- Set cpu_impl early in sparc64_init so that we can use it to detect

UltraSPARC III and higher cpus and do needed setup.
- Disable the "system tick" interrupt for UltraSPARC III.  This avoids
  an interrupt storm on startup since we're not prepared for these at
  all.  This feature has questionable use anyway.
- Clear tick on startup and then leave it alone.

sys/sparc64/sparc64/identcpu.c

@@ -47,8 +47,7 @@ cpu_identify(u_long vers, u_int freq, u_int id)
 		manus = NULL;
 		break;
 	}
-	cpu_impl = VER_IMPL(vers);
-	switch (cpu_impl) {
+	switch (VER_IMPL(vers)) {
 	case CPU_IMPL_SPARC64:
 		impls = "SPARC64";
 		break;

sys/sparc64/sparc64/locore.S

@@ -56,6 +56,7 @@ ENTRY(_start)
 	wrpr	%g0, 0, %cleanwin
 	wrpr	%g0, 0, %pil
 	wr	%g0, 0, %fprs
+	wrpr	%g0, 0, %tick
 
 	/*
 	 * Get onto our per-cpu panic stack, which precedes the struct pcpu in

sys/sparc64/sparc64/machdep.c

@@ -206,6 +206,12 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 	end = 0;
 	kmdp = NULL;
 
+	/*
+	 * Find out what kind of cpu we have first, for anything that changes
+	 * behaviour.
+	 */
+	cpu_impl = VER_IMPL(rdpr(ver));
+
 	/*
 	 * Initialize openfirmware (needed for console).
 	 */

sys/sparc64/sparc64/tick.c

@@ -46,6 +46,7 @@
 #include <machine/frame.h>
 #include <machine/intr_machdep.h>
 #include <machine/tick.h>
+#include <machine/ver.h>
 #ifdef SMP
 #include <machine/cpu.h>
 #endif
@@ -137,6 +138,8 @@ tick_start_ap(void)
 void
 tick_stop(void)
 {
-	wrpr(tick, 0, 0);
+
+	if (cpu_impl >= CPU_IMPL_ULTRASPARCIII)
+		wr(asr24, 1L << 63, 0);
 	wr(asr23, 1L << 63, 0);
 }