2 files changed, 22 insertions, 0 deletions

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 31dfb42d8649..99a416ed16b7 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -187,6 +187,7 @@ extern struct mp_ioapic_gsi  mp_gsi_routing[];
 int mp_find_ioapic(int gsi);
 int mp_find_ioapic_pin(int ioapic, int gsi);
 void __init mp_register_ioapic(int id, u32 address, u32 gsi_base);
+extern void __init pre_init_apic_IRQ0(void);
 
 #else  /* !CONFIG_X86_IO_APIC */
 
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index b34854358ee6..8c848b5877a0 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -4289,3 +4289,24 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
 
         nr_ioapics++;
 }
+
+/* Enable IOAPIC early just for system timer */
+void __init pre_init_apic_IRQ0(void)
+{
+        struct irq_cfg *cfg;
+        struct irq_desc *desc;
+
+        printk(KERN_INFO "Early APIC setup for system timer0\n");
+#ifndef CONFIG_SMP
+        phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);
+#endif
+        desc = irq_to_desc_alloc_node(0, 0);
+
+        setup_local_APIC();
+
+        cfg = irq_cfg(0);
+        add_pin_to_irq_node(cfg, 0, 0, 0);
+        set_irq_chip_and_handler_name(0, &ioapic_chip, handle_edge_irq, "edge");
+
+        setup_IO_APIC_irq(0, 0, 0, desc, 0, 0);
+}