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-rw-r--r--arch/x86_64/kernel/apic.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index e5b14c5..d70605e 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -962,12 +962,14 @@ void smp_apic_timer_interrupt(struct pt_regs *regs)
irq_exit();
}
+int __initdata unsync_tsc_on_multicluster;
+
/*
* oem_force_hpet_timer -- force HPET mode for some boxes.
*
* Thus far, the major user of this is IBM's Summit2 series:
*
- * Clustered boxes may have unsynced TSC problems if they are
+ * Some clustered boxes may have unsynced TSC problems if they are
* multi-chassis. Use available data to take a good guess.
* If in doubt, go HPET.
*/
@@ -977,6 +979,11 @@ __cpuinit int oem_force_hpet_timer(void)
unsigned id;
DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
+ /* Only do this check on IBM machines - big Unisys systems
+ use multiple clusters too, but have synchronized TSC */
+ if (!unsync_tsc_on_multicluster)
+ return 0;
+
bitmap_zero(clustermap, NUM_APIC_CLUSTERS);
for (i = 0; i < NR_CPUS; i++) {
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