Re: [qemu-web PATCH] add post about plans for Python venvs

[Paolo Bonzini <pbonzini@redhat.com>]

On 3/22/23 16:18, Peter Maydell wrote:
> On Wed, 22 Mar 2023 at 15:15, Paolo Bonzini<pbonzini@redhat.com>  wrote:
>> +Some of these tools are run through the `python3` executable, while others
>> +are invoked directly as `sphinx-build` or `meson`, and this can create
>> +inconsistencies.  For example, QEMU's `configure` script checks for a
>> +minimum version of Python and rejects too-old interpreters.  What would
>> +happen if code run via Sphinx or Meson used a different version?
> ...this is why configure also separately checks that when you run sphinx
> it is executing with a new enough Python version.

Point taken, though "new enough" is not "the same version" used by 
--python or $PYTHON.  I will tweak the end of the introduction as follows:

====
As a result, even if `configure` is told to use `/usr/bin/python3.8` for 
the build, QEMU's custom Sphinx extensions would still run under Python 
3.6.  configure does separately check that Sphinx is executing with a 
new enough Python version, but it would be nice if there were a more 
generic way to prepare a consistent Python environment.

This post will explain how QEMU 8.1 will ensure that a single 
interpreter is used for the whole of the build process.  Getting there 
will require some familiarity with Python packaging, so let's start with 
virtual environments.
====

Paolo