Re: [dpdk-dev] [PATCH 3/6] net/mlx: fix library search in meson build

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

On Thu, Apr 18, 2019 at 10:25:19AM +0100, Luca Boccassi wrote:
> On Mon, 2019-04-15 at 19:48 +0000, Yongseok Koh wrote:
> > Hi,
> > 
> > 
> > 
> > Thanks,
> > Yongseok
> > 
> > > On Apr 15, 2019, at 3:12 AM, Luca Boccassi <
> > > bluca@debian.org
> > > > wrote:
> > > 
> > > On Fri, 2019-04-12 at 16:24 -0700, Yongseok Koh wrote:
> > > > If MLNX_OFED is installed, there's no .pc file installed for
> > > > libraries and
> > > > dependency() can't find libraries by pkg-config. By adding
> > > > fallback
> > > > of
> > > > using cc.find_library(), libraries are properly located.
> > > > 
> > > > Fixes: e30b4e566f47 ("build: improve dependency handling")
> > > > Cc: 
> > > > bluca@debian.org
> > > > 
> > > > 
> > > > Cc: 
> > > > stable@dpdk.org
> > > > 
> > > > 
> > > > 
> > > > Signed-off-by: Yongseok Koh <
> > > > yskoh@mellanox.com
> > > > 
> > > > 
> > > > ---
> > > > drivers/net/mlx4/meson.build | 19 +++++++++++--------
> > > > drivers/net/mlx5/meson.build | 19 +++++++++++--------
> > > > 2 files changed, 22 insertions(+), 16 deletions(-)
> > > > 
> > > > diff --git a/drivers/net/mlx4/meson.build
> > > > b/drivers/net/mlx4/meson.build
> > > > index de020701d1..9082f69f25 100644
> > > > --- a/drivers/net/mlx4/meson.build
> > > > +++ b/drivers/net/mlx4/meson.build
> > > > @@ -13,21 +13,24 @@ if pmd_dlopen
> > > > 		'-DMLX4_GLUE_VERSION="@0@"'.format(LIB_GLUE_VERSION),
> > > > 	]
> > > > endif
> > > > -libs = [
> > > > -	dependency('libmnl', required:false),
> > > > -	dependency('libmlx4', required:false),
> > > > -	dependency('libibverbs', required:false),
> > > > -]
> > > > +libs = [ 'libmnl', 'libmlx4', 'libibverbs' ]
> > > > +lib_deps = []
> > > > build = true
> > > > foreach lib:libs
> > > > -	if not lib.found()
> > > > +	lib_dep = dependency(lib, required:false)
> > > > +	if not lib_dep.found()
> > > > +		lib_dep = cc.find_library(lib, required:false)
> > > 
> > > Doesn't this end up trying to link the test program to -llibmnl and
> > > thus failing?
> > 
> > I also worried about that. But it works fine.
> > Looks meson is smart enough. :-)
> 
> Sorry, not to be skeptical, but at least with the meson version I was
> using when doing something similar I'm sure this didn't work -
> find_library just takes the parameter, adds "-l" in front of it and
> uses it to compile.
> 
> In the meson configure log, do you see:
> 
> Dependency libmlx4 found: NO
> Library libmlx4 found: YES
> 

My understanding was the same as yours, Luca, and I'm pretty sure older
versions used to have that restriction. I think we should - out of an
abundance of caution - remove the "lib" prefix from all library/dependency
requests.

/Bruce