From a2b21d60c7bf1d4539da89aaca49b5575e8a4549 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 18 Aug 2025 23:19:48 +0300 Subject: [PATCH] py: libcamera: Get dependency from meson python module unconditionally MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit libcamera uses the meson python module to handle native compilation of Python extension modules. When cross-compiling, the module uses the build machine suffix instead of the host machine suffix in some enviroments (for instance naming the shared object file _libcamera.cpython-313-x86_64-linux-gnu.so instead of _libcamera.cpython-313-aarch64-linux-gnu.so when cross-compiling from x86_64 to aarch64). This prevents using the python module in that case, and libcamera uses the normal dependency() function to locate the Python libraries, and the shared_module() function to build the module. Not using the meson python module to get the Python dependency prevents selecting a specific Python interpreter, the same way as it does for native builds. While having multiple Python interpreter versions in a cross-build environment is likely less common, different behaviours and features between native and cross-compilation are still not optimal. Improve this situation by getting the dependency from the python module for cross-compilation as well. This also prepares for usage of py.extension_module() once the file suffix issue will be fixed in meson. The user will need to ensure that the Python interpreter for the build machine matches the version of the interpreter in the cross-compilation environment for the host machine. Otherwise, meson will fail to find the Python dependency. Cross-compilation environment provided by Linux distributions (such as Debian multi-arch support) should work out of the box, but compiling libcamera manually against a cross-compilation environment provided by Buildroot or Yocto may require manual configuration. When the interpreters versions do not match, meson needs to be pointed to the build ùachine interpreter from the cross-compilation environment using the cross file. For instance, assuming a 'br_host_dir' variable pointing to the host directory from Buildroot, the cross file should contain [binaries] python = br_host_dir / 'bin/python3' Signed-off-by: Laurent Pinchart Reviewed-by: Tomi Valkeinen --- src/py/libcamera/meson.build | 4 ++-- src/py/meson.build | 16 +++------------- 2 files changed, 5 insertions(+), 15 deletions(-) diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build index fe22ffd2..d5433fbc 100644 --- a/src/py/libcamera/meson.build +++ b/src/py/libcamera/meson.build @@ -47,7 +47,7 @@ pycamera_sources += custom_target('py_gen_formats', pycamera_deps = [ libcamera_private, - py3_dep, + py3.dependency(), pybind11_dep, ] @@ -62,7 +62,7 @@ if meson.is_cross_build() # module. There's work in progress to fix this, based on PEP 739 # (https://github.com/mesonbuild/meson/pull/14657). While waiting for this # to become available, work around the issue by using shared_module(). - destdir = get_option('libdir') / ('python' + py3_dep.version()) / 'site-packages' / 'libcamera' + destdir = get_option('libdir') / ('python' + py3.language_version()) / 'site-packages' / 'libcamera' pycamera = shared_module('_libcamera', pycamera_sources, diff --git a/src/py/meson.build b/src/py/meson.build index 24102f83..88ad8b7e 100644 --- a/src/py/meson.build +++ b/src/py/meson.build @@ -1,20 +1,10 @@ # SPDX-License-Identifier: CC0-1.0 -if meson.is_cross_build() - py3_dep = dependency('python3', required : get_option('pycamera')) -else - py3 = import('python').find_installation('python3', required : get_option('pycamera')) - if not py3.found() - pycamera_enabled = false - subdir_done() - endif - - py3_dep = py3.dependency(required : get_option('pycamera')) -endif - +py_mod = import('python') +py3 = py_mod.find_installation('python3', required : get_option('pycamera')) pybind11_dep = dependency('pybind11', required : get_option('pycamera')) -pycamera_enabled = py3_dep.found() and pybind11_dep.found() +pycamera_enabled = py3.found() and pybind11_dep.found() if not pycamera_enabled subdir_done() endif