Index: sys/x86/x86/tsc.c
===================================================================
--- sys/x86/x86/tsc.c	(revision 352137)
+++ sys/x86/x86/tsc.c	(working copy)
@@ -146,8 +146,15 @@
 	if (cpu_high < 0x15)
 		return (false);
 	do_cpuid(0x15, regs);
-	if (regs[0] == 0 || regs[1] == 0 || regs[2] == 0)
+	if (regs[0] == 0 || regs[1] == 0 || regs[2] == 0) {
+		if (cpu_high >= 0x16) {
+			u_int freq_regs[4];
+			do_cpuid(0x16, freq_regs);
+			tsc_freq = (uint64_t) freq_regs[0] * 1000000;
+			return (true);
+		}
 		return (false);
+	}
 	tsc_freq = (uint64_t)regs[2] * regs[1] / regs[0];
 	return (true);
 }