2.8 branch: This is a backport of r11055 from trunk so that libosg and libosgDB link against libdl on Linux systems. Backported by Ryan Pavlik. Trunk commit messages: "From Jim Brooks, fix for FreeBSD build where FIND_LIBRARY(DL_LIBRARY..) return NOT_FOUND. And From Alberto Luaces, "he new GNU linker, "gold", is going to replace soon the current ld in almost all Linux distributions. Although it is 100% compatible with ld, by default it gives an error if a library has unresolved symbols at link time, that is, it has set -Wl,--no-undefined by default. Debian folks have found that libosg.so and libosgDB.so use some functions belonging to libdl.so {dlsym,dlopen,dlclose,dlerror} without linking to it. My changes link those two libraries to libdl.so explicitly in the same way it is already done for libm.so and librt.so."

CMakeLists.txt

@@ -153,6 +153,12 @@ IF(UNIX)
     FIND_PACKAGE(X11)
     # Some Unicies need explicit linkage to the Math library or the build fails.
     FIND_LIBRARY(MATH_LIBRARY m)
+
+    FIND_LIBRARY(DL_LIBRARY dl)
+    IF(NOT DL_LIBRARY)
+        SET(DL_LIBRARY "") # change from NOTFOUND to empty when passed to linker
+    ENDIF()
+
 ENDIF(UNIX)
 
 # Make the headers visible to everything

src/osg/CMakeLists.txt

@@ -326,7 +326,7 @@ ADD_LIBRARY(${LIB_NAME}
 LINK_INTERNAL(${LIB_NAME}     
     OpenThreads
 )
-LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} )
+LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} ${DL_LIBRARY})
 LINK_CORELIB_DEFAULT(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT} ${MATH_LIBRARY} )
 
 INCLUDE(ModuleInstall OPTIONAL)

src/osgDB/CMakeLists.txt

@@ -110,7 +110,7 @@ LINK_INTERNAL(${LIB_NAME}
     osg
     OpenThreads
 )
-LINK_EXTERNAL(${LIB_NAME}     ${OSGDB_PLATFORM_SPECIFIC_LIBRARIES} )
+LINK_EXTERNAL(${LIB_NAME}     ${OSGDB_PLATFORM_SPECIFIC_LIBRARIES} ${DL_LIBRARY})
 LINK_CORELIB_DEFAULT(${LIB_NAME})
 
 INCLUDE(ModuleInstall OPTIONAL)