Index: sys/compat/linuxkpi/common/include/linux/string_helpers.h
===================================================================
--- /dev/null
+++ sys/compat/linuxkpi/common/include/linux/string_helpers.h
@@ -0,0 +1,16 @@
+/* Public domain */
+
+#ifndef	_LINUXKPI_LINUX_STRING_HELPERS_H_
+#define	_LINUXKPI_LINUX_STRING_HELPERS_H_
+
+#include <sys/types.h>
+
+static inline const char *str_yes_no(bool value)
+{
+	if (value)
+		return "yes";
+	else
+		return "no";
+}
+
+#endif	/* _LINUXKPI_LINUX_STRING_HELPERS_H_ */