Re: [PATCH bpf-next v4] tools/bpf: generate pkg-config file for libbpf

[Andrey Ignatov <rdna@fb.com>]

luca.boccassi@gmail.com <luca.boccassi@gmail.com> [Thu, 2019-03-21 03:26 -0700]:
> From: Luca Boccassi <bluca@debian.org>
> 
> Generate a libbpf.pc file at build time so that users can rely
> on pkg-config to find the library, its CFLAGS and LDFLAGS.
> 
> Signed-off-by: Luca Boccassi <bluca@debian.org>
> ---
> v2: use QUIET_GEN instead of QUIET_LINK to generate pc file,
>     save kernel version in its own variable instead of calling
>     make inline
> v3: use LIBBPF_VERSION instead of kernel_version
> v4: use -I${prefix}/include rather than -I${prefix}/include/bpf
>     in the Cflags field as requested, to keep consistency with
>     how the headers are used now and to avoid a dependency from
>     the pc file to the headers installation

Thanks for the change Luca!
The other part about install target is nit, so no strong preference.

Acked-by: Andrey Ignatov <rdna@fb.com>


>  tools/lib/bpf/.gitignore         |  1 +
>  tools/lib/bpf/Makefile           | 18 +++++++++++++++---
>  tools/lib/bpf/libbpf.pc.template | 11 +++++++++++
>  3 files changed, 27 insertions(+), 3 deletions(-)
>  create mode 100644 tools/lib/bpf/libbpf.pc.template
> 
> diff --git a/tools/lib/bpf/.gitignore b/tools/lib/bpf/.gitignore
> index 4db74758c674..7d9e182a1f51 100644
> --- a/tools/lib/bpf/.gitignore
> +++ b/tools/lib/bpf/.gitignore
> @@ -1,3 +1,4 @@
>  libbpf_version.h
> +libbpf.pc
>  FEATURE-DUMP.libbpf
>  test_libbpf
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 61aaacf0cfa1..891fe3da1410 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -80,6 +80,7 @@ libdir_SQ = $(subst ','\'',$(libdir))
>  libdir_relative_SQ = $(subst ','\'',$(libdir_relative))
>  
>  LIB_FILE = libbpf.a libbpf.so
> +PC_FILE = libbpf.pc
>  
>  VERSION		= $(BPF_VERSION)
>  PATCHLEVEL	= $(BPF_PATCHLEVEL)
> @@ -137,7 +138,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN) | \
>  VERSIONED_SYM_COUNT = $(shell readelf -s --wide $(OUTPUT)libbpf.so | \
>  			      grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
>  
> -CMD_TARGETS = $(LIB_FILE)
> +CMD_TARGETS = $(LIB_FILE) $(PC_FILE)
>  
>  CXX_TEST_TARGET = $(OUTPUT)test_libbpf
>  
> @@ -180,6 +181,12 @@ $(OUTPUT)libbpf.a: $(BPF_IN)
>  $(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
>  	$(QUIET_LINK)$(CXX) $(INCLUDES) $^ -lelf -o $@
>  
> +$(OUTPUT)libbpf.pc:
> +	$(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \
> +		-e "s|@LIBDIR@|$(libdir_SQ)|" \
> +		-e "s|@VERSION@|$(LIBBPF_VERSION)|" \
> +		< $@.template > $@
> +
>  check: check_abi
>  
>  check_abi: $(OUTPUT)libbpf.so
> @@ -209,7 +216,12 @@ install_headers:
>  		$(call do_install,libbpf.h,$(prefix)/include/bpf,644);
>  		$(call do_install,btf.h,$(prefix)/include/bpf,644);
>  
> -install: install_lib
> +install_pkgconfig: $(PC_FILE)
> +	$(call QUIET_INSTALL, $(PC_FILE)) \
> +		$(call do_install,$(PC_FILE),$(libdir_SQ)/pkgconfig,644)
> +
> +
> +install: install_lib install_pkgconfig
>  
>  ### Cleaning rules
>  
> @@ -219,7 +231,7 @@ config-clean:
>  
>  clean:
>  	$(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \
> -		*.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS
> +		*.o *~ *.a *.so .*.d .*.cmd *.pc LIBBPF-CFLAGS
>  	$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf
>  
>  
> diff --git a/tools/lib/bpf/libbpf.pc.template b/tools/lib/bpf/libbpf.pc.template
> new file mode 100644
> index 000000000000..0ecd334c109f
> --- /dev/null
> +++ b/tools/lib/bpf/libbpf.pc.template
> @@ -0,0 +1,11 @@
> +prefix=@PREFIX@
> +libdir=@LIBDIR@
> +includedir=${prefix}/include
> +
> +Name: libbpf
> +URL: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> +Description: Linux kernel BPF library
> +Version: @VERSION@
> +Libs: -L${libdir} -lbpf
> +Requires.private: libelf
> +Cflags: -I${includedir}
> -- 
> 2.20.1
> 

-- 
Andrey Ignatov