diff --git a/share/man/man9/cdefs.9 b/share/man/man9/cdefs.9
--- a/share/man/man9/cdefs.9
+++ b/share/man/man9/cdefs.9
@@ -85,8 +85,12 @@
 .It Sy __weak_symbol Ta Declare the symbol to be a weak symbol
 .It Sy __dead2 Ta Function will not return
 .It Sy __pure2 Ta Function has no side effects
-.It Sy __unused Ta To Variable may be unused (usually arguments), so do not warn about it
+.It Sy __unused Ta To Variable may be unused (usually arguments), so do not
+warn about it
 .It Sy __used Ta Function really is used, so emit it even if it appears unused.
+.It Sy __deprecated Ta Function interface has been deprecated, and clients
+should migrate to a new interface.
+A warning will be issued for clients of this interface.
 .It Sy __packed Ta \&Do not have space between structure elements for natural alignment.
 Used when communicating with external protocols.
 .It Sy __aligned(x) Ta Specify in bytes the minimum alignment for the specified field, structure or variable
diff --git a/sys/compat/linuxkpi/common/include/linux/compiler.h b/sys/compat/linuxkpi/common/include/linux/compiler.h
--- a/sys/compat/linuxkpi/common/include/linux/compiler.h
+++ b/sys/compat/linuxkpi/common/include/linux/compiler.h
@@ -48,7 +48,9 @@
 #define __cond_lock(x,c)		(c)
 #define	__bitwise
 #define __devinitdata
+#ifndef	__deprecated
 #define	__deprecated
+#endif
 #define __init
 #define	__initconst
 #define	__devinit
diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h
--- a/sys/sys/cdefs.h
+++ b/sys/sys/cdefs.h
@@ -154,6 +154,7 @@
 #define	__pure2		__attribute__((__const__))
 #define	__unused	__attribute__((__unused__))
 #define	__used		__attribute__((__used__))
+#define __deprecated	__attribute__((__deprecated__))
 #define	__packed	__attribute__((__packed__))
 #define	__aligned(x)	__attribute__((__aligned__(x)))
 #define	__section(x)	__attribute__((__section__(x)))