Re: [dpdk-dev] [PATCHv6 16/33] drivers/pool/dpaa2: adding hw offloaded mempool

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2017-01-24 20:07, Hemant Agrawal:
> On 1/24/2017 4:19 PM, Ferruh Yigit wrote:
> > On 1/24/2017 9:12 AM, Shreyansh Jain wrote:
> >> On Monday 23 January 2017 11:04 PM, Ferruh Yigit wrote:
> >>> On 1/23/2017 11:59 AM, Hemant Agrawal wrote:
> >>>> +# library dependencies
> >>>> +DEPDIRS-$(CONFIG_RTE_LIBRTE_DPAA2_POOL) += lib/librte_eal
> >>>> +DEPDIRS-$(CONFIG_RTE_LIBRTE_DPAA2_POOL) += lib/librte_mempool
> >>>> +DEPDIRS-$(CONFIG_RTE_LIBRTE_DPAA2_POOL) += lib/librte_common_dpaa2_qbman
> >>>
> >>> This dependeny doesn not looks correct, there is no folder like that.
> >>
> >> This is something even I need to understand. From the DEPDIRS what I
> >> understood was that though it refers to a directory, it essentially
> >> links libraries in build/lib/*.
> >>
> >> Further, somehow the development is deploying drivers/bus,
> >> drivers/common and drivers/pool in lib/* under the name specified as
> >> LIB in Makefile. My understanding was that it is expected behavior and
> >> not special because of drivers folder.
> >>
> >> Thus, above line only links lib/librte_common_dpaa2_qbman generated by
> >> drivers/common/dpaa2/qbman code.
> >>
> >> In fact, I think, this might also one of the issues why a parallel
> >> shared build fails for DPAA2 PMD (added in Cover letter).
> >> The dependency graph cannot create a graph for drivers/common
> >> as dependency for drivers/net or drivers/bus and hence parallel build
> >> fails because of missing libraries which are being parallely compiled.
> >
> > DEPDIRS-y is mainly to resolve dependencies for compilation order, and
> > should point to the folder,
> >
> > Following line will cause "librte_eal" to be compiled before driver:
> > DEPDIRS-$(CONFIG_RTE_LIBRTE_DPAA2_POOL) += lib/librte_eal
> >
> > So "lib/librte_common_dpaa2_qbman" does not makes more sense, since
> > there is no folder like that.
> >
> >
> > Somewhere in the history, with following commit, DEPDIRS-y gained a side
> > effect, it has been used to set dynamic linking dependencies, to fix
> > underlinking issue:
> >  bf5a46fa5972 ("mk: generate internal library dependencies")
> >
> > I guess you are having that line to benefit from this side effect, but
> > this can be done with following more properly:
> > LDLIBS += lib/librte_common_dpaa2_qbman
> >
> >
> > To resolve the drivers/net to drivers/common dependency, following line
> > in this Makefile should work:
> > DEPDIRS-$(CONFIG_RTE_LIBRTE_DPAA2_PMD) += drivers/common/dpaa2
> >
> > This adds following, which will cause "drivers/common" compiled before
> > any "drivers/net":
> > LOCAL_DEPDIRS-drivers/net += drivers/common
> 
> Thanks for your suggestion. This is one thing, I am not yet able to fix.
> 
> Based on your suggestions:
> e.g.
> LDLIBS += -lrte_common_dpaa2_qbman
> DEPDIRS-$(CONFIG_RTE_LIBRTE_FSLMC_BUS) += drivers/common/dpaa2
> 
> It does add entry in the ".depdirs"
> ./arm64-dpaa2-linuxapp-gcc/.depdirs:168:LOCAL_DEPDIRS-drivers/bus += 
> drivers/common
> ./arm64-dpaa2-linuxapp-gcc/.depdirs:170:LOCAL_DEPDIRS-drivers += lib
> ./arm64-dpaa2-linuxapp-gcc/.depdirs:172:LOCAL_DEPDIRS-drivers += lib
> ./arm64-dpaa2-linuxapp-gcc/.depdirs:174:LOCAL_DEPDIRS-drivers/pool += 
> drivers/common
> 
> However,  we keep on getting:
> LD librte_bus_fslmc.so.1.1
> aarch64-linux-gnu-gcc: error: drivers/common/dpaa2: No such file or 
> directory
> make[6]: *** [librte_bus_fslmc.so.1.1] Error 1

Probably because of:

# Translate DEPDIRS-y into LDLIBS
# Ignore (sub)directory dependencies which do not provide an actual library
_IGNORE_DIRS = lib/librte_eal/% lib/librte_compat
_DEPDIRS = $(filter-out $(_IGNORE_DIRS),$(DEPDIRS-y))
_LDDIRS = $(subst librte_ether,librte_ethdev,$(_DEPDIRS))
LDLIBS += $(subst lib/lib,-l,$(_LDDIRS))

It shows one important thing: qbman is not a driver, it is a lib.
So drivers/common/dpaa2 should be handled differently.

Solution 1: tweak mk/rte.lib.mk for directories in drivers/common/
Solution 2: host your bus libs outside of DPDK