diff --git a/arch/x86/include/asm/prom.h b/arch/x86/include/asm/prom.h
index 83833ac33dd1..35ec32b47500 100644
--- a/arch/x86/include/asm/prom.h
+++ b/arch/x86/include/asm/prom.h
@@ -23,10 +23,17 @@
 #include <asm/irq_controller.h>
 
 #ifdef CONFIG_OF
+extern int of_ioapic;
+extern u64 initial_dtb;
 extern void add_dtb(u64 data);
+void x86_dtb_find_config(void);
+void x86_dtb_get_config(unsigned int unused);
 void add_interrupt_host(struct irq_domain *ih);
 #else
 static inline void add_dtb(u64 data) { }
+#define x86_dtb_find_config x86_init_noop
+#define x86_dtb_get_config x86_init_uint_noop
+#define of_ioapic 0
 #endif
 
 extern char cmd_line[COMMAND_LINE_SIZE];
diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index ef98e4edada1..2739d5613a38 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -7,15 +7,20 @@
 #include <linux/list.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
+#include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/slab.h>
 
 #include <asm/irq_controller.h>
+#include <asm/apic.h>
 
+__initdata u64 initial_dtb;
 char __initdata cmd_line[COMMAND_LINE_SIZE];
 static LIST_HEAD(irq_domains);
 static DEFINE_RAW_SPINLOCK(big_irq_lock);
 
+int __initdata of_ioapic;
+
 void add_interrupt_host(struct irq_domain *ih)
 {
 	unsigned long flags;
@@ -90,6 +95,107 @@ void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
 
 void __init add_dtb(u64 data)
 {
-	initial_boot_params = phys_to_virt((u64) (u32) data +
-				offsetof(struct setup_data, data));
+	initial_dtb = data + offsetof(struct setup_data, data);
+}
+
+static void __init dtb_lapic_setup(void)
+{
+#ifdef CONFIG_X86_LOCAL_APIC
+	if (apic_force_enable())
+		return;
+
+	smp_found_config = 1;
+	pic_mode = 1;
+	/* Required for ioapic registration */
+	set_fixmap_nocache(FIX_APIC_BASE, mp_lapic_addr);
+	if (boot_cpu_physical_apicid == -1U)
+		boot_cpu_physical_apicid = read_apic_id();
+
+	generic_processor_info(boot_cpu_physical_apicid,
+			GET_APIC_VERSION(apic_read(APIC_LVR)));
+#endif
+}
+
+#ifdef CONFIG_X86_IO_APIC
+static unsigned int ioapic_id;
+
+static void __init dtb_add_ioapic(struct device_node *dn)
+{
+	struct resource r;
+	int ret;
+
+	ret = of_address_to_resource(dn, 0, &r);
+	if (ret) {
+		printk(KERN_ERR "Can't obtain address from node %s.\n",
+				dn->full_name);
+		return;
+	}
+	mp_register_ioapic(++ioapic_id, r.start, gsi_top);
+}
+
+static void __init dtb_ioapic_setup(void)
+{
+	struct device_node *dn;
+
+	if (!smp_found_config)
+		return;
+
+	for_each_compatible_node(dn, NULL, "intel,ce4100-ioapic")
+		dtb_add_ioapic(dn);
+
+	if (nr_ioapics) {
+		of_ioapic = 1;
+		return;
+	}
+	printk(KERN_ERR "Error: No information about IO-APIC in OF.\n");
+	smp_found_config = 0;
+}
+#else
+static void __init dtb_ioapic_setup(void) {}
+#endif
+
+static void __init dtb_apic_setup(void)
+{
+	dtb_lapic_setup();
+	dtb_ioapic_setup();
+}
+
+void __init x86_dtb_find_config(void)
+{
+	if (initial_dtb)
+		smp_found_config = 1;
+	else
+		printk(KERN_ERR "Missing device tree!.\n");
+}
+
+void __init x86_dtb_get_config(unsigned int unused)
+{
+	u32 size, map_len;
+	void *new_dtb;
+
+	if (!initial_dtb)
+		return;
+
+	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK),
+			(u64)sizeof(struct boot_param_header));
+
+	initial_boot_params = early_memremap(initial_dtb, map_len);
+	size = be32_to_cpu(initial_boot_params->totalsize);
+	if (map_len < size) {
+		early_iounmap(initial_boot_params, map_len);
+		initial_boot_params = early_memremap(initial_dtb, size);
+		map_len = size;
+	}
+
+	new_dtb = alloc_bootmem(size);
+	memcpy(new_dtb, initial_boot_params, size);
+	early_iounmap(initial_boot_params, map_len);
+
+	initial_boot_params = new_dtb;
+
+	/* root level address cells */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
+	unflatten_device_tree();
+	dtb_apic_setup();
 }
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index c752e973958d..4cadf8688dbd 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -25,6 +25,7 @@
 #include <asm/setup.h>
 #include <asm/i8259.h>
 #include <asm/traps.h>
+#include <asm/prom.h>
 
 /*
  * ISA PIC or low IO-APIC triggered (INTA-cycle or APIC) interrupts:
@@ -243,7 +244,7 @@ void __init native_init_IRQ(void)
 			set_intr_gate(i, interrupt[i-FIRST_EXTERNAL_VECTOR]);
 	}
 
-	if (!acpi_ioapic)
+	if (!acpi_ioapic && !of_ioapic)
 		setup_irq(2, &irq2);
 
 #ifdef CONFIG_X86_32