merge mainline into newreloc

configure.ac

@@ -786,6 +786,22 @@ AC_SUBST([enable_grub_mkfont])
 AC_SUBST([freetype_cflags])
 AC_SUBST([freetype_libs])
 
+AC_ARG_ENABLE([device-mapper],
+              [AS_HELP_STRING([--enable-device-mapper],
+                              [enable Linux device-mapper support (default=guessed)])])
+if test x"$enable_device_mapper" = xno ; then
+  device_mapper_excuse="explicitly disabled"
+fi
+
+if test x"$device_mapper_excuse" = x ; then
+  # Check for device-mapper library.
+  AC_CHECK_LIB([devmapper], [dm_task_create],
+               [LDFLAGS="$LDFLAGS -ldevmapper"
+                AC_DEFINE([HAVE_DEVICE_MAPPER], [1],
+                          [Define to 1 if you have the devmapper library.])],
+               [device_mapper_excuse="need devmapper library"])
+fi
+
 AC_SUBST(ASFLAGS)
 
 # Output files.