Handling all the three clocks (hardclock, softclock, profclock) with the

LAPIC may lead to aliasing for softclock and profclock because frequencies
are sized in order to fit mainly hardclock.
atrtc used to take care of the softclock and profclock and it does still
do, if the LAPIC can't handle the clocks properly.

Revert the change when the LAPIC started taking charge of all three of
them and let atrtc handle softclock and profclock if not explicitly
requested. Such request can be made setting != 0 the new tunable
machdep.lapic_allclocks or if the new device ATPIC is not present
within the i386 kernel config (atrtc is linked to atpic presence).

Diagnosed by:	Sandvine Incorporated
Reviewed by:	jhb, emaste
Sponsored by:	Sandvine Incorporated
MFC:		3 weeks

1 files changed, 8 insertions, 7 deletions

diff --git a/sys/i386/isa/clock.c b/sys/i386/isa/clock.c
index 12e76e4..1549b17 100644
--- a/sys/i386/isa/clock.c
+++ b/sys/i386/isa/clock.c
@@ -106,7 +106,7 @@ static	u_int32_t i8254_offset;
 static	int	(*i8254_pending)(struct intsrc *);
 static	int	i8254_ticked;
 static	int	using_atrtc_timer;
-static	int	using_lapic_timer;
+static	enum lapic_clock using_lapic_timer = LAPIC_CLOCK_NONE;
 
 /* Values for timerX_state: */
 #define	RELEASED	0
@@ -175,7 +175,8 @@ clkintr(struct trapframe *frame)
 		clkintr_pending = 0;
 		mtx_unlock_spin(&clock_lock);
 	}
-	KASSERT(!using_lapic_timer, ("clk interrupt enabled with lapic timer"));
+	KASSERT(using_lapic_timer == LAPIC_CLOCK_NONE,
+	    ("clk interrupt enabled with lapic timer"));
 
 #ifdef KDTRACE_HOOKS
 	/*
@@ -453,7 +454,7 @@ set_i8254_freq(u_int freq, int intr_freq)
 	i8254_timecounter.tc_frequency = freq;
 	mtx_lock_spin(&clock_lock);
 	i8254_freq = freq;
-	if (using_lapic_timer)
+	if (using_lapic_timer != LAPIC_CLOCK_NONE)
 		new_i8254_real_max_count = 0x10000;
 	else
 		new_i8254_real_max_count = TIMER_DIV(intr_freq);
@@ -533,7 +534,7 @@ cpu_initclocks()
 	 * that it can drive hardclock().  Otherwise, change the 8254
 	 * timecounter to user a simpler algorithm.
 	 */
-	if (!using_lapic_timer) {
+	if (using_lapic_timer == LAPIC_CLOCK_NONE) {
 		intr_add_handler("clk", 0, (driver_filter_t *)clkintr, NULL,
 		    NULL, INTR_TYPE_CLK, NULL);
 		i8254_intsrc = intr_lookup_source(0);
@@ -556,7 +557,7 @@ cpu_initclocks()
 	 * kernel clocks, then setup the RTC to periodically interrupt to
 	 * drive statclock() and profclock().
 	 */
-	if (!using_lapic_timer) {
+	if (using_lapic_timer != LAPIC_CLOCK_ALL) {
 		using_atrtc_timer = atrtc_setup_clock();
 		if (using_atrtc_timer) {
 			/* Enable periodic interrupts from the RTC. */
@@ -580,7 +581,7 @@ void
 cpu_startprofclock(void)
 {
 
-	if (using_lapic_timer || !using_atrtc_timer)
+	if (using_lapic_timer == LAPIC_CLOCK_ALL || !using_atrtc_timer)
 		return;
 	atrtc_rate(RTCSA_PROF);
 	psdiv = pscnt = psratio;
@@ -590,7 +591,7 @@ void
 cpu_stopprofclock(void)
 {
 
-	if (using_lapic_timer || !using_atrtc_timer)
+	if (using_lapic_timer == LAPIC_CLOCK_ALL || !using_atrtc_timer)
 		return;
 	atrtc_rate(RTCSA_NOPROF);
 	psdiv = pscnt = 1;