Index: lib/libc/sys/clock_gettime.2
===================================================================
--- lib/libc/sys/clock_gettime.2
+++ lib/libc/sys/clock_gettime.2
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 13, 2021
+.Dd July 1, 2021
 .Dt CLOCK_GETTIME 2
 .Os
 .Sh NAME
@@ -68,10 +68,12 @@
 .It Dv CLOCK_REALTIME
 .It Dv CLOCK_REALTIME_PRECISE
 .It Dv CLOCK_REALTIME_FAST
+.It Dv CLOCK_REALTIME_COARSE
 Increments as a wall clock should.
 .It Dv CLOCK_MONOTONIC
 .It Dv CLOCK_MONOTONIC_PRECISE
 .It Dv CLOCK_MONOTONIC_FAST
+.It Dv CLOCK_MONOTONIC_COARSE
 Increments in SI seconds.
 .It Dv CLOCK_UPTIME
 .It Dv CLOCK_UPTIME_PRECISE
@@ -104,6 +106,11 @@
 .Fa CLOCK_UPTIME_PRECISE
 are used to get the most exact value as possible, at the expense of
 execution time.
+Finally, the clock IDs
+.Fa CLOCK_REALTIME_COARSE ,
+.Fa CLOCK_MONOTONIC_COARSE
+are aliases of corresponding IDs wit _FAST suffix for compatibility with other
+systems.
 .Pp
 The structure pointed to by
 .Fa tp
Index: sys/sys/time.h
===================================================================
--- sys/sys/time.h
+++ sys/sys/time.h
@@ -486,8 +486,10 @@
 #define	CLOCK_UPTIME_FAST	8	/* FreeBSD-specific. */
 #define	CLOCK_REALTIME_PRECISE	9	/* FreeBSD-specific. */
 #define	CLOCK_REALTIME_FAST	10	/* FreeBSD-specific. */
+#define	CLOCK_REALTIME_COARSE	CLOCK_REALTIME_FAST	/* Linux compat */
 #define	CLOCK_MONOTONIC_PRECISE	11	/* FreeBSD-specific. */
 #define	CLOCK_MONOTONIC_FAST	12	/* FreeBSD-specific. */
+#define	CLOCK_MONOTONIC_COARSE	CLOCK_MONOTONIC_FAST	/* Linux compat */
 #define	CLOCK_SECOND	13		/* FreeBSD-specific. */
 #define	CLOCK_THREAD_CPUTIME_ID	14
 #define	CLOCK_PROCESS_CPUTIME_ID	15