1 # Linking SPDK applications with pkg-config {#pkgconfig} 2 3 The SPDK build system generates pkg-config files to facilitate linking 4 applications with the correct set of SPDK and DPDK libraries. Using pkg-config 5 in your build system will ensure you do not need to make modifications 6 when SPDK adds or modifies library dependencies. 7 8 If your application is using the SPDK nvme library, you would use the following 9 to get the list of required SPDK libraries, and the DPDK libraries for the 10 DPDK-based environment layer: 11 12 ~~~bash 13 PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_nvme spdk_env_dpdk 14 ~~~ 15 16 When linking with static libraries, the dependent system libraries must also be 17 specified. To get the list of required system libraries: 18 19 ~~~bash 20 PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs --static spdk_syslibs 21 ~~~ 22 23 Note that SPDK libraries use constructor functions liberally, so you must surround 24 the library list with extra linker options to ensure these functions are not dropped 25 from the resulting application binary. With shared libraries this is achieved through 26 the `-Wl,--no-as-needed` parameters while with static libraries `-Wl,--whole-archive` 27 is used. Here is an example Makefile snippet that shows how to use pkg-config to link 28 an application that uses the SPDK nvme shared library: 29 30 ~~~bash 31 PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig 32 SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme spdk_env_dpdk 33 34 app: 35 $(CC) -o app app.o -pthread -Wl,--no-as-needed $(SPDK_LIB) -Wl,--as-needed 36 ~~~ 37 38 If using the SPDK nvme static library, you should also wrap with `-Wl,-Bstatic` and 39 `-Wl,-Bdynamic`. DPDK by default builds both shared and static libraries - these 40 linker args will ensure that linker uses the static versions: 41 42 ~~~bash 43 PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig 44 SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme spdk_env_dpdk 45 SYS_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs --static spdk_syslibs 46 47 app: 48 $(CC) -o app app.o -pthread -Wl,--whole-archive -Wl,-Bstatic $(SPDK_LIB) \ 49 -Wl,-Bdynamic -Wl,--no-whole-archive $(SYS_LIB) 50 ~~~ 51