build: fix plugin load on static build

When dpdk is compiled as static libraries, it is not possible
to load a plugin from an application. We get the following error:

  EAL: librte_pmd_xxxx.so: undefined symbol: per_lcore__rte_errno

This happens because the dpdk symbols are not exported. Add them to the
dynamic symbol table by using '-Wl,--export-dynamic'. This option was
previously present when compiled with Makefiles, it was introduced in
commit f9a08f6502 ("eal: add support for shared object drivers")

Also add it to the pkg-config file.

Fixes: 16ade738fd ("app/testpmd: build with meson")
Fixes: 89f0711f9d ("examples: build some samples with meson")
Cc: stable@dpdk.org

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>

app/meson.build

@@ -25,6 +25,10 @@ apps = [
 lib_execinfo = cc.find_library('execinfo', required: false)
 
 default_cflags = machine_args + ['-DALLOW_EXPERIMENTAL_API']
+default_ldflags = []
+if get_option('default_library') == 'static'
+	default_ldflags += ['-Wl,--export-dynamic']
+endif
 
 foreach app:apps
 	build = true
@@ -32,6 +36,7 @@ foreach app:apps
 	sources = []
 	includes = []
 	cflags = default_cflags
+	ldflags = default_ldflags
 	objs = [] # other object files to link against, used e.g. for
 	          # instruction-set optimized versions of code
 
@@ -58,6 +63,7 @@ foreach app:apps
 		executable('dpdk-' + name,
 				sources,
 				c_args: cflags,
+				link_args: ldflags,
 				link_whole: link_libs,
 				dependencies: dep_objs,
 				install_rpath: join_paths(get_option('prefix'),

buildtools/pkg-config/meson.build

@@ -47,7 +47,7 @@ This is required for a number of static inline functions in the public headers.'
 	                  # if libbsd is not enabled, then this is blank
 	libraries_private: ['-Wl,--whole-archive'] +
 			dpdk_drivers + dpdk_static_libraries +
-			['-Wl,--no-whole-archive']
+			['-Wl,--no-whole-archive', '-Wl,--export-dynamic']
 )
 
 # For static linking with dependencies as shared libraries,

examples/meson.build

@@ -63,6 +63,10 @@ default_cflags = machine_args
 if cc.has_argument('-Wno-format-truncation')
 	default_cflags += '-Wno-format-truncation'
 endif
+default_ldflags = dpdk_extra_ldflags
+if get_option('default_library') == 'static'
+	default_ldflags += ['-Wl,--export-dynamic']
+endif
 
 foreach example: examples
 	name = example.split('/')[-1]
@@ -70,6 +74,7 @@ foreach example: examples
 	sources = []
 	allow_experimental_apis = false
 	cflags = default_cflags
+	ldflags = default_ldflags
 
 	ext_deps = [execinfo]
 	includes = [include_directories(example)]
@@ -91,7 +96,7 @@ foreach example: examples
 		executable('dpdk-' + name, sources,
 			include_directories: includes,
 			link_whole: link_whole_libs,
-			link_args: dpdk_extra_ldflags,
+			link_args: ldflags,
 			c_args: cflags,
 			dependencies: dep_objs)
 	elif not allow_skips