x86: enable NMI watchdog on nosmp
if nosmp has been passed as a boot option, but nmi_watchdog=2 has also
been enabled then keep minimal local APIC functionality around to make
the watchdog work.
this allowed me to debug a hard hang that would only occur with a nosmp
bootup.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/smpboot_32.c b/arch/x86/kernel/smpboot_32.c
index edc9db6..83e4f40 100644
--- a/arch/x86/kernel/smpboot_32.c
+++ b/arch/x86/kernel/smpboot_32.c
@@ -1021,6 +1021,12 @@
if (!max_cpus) {
smp_found_config = 0;
printk(KERN_INFO "SMP mode deactivated, forcing use of dummy APIC emulation.\n");
+
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
+ printk(KERN_INFO "activating minimal APIC for NMI watchdog use.\n");
+ connect_bsp_APIC();
+ setup_local_APIC();
+ }
smpboot_clear_io_apic_irqs();
phys_cpu_present_map = physid_mask_of_physid(0);
cpu_set(0, per_cpu(cpu_sibling_map, 0));