9 files changed, 15 insertions, 13 deletions

diff --git a/arch/i386/kernel/cpu/cyrix.c b/arch/i386/kernel/cpu/cyrix.c
index f0badfdd4e45..e77f8e1cf7aa 100644
--- a/arch/i386/kernel/cpu/cyrix.c
+++ b/arch/i386/kernel/cpu/cyrix.c
@@ -279,7 +279,7 @@ static void __cpuinit init_cyrix(struct cpuinfo_x86 *c)
                  */  
                 if (vendor == PCI_VENDOR_ID_CYRIX &&
          (device == PCI_DEVICE_ID_CYRIX_5510 || device == PCI_DEVICE_ID_CYRIX_5520))
-                        mark_tsc_unstable();
+                        mark_tsc_unstable("cyrix 5510/5520 detected");
         }
 #endif
                 c->x86_cache_size=16;   /* Yep 16K integrated cache thats it */
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 6cb8f5336732..755209dc93e1 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -233,7 +233,7 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
                                  * TSC based sched_clock turns
                                  * to junk w/ cpufreq
                                  */
-                                mark_tsc_unstable();
+                                mark_tsc_unstable("cpufreq changes");
                         }
                 }
         }
@@ -281,11 +281,12 @@ static struct clocksource clocksource_tsc = {
                                   CLOCK_SOURCE_MUST_VERIFY,
 };
 
-void mark_tsc_unstable(void)
+void mark_tsc_unstable(char *reason)
 {
         if (!tsc_unstable) {
                 tsc_unstable = 1;
                 tsc_enabled = 0;
+                printk("Marking TSC unstable due to: %s.\n", reason);
                 /* Can be called before registration */
                 if (clocksource_tsc.mult)
                         clocksource_change_rating(&clocksource_tsc, 0);
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;
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index ae0654cd11ea..ee5759bef945 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -475,7 +475,7 @@ static void acpi_processor_idle(void)
 
 #ifdef CONFIG_GENERIC_TIME
                 /* TSC halts in C2, so notify users */
-                mark_tsc_unstable();
+                mark_tsc_unstable("possible TSC halt in C2");
 #endif
                 /* Re-enable interrupts */
                 local_irq_enable();
@@ -517,7 +517,7 @@ static void acpi_processor_idle(void)
 
 #ifdef CONFIG_GENERIC_TIME
                 /* TSC halts in C3, so notify users */
-                mark_tsc_unstable();
+                mark_tsc_unstable("TSC halts in C3");
 #endif
                 /* Re-enable interrupts */
                 local_irq_enable();
diff --git a/include/asm-i386/mach-summit/mach_mpparse.h b/include/asm-i386/mach-summit/mach_mpparse.h
index 94268399170d..c2520539d934 100644
--- a/include/asm-i386/mach-summit/mach_mpparse.h
+++ b/include/asm-i386/mach-summit/mach_mpparse.h
@@ -30,7 +30,7 @@ static inline int mps_oem_check(struct mp_config_table *mpc, char *oem,
                         (!strncmp(productid, "VIGIL SMP", 9) 
                          || !strncmp(productid, "EXA", 3)
                          || !strncmp(productid, "RUTHLESS SMP", 12))){
-                mark_tsc_unstable();
+                mark_tsc_unstable("Summit based system");
                 use_cyclone = 1; /*enable cyclone-timer*/
                 setup_summit();
                 return 1;
@@ -44,7 +44,7 @@ static inline int acpi_madt_oem_check(char *oem_id, char *oem_table_id)
         if (!strncmp(oem_id, "IBM", 3) &&
             (!strncmp(oem_table_id, "SERVIGIL", 8)
              || !strncmp(oem_table_id, "EXA", 3))){
-                mark_tsc_unstable();
+                mark_tsc_unstable("Summit based system");
                 use_cyclone = 1; /*enable cyclone-timer*/
                 setup_summit();
                 return 1;
diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
index 84016ff481b9..346976632e15 100644
--- a/include/asm-i386/tsc.h
+++ b/include/asm-i386/tsc.h
@@ -53,7 +53,7 @@ static __always_inline cycles_t get_cycles_sync(void)
 }
 
 extern void tsc_init(void);
-extern void mark_tsc_unstable(void);
+extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
 extern void init_tsc_clocksource(void);
 
diff --git a/include/asm-x86_64/timex.h b/include/asm-x86_64/timex.h
index 8c6808a3fba4..f6527e1b6c1c 100644
--- a/include/asm-x86_64/timex.h
+++ b/include/asm-x86_64/timex.h
@@ -27,6 +27,6 @@ extern int read_current_timer(unsigned long *timer_value);
 #define NS_SCALE        10 /* 2^10, carefully chosen */
 #define US_SCALE        32 /* 2^32, arbitralrily chosen */
 
-extern void mark_tsc_unstable(void);
+extern void mark_tsc_unstable(char *msg);
 extern void set_cyc2ns_scale(unsigned long khz);
 #endif