 Index: head/lib/libc/sys/ffclock.2
 ===================================================================
 --- /dev/null	1970-01-01 00:00:00.000000000 +0000
-+++ head/lib/libc/sys/ffclock.2	2011-11-02 16:31:10.000000000 +1100
-@@ -0,0 +1,126 @@
++++ head/lib/libc/sys/ffclock.2	2011-11-07 13:31:00.000000000 +1100
+@@ -0,0 +1,171 @@
 +.\" Copyright (C) 2011 The University of Melbourne
 +.\" All rights reserved.
 +.\"

+.Ft int
+.Fn ffclock_setestimate "struct ffclock_estimate *cest"
+.Sh DESCRIPTION
+The
+.Fn ffclock_getcounter
+system call allows the calling process to retrieve the current value of the

+parameters.
+.El
+.Sh USAGE
+The feed-forward paradigm enables the definition of specialised clock functions.
+.Pp
+In its simplest form,
+.Fn ffclock_getcounter
+can be used to establish strict order between events or to measure small time
+intervals very accurately with a minimum performance cost.
+.Pp
+Different methods exist to access absolute time
+.Po or
+.Qq wall-clock time
+.Pc tracked by the ffclock.
+The simplest method uses the ffclock sysctl interface
+.Va kern.ffclock
+to make the system clock return the ffclock time.
+The
+.Xr clock_gettime 2
+system call can then be used to retrieve the current time seen by the
+feed-forward clock.
+Note that this setting affects the entire system and that a feed-forward
+synchronisation daemon should be running.
+.Pp
+A less automated method consists in retrieving the feed-forward counter
+timestamp from the kernel and use the feed-forward clock parameters maintained
+to convert the timestamps into seconds.
+The feed-forward clock parameters can be retrieved from the kernel or from the
+synchronisation daemon directly (preferred).
+This method allows converting timestamps using different clock models as needed
+by the application, while collecting meaningful upper bounds on current clock
+error.
+.Sh SEE ALSO
+.Xr date 1 ,
+.Xr adjtime 2 ,
+.Xr clock_gettime 2,
+.Xr ctime 3
+.Xr radclock 8
+.Sh AUTHORS
+The feed-forward clock support was written by Julien Ridoux at the University
+of Melbourne in collaboration with Darryl Veitch and under sponsorship from
+the FreeBSD Foundation.
Index: head/sys/compat/freebsd32/syscalls.master
===================================================================
--- head.orig/sys/compat/freebsd32/syscalls.master	2011-11-07 11:54:23.000000000 +1100
+++ head/sys/compat/freebsd32/syscalls.master	2011-11-07 11:54:34.000000000 +1100
@@ -440,23 +440,25 @@
 234	AUE_NULL	STD	{ int freebsd32_clock_getres(clockid_t clock_id, \
 				    struct timespec32 *tp); }
