On Tue, Feb 04, 2020 at 04:14:46PM +0100, Thomas Monjalon wrote: > 04/02/2020 15:33, Bruce Richardson: > > On Tue, Feb 04, 2020 at 03:27:50PM +0100, Thomas Monjalon wrote: > > > 04/02/2020 12:48, Bruce Richardson: > > > > as we discussed offline, I really don't like the necessity of the > > > > hidden_deps part of this, so I've tried coming up with some other > > > > solutions. > > > > > > Thanks for looking closely at these patches. > > > > > > > For example, in my testing I get the same result with the > > > > following diff instead of the second two patches (just showing for mlx5 > > > > - > > > > changes for mlx4 are identical): > > > [...] > > > > - # Build without adding shared libs to > > > > Requires.private > > > > - hidden_deps += > > > > lib.partial_dependency(compile_args:true) > > > [...] > > > > + ibv_cflags = run_command(find_program('pkg-config'), > > > > '--cflags', 'libibverbs').stdout() > > > [...] > > > > By doing things this way - assuming it works in your tests too - we > > > > avoid > > > > any need to change anything in the common drivers code. > > > > > > Yes, you hide the dependency by getting cflags directly with pkg-config. > > > I wanted to avoid such solution because I was trying to use as much > > > as possible the meson infrastructure. > > > > > > I think your solution relying on one more call to pkg-config is > > > acceptable. > > > I will test it and will review whether we get all corner cases. > > > > > > > Thanks. > > It's not really ideal, but this is likely always going to be a bit flakey > > since we can't use distro-supplied .a files, and your scripting is needed > > to prevent even accidentally taking a non-custom-build rdma-core file. > > Furthermore, I see that while meson tracks PKG_CONFIG_PATH value itself for > > finding things, this does not get tracked between runs for shell calls. > > This can catch one out, for example: > > > > PKG_CONFIG_PATH=/path/to/pc/files meson build > > > > will work correctly for everything. However, if one does a reconfigure > > subsequently doing e.g. ninja reconfigure, meson will correctly pick up the > > .pc files, but the ibverbs-static script, or any run_command calls to > > pkg-config won't as it's not actually in the environment :-( > > In my setup, I export PKG_CONFIG_PATH, so it is not an issue. > But I understand your point that we may hit the issue. > That's why I will work in meson upstream to avoid all of this in future. > +1
> > > > In the meantime I discovered we are overlinking with meson > > > when using the dlopen linking option. > > > I will try to fix it as well with the same method. > > > > > Right. Overlinking is probably less serious an issue though. Does it cause > > any real-world problems? > > Overlinking defeats the benefit of dlopen. > The idea of dlopen is to avoid having ibverbs as mandatory DPDK dependency. > The ibverbs lib is loaded with dlopen only if probing a Mellanox device. > The dlopen solution makes the PMD really like an optional plugin, > same as for static linkage in the PMD. > Right, I understand the issue now.