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diff --git a/sys/x86/include/clock.h b/sys/x86/include/clock.h
--- a/sys/x86/include/clock.h
+++ b/sys/x86/include/clock.h
@@ -28,6 +28,7 @@
void i8254_delay(int);
void clock_init(void);
void lapic_calibrate(void);
+void tsc_calibrate(void);
/*
* Driver to clock driver interface.
diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -413,6 +413,7 @@
td = curthread;
+ tsc_calibrate();
lapic_calibrate_timer();
cpu_initclocks_bsp();
CPU_FOREACH(i) {
@@ -428,6 +429,7 @@
sched_unbind(td);
thread_unlock(td);
#else
+ tsc_calibrate();
lapic_calibrate_timer();
cpu_initclocks_bsp();
#endif
diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c
--- a/sys/x86/x86/tsc.c
+++ b/sys/x86/x86/tsc.c
@@ -695,23 +695,27 @@
/*
* Perform late calibration of the TSC frequency once ACPI-based timecounters
- * are available.
+ * are available. At this point timehands are not set up, so we read the
+ * highest-quality timecounter directly rather than using (s)binuptime().
*/
-static void
-tsc_calib(void *arg __unused)
+void
+tsc_calibrate(void)
{
- sbintime_t t_start, t_end;
+ struct timecounter *tc;
uint64_t freq_khz, tsc_start, tsc_end;
+ u_int t_start, t_end;
register_t flags;
int cpu;
if (tsc_disabled)
return;
+ tc = atomic_load_ptr(&timecounter);
+
flags = intr_disable();
cpu = curcpu;
tsc_start = rdtsc_ordered();
- t_start = sbinuptime();
+ t_start = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
intr_restore(flags);
DELAY(1000000);
@@ -721,19 +725,23 @@
flags = intr_disable();
tsc_end = rdtsc_ordered();
- t_end = sbinuptime();
+ t_end = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
intr_restore(flags);
sched_unbind(curthread);
thread_unlock(curthread);
- freq_khz = (SBT_1S / 1024) * (tsc_end - tsc_start) / (t_end - t_start);
+ if (t_end <= t_start) {
+ /* Assume that the counter has wrapped around at most once. */
+ t_end += (uint64_t)tc->tc_counter_mask + 1;
+ }
+
+ freq_khz = tc->tc_frequency * (tsc_end - tsc_start) / (t_end - t_start);
- tsc_update_freq(freq_khz * 1024);
+ tsc_update_freq(freq_khz);
tc_init(&tsc_timecounter);
set_cputicker(rdtsc, tsc_freq, !tsc_is_invariant);
}
-SYSINIT(tsc_calib, SI_SUB_CLOCKS + 1, SI_ORDER_ANY, tsc_calib, NULL);
void
resume_TSC(void)

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