[dpdk-dev] meson: wrong dependency in cross compilation on ARM

[Ferruh Yigit]

On 12/21/2020 2:04 PM, Bruce Richardson wrote:
> On Mon, Dec 21, 2020 at 12:19:17PM +0000, Hemant Agrawal wrote:
>> Hi,
>>                  I am trying to cross compile DPDK for arm64 on a ubuntu machine, which has a zlib pre-installed for native env.
>>
>> I am encountering following build error in net_bnx2x as it has dependency on zlib.  It is trying to link with x86 arch based zlib.
>>
>> Cross compiling zlib and setting the PKG_CONFIG_PATH solve the issue. But, Is their an easy way to disable these dependencies?
>>
> Can you try with setting PKG_CONFIG_LIBDIR rather than PKG_CONFIG_PATH?
> PKG_CONFIG_PATH simply extends the search locations, which means that
> host-paths will still be searched, while PKG_CONFIG_LIBDIR replaces the
> default path, eliminating the host-based search paths.
> 

The 'PKG_CONFIG_LIBDIR' seems not taken into account by meson, Akhil reported a 
32bit build error when zlib is missing, I can reproduce the same.

I have only 64bit version of the library:

$ pkg-config --path zlib
/usr/lib64/pkgconfig/zlib.pc

$ PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig/ pkg-config --path zlib
<no output>
$ echo $?
1

When I run the meson as following:
"PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig/ meson --werror -Dc_args=-m32 
-Dc_link_args=-m32 -Dexamples=all build32"

It still detects the zlib:
Run-time dependency zlib found: YES 1.2.11

And build fails:
/usr/bin/ld: /usr/lib64/libz.so: error adding symbols: file in wrong format


If I install the 32 bit version of the zlib, everything works as expected:
$ PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig/ pkg-config --path zlib
/usr/lib/pkgconfig//zlib.pc


As far as I can see there is a meson 'pkg_config_libdir' property, putting it to 
the config/arm/arm64_* can solve the issue for arm, @Hemant can you please try it?
Some more details on:
github.com/mesonbuild/meson/blob/master/docs/markdown/Cross-compilation.md


But not sure how to solve issue for 32bit build, any idea?