Even without a PIC/PIT we need the legacy timer interrupt for HPET in legacy replacement mode. Cc: Zhang Rui Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/time.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -69,9 +69,12 @@ static struct irqaction irq0 = { static void __init setup_default_timer_irq(void) { - if (!nr_legacy_irqs()) - return; - setup_irq(0, &irq0); + /* + * Unconditionally register the legacy timer; even without legacy + * PIC/PIT we need this for the HPET0 in legacy replacement mode. + */ + if (setup_irq(0, &irq0)) + pr_info("Failed to register legacy timer interrupt\n"); } /* Default timer init function */