As far as I understand the HPET legacy mode is not required on systems with ARAT after the timer IRQ test. For previous discussion see [1]. Keeping it enabled prevents reaching S0ix residency.
Link: https://lore.kernel.org/xen-devel/[email protected]/ # [1] Signed-off-by: Simon Gaiser <[email protected]> --- xen/arch/x86/io_apic.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c index 9b8a972cf5..ea98d717d0 100644 --- a/xen/arch/x86/io_apic.c +++ b/xen/arch/x86/io_apic.c @@ -1966,6 +1966,10 @@ static void __init check_timer(void) if ( timer_irq_works() ) { + if ( boot_cpu_has(X86_FEATURE_ARAT) ) { + printk(XENLOG_INFO "IRQ test with HPET Legacy Replacement Mode worked. Disabling it again.\n"); + hpet_disable_legacy_replacement_mode(); + } local_irq_restore(flags); return; } -- 2.40.1
