+#ifdef CONFIG_HOTPLUG_CPU
+
+static void remove_siblinginfo(int cpu)
+{
+ int sibling;
+ struct cpuinfo_x86 *c = cpu_data;
+
+ for_each_cpu_mask(sibling, cpu_core_map[cpu]) {
+ cpu_clear(cpu, cpu_core_map[sibling]);
+ /*
+ * last thread sibling in this cpu core going down
+ */
+ if (cpus_weight(cpu_sibling_map[cpu]) == 1)
+ c[sibling].booted_cores--;
+ }
+
+ for_each_cpu_mask(sibling, cpu_sibling_map[cpu])
+ cpu_clear(cpu, cpu_sibling_map[sibling]);
+ cpus_clear(cpu_sibling_map[cpu]);
+ cpus_clear(cpu_core_map[cpu]);
+ c[cpu].phys_proc_id = 0;
+ c[cpu].cpu_core_id = 0;
+ cpu_clear(cpu, cpu_sibling_setup_map);
+}
+
+void remove_cpu_from_maps(void)
+{
+ int cpu = smp_processor_id();
+
+ cpu_clear(cpu, cpu_callout_map);
+ cpu_clear(cpu, cpu_callin_map);
+ clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
+ clear_node_cpumask(cpu);
+}
+
+int __cpu_disable(void)
+{
+ int cpu = smp_processor_id();
+
+ /*
+ * Perhaps use cpufreq to drop frequency, but that could go
+ * into generic code.
+ *
+ * We won't take down the boot processor on i386 due to some
+ * interrupts only being able to be serviced by the BSP.
+ * Especially so if we're not using an IOAPIC -zwane
+ */
+ if (cpu == 0)
+ return -EBUSY;
+
+ if (nmi_watchdog == NMI_LOCAL_APIC)
+ stop_apic_nmi_watchdog(NULL);
+ clear_local_APIC();
+
+ /*
+ * HACK:
+ * Allow any queued timer interrupts to get serviced
+ * This is only a temporary solution until we cleanup
+ * fixup_irqs as we do for IA64.
+ */
+ local_irq_enable();
+ mdelay(1);
+
+ local_irq_disable();
+ remove_siblinginfo(cpu);
+
+ spin_lock(&vector_lock);
+ /* It's now safe to remove this processor from the online map */
+ cpu_clear(cpu, cpu_online_map);
+ spin_unlock(&vector_lock);
+ remove_cpu_from_maps();
+ fixup_irqs(cpu_online_map);
+ return 0;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+ /* We don't do anything here: idle task is faking death itself. */
+ unsigned int i;
+
+ for (i = 0; i < 10; i++) {
+ /* They ack this in play_dead by setting CPU_DEAD */
+ if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+ printk ("CPU %d is now offline\n", cpu);
+ if (1 == num_online_cpus())
+ alternatives_smp_switch(0);
+ return;
+ }
+ msleep(100);
+ }
+ printk(KERN_ERR "CPU %u didn't die...\n", cpu);
+}
+
+static __init int setup_additional_cpus(char *s)
+{
+ return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL;
+}
+early_param("additional_cpus", setup_additional_cpus);
+
+#else /* ... !CONFIG_HOTPLUG_CPU */
+
+int __cpu_disable(void)
+{
+ return -ENOSYS;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+ /* We said "no" in __cpu_disable */
+ BUG();
+}
+#endif /* CONFIG_HOTPLUG_CPU */