Re: [dpdk-dev] [PATCH v2] mk: fix build with shared pcap pmd

[Neil Horman <nhorman@tuxdriver.com>]

On Tue, Dec 16, 2014 at 03:39:56PM +0100, Thomas Monjalon wrote:
> 2014-12-16 08:58, Neil Horman:
> > On Tue, Dec 16, 2014 at 12:04:44AM +0100, Thomas Monjalon wrote:
> > > Some applications doesn't have the pcap link flag
> > > when shared libraries are enabled.
> > > Indeed in such case, pcap PMD must not be linked but pcap library should.
> > > 
> > > Actually -lpcap is always needed if pcap PMD is used,
> > > and -lrte_pmd_pcap must be set only with static PMD library.
> > > So the flags -lrte_pmd_pcap and -lpcap are enabled separately.
> > > 
> > > Workarounds in test-pmd/ and test-pipeline/ can be removed.
> > > 
> > > Reported-by: Stepan Sojka <stepan.sojka@adaptivemobile.com>
> > > Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> [...]
> > > --- a/mk/rte.app.mk
> > > +++ b/mk/rte.app.mk
> > > @@ -119,6 +119,10 @@ LDLIBS += -lm
> > >  LDLIBS += -lrt
> > >  endif
> > >  
> > > +ifeq ($(CONFIG_RTE_LIBRTE_PMD_PCAP),y)
> > > +LDLIBS += -lpcap
> > > +endif
> > > +
> > >  LDLIBS += --start-group
> > >  
> > >  ifeq ($(CONFIG_RTE_LIBRTE_KVARGS),y)
> > > @@ -207,7 +211,7 @@ LDLIBS += -lrte_pmd_ring
> > >  endif
> > >  
> > >  ifeq ($(CONFIG_RTE_LIBRTE_PMD_PCAP),y)
> > > -LDLIBS += -lrte_pmd_pcap -lpcap
> > > +LDLIBS += -lrte_pmd_pcap
> > >  endif
> > >  
> > >  ifeq ($(CONFIG_RTE_LIBRTE_PMD_AF_PACKET),y)
> > 
> > Actually, what if we just add $(LDFLAGS) to the O_TO_S rule in mk/rte.lib.mk?
> > Then in lib/librte_pmd_pcap/Makefile, we can just add LDFLAGS+=-lpcap, and the
> > loading of the pcap pmd will itself require the loading of libpcap.  That would
> > be a nice clean implementation that allows applications to just link the pmd and
> > not have to worry about dependencies.  It would also allow us to clean up other
> > dependencies like the xenvirt pmd and vhost.
> 
> Yes it makes sense. Could you test it please?
> What about applying my patch (which keep the existing logic) as a first
> fix/clean-up and then move -lpcap in PMD as a second step?
> Proceeding this way would allow to integrate a safe fix for 1.8.0.
> Maybe that linking pcap in the PMD could unveil new bugs with some distributions,
> so it would need some time to validate it.
> 
> -- 
> Thomas
> 
ACK, I'm fine with your patch currently.  I'll revisit this after 1.8 is
released
Neil