http://code.ros.org/trac/opencv/ticket/141
http://bugs.gentoo.org/313649

--- src/highgui/cvcap_libv4l.cpp
+++ src/highgui/cvcap_libv4l.cpp
@@ -782,7 +782,7 @@
 
        capture->buffers[n_buffers].length = buf.length;
        capture->buffers[n_buffers].start =
-         mmap (NULL /* start anywhere */,
+         v4l2_mmap (NULL /* start anywhere */,
                buf.length,
                PROT_READ | PROT_WRITE /* required */,
                MAP_SHARED /* recommended */,