commit f9690982b8c2f9a2c65acdc113e758ec356676a3 removed the check for
cpu_khz from sched_clock(), which prevented early access to the TSC by
non obvious magic.
This is harmless as long as the CPU has a TSC. On TSCless systems this
results in an illegal instruction trap.
Replace tsc_disabled and tsc_unstable by tsc_enabled, which is only set
when the tsc is available and not unstable.
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 0e65f7a..6cb8f53 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -18,6 +18,8 @@
#include "mach_timer.h"
+static int tsc_enabled;
+
/*
* On some systems the TSC frequency does not
* change with the cpu frequency. So we need
@@ -105,7 +107,7 @@ unsigned long long sched_clock(void)
/*
* Fall back to jiffies if there's no TSC available:
*/
- if (tsc_unstable || unlikely(tsc_disable))
+ if (unlikely(!tsc_enabled))
/* No locking but a rare wrong value is not a big deal: */
return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
@@ -283,6 +285,7 @@ void mark_tsc_unstable(void)
{
if (!tsc_unstable) {
tsc_unstable = 1;
+ tsc_enabled = 0;
/* Can be called before registration */
if (clocksource_tsc.mult)
clocksource_change_rating(&clocksource_tsc, 0);
@@ -383,7 +386,9 @@ void __init tsc_init(void)
if (check_tsc_unstable()) {
clocksource_tsc.rating = 0;
clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
- }
+ } else
+ tsc_enabled = 1;
+
clocksource_register(&clocksource_tsc);
return;
-
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