Re: [dpdk-dev] [PATCH] pci: fix missing pci bus with shared library build

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

On Mon, Jul 15, 2019 at 05:19:12PM -0700, Stephen Hemminger wrote:
> On Mon, 15 Jul 2019 16:41:36 -0700
> Stephen Hemminger <stephen@networkplumber.org> wrote:
> 
> > If DPDK is built as a shared library, then any application linked
> > with rte.app.mk will not find any PCI devices. When the application
> > is started no ethernet devices are found.
> > 
> > This is because the link order of libraries on the command line matters.
> > And PCI is before EAL. That causes there to be no dependency on PCI
> > so linker ignores linking the library. 
> > Swapping the order fixes this.
> > 
> > Fixes: c752998b5e2e ("pci: introduce library and driver")
> > Cc: stable@dpdk.org
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> >  mk/rte.app.mk | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/mk/rte.app.mk b/mk/rte.app.mk
> > index a277c808ed8e..470b92e4d73e 100644
> > --- a/mk/rte.app.mk
> > +++ b/mk/rte.app.mk
> > @@ -90,8 +90,8 @@ _LDLIBS-$(CONFIG_RTE_LIBRTE_STACK)          += -lrte_stack
> >  _LDLIBS-$(CONFIG_RTE_DRIVER_MEMPOOL_RING)   += -lrte_mempool_ring
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_OCTEONTX2_MEMPOOL) += -lrte_mempool_octeontx2
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_RING)           += -lrte_ring
> > -_LDLIBS-$(CONFIG_RTE_LIBRTE_PCI)            += -lrte_pci
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_EAL)            += -lrte_eal
> > +_LDLIBS-$(CONFIG_RTE_LIBRTE_PCI)            += -lrte_pci
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_CMDLINE)        += -lrte_cmdline
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_REORDER)        += -lrte_reorder
> >  _LDLIBS-$(CONFIG_RTE_LIBRTE_SCHED)          += -lrte_sched
> 
> It still happens with 19.08. Testpmd works but only because it is
> linked with so many things. But l3fwd fails...
> 
> # ./examples/l3fwd/build/l3fwd -n4 -l0-3 -w 02:00.0
> EAL: Detected 8 lcore(s)
> EAL: Detected 1 NUMA nodes
> EAL: failed to parse device "02:00.0"
> EAL: Unable to parse device '02:00.0'
> EAL: Error - exiting with code: 1
>   Cause: Invalid EAL parameters

I don't think the position of these is going to be the cause here, the more
likely cause is that the pci bus driver - and all other drivers - are not
linked into apps for shared library builds. You always need to pass "-d"
parameter to load drivers at init time (or have them installed in the
correct driver path). For example, for me with a shared library build the
following gives a no ports error:

	sudo ./build/l2fwd -c F00000 -- -p 3

while this succeeds and runs fine

	sudo ./build/l2fwd -c F00000 -d $RTE_SDK/$RTE_TARGET/lib/librte_pmd_i40e.so -- -p 3