[Buildroot] [PATCH v2 2/2] package/gnuradio: fix gnuradio python libraries for cross-compile

[Gwenhael Goavec-Merou]

Arnout, all

On Tue, 4 Jul 2023 22:51:57 +0200
Arnout Vandecappelle <arnout at mind.be> wrote:

> On 26/06/2023 09:05, Gwenhael Goavec-Merou wrote:
> > From: Gwenhael Goavec-Merou <gwenhael.goavec-merou at trabucayre.com>
> > 
> > By default, module libraries have a suffix based on cpython version + host
> > architecture: this is fine for a native compile when these libraries are
> > used on  
> 
>   I think that this is solved in the python infrastructure by setting
> 
> _PYTHON_HOST_PLATFORM="$(PKG_PYTHON_HOST_PLATFORM)"
> 
> Or it may be some other environment variable that is set. For sure though,
> the same problem would exist in normal python packages, and it is resolved
> there. So ideally we should use the same solution for gnuradio.
> 
In fact I see I have missed to explain in my message this issue is related to
pybind.
If PYTHON_MODULE_EXTENSION is unset, .cmake uses a python script containing
sysconfig.get_config_var('EXT_SUFFIX')
This one return .cpython-311-x86_64-linux-gnu.so, because host-python is used.
>   Regards,
>   Arnout
> 
Regards,
Gwenhael

> > the same computer (or similar computers). But when target architecture is
> > not the same python is unable to find libraries due to the wrong suffix and
> > produces unclear errors messages:
> > 
> > # python3
> > Python 3.11.3 (main, Jun 19 2023, 14:15:44) [GCC 11.4.0] on linux
> > Type "help", "copyright", "credits" or "license" for more information.  
> >>>> from gnuradio import blocks  
> > Traceback (most recent call last):
> >    File
> > "/home/xxx/buildroot/output/build/gnuradio-3.10.4.0/gr-blocks/python/blocks/__init__.py",
> > line 18, in <module> ModuleNotFoundError: No module named
> > 'gnuradio.blocks.blocks_python'
> > 
> > During handling of the above exception, another exception occurred:
> > 
> > Traceback (most recent call last):
> >    File "<stdin>", line 1, in <module>
> >    File
> > "/home/xxx/buildroot/output/build/gnuradio-3.10.4.0/gr-blocks/python/blocks/__init__.py",
> > line 22, in <module> ModuleNotFoundError: No module named
> > 'gnuradio.blocks.blocks_python'  
> >>>>  
> > 
> > By adding -DPYTHON_MODULE_EXTENSION=".so" at configure time, pybind11 will
> > use this option instead of using host-python to forge suffix.
> > 
> > Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou at trabucayre.com>
> > ---
> > Changes v1 -> v2:
> > - replaces patch by PYTHON_MODULE_EXTENSION option (result is the same
> >    but less "noisy")
> > ---
> >   package/gnuradio/gnuradio.mk | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/package/gnuradio/gnuradio.mk b/package/gnuradio/gnuradio.mk
> > index 1453b78493..d7b3b86c31 100644
> > --- a/package/gnuradio/gnuradio.mk
> > +++ b/package/gnuradio/gnuradio.mk
> > @@ -119,6 +119,8 @@ GNURADIO_CONF_OPTS += -DENABLE_PYTHON=ON
> >   # mandatory to avoid pybind11 to overwrite variables provided
> >   # by gnuradio and buildroot
> >   GNURADIO_CONF_OPTS += -DPYBIND11_PYTHONLIBS_OVERWRITE=OFF
> > +# force libraries suffix (avoid to have libxxx.PYTHONVER-HOST_ARCH.so)
> > +GNURADIO_CONF_OPTS += -DPYTHON_MODULE_EXTENSION=".so"
> >   # mandatory to install python modules in site-packages and to use
> >   # correct path for python libraries
> >   GNURADIO_CONF_OPTS += -DGR_PYTHON_RELATIVE=ON \