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

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Jan 18, 2021 at 12:16:04PM +0000, Ferruh Yigit wrote:
> On 1/18/2021 12:05 PM, Ferruh Yigit wrote:
> > On 1/18/2021 11:58 AM, Ferruh Yigit wrote:
> > > On 1/18/2021 10:51 AM, Bruce Richardson wrote:
> > > > On Fri, Jan 15, 2021 at 06:40:56PM +0000, Ferruh Yigit wrote:
> > > > > 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
> > > > > 
> > > > 
> > > > I've just tried this on my system and it works as expected: the 32-bit lib
> > > > is not found and a build succeeds. Omitting the PKG_CONFIG_LIBDIR and it is
> > > > found, but linking fails due to "file in wrong format" errors, again as
> > > > expected.
> > > > 
> > > > In your case, I suspect it might be meson falling back to cmake in the
> > > > detection logic. If you have cmake installed on your system, can you
> > > > perhaps temporarily remove it, and retry the 32-bit build? If that is the
> > > > cause, we can modify the dependency call to add "method: 'pkg-config'" to
> > > > it, to force pkg-config searches only.
> > > > 
> > > 
> > > Yes I have cmake, I will try without it.
> > > 
> > > Meanwhile I have Fedora, and it seems it is using different version
> > > of the pkg-config (pkgconf), not sure if this can be a problem.
> > > 
> > 
> > I confirm removing the 'cmake' solved the issue, now I am getting:
> > "Run-time dependency zlib found: NO (tried pkgconfig and cmake)"
> > 
> > And zlib dependent modules not enabled, so build runs successfully.
> 
> Following is fixing the problem [1], but isn't this a generic problem when
> 64bit version of a library installed but 32bit version of it is missing and
> 'cmake' exists?
> 
> Should all library discovery reduced to the 'pkg-config' only?
> 
Yes, I'm in the process of doing up a patch for this.