From 846693813977e7301e8d54540e0b866100249dea Mon Sep 17 00:00:00 2001
From: phk <phk@FreeBSD.org>
Date: Wed, 4 Sep 2002 19:32:18 +0000
Subject: [PATCH] Do not employ timecounter hardware if our hz does not support
 their correct rewinding.

---
 sys/kern/kern_tc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index d3d437d441d1..42c713486507 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -278,11 +278,19 @@ getmicrotime(struct timeval *tvp)
 void
 tc_init(struct timecounter *tc)
 {
+	unsigned u;
 
+	printf("Timecounter \"%s\"  frequency %lu Hz",
+	    tc->tc_name, (u_long)tc->tc_frequency);
+
+	u = tc->tc_frequency / tc->tc_counter_mask;
+	if (u > hz) {
+		printf(" -- Insufficient hz, needs at least %u\n", u);
+		return;
+	}
 	tc->tc_next = timecounters;
 	timecounters = tc;
-	printf("Timecounter \"%s\"  frequency %lu Hz\n",
-	    tc->tc_name, (u_long)tc->tc_frequency);
+	printf("\n");
 	(void)tc->tc_get_timecount(tc);
 	(void)tc->tc_get_timecount(tc);
 	timecounter = tc;