dectree.py uses env python3 rather than configured python

dectree.py uses env python3 rather than configured python

[Dr. David Alan Gilbert]

Hi Taylor,
  I tripped over dectree.py using 'env python3'; the qemu configure
script lets you specify a python with e.g.:
    --with-python=/usr/libexec/platform-python

and I think everywhere else in qemu uses the configured python.
(This host, like most standard rhel8, doesn't have a python3 binary out
of the box)

Dave

-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: dectree.py uses env python3 rather than configured python

[John Snow]

On 4/6/21 2:50 PM, Dr. David Alan Gilbert wrote:
> Hi Taylor,
>    I tripped over dectree.py using 'env python3'; the qemu configure
> script lets you specify a python with e.g.:
>      --with-python=/usr/libexec/platform-python
> 
> and I think everywhere else in qemu uses the configured python.
> (This host, like most standard rhel8, doesn't have a python3 binary out
> of the box)
> 
> Dave
> 

Hi,

Instead of allowing meson to invoke this script directly (and have the 
shebang be processed by the shell), meson ought to be taught to invoke 
it directly using the user's configured python interpreter.

The shebang "#!/usr/bin/env python3" is otherwise the correct one to 
use, and should (probably) be left alone.

--js

RE: dectree.py uses env python3 rather than configured python

[Taylor Simpson]

> -----Original Message-----
> From: John Snow <jsnow@redhat.com>
> Sent: Tuesday, April 6, 2021 2:38 PM
> To: Dr. David Alan Gilbert <dgilbert@redhat.com>; Taylor Simpson
> <tsimpson@quicinc.com>
> Cc: qemu-devel@nongnu.org
> Subject: Re: dectree.py uses env python3 rather than configured python
>
> On 4/6/21 2:50 PM, Dr. David Alan Gilbert wrote:
> > Hi Taylor,
> >    I tripped over dectree.py using 'env python3'; the qemu configure
> > script lets you specify a python with e.g.:
> >      --with-python=/usr/libexec/platform-python
> >
> > and I think everywhere else in qemu uses the configured python.
> > (This host, like most standard rhel8, doesn't have a python3 binary out
> > of the box)
> >
> > Dave
> >
>
> Hi,
>
> Instead of allowing meson to invoke this script directly (and have the
> shebang be processed by the shell), meson ought to be taught to invoke
> it directly using the user's configured python interpreter.
>
> The shebang "#!/usr/bin/env python3" is otherwise the correct one to
> use, and should (probably) be left alone.
>
> --js

Yes, I think meson.build would be the right place to change the behavior.

On the other hand, isn't python3 standard for building qemu now?  This page
https://wiki.qemu.org/Hosts/Linux#Required_additional_packages
lists python3 as an additional required package for RHEL8.

Thanks,
Taylor

Re: dectree.py uses env python3 rather than configured python

[Peter Maydell]

On Tue, 6 Apr 2021 at 20:49, Taylor Simpson <tsimpson@quicinc.com> wrote:
> On the other hand, isn't python3 standard for building qemu now?  This page
> https://wiki.qemu.org/Hosts/Linux#Required_additional_packages
> lists python3 as an additional required package for RHEL8.

Python 3 is required, but there's no guarantee that Python 3 will
be the executable "python3" on the path, as opposed to available
under some other name...

thanks
-- PMM