3 files changed, 5 insertions, 4 deletions

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 5f862e216a42..91c9066a380d 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -397,7 +397,7 @@ void __init time_init(void)
                 cpu_khz = tsc_calibrate_cpu_khz();
 
         if (unsynchronized_tsc())
-                mark_tsc_unstable();
+                mark_tsc_unstable("TSCs unsynchronized");
 
         if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
                 vgetcpu_mode = VGETCPU_RDTSCP;
diff --git a/arch/x86_64/kernel/tsc.c b/arch/x86_64/kernel/tsc.c
index 5c84992c676d..48f9a8e6aa91 100644
--- a/arch/x86_64/kernel/tsc.c
+++ b/arch/x86_64/kernel/tsc.c
@@ -111,7 +111,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 
                 tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
                 if (!(freq->flags & CPUFREQ_CONST_LOOPS))
-                        mark_tsc_unstable();
+                        mark_tsc_unstable("cpufreq changes");
         }
 
         set_cyc2ns_scale(tsc_khz_ref);
@@ -199,10 +199,11 @@ static struct clocksource clocksource_tsc = {
         .vread                  = vread_tsc,
 };
 
-void mark_tsc_unstable(void)
+void mark_tsc_unstable(char *reason)
 {
         if (!tsc_unstable) {
                 tsc_unstable = 1;
+                printk("Marking TSC unstable due to %s\n", reason);
                 /* Change only the rating, when not registered */
                 if (clocksource_tsc.mult)
                         clocksource_change_rating(&clocksource_tsc, 0);
diff --git a/arch/x86_64/kernel/tsc_sync.c b/arch/x86_64/kernel/tsc_sync.c
index 72d444dede9b..355f5f506c81 100644
--- a/arch/x86_64/kernel/tsc_sync.c
+++ b/arch/x86_64/kernel/tsc_sync.c
@@ -138,7 +138,7 @@ void __cpuinit check_tsc_sync_source(int cpu)
                 printk("\n");
                 printk(KERN_WARNING "Measured %Ld cycles TSC warp between CPUs,"
                                     " turning off TSC clock.\n", max_warp);
-                mark_tsc_unstable();
+                mark_tsc_unstable("check_tsc_sync_source failed");
                 nr_warps = 0;
                 max_warp = 0;
                 last_tsc = 0;