build: improve dependency handling

Whenever possible (if the library ships a pkg-config file) use meson's
dependency() function to look for it, as it will automatically add it
to the Requires.private list if needed, to allow for static builds to
succeed for reverse dependencies of DPDK. Otherwise the recursive
dependencies are not parsed, and users doing static builds have to
resolve them manually by themselves.
When using this API avoid additional checks that are superfluous and
take extra time, and avoid adding the linker flag manually which causes
it to be duplicated.

Signed-off-by: Luca Boccassi <bluca@debian.org>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Tested-by: Bruce Richardson <bruce.richardson@intel.com>

drivers/compress/zlib/meson.build

@@ -9,6 +9,5 @@ endif
 deps += 'bus_vdev'
 sources = files('zlib_pmd.c', 'zlib_pmd_ops.c')
 ext_deps += dep
-pkgconfig_extra_libs += '-lz'
 
 allow_experimental_apis = true

drivers/crypto/ccp/meson.build

@@ -18,4 +18,3 @@ sources = files('rte_ccp_pmd.c',
 		'ccp_pmd_ops.c')
 
 ext_deps += dep
-pkgconfig_extra_libs += '-lcrypto'

drivers/crypto/openssl/meson.build

@@ -9,4 +9,3 @@ allow_experimental_apis = true
 deps += 'bus_vdev'
 sources = files('rte_openssl_pmd.c', 'rte_openssl_pmd_ops.c')
 ext_deps += dep
-pkgconfig_extra_libs += '-lcrypto'

drivers/crypto/qat/meson.build

@@ -13,6 +13,5 @@ if dep.found()
 			     'qat_sym.c',
 			     'qat_sym_session.c')
 	qat_ext_deps += dep
-	pkgconfig_extra_libs += '-lcrypto'
 	qat_cflags += '-DBUILD_QAT_SYM'
 endif

drivers/meson.build

@@ -46,10 +46,11 @@ foreach class:driver_classes
 		# set up internal deps. Drivers can append/override as necessary
 		deps = std_deps
 		# ext_deps: Stores external library dependency got
-		# using dependency() or cc.find_library(). For most cases, we
-		# probably also need to specify the "-l" flags in
-		# pkgconfig_extra_libs variable too, so that it can be reflected
-		# in the pkgconfig output for static builds
+		# using dependency() (preferred) or find_library().
+		# For the find_library() case (but not with dependency()) we also
+		# need to specify the "-l" flags in pkgconfig_extra_libs variable
+		# too, so that it can be reflected in the pkgconfig output for
+		# static builds.
 		ext_deps = []
 		pkgconfig_extra_libs = []
 

drivers/net/bnx2x/meson.build

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright(c) 2018 Intel Corporation
 
-dep = cc.find_library('z', required: false)
+dep = dependency('zlib', required: false)
 build = dep.found()
 ext_deps += dep
 cflags += '-DZLIB_CONST'

drivers/net/mlx4/meson.build

@@ -14,9 +14,9 @@ if pmd_dlopen
 	]
 endif
 libs = [
-	cc.find_library('mnl', required:false),
-	cc.find_library('mlx4', required:false),
-	cc.find_library('ibverbs', required:false),
+	dependency('libmnl', required:false),
+	dependency('libmlx4', required:false),
+	dependency('libibverbs', required:false),
 ]
 build = true
 foreach lib:libs

drivers/net/mlx5/meson.build

@@ -14,9 +14,9 @@ if pmd_dlopen
 	]
 endif
 libs = [
-	cc.find_library('mnl', required:false),
-	cc.find_library('mlx5', required:false),
-	cc.find_library('ibverbs', required:false),
+	dependency('libmnl', required:false),
+	dependency('libmlx5', required:false),
+	dependency('libibverbs', required:false),
 ]
 build = true
 foreach lib:libs

lib/librte_bpf/meson.build

@@ -18,8 +18,8 @@ install_headers = files('bpf_def.h',
 
 deps += ['mbuf', 'net', 'ethdev']
 
-dep = cc.find_library('elf', required: false)
-if dep.found() == true and cc.has_header('libelf.h', dependencies: dep)
+dep = dependency('libelf', required: false)
+if dep.found()
 	sources += files('bpf_load_elf.c')
 	ext_deps += dep
 endif

lib/librte_telemetry/meson.build

@@ -6,7 +6,7 @@ headers = files('rte_telemetry.h', 'rte_telemetry_internal.h', 'rte_telemetry_pa
 deps += ['metrics', 'ethdev']
 cflags += '-DALLOW_EXPERIMENTAL_API'
 
-jansson = cc.find_library('jansson', required: false)
+jansson = dependency('jansson', required: false)
 if jansson.found()
 	ext_deps += jansson
 	dpdk_app_link_libraries += ['telemetry']