Re: [dpdk-stable] [PATCH 2/2] build: use dependency() instead of find_library()

From: Luca Boccassi <bluca@debian.org>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: dev@dpdk.org, stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH 2/2] build: use dependency() instead of find_library()
Date: Fri, 11 Jan 2019 12:39:23 +0000	[thread overview]
Message-ID: <1547210363.4501.10.camel@debian.org> (raw)
In-Reply-To: <20190111115254.GA3336@bricha3-MOBL.ger.corp.intel.com>

On Fri, 2019-01-11 at 11:52 +0000, Bruce Richardson wrote:
> On Fri, Jan 11, 2019 at 11:10:28AM +0000, Luca Boccassi wrote:
> > On Mon, 2019-01-07 at 16:55 +0000, Bruce Richardson wrote:
> > > On Mon, Jan 07, 2019 at 04:39:34PM +0000, Luca Boccassi wrote:
> > > > On Mon, 2019-01-07 at 14:28 +0000, Bruce Richardson wrote:
> > > > > On Thu, Jan 03, 2019 at 06:57:25PM +0100, Luca Boccassi
> > > > > wrote:
> > > > > > For libbsd, which is checked in a top level file and used
> > > > > > to be
> > > > > > added
> > > > > > to the global linker flags array, add it to the ext_deps
> > > > > > array
> > > > > > of
> > > > > > all top level meson files (app, test, lib, examples,
> > > > > > drivers).
> > > > > > The
> > > > > > most correct change would be to let each individual
> > > > > > library/driver/app
> > > > > > depend on it individually if they use symbols from it, but
> > > > > > it
> > > > > > would
> > > > > > diverge from the legacy Makefile's behaviour and make life
> > > > > > a
> > > > > > bit
> > > > > > more
> > > > > > difficult for contributors.
> > > > > 
> > > > > It shouldn't be necessary to add libbsd as a dependency for
> > > > > everything. I
> > > > > think just adding it as a dependency of EAL should work
> > > > > fine. 
> > > > 
> > > > Won't that mean that the shared libraries other than EAL will
> > > > have
> > > > undefined references?
> > > 
> > > Should not happen. AFAIK when you link against a library in meson
> > > it
> > > will
> > > also link against any of that libraries dependencies too. For
> > > shared
> > > libraries meson always disallowed undefined references in the
> > > linker
> > > commandline. [To have libs with undefined refs, e.g. plugins, you
> > > need to
> > > use "shared_module" rather than "shared_library" command].
> > 
> > Looked at this again, and rte_cmdline is using strlcpy as well, and
> > it's built before rte_eal, so it fails:
> > 
> > lib/76b5a35@@rte_cmdline@sta/librte_cmdline_cmdline_parse.c.o: In
> > function `cmdline_complete':
> > cmdline_parse.c:(.text+0x861): undefined reference to `strlcpy'
> > 
> > Adding it to ext_deps in both rte_cmdline and rte_eal works. Is
> > that an acceptable compromise?
> > 
> 
> Sure. If eal has a dependency on cmdline, you probably don't need to
> add it
> as an external dependency to EAL too, but it doesn't really hurt to
> do so.
> 
> /Bruce

eal does not depend on cmdline, so added in both in v2. I also split
the libbsd change and meson bump to 0.47.1 in a separate commit in the
series.

-- 
Kind regards,
Luca Boccassi