Re: Cross compile gpsd-3.20.1~dev for arm with buildroot

[Florian Kiera]

Greg Troxel <gdt@lexort.com> writes:
> Florian Kiera <florian.kiera@logicway.de> writes:
>
> > Checkout SConstruct line 2147 and line 2158. It uses "DESTDIR +
> > str(python_libdir)" to give the install path. The problem here is that
> > python_libdir is already an absolute path to the STAGING_DIR's python
> > module. (in my case
> Then don't do that.  python_libdir and other dir paths are in terms of
> the target filesystem.  DESTDIR is about a chroot on the build host
> where things should be put, either for packaging staging, cross,
> whatever.
I don't do that, gpsd does so. I just use DESTDIR as root for the 
corresponding directory for each stage. (staging and target install) I 
haven't set python_libdir in the gpsd.mk.
> To repeat: it is an error to make python_libdir a path that includes DESTDIR.

python_libdir gets choosen by gpsd through checking who is compiling the 
python modules. Since the modules are build from the buildroots 
host-python it contains most of the DESTDIR... So as you just said 
DESTDIR which is supposed to be the chroot cant be used as chroot in 
buildroot if python_libdir contains the path from where its executed in 
all cases.

As example the staging stage:
DESTDIR gets set to the STAGING_DIR's root (which buildroot uses as 
source for libraries): 
/home/user/buildroot-2020.05.2/output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot
python_libdir contains the path from where python is building the gpsd 
modules because gpsd calls the executer: 
/home/user/buildroot-2020.05.2/output/host/lib/python3.8 (HOST_DIR)
In the case building gpsd's python modules with buildroot, python_libdir 
is supposed to just contain lib/python3.8/site-packages because the 
python modules are needed in the TARGET_DIR and STAGING_DIR not in the 
HOST_DIR...

So the way you define DESTDIR, I use it right. Just the way 
python_libdir gets its value doesnt fit in.


In the end we solved it by giving python_libdir a value in the gpsd.mk 
file.

GPSD_SCONS_OPTS = \
        arch=$(ARCH) \
        manbuild=no \
        prefix=/usr \
        sysroot=$(STAGING_DIR) \
        strip=no \
        python=yes \
        qt=no \
        ntpshm=yes \
        systemd=$(if $(BR2_INIT_SYSTEMD),yes,no) \
        python_libdir=/usr/lib/python3.8/site-packages/

From the logic of DESTDIR as root for the corresponding device/stage 
and python_libdir as path from the logical root to the python library 
its still not right, in my opinion.

Regards Florian