may implicitly disable the NMI watchdog.]
For x86-64, the needed APIC is always compiled in, and the NMI watchdog is
-always enabled with I/O-APIC mode (nmi_watchdog=1). Currently, local APIC
-mode (nmi_watchdog=2) does not work on x86-64.
+always enabled with I/O-APIC mode (nmi_watchdog=1).
Using local APIC (nmi_watchdog=2) needs the first performance register, so
you can't use it for other purposes (such as high precision performance