Re: Building Python 3 on old distributions

[Joseph Myers <joseph at codesourcery dot com>]

On Sat, 8 Sep 2018, Siddhesh Poyarekar wrote:

> We should not need openssl support to build glibc, so this shouldn't be a
> problem.

Note that build-many-glibcs.py uses such support indirectly (to download 
component source tarballs over https), but I don't think that's an issue 
at all as it's not relevant to the context of minimal python for 
bootstraps or building on limited systems.  (However, I think the minimum 
python version for build-many-glibcs.py should be at least that for glibc 
as a whole - so if we require 3.4 as minimum for glibc, we should also 
remove the compatibility for older versions from build-many-glibcs.py - 
while keeping the compatibility code needed to work wth 3.4 rather than 
only 3.5 and later.)

> It might be a good idea to make a list of modules that are allowed when
> writing scripts directly related to build or bootstrap, maybe starting with
> the following:
> 
> - os
> - sys
> - argparse
> - subprocess
> - time
> - io
> - re
> 
> and then adding as required, keeping the list as small as possible.

Existing tests also use shutil, tempfile, collections, string - I see no 
reason why those should be problematic for the glibc build either (and 
there are enough modules of generic use in the standard library, without 
dependencies on external C libraries, that I'm wary of trying to produce a 
short list of modules that are OK in glibc build scripts).

As far as I could tell from the BoF, we have consensus on requiring python 
3.4 (suitable subset of the standard library only) or later for building 
glibc, even if a few people were concerned and there was no agreement on 
whether python or perl is harder to bring up when bootstrapping a new 
architecture.  Before we actually replace any awk scripts used during the 
build with python ones we'll need to make the configure test ensure that a 
suitable version is available and otherwise set critic_missing, and remove 
the PYTHON conditionals in the makefiles.

-- 
Joseph S. Myers
joseph@codesourcery.com