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: sta...@dpdk.org

Signed-off-by: Olivier Matz <olivier.m...@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

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