diff options
Diffstat (limited to 'arch/x86/kernel/tsc_32.c')
| -rw-r--r-- | arch/x86/kernel/tsc_32.c | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index 068759db63d..774a5a83c29 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -14,7 +14,10 @@ #include "mach_timer.h" -static int tsc_disabled; +/* native_sched_clock() is called before tsc_init(), so + we must start with the TSC soft disabled to prevent + erroneous rdtsc usage on !cpu_has_tsc processors */ +static int tsc_disabled = -1; /* * On some systems the TSC frequency does not @@ -283,7 +286,6 @@ core_initcall(cpufreq_tsc); /* clock source code */ -static unsigned long current_tsc_khz; static struct clocksource clocksource_tsc; /* @@ -402,25 +404,20 @@ void __init tsc_init(void) { int cpu; - if (!cpu_has_tsc || tsc_disabled) { - /* Disable the TSC in case of !cpu_has_tsc */ - tsc_disabled = 1; + if (!cpu_has_tsc || tsc_disabled > 0) return; - } cpu_khz = calculate_cpu_khz(); tsc_khz = cpu_khz; if (!cpu_khz) { mark_tsc_unstable("could not calculate TSC khz"); - /* - * We need to disable the TSC completely in this case - * to prevent sched_clock() from using it. - */ - tsc_disabled = 1; return; } + /* now allow native_sched_clock() to use rdtsc */ + tsc_disabled = 0; + printk("Detected %lu.%03lu MHz processor.\n", (unsigned long)cpu_khz / 1000, (unsigned long)cpu_khz % 1000); @@ -441,9 +438,8 @@ void __init tsc_init(void) unsynchronized_tsc(); check_geode_tsc_reliable(); - current_tsc_khz = tsc_khz; - clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz, - clocksource_tsc.shift); + clocksource_tsc.mult = clocksource_khz2mult(tsc_khz, + clocksource_tsc.shift); /* lower the rating if we already know its unstable: */ if (check_tsc_unstable()) { clocksource_tsc.rating = 0; |