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Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index fdd4c1078632..49d925043171 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -41,6 +41,7 @@ EXPORT_SYMBOL(tsc_khz);
* TSC can be unstable due to cpufreq or due to unsynced TSCs
*/
static int __read_mostly tsc_unstable;
+static unsigned int __initdata tsc_early_khz;
static DEFINE_STATIC_KEY_FALSE(__use_tsc);
@@ -59,6 +60,12 @@ struct cyc2ns {
static DEFINE_PER_CPU_ALIGNED(struct cyc2ns, cyc2ns);
+static int __init tsc_early_khz_setup(char *buf)
+{
+ return kstrtouint(buf, 0, &tsc_early_khz);
+}
+early_param("tsc_early_khz", tsc_early_khz_setup);
+
__always_inline void cyc2ns_read_begin(struct cyc2ns_data *data)
{
int seq, idx;
@@ -1412,7 +1419,10 @@ static bool __init determine_cpu_tsc_frequencies(bool early)
if (early) {
cpu_khz = x86_platform.calibrate_cpu();
- tsc_khz = x86_platform.calibrate_tsc();
+ if (tsc_early_khz)
+ tsc_khz = tsc_early_khz;
+ else
+ tsc_khz = x86_platform.calibrate_tsc();
} else {
/* We should not be here with non-native cpu calibration */
WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);