libudev libs: Host dependency and cross compilation

[vithalsm]

What is your question?

Hi !, my question is regarding building libudev libs for linking to host - for cross compilation purposes.
Existing libudev only seem to install/check 'system' udev libs, but doesn't pull source code and build. As a result even cross compilation of 'libudev' itself fails (in test_package) as it doesn't find right '.h' files.

So, for cross compilation case, wherein linker requires corresponding udev libs, what is the suggested option?

[valgur]

I have a pending PR for exactly this case: master...valgur:conan-center-index:cross/libudev
It adds non-system libudev to enable cross-compilation of packages that depend on it.

For the time being you can copy the recipe or use my repo as an additional remote: https://github.com/valgur/conan-center-index?tab=readme-ov-file#setup

[valgur]

Created a PR as well now: #26162.

[vithalsm]

Thanks @valgur.
Will look forward for the merge/release.

[jcar87]

Hi @vithalsm -in some scenarios the recipes are already able to resolve this without further changes. Could you provide the following details:

• which distro, distro version and architecture are you targetting?
• which distro, distro version and architecture are you building on?
• could you paste your host conan profile including all confs?
  thanks!

[vithalsm]

Hi @jcar87, could you please elaborate on how the recipes are able to handle the cross compilation case?
I am cross compiling from x86 machine to x86 target. I have installed 'libudev-dev' on my build machine (thats what libudev intends to do). Please find the conan profiles as below:

======= Input profiles ========
Profile host:
[settings]
arch=x86_64
build_type=RelWithDebInfo
compiler=gcc
compiler.cppstd=gnu14
compiler.libc=glibc
compiler.libc.version=2.34
compiler.libcxx=libstdc++
compiler.version=10.3
os=Linux
os.platform=myplat
os.version=5.10.209

[options]
*:fPIC=True
*:shared=True

[conf]
tools.build.cross_building:can_run=False
tools.build.cross_building:cross_build=True
tools.build:skip_test=True
tools.build:sysroot=/usr/myplat-sysroot
tools.cmake.cmake_layout:build_folder_vars=['settings.os.platform']
tools.gnu:host_triplet=x86_64-myplat-linux-gnu

[buildenv]
CONAN_CMAKE_FIND_ROOT_PATH=/usr/x86-10.3-glibc-2.34
CONAN_CMAKE_SYSROOT=/usr/myplat-sysroot
CC=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-gcc
CXX=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-g++
STRIP=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-strip
AR=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-ar
AS=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-as
LD=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-ld
RANLIB=/usr/x86-10.3-glibc-2.34/bin/x86_64-myplat_buildroot-linux-gnu-ranlib

Profile build:

[settings]
arch=x86_64
build_type=RelWithDebInfo
compiler=gcc
compiler.cppstd=gnu14
compiler.libc=glibc
compiler.libc.version=2.31
compiler.libcxx=libstdc++11
compiler.version=9
os=Linux
os.platform=native
os.version=5.15

[options]
*:fPIC=True
*:shared=True

[conf]
tools.build:compiler_executables={'c': '/usr/bin/gcc'}
tools.cmake.cmake_layout:build_folder_vars=['settings.os.platform']

[vithalsm]

Using the changes from PR mentioned above by @valgur. Build still fails with libudev not able to find one of the dependency

header file.In file included from ../src/src/libsystemd/sd-bus/bus-control.c:16:
../src/src/basic/capability-util.h:6:10: fatal error: sys/capability.h: No such file or directory
6 | #include <sys/capability.h>
| ^~~~~~~~~~~~~~~~~~

libcap is included as dependency both in conanfile.py and meson.build of libudev. I see that, libcap.pc file is generated and looks fine. But what I see is, INCLUDE and LIB paths (as exported from libpcap.pc file) are not being included and hence could be the reason for not able to find above file.

Can someone please give me some hints on what could be issue and where to look at please? At the moment stuck/blocked with this issue.
@valgur @memsharded @uilianries

[valgur]

I added a fix for the libcap issue to my PR.

[jcar87]

Hi @vithalsm - which recipes from Conan center are you trying to build?

[valgur]

@jcar87
@vithalsm said that he's trying to build DPDK from #24817 in the related PR.