Drivers librte_mempool_ring.so and librte_pmd_null.so are loaded by
librte_eal.so when running testpmd.
In Ubuntu Xenial, driver path is installed to RPATH on testpmd. This
allows librte_eal.so to find drivers by using the RPATH.
However, in Ubuntu Bionic, driver path is installed to RUNPATH instead.
The RUNPATH on testpmd is not available by librte_eal.so and therefore
lead to driver load failure:

EAL: Detected 32 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: librte_mempool_ring.so: cannot open shared object file:
					No such file or directory
EAL: FATAL: Cannot init plugins
EAL: Cannot init plugins

Add 'drivers' into LD_LIBRARY_PATH so that testpmd can find and make
use of these shared libraries.

Signed-off-by: Ruifeng Wang <redacted>
Reviewed-by: Gavin Hu <redacted>
---
 devtools/test-null.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/devtools/test-null.sh b/devtools/test-null.sh
index f39af2c06..548de8113 100755
--- a/devtools/test-null.sh
+++ b/devtools/test-null.sh

@@ -20,7 +20,7 @@ if [ ! -f "$testpmd" ] ; then
 fi
 
 if ldd $testpmd | grep -q librte_ ; then
-	export LD_LIBRARY_PATH=$build/lib:$LD_LIBRARY_PATH
+	export LD_LIBRARY_PATH=$build/drivers:$build/lib:$LD_LIBRARY_PATH
 	libs='-d librte_mempool_ring.so -d librte_pmd_null.so'
 else
 	libs=

-- 
2.17.1