Jim Harris 79f9a7f572 build: generate pkg-config files for SPDK

Users can now generate the necessary linker args for their
own applications using something like:

PKG_CONFIG_PATH=build/lib/pkgconfig pkg-config --libs spdk_nvme

Dependencies between libraries are included in the generated
.pc files, so the user only needs to pass the top-level subsystems
or individual SPDK libraries they are using in their application.

Modules will automatically be added to the output if the associated
library is specified.  For example, specifying "spdk_bdev" will include
the libraries not only for spdk_bdev, but also all of the bdev modules.

Users still need to supply the -Wl,--no-as-needed or -Wl,--whole-archive
flags. They cannot be added to the .pc files without increasing the length
of the argument string by a factor of 15x to 20x.

Modify the test/external_code/hello_world Makefile to use pkg-config to
ensure this gets tested at some level in our autotest environment.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ie48a75f11969d5d775d514cf10bcb82d197eabfd
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4371
Community-CI: Broadcom CI
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

2021-01-21 09:46:32 +00:00

2.1 KiB

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Linking SPDK applications with pkg-config

The SPDK build system generates pkg-config files to facilitate linking applications with the correct set of SPDK and DPDK libraries. Using pkg-config in your build system will ensure you do not need to make modifications when SPDK adds or modifies library dependencies.

If your application is using the SPDK nvme library, you would use the following to get the list of required SPDK libraries:

PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_nvme

To get the list of required SPDK and DPDK libraries to use the DPDK-based environment layer:

PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_env_dpdk

When linking with static libraries, the dependent system libraries must also be specified. To get the list of required system libraries:

PKG_CONFIG_PATH=/path/to/spdk/build/lib/pkgconfig pkg-config --libs spdk_syslibs

Note that SPDK libraries use constructor functions liberally, so you must surround the library list with extra linker options to ensure these functions are not dropped from the resulting application binary. Here is an example Makefile snippet that shows how to use pkg-config to link an application that uses the SPDK nvme shared library:

PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig
SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme
DPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_env_dpdk

app:
	$(CC) -o app app.o -pthread -Wl,--no-as-needed $(SPDK_LIB) $(DPDK_LIB) -Wl,--as-needed

If using the SPDK nvme static library:

PKG_CONFIG_PATH = $(SPDK_DIR)/build/lib/pkgconfig
SPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_nvme
DPDK_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs spdk_env_dpdk
SYS_LIB := $(shell PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" pkg-config --libs --static spdk_syslibs

app:
	$(CC) -o app app.o -pthread -Wl,--whole-archive $(SPDK_LIB) $(DPDK_LIB) -Wl,--no-whole-archive \
		$(SYS_LIB)

2.1 KiB Raw Blame History

Linking SPDK applications with pkg-config

2.1 KiB

Raw Blame History