Re: [ptxdist] host-python

[Erwin Rol <mailinglists@erwinrol.com>]

On 15-2-2016 9:48, Michael Olbrich wrote:
> 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:

Yep I noticed that, my not deleting python hack broke ptxdist due to
missing imports.

> 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.

My real-host (redhat/centos 6) python is to old (2.6), qt5 needs 2.7.

> 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.

I now tricked it by making a sym-link to the host-python 2.7 exe in the
qt5 build directory and change the QT5_PATH in the qt5.make file. That
way it seems host-python is only picked up when building qt5
(qtwebengine needs it). This probably only works because qt5/webengine
uses the "/usr/bin/env python" construct.

- Erwin




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