Delivery mode should be APIC_DM_FIXED when using physical mode. From: Ashok Raj Signed-off-by: Andi Kleen Index: linux/arch/x86_64/kernel/genapic_flat.c =================================================================== --- linux.orig/arch/x86_64/kernel/genapic_flat.c +++ linux/arch/x86_64/kernel/genapic_flat.c @@ -167,9 +167,9 @@ static unsigned int physflat_cpu_mask_to struct genapic apic_physflat = { .name = "physical flat", - .int_delivery_mode = dest_LowestPrio, + .int_delivery_mode = dest_Fixed, .int_dest_mode = (APIC_DEST_PHYSICAL != 0), - .int_delivery_dest = APIC_DEST_PHYSICAL | APIC_DM_LOWEST, + .int_delivery_dest = APIC_DEST_PHYSICAL | APIC_DM_FIXED, .target_cpus = physflat_target_cpus, .apic_id_registered = flat_apic_id_registered, .init_apic_ldr = flat_init_apic_ldr,/*not needed, but shouldn't hurt*/