Re: [ptxdist] host-python

[Michael Olbrich <m.olbrich@pengutronix.de>]

Hi,

On Thu, Feb 11, 2016 at 02:42:19PM +0100, Erwin Rol wrote:
> The host-python package removes the "python" file after install with the
> following reason;
> 
> # remove "python" so that it doesn't interfere with the build
> # machine's python
> #
> # the target build proces will only use python with the
> # python-$(PYTHON_MAJORMINOR)
> 
> But isn't the reason of wanting host-python that the real host python
> isn't good enough (wrong version) ?
> 
> So I don't really understand the idea behind using host-python and than
> "breaking" it so it doesn't get found unless you change every reference
> to "python" into "pyhton-2"
> 
> Do things break when "python" from host-python is found ?

This stuff is a bit tricky:

We have the Python 2.x installed in the system by your distribution.
PTXdist does the basic check for this in it's configure script.
This is for any package that uses Python in it's build process but not on
the target and works with any recent Python 2.x version.
If extra modules are needed, they are handled by the host-system-python
package.

Then we have host-python. This is used for anything that is related to
Python on the target. Usually that means packages that install Python
modules on the target.

We could use host-python for everything, but that would mean, that we need
to compile it for basically every BSP and add a lot of host Python modules.
I'd like to avoid that.

In the first case, there are usually scripts with "/usr/bin/env python" as
shebang, so the 'python' used for this should be the first in $PATH.
For the second case we can usually specify the python binary, because we're
building for a specific version.
By deleting the 'python' link for host-python we can handle both cases.

Regards,
Michael

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