[dpdk-dev] [PATCH] app: fix plugin load on static builds

[Olivier Matz]

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 f9a08f650211 ("eal: add support for shared object drivers")

Fixes: 16ade738fd0d ("app/testpmd: build with meson")
Fixes: 89f0711f9ddf ("examples: build some samples with meson")
Cc: stable at dpdk.org

Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
---

Hi,

Maybe the patch can be improved: I suppose that --export-dynamic
should only be added in case we are linking in static mode. Any
help about how to do that is welcome.

There is probably a better place to define the default ldflags for
all applications (to factorize between app and example).

Also, should this flag be advertised in pkg-config?

Thanks,
Olivier


 app/meson.build      | 3 +++
 examples/meson.build | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/app/meson.build b/app/meson.build
index eb74f215a3..92479c7729 100644
--- a/app/meson.build
+++ b/app/meson.build
@@ -25,6 +25,7 @@ apps = [
 lib_execinfo = cc.find_library('execinfo', required: false)
 
 default_cflags = machine_args + ['-DALLOW_EXPERIMENTAL_API']
+default_ldflags = ['-Wl,--export-dynamic']
 
 foreach app:apps
 	build = true
@@ -32,6 +33,7 @@ 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 +60,7 @@ 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'),
diff --git a/examples/meson.build b/examples/meson.build
index 46ec80919e..def4540e8f 100644
--- a/examples/meson.build
+++ b/examples/meson.build
@@ -63,6 +63,7 @@ default_cflags = machine_args
 if cc.has_argument('-Wno-format-truncation')
 	default_cflags += '-Wno-format-truncation'
 endif
+default_ldflags = ['-Wl,--export-dynamic'] + dpdk_extra_ldflags
 
 foreach example: examples
 	name = example.split('/')[-1]
@@ -70,6 +71,7 @@ foreach example: examples
 	sources = []
 	allow_experimental_apis = false
 	cflags = default_cflags
+	ldflags = default_ldflags
 
 	ext_deps = [execinfo]
 	includes = [include_directories(example)]
@@ -91,7 +93,7 @@ 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
-- 
2.25.1