Index: sys/compat/linuxkpi/common/include/linux/bitfield.h
===================================================================
--- /dev/null
+++ sys/compat/linuxkpi/common/include/linux/bitfield.h
@@ -0,0 +1,16 @@
+/* Public domain. */
+
+#ifndef _LINUX_BITFIELD_H
+#define _LINUX_BITFIELD_H
+
+#include <asm/byteorder.h>
+
+#define __bf_shf(x) (__builtin_ffsll(x) - 1)
+
+#define FIELD_GET(_m, _v) \
+    ((typeof(_m))(((_v) & (_m)) >> __bf_shf(_m)))
+
+#define FIELD_PREP(_m, _v) \
+    (((typeof(_m))(_v) << __bf_shf(_m)) & (_m))
+
+#endif