Improving the clocks auto-tunning by firstly checking if the atrtc may be

correctly initialized and just then assign to softclock/profclock.
Right now, some atrtc seems reporting strange diagnostic error* making the
current pattern bogus.

In order to do that cleanly, lapic_setup_clock(), on both ia32 and amd64,
now accepts as arguments the desired sources to handle, and returns the
actual ones (LAPIC_CLOCK_NONE is forbidden because otherwise there is no
meaning in calling such function).
This allows to bring out into commont x86 code the handling part for
machdep.lapic_allclocks tunable, which is retained.

Sponsored by:	Sandvine Incorporated
Tested by:	yongari, Richard Todd
		<rmtodd at ichotolot dot servalan dot com>
MFC:		3 weeks
X-MFC:		r202387, 204309

1 files changed, 20 insertions, 5 deletions

diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
index 6ced537..4a20709 100644
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -97,6 +97,9 @@ TUNABLE_INT("hw.i8254.freq", &i8254_freq);
 int	i8254_max_count;
 static int i8254_real_max_count;
 
+static int lapic_allclocks;
+TUNABLE_INT("machdep.lapic_allclocks", &lapic_allclocks);
+
 struct mtx clock_lock;
 static	struct intsrc *i8254_intsrc;
 static	u_int32_t i8254_lastcount;
@@ -526,9 +529,24 @@ startrtclock()
 void
 cpu_initclocks()
 {
+#if defined(__amd64__) || defined(DEV_APIC)
+	enum lapic_clock tlsca;
+#endif
+	int tasc;
+
+	/* Initialize RTC. */
+	atrtc_start();
+	tasc = atrtc_setup_clock();
 
+	/*
+	 * If the atrtc successfully initialized and the users didn't force
+	 * otherwise use the LAPIC in order to cater hardclock only, otherwise
+	 * take in charge all the clock sources.
+	 */
 #if defined(__amd64__) || defined(DEV_APIC)
-	using_lapic_timer = lapic_setup_clock();
+	tlsca = (lapic_allclocks == 0 && tasc != 0) ? LAPIC_CLOCK_HARDCLOCK :
+	    LAPIC_CLOCK_ALL;
+	using_lapic_timer = lapic_setup_clock(tlsca);
 #endif
 	/*
 	 * If we aren't using the local APIC timer to drive the kernel
@@ -550,9 +568,6 @@ cpu_initclocks()
 		set_i8254_freq(i8254_freq, hz);
 	}
 
-	/* Initialize RTC. */
-	atrtc_start();
-
 	/*
 	 * If the separate statistics clock hasn't been explicility disabled
 	 * and we aren't already using the local APIC timer to drive the
@@ -560,7 +575,7 @@ cpu_initclocks()
 	 * drive statclock() and profclock().
 	 */
 	if (using_lapic_timer != LAPIC_CLOCK_ALL) {
-		using_atrtc_timer = atrtc_setup_clock();
+		using_atrtc_timer = tasc; 
 		if (using_atrtc_timer) {
 			/* Enable periodic interrupts from the RTC. */
 			intr_add_handler("rtc", 8,