Give timecounters a numeric quality field.

A timecounter will be selected when registered if its quality is
not negative and no less than the current timecounters.

Add a sysctl to report all available timecounters and their qualities.

Give the dummy timecounter a solid negative quality of minus a million.

Give the i8254 zero and the ACPI 1000.

The TSC gets 800, unless APM or SMP forces it negative.

Other timecounters default to zero quality and thereby retain current
selection behaviour.

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/isa/atrtc.c b/sys/isa/atrtc.c
index 3c9c9154656c..3d7d8c11ae1f 100644
--- a/sys/isa/atrtc.c
+++ b/sys/isa/atrtc.c
@@ -155,7 +155,8 @@ static struct timecounter i8254_timecounter = {
 	0,			/* no poll_pps */
 	~0u,			/* counter_mask */
 	0,			/* frequency */
-	"i8254"			/* name */
+	"i8254",		/* name */
+	0			/* quality */
 };
 
 static void