nr-oru linking fails when DPDK is not installed in default installation path

[beurdouc]

DPDK may be installed in a different location than the default install path.
For example, by using meson setup --prefix=/opt/dpdk build, DPDK is installed in /opt/dpdk.
This is especially useful on setups where several versions of DPDK may coexist for any reason.
Then pkgconfig can be used to build the 7.2 fronthaul and ldpc_aal library:

PKG_CONFIG_PATH=/opt/dpdk/lib/x86_64-linux-gnu/pkgconfig/ ./build_oai [...]

But this does not work for nr-oru which also requires DPDK.
Linking fails as the library cannot be found:

344.6 [11945/11946] Linking CXX executable nr-oru
344.6 FAILED: nr-oru 
344.6 : && /usr/bin/c++ -DSIMDE_X86_AVX_NATIVE -DSIMDE_X86_AVX_NATIVE -DSIMDE_X86_F16C_NATIVE -DSIMDE_X86_FMA_NATIVE -DSIMDE_X86_MMX_NATIVE -DSIMDE_X86_PCLMUL_NATIVE -DSIMDE_X86_SSE2_NATIVE -DSIMDE_X86_SSE3_NATIVE -DSIMDE_X86_SSE_NATIVE -DSIMDE_X86_XOP_HAVE_COM_ -DSIMDE_X86_XOP_NATIVE -DSIMDE_X86_AVX512BW_NATIVE -DSIMDE_X86_AVX512F_NATIVE -DSIMDE_X86_AVX512VL_NATIVE -mavx512bw -march=skylake-avx512 -mtune=skylake-avx512 -DSIMDE_X86_AVX2_NATIVE -DSIMDE_X86_VPCLMULQDQ_NATIVE -DSIMDE_X86_GFNI_NATIVE -mgfni -DSIMDE_X86_SSE4_1_NATIVE -DSIMDE_X86_SSE4_2_NATIVE -DSIMDE_X86_SSSE3_NATIVE -march=native -pipe -fPIC -Wall -fno-strict-aliasing -rdynamic -Wno-packed-bitfield-compat  -O2 -g  CMakeFiles/shlib_loader.dir/common/utils/load_module_shlib.c.o CMakeFiles/nr-oru.dir/executables/nr-ru.c.o CMakeFiles/nr-oru.dir/openair1/PHY/INIT/nr_parms.c.o CMakeFiles/nr-oru.dir/openair1/SCHED_NR/phy_frame_config_nr.c.o CMakeFiles/nr-oru.dir/openair1/SCHED_NR/nr_prach_procedures.c.o CMakeFiles/nr-oru.dir/openair1/SCHED_NR/nr_ru_procedures.c.o CMakeFiles/nr-oru.dir/openair1/SCHED/phy_procedures_lte_common.c.o CMakeFiles/nr-oru.dir/executables/main_nr_ru.c.o CMakeFiles/nr-oru.dir/executables/nr-oru.c.o -o nr-oru  -Wl,-rpath,/oai-ran/cmake_targets/ran_build/build  libUTIL.a  libNR_PHY_RU.a  libPHY_NR.a  -ldl  fronthaul/oru/liboru_fh.a  openair2/LAYER2/NR_MAC_COMMON/libMAC_NR_COMMON.a  radio/COMMON/libradio_common.a  executables/libsoftmodem_common.a  nfapi/open-nFAPI/pnf/libnfapi_pnf_lib.a  common/utils/symbol_reorder/libsymbol_reorder.a  -lpthread  -lm  libCONFIG_LIB.a  -lrt  common/utils/T/libT.a  common/utils/libutils.a  common/utils/barrier/libbarrier.a  common/utils/actor/libactor.a  nfapi/oai_integration/libnfapi_user_lib.a  openair1/PHY/nr_phy_common/libnr_phy_common.a  common/utils/time_manager/libtime_management.a  libPHY_COMMON.a  common/utils/nr/libnr_common.a  openair1/PHY/CODING/nrPolar_tools/libpolar.a  openair1/PHY/CODING/nrSmallBlock/libsmallblock.a  fronthaul/oru/liboru_io.a  fronthaul/core/libfh_send.a  fronthaul/core/libfh_recv.a  fronthaul/core/libfh_timer.a  -lm  fronthaul/oru/liboru_packet_processor.a  fronthaul/xran_pkt/libxran_pkt.a  fronthaul/oru/libfh_compression.a  -lrte_node  -lrte_graph  -lrte_pipeline  -lrte_table  -lrte_pdump  -lrte_port  -lrte_fib  -lrte_ipsec  -lrte_vhost  -lrte_stack  -lrte_security  -lrte_sched  -lrte_reorder  -lrte_rib  -lrte_dmadev  -lrte_regexdev  -lrte_rawdev  -lrte_power  -lrte_pcapng  -lrte_member  -lrte_lpm  -lrte_latencystats  -lrte_jobstats  -lrte_ip_frag  -lrte_gso  -lrte_gro  -lrte_gpudev  -lrte_eventdev  -lrte_efd  -lrte_distributor  -lrte_cryptodev  -lrte_compressdev  -lrte_cfgfile  -lrte_bpf  -lrte_bitratestats  -lrte_bbdev  -lrte_acl  -lrte_timer  -lrte_hash  -lrte_metrics  -lrte_cmdline  -lrte_pci  -lrte_ethdev  -lrte_meter  -lrte_net  -lrte_mbuf  -lrte_mempool  -lrte_rcu  -lrte_ring  -lrte_eal  -lrte_telemetry  -lrte_kvargs  nfapi/oai_integration/socket/libnfapi_socket_lib.a  nfapi/open-nFAPI/vnf/libnfapi_vnf_lib.a  nfapi/open-nFAPI/pnf/libnfapi_pnf_lib.a  nfapi/oai_integration/libnfapi_user_lib.a  nfapi/oai_integration/socket/libnfapi_socket_lib.a  nfapi/open-nFAPI/vnf/libnfapi_vnf_lib.a  libUTIL.a  libCONFIG_LIB.a  common/utils/T/libT.a  common/utils/libutils.a  common/utils/LOG/libLOG.a  common/utils/threadPool/libthread-pool.a  libUTIL.a  libCONFIG_LIB.a  common/utils/T/libT.a  common/utils/libutils.a  common/utils/LOG/libLOG.a  common/utils/threadPool/libthread-pool.a  common/utils/barrier/libbarrier.a  -lpthread  common/utils/actor/libactor.a  -ldl  -lrt  nfapi/open-nFAPI/nfapi/libnfapi_nr_lib.a  nfapi/open-nFAPI/fapi/libnr_fapi_p5.a  nfapi/open-nFAPI/fapi/libnr_fapi_p7.a  nfapi/open-nFAPI/fapi/libnr_fapi_common.a  nfapi/open-nFAPI/nfapi/libnfapi_lte_lib.a  nfapi/open-nFAPI/common/libnfapi_common.a  -lz && :
344.6 /usr/bin/ld: cannot find -lrte_node: No such file or directory
344.6 /usr/bin/ld: cannot find -lrte_graph: No such file or directory
344.6 /usr/bin/ld: cannot find -lrte_pipeline: No such file or directory
[...]

This is no big issue from the moment no-one has a good reason to swap DPDK versions for nr-oru.
I personally just removed nr-oru from the build command that caused me this problem as I didn't need it.
I just wanted to let you know about this behavior just in case you consider relevant to fix it.

[rorsc]

either only this

diff --git a/fronthaul/oru/CMakeLists.txt b/fronthaul/oru/CMakeLists.txt
index 3ef6e59900..e2201b52e3 100644
--- a/fronthaul/oru/CMakeLists.txt
+++ b/fronthaul/oru/CMakeLists.txt
@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: LicenseRef-CSSL-1.0
 
+# use env var PKG_CONFIG_PATH to override paths to libdpdk.pc
+pkg_check_modules(dpdk REQUIRED libdpdk)
+
 add_library(oru_io oru_io.c)
 target_include_directories(oru_io PUBLIC ./)
 target_link_libraries(oru_io PUBLIC fh_core ${dpdk_LIBRARIES})

or it is because you need to also change LIBRARIES into LINK_LIBRARIES:

diff --git a/fronthaul/oru/CMakeLists.txt b/fronthaul/oru/CMakeLists.txt
index 3ef6e59900..be34f1e737 100644
--- a/fronthaul/oru/CMakeLists.txt
+++ b/fronthaul/oru/CMakeLists.txt
@@ -1,8 +1,11 @@
 # SPDX-License-Identifier: LicenseRef-CSSL-1.0
 
+# use env var PKG_CONFIG_PATH to override paths to libdpdk.pc
+pkg_check_modules(dpdk REQUIRED libdpdk)
+
 add_library(oru_io oru_io.c)
 target_include_directories(oru_io PUBLIC ./)
-target_link_libraries(oru_io PUBLIC fh_core ${dpdk_LIBRARIES})
+target_link_libraries(oru_io PUBLIC fh_core ${dpdk_LINK_LIBRARIES})
 target_include_directories(oru_io PRIVATE ${dpdk_INCLUDE_DIRS})
 
 add_library(fh_compression fh_compression.c)
@@ -11,11 +14,11 @@ target_link_libraries(fh_compression PRIVATE UTIL)
 
 add_library(oru_packet_processor oru_packet_processor.c)
 target_include_directories(oru_packet_processor PUBLIC ./)
-target_link_libraries(oru_packet_processor PUBLIC ${dpdk_LIBRARIES} PRIVATE xran_pkt UTIL fh_compression)
+target_link_libraries(oru_packet_processor PUBLIC ${dpdk_LINK_LIBRARIES} PRIVATE xran_pkt UTIL fh_compression)
 
 add_library(oru_fh oru_fh.c)
 target_include_directories(oru_fh PUBLIC ./)
-target_link_libraries(oru_fh PUBLIC fh_core oru_io xran_pkt oru_packet_processor ${dpdk_LIBRARIES})
+target_link_libraries(oru_fh PUBLIC fh_core oru_io xran_pkt oru_packet_processor ${dpdk_LINK_LIBRARIES})
 target_include_directories(oru_fh PRIVATE ${dpdk_INCLUDE_DIRS})
 
 if (ENABLE_TESTS)

on the latter, doc:

_LIBRARIES: A list of only the libraries (without the -l).

_LINK_LIBRARIES: The libraries and their absolute paths.

highlight mine, maybe that's why.

we could put this into the integration branch, I think the CI already build-tests.

[beurdouc]

_LINK_LIBRARIES didn't work but I tried _LDFLAGS as well and it worked.

[rorsc]

_LINK_LIBRARIES didn't work but I tried _LDFLAGS as well and it worked.

that is suspicious. the fhi_72 library does compile, does it?

[beurdouc]

_LINK_LIBRARIES didn't work but I tried _LDFLAGS as well and it worked.

that is suspicious. the fhi_72 library does compile, does it?

Yes, the fronthaul is linked successfully with _LINK_LIBRARIES indeed.

[beurdouc]

I may have an idea:
The link error happens when linking nr-oru, not when linking oru_io, oru_packet_processor or oru_fh which are linked successfully.
I believe DPDK is linked with nr-oru because oru_io, oru_packet_processor or oru_fh link DPDK with scope PUBLIC.
If it was scope private, DPDK would be linked while building oru_io, oru_packet_processor or oru_fh but not when building nr-oru.
The recipe for nr-oru is in the main CMakeLists.txt where there is no pkg_check_modules to locate DPDK so maybe it is unable to find DPDK there.

With target oran_fhlib_5g there are no such issue because DPDK is linked with scope PRIVATE and anyway oran_fhlib_5g is a module that is not linked in any other target at compile time.