New Build System Status

[Chris Johns]

On 26/11/19 8:05 am, Joel Sherrill wrote:
> On Mon, Nov 25, 2019 at 2:12 AM Sebastian Huber
> <sebastian.huber at embedded-brains.de <mailto:sebastian.huber at embedded-brains.de>>
> wrote:
> 
>     On 25/11/2019 08:55, Chris Johns wrote:
>     >
>     > On 25/11/19 5:28 pm, Sebastian Huber wrote:
>     >>
>     >> On 24/11/2019 23:25, Chris Johns wrote:
>     >>>>> Should there be a note or something about waf needing python and we
>     recommend
>     >>>>> python3? Plus waf needs a `python` installed and not just `python2` or
>     >>>>> `python3`?
>     >>>> I think this belongs to the Host Computer section. The quick start uses the
>     >>>> RSB, so if you managed to build the tools, you must have a working Python.
>     >>>> The RSB uses Python and the RTEMS Tools use waf.
>     >>> The RSB can use python2 or python3 without a python. What about a note
>     to say
>     >>> ... "Waf uses python and you need to make this command available on your
>     system".
>     >> Now I am a bit confused. I thought every UNIX-like system provides a
>     >>
>     >> #!/usr/bin/env python
>     >>
>     >> which maps to Python 2 or 3?
>     >>
>     > Apparently on some distros the python executable is not automatically
>     installed
>     > with a suitable python2 or python3. I am not aware of the specifics of
>     this but
>     > it was raised as an issue that I fixed in the RSB:
>     >
>     > https://devel.rtems.org/ticket/3537
> 
>     I have never seen a system in which
> 
>     #!/usr/bin/env python2
> 
>     or
> 
>     #!/usr/bin/env python3
> 
>     works, but not
> 
>     #!/usr/bin/env python

I agree however this is the post from Joel about a class he held ...

https://lists.rtems.org/pipermail/devel/2018-October/023150.html

and I posted the change here ...

https://lists.rtems.org/pipermail/devel/2018-October/023296.html

>     How many Python scripts would stop to work in this case? However, the
>     availability of a python command is not mandatory according to:
> 
>     https://www.python.org/dev/peps/pep-0394/

I am aware of this and I support it however Linux distros seems to feel there
are cases for exceptions, we have this one and there is also pax.

The pax and this python case are similar, do we say "We are correct, fix your
host or raise a bug on your distro" or do we attempt to smooth over the cracks
and attempt to just work?

In the case of ubuntu, maybe someone with some experience with it can see what
is needed and update the documentation?

>     I think we should note in the "Host Computer" section that a "python"
>     command is mandatory for RTEMS and remove the RSB extra stuff.

The argument was presented to me that the RSB should just work even in this case
and so that is what I did. I am fine to remove that support, it is an average hack.

> Chris can answer to that.

Done.

> But on Centos 7, we have:
> 
> $ type python
> python is /usr/bin/python
> $ python --version
> Python 2.7.5
> $ type python2
> python2 is /usr/bin/python2
> $ type python3
> bash: type: python3: not found
> $ env python
> Python 2.7.5 (default, Aug  7 2019, 00:51:29)
> [GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>> 
> 
> and if I activate the SCL for Python 3:
> 
> $ scl enable rh-python36 bash                                                  
>                                                                              
> [joel at localhost rtems-work]$ type python                                        
>                                                                              
> python is /opt/rh/rh-python36/root/usr/bin/python                              
>                                                                              
> [joel at localhost rtems-work]$ python --version                                  
>                                                                              
> Python 3.6.3                                                

And on ubuntu? The original post was about that distro.

Chris