1# Linking SPDK applications with pkg-config {#pkgconfig} 2 3The SPDK build system generates pkg-config files to facilitate linking 4applications with the correct set of SPDK and DPDK libraries. Using pkg-config 5in your build system will ensure you do not need to make modifications 6when SPDK adds or modifies library dependencies. 7 8If your application is using the SPDK nvme library, you would use the following 9to get the list of required SPDK libraries: 10 11~~~ 12PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_nvme 13~~~ 14 15To get the list of required SPDK and DPDK libraries to use the DPDK-based 16environment layer: 17 18~~~ 19PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_env_dpdk 20~~~ 21 22When linking with static libraries, the dependent system libraries must also be 23specified. To get the list of required system libraries: 24 25~~~ 26PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_syslibs 27~~~ 28 29Note that SPDK libraries use constructor functions liberally, so you must surround 30the library list with extra linker options to ensure these functions are not dropped 31from the resulting application binary. With shared libraries this is achieved through 32the `-Wl,--no-as-needed` parameters while with static libraries `-Wl,--whole-archive` 33is used. Here is an example Makefile snippet that shows how to use pkg-config to link 34an application that uses the SPDK nvme shared library: 35 36~~~ 37PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig 38SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme 39DPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_env_dpdk 40 41app: 42 $(CC) -o app app.o -pthread -Wl,--no-as-needed $(SPDK_LIB) $(DPDK_LIB) -Wl,--as-needed 43~~~ 44 45If using the SPDK nvme static library: 46 47~~~ 48PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig 49SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme 50DPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_env_dpdk 51SYS_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs --static spdk_syslibs 52 53app: 54 $(CC) -o app app.o -pthread -Wl,--whole-archive $(SPDK_LIB) $(DPDK_LIB) -Wl,--no-whole-archive \ 55 $(SYS_LIB) 56~~~ 57