardo Habkost <address@hidden>
> >> ---
> >> I'd like to do this in QEMU 3.1.  I think it's time to drop
> >> support for old systems that have only Python 2.
> >>
> >> We still have a few scripts that are not required for building
> >> QEMU that still work only with Python 2 (iotests being the most
> >> relevant set).  Requiring Python 3 for building QEMU won't
> >> prevent people from using those scripts with Python 2 until they
> >> are finally ported.
> >
> > I think it is premature & unecessary to do this. We just got QEMU building
> > with dual Python2/3 in 3.0 to give people leeway in the migration path to
> > a fully v3 future. The code to support building 2/3 in parallel is not
> > imposing a unreasonable maint burden. Dropping py2 suport would have
> > negligible impact on the code, as there's no v3-only features we have
> > used. IOW, I don't think there's a compelling reason to rush into forcing
> > users onto v3.
> >
> > If we want to drop py2, we should give people a warning of such a planned
> > change, especially since some of our targetted host OS[1] don't even
> > include a py3 as standard without acquiring extra add-on repos. Devs in
> > a typical corporate env will not have the freedom to install such extra
> > repos on their machines.
> 
> I agree. I also think that dropping python 2 support before we've
> even converted all our python scripts to handle python 3 is the
> wrong order to do things. People interested in moving forward with
> the transition to python-3-only should start by making sure everything
> we have works with python 3...

FWIW,  I would /not/ object to the iotests directory being converted to
pure py3 only, skipping 2/3 compat, if that made it easier, since it is
not a commonly used thing by most people building QEMU.

Regards,
Daniel
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