Re: [PATCH] docs: document python version used for compilation

[Mauro Carvalho Chehab <mchehab@kernel.org>]

Em Fri, 10 May 2024 13:39:17 +0300
Dmitry Baryshkov <dmitry.baryshkov@linaro.org> escreveu:

> On Fri, 10 May 2024 at 13:09, Jani Nikula <jani.nikula@intel.com> wrote:
> >
> > On Fri, 10 May 2024, Mauro Carvalho Chehab <mchehab@kernel.org> wrote:  
> > > Em Fri, 10 May 2024 11:08:38 +0300
> > > Jani Nikula <jani.nikula@intel.com> escreveu:
> > >  
> > >> On Thu, 09 May 2024, Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:  
> > >> > The drm/msm driver had adopted using Python3 script to generate register
> > >> > header files instead of shipping pre-generated header files. Document
> > >> > the minimal Python version supported by the script.
> > >> >
> > >> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > >> > ---
> > >> >  Documentation/process/changes.rst | 1 +
> > >> >  1 file changed, 1 insertion(+)
> > >> >
> > >> > diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
> > >> > index 5685d7bfe4d0..8d225a9f65a2 100644
> > >> > --- a/Documentation/process/changes.rst
> > >> > +++ b/Documentation/process/changes.rst
> > >> > @@ -63,6 +63,7 @@ cpio                   any              cpio --version
> > >> >  GNU tar                1.28             tar --version
> > >> >  gtags (optional)       6.6.5            gtags --version
> > >> >  mkimage (optional)     2017.01          mkimage --version
> > >> > +Python (optional)      3.5.x            python3 --version  
> > >>
> > >> Python 3.5 reached end-of-life 3½ years ago [1]. What's the point in
> > >> using anything older than the oldest supported version of Python,
> > >> i.e. 3.8 at this time?  
> > >
> > > What's the point of breaking compilation with on older distros?
> > > The idea of minimal versions here is to specify the absolute minimum
> > > version that it is required for the build to happen. If 3.5 is
> > > the minimal one, then be it.  
> >
> > AFAICT 3.5 was an arbitrary rather than a deliberate choice. We should
> > at least be aware *why* we'd be sticking to old versions.  
> 
> From my side, the 3.5 was chosen basing on the previous feedback from
> Jon Hunter: https://lore.kernel.org/dri-devel/20240412165407.42163-1-jonathanh@nvidia.com/

Patch there seems small/simple enough if it is all it takes for 3.5.

Yet, it would be nice to hear from Jon Hunter about the rationale
for 3.5 support (if any).

> > Minimum versions here also means sticking to features available in said
> > versions, for Python just as well as for GCC or any other tool. That's
> > not zero cost.
> >
> > I guess there are two angles here too. The absolute minimum version
> > currently required, and the, uh, maximum the minimum version can be
> > safely bumped to. Say, you want to use a feature not available in the
> > current minimum, how far up can you bump the version to?
> >
> > Could we define and document the criteria (e.g. based on distros as you
> > suggest below) so we don't have to repeat the discussion?

Agreed. While we should not bump version randomly, defining a
criteria about when we should update the requirement sounds a great idea.

For me, the criteria is:

- the minimal version shall be at least the minimal one required for the
  Kernel to build at the most used LTS distros that are not EOL, e. g.: 
  Debian, openSUSE/SUSE, CentOS/RHEL and Ubuntu LTS[1].

[1] In practice, Ubuntu LTS usually has a python version newer than
    Debian LTS, and CentOS versions are identical to RHEL ones, so
    I guess checking for Debian, openSUSE, SUSE and RHEL should be
    enough.

Regards,
Mauro