* kern/emu/misc.c (device_mapper_null_log): New function.

(grub_device_mapper_supported): New function.
* include/grub/emu/misc.h (grub_device_mapper_supported): Add
prototype.
* kern/emu/hostdisk.c (find_partition_start): Check whether
device-mapper is supported before trying to use it.
* util/deviceiter.c (grub_util_iterate_devices): Likewise.

include/grub/emu/misc.h

@@ -48,4 +48,8 @@ int EXPORT_FUNC(asprintf) (char **buf, const char *fmt, ...);
 char * EXPORT_FUNC(xasprintf) (const char *fmt, ...);
 extern char * canonicalize_file_name (const char *path);
 
+#ifdef HAVE_DEVICE_MAPPER
+int grub_device_mapper_supported (void);
+#endif
+
 #endif /* GRUB_EMU_MISC_H */