+dnl Whether (and which) elfutils libdw.so to use for unwinding.
+AC_ARG_WITH(elfutils,
+ AS_HELP_STRING([--with-elfutils], [Use elfutils libdwfl unwinding support]),
+ [case "${withval}" in
+ (yes|no) enable_elfutils=$withval;;
+ (*) enable_elfutils=yes
+ AM_CPPFLAGS="${AM_CPPFLAGS} -I${withval}/include"
+ AM_LDFLAGS="${AM_LDFLAGS} -L${withval}/lib"
+ elfutils_LD_LIBRARY_PATH="${withval}/lib:${withval}/lib/elfutils"
+ ;;
+esac],[enable_elfutils=maybe])
+
+dnl Check whether we have the elfutils libdwfl.h header installed.
+saved_CPPFLAGS="${CPPFLAGS}"
+CPPFLAGS="${CPPFLAGS} ${AM_CPPFLAGS}"
+AC_CHECK_HEADERS([elfutils/libdwfl.h],[have_libdwfl_h=yes])
+CPPFLAGS="${saved_CPPFLAGS}"
+
+dnl And whether libdw.so provides the unwinding functions.
+saved_LDFLAGS="${LDFLAGS}"
+LDFLAGS="${LDFLAGS} ${AM_LDFLAGS}"
+AC_CHECK_LIB([dw], [dwfl_getthread_frames], [have_libdw_dwfl_frames=yes])
+LDFLAGS="${saved_LDFLAGS}"
+
+AC_MSG_CHECKING([whether to use elfutils libdwfl unwinding support])
+case "${enable_elfutils}" in
+(yes|maybe)
+ if test x$have_libdwfl_h = xyes -a x$have_libdw_dwfl_frames = xyes; then
+ enable_elfutils=yes
+ elif test $enable_elfutils = maybe; then
+ enable_elfutils=no
+ else
+ AC_MSG_RESULT([$enable_elfutils])
+ AC_MSG_ERROR([Missing elfutils/libdwfl.h or dwfl_getthread_frames not in libdw.so])
+ fi
+ ;;
+(*) ;;
+esac
+AC_MSG_RESULT([$enable_elfutils])
+
+if test x"$enable_elfutils" = xyes; then
+ libdw_LIBS=-ldw
+ AC_SUBST(libdw_LIBS)
+ AC_DEFINE([HAVE_LIBDW], [1], [we have elfutils libdw])
+fi