Patch from Stephen Hemminger <shemminger@osdl.org>
For machines that don't want to cooperate and have bad TSC counter and/or
change CPU frequency without change support.
This fixes the problem on Jerry Cooperstein's PIII laptop. Could be useful
for other people and tech support situations.
25-akpm/Documentation/kernel-parameters.txt | 7 ++++++-
25-akpm/arch/i386/kernel/timers/timer_tsc.c | 10 +++++++++-
2 files changed, 15 insertions(+), 2 deletions(-)
diff -puN arch/i386/kernel/timers/timer_tsc.c~notsclock-option arch/i386/kernel/timers/timer_tsc.c
--- 25/arch/i386/kernel/timers/timer_tsc.c~notsclock-option Tue Mar 18 17:52:24 2003
+++ 25-akpm/arch/i386/kernel/timers/timer_tsc.c Tue Mar 18 17:52:24 2003
@@ -15,6 +15,7 @@
#include <asm/processor.h>
int tsc_disable __initdata = 0;
+static int tsc_clock_disable __initdata = 0;
extern spinlock_t i8253_lock;
@@ -243,6 +244,13 @@ static struct notifier_block time_cpufre
};
#endif
+/* Don't use TSC for time of day clock */
+static int __init tsc_noclock_setup(char *str)
+{
+ tsc_clock_disable = 1;
+ return 1;
+}
+__setup("notsclock", tsc_noclock_setup);
static int init_tsc(void)
{
@@ -275,7 +283,7 @@ static int init_tsc(void)
cpufreq_register_notifier(&time_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
#endif
- if (cpu_has_tsc) {
+ if (cpu_has_tsc && !tsc_clock_disable) {
unsigned long tsc_quotient = calibrate_tsc();
if (tsc_quotient) {
fast_gettimeoffset_quotient = tsc_quotient;
diff -puN Documentation/kernel-parameters.txt~notsclock-option Documentation/kernel-parameters.txt
--- 25/Documentation/kernel-parameters.txt~notsclock-option Tue Mar 18 17:52:24 2003
+++ 25-akpm/Documentation/kernel-parameters.txt Tue Mar 18 17:52:24 2003
@@ -627,7 +627,12 @@ running once the system is up.
nosync [HW,M68K] Disables sync negotiation for all devices.
- notsc [BUGS=IA-32] Disable Time Stamp Counter
+ notsc [BUGS=IA-32] Disable Time Stamp Counter.
+ Turns off TSC in processor. Kernel must
+ be compiled without TSC support.
+
+ notsclock [BUGS=IA-32] Tells kernel not to use
+ Time Stamp Counter for gettimeofday.
nousb [USB] Disable the USB subsystem
_