Revise the sysctl handling code and restructure the hierarchy of sysctls

introduced when feed-forward clock support is enabled in the kernel:

- Rename the "choice" variable to "available".

- Streamline the implementation of the "active" variable's sysctl handler
  function.

- Create a kern.sysclock sysctl node for general sysclock related configuration
  options. Place the "available" and "active" variables under this node.

- Create a kern.sysclock.ffclock sysctl node for feed-forward clock specific
  configuration options. Place the "version" and "ffcounter_bypass" variables
  under this node.

- Tweak some of the description strings.

Discussed with:	Julien Ridoux (jridoux at unimelb edu au)

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/sys/timeffc.h b/sys/sys/timeffc.h
index bc08e27..6a5bcc0 100644
--- a/sys/sys/timeffc.h
+++ b/sys/sys/timeffc.h
@@ -55,6 +55,12 @@ struct ffclock_estimate {
 #if __BSD_VISIBLE
 #ifdef _KERNEL
 
+/* Define the kern.sysclock sysctl tree. */
+SYSCTL_DECL(_kern_sysclock);
+
+/* Define the kern.sysclock.ffclock sysctl tree. */
+SYSCTL_DECL(_kern_sysclock_ffclock);
+
 /*
  * Index into the sysclocks array for obtaining the ASCII name of a particular
  * sysclock.