x86: rename apic_32.c and apic_64.c to apic.c

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2311 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c
new file mode 100644
index 00000000000..6e99af5ce67
--- /dev/null
+++ b/arch/x86/kernel/apic.c
@@ -0,0 +1,2311 @@
+/*
+ *	Local APIC handling, local APIC timers
+ *
+ *	(c) 1999, 2000 Ingo Molnar <mingo@redhat.com>
+ *
+ *	Fixes
+ *	Maciej W. Rozycki	:	Bits for genuine 82489DX APICs;
+ *					thanks to Eric Gilmore
+ *					and Rolf G. Tews
+ *					for testing these extensively.
+ *	Maciej W. Rozycki	:	Various updates and fixes.
+ *	Mikael Pettersson	:	Power Management for UP-APIC.
+ *	Pavel Machek and
+ *	Mikael Pettersson	:	PM converted to driver model.
+ */
+
+#include <linux/init.h>
+
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/bootmem.h>
+#include <linux/interrupt.h>
+#include <linux/mc146818rtc.h>
+#include <linux/kernel_stat.h>
+#include <linux/sysdev.h>
+#include <linux/ioport.h>
+#include <linux/cpu.h>
+#include <linux/clockchips.h>
+#include <linux/acpi_pmtmr.h>
+#include <linux/module.h>
+#include <linux/dmi.h>
+#include <linux/dmar.h>
+
+#include <asm/atomic.h>
+#include <asm/smp.h>
+#include <asm/mtrr.h>
+#include <asm/mpspec.h>
+#include <asm/desc.h>
+#include <asm/arch_hooks.h>
+#include <asm/hpet.h>
+#include <asm/pgalloc.h>
+#include <asm/i8253.h>
+#include <asm/nmi.h>
+#include <asm/idle.h>
+#include <asm/proto.h>
+#include <asm/timex.h>
+#include <asm/apic.h>
+#include <asm/i8259.h>
+
+#include <mach_apic.h>
+#include <mach_apicdef.h>
+#include <mach_ipi.h>
+
+/*
+ * Sanity check
+ */
+#if ((SPURIOUS_APIC_VECTOR & 0x0F) != 0x0F)
+# error SPURIOUS_APIC_VECTOR definition error
+#endif
+
+#ifdef CONFIG_X86_32
+/*
+ * Knob to control our willingness to enable the local APIC.
+ *
+ * +1=force-enable
+ */
+static int force_enable_local_apic;
+/*
+ * APIC command line parameters
+ */
+static int __init parse_lapic(char *arg)
+{
+	force_enable_local_apic = 1;
+	return 0;
+}
+early_param("lapic", parse_lapic);
+/* Local APIC was disabled by the BIOS and enabled by the kernel */
+static int enabled_via_apicbase;
+
+#endif
+
+#ifdef CONFIG_X86_64
+static int apic_calibrate_pmtmr __initdata;
+static __init int setup_apicpmtimer(char *s)
+{
+	apic_calibrate_pmtmr = 1;
+	notsc_setup(NULL);
+	return 0;
+}
+__setup("apicpmtimer", setup_apicpmtimer);
+#endif
+
+#ifdef CONFIG_X86_64
+#define HAVE_X2APIC
+#endif
+
+#ifdef HAVE_X2APIC
+int x2apic;
+/* x2apic enabled before OS handover */
+int x2apic_preenabled;
+int disable_x2apic;
+static __init int setup_nox2apic(char *str)
+{
+	disable_x2apic = 1;
+	setup_clear_cpu_cap(X86_FEATURE_X2APIC);
+	return 0;
+}
+early_param("nox2apic", setup_nox2apic);
+#endif
+
+unsigned long mp_lapic_addr;
+int disable_apic;
+/* Disable local APIC timer from the kernel commandline or via dmi quirk */
+static int disable_apic_timer __cpuinitdata;
+/* Local APIC timer works in C2 */
+int local_apic_timer_c2_ok;
+EXPORT_SYMBOL_GPL(local_apic_timer_c2_ok);
+
+int first_system_vector = 0xfe;
+
+char system_vectors[NR_VECTORS] = { [0 ... NR_VECTORS-1] = SYS_VECTOR_FREE};
+
+/*
+ * Debug level, exported for io_apic.c
+ */
+unsigned int apic_verbosity;
+
+int pic_mode;
+
+/* Have we found an MP table */
+int smp_found_config;
+
+static struct resource lapic_resource = {
+	.name = "Local APIC",
+	.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
+};
+
+static unsigned int calibration_result;
+
+static int lapic_next_event(unsigned long delta,
+			    struct clock_event_device *evt);
+static void lapic_timer_setup(enum clock_event_mode mode,
+			      struct clock_event_device *evt);
+static void lapic_timer_broadcast(cpumask_t mask);
+static void apic_pm_activate(void);
+
+/*
+ * The local apic timer can be used for any function which is CPU local.
+ */
+static struct clock_event_device lapic_clockevent = {
+	.name		= "lapic",
+	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT
+			| CLOCK_EVT_FEAT_C3STOP | CLOCK_EVT_FEAT_DUMMY,
+	.shift		= 32,
+	.set_mode	= lapic_timer_setup,
+	.set_next_event	= lapic_next_event,
+	.broadcast	= lapic_timer_broadcast,
+	.rating		= 100,
+	.irq		= -1,
+};
+static DEFINE_PER_CPU(struct clock_event_device, lapic_events);
+
+static unsigned long apic_phys;
+
+/*
+ * Get the LAPIC version
+ */
+static inline int lapic_get_version(void)
+{
+	return GET_APIC_VERSION(apic_read(APIC_LVR));
+}
+
+/*
+ * Check, if the APIC is integrated or a separate chip
+ */
+static inline int lapic_is_integrated(void)
+{
+#ifdef CONFIG_X86_64
+	return 1;
+#else
+	return APIC_INTEGRATED(lapic_get_version());
+#endif
+}
+
+/*
+ * Check, whether this is a modern or a first generation APIC
+ */
+static int modern_apic(void)
+{
+	/* AMD systems use old APIC versions, so check the CPU */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+	    boot_cpu_data.x86 >= 0xf)
+		return 1;
+	return lapic_get_version() >= 0x14;
+}
+
+/*
+ * Paravirt kernels also might be using these below ops. So we still
+ * use generic apic_read()/apic_write(), which might be pointing to different
+ * ops in PARAVIRT case.
+ */
+void xapic_wait_icr_idle(void)
+{
+	while (apic_read(APIC_ICR) & APIC_ICR_BUSY)
+		cpu_relax();
+}
+
+u32 safe_xapic_wait_icr_idle(void)
+{
+	u32 send_status;
+	int timeout;
+
+	timeout = 0;
+	do {
+		send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
+		if (!send_status)
+			break;
+		udelay(100);
+	} while (timeout++ < 1000);
+
+	return send_status;
+}
+
+void xapic_icr_write(u32 low, u32 id)
+{
+	apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(id));
+	apic_write(APIC_ICR, low);
+}
+
+u64 xapic_icr_read(void)
+{
+	u32 icr1, icr2;
+
+	icr2 = apic_read(APIC_ICR2);
+	icr1 = apic_read(APIC_ICR);
+
+	return icr1 | ((u64)icr2 << 32);
+}
+
+static struct apic_ops xapic_ops = {
+	.read = native_apic_mem_read,
+	.write = native_apic_mem_write,
+	.icr_read = xapic_icr_read,
+	.icr_write = xapic_icr_write,
+	.wait_icr_idle = xapic_wait_icr_idle,
+	.safe_wait_icr_idle = safe_xapic_wait_icr_idle,
+};
+
+struct apic_ops __read_mostly *apic_ops = &xapic_ops;
+EXPORT_SYMBOL_GPL(apic_ops);
+
+#ifdef HAVE_X2APIC
+static void x2apic_wait_icr_idle(void)
+{
+	/* no need to wait for icr idle in x2apic */
+	return;
+}
+
+static u32 safe_x2apic_wait_icr_idle(void)
+{
+	/* no need to wait for icr idle in x2apic */
+	return 0;
+}
+
+void x2apic_icr_write(u32 low, u32 id)
+{
+	wrmsrl(APIC_BASE_MSR + (APIC_ICR >> 4), ((__u64) id) << 32 | low);
+}
+
+u64 x2apic_icr_read(void)
+{
+	unsigned long val;
+
+	rdmsrl(APIC_BASE_MSR + (APIC_ICR >> 4), val);
+	return val;
+}
+
+static struct apic_ops x2apic_ops = {
+	.read = native_apic_msr_read,
+	.write = native_apic_msr_write,
+	.icr_read = x2apic_icr_read,
+	.icr_write = x2apic_icr_write,
+	.wait_icr_idle = x2apic_wait_icr_idle,
+	.safe_wait_icr_idle = safe_x2apic_wait_icr_idle,
+};
+#endif
+
+/**
+ * enable_NMI_through_LVT0 - enable NMI through local vector table 0
+ */
+void __cpuinit enable_NMI_through_LVT0(void)
+{
+	unsigned int v;
+
+	/* unmask and set to NMI */
+	v = APIC_DM_NMI;
+
+	/* Level triggered for 82489DX (32bit mode) */
+	if (!lapic_is_integrated())
+		v |= APIC_LVT_LEVEL_TRIGGER;
+
+	apic_write(APIC_LVT0, v);
+}
+
+#ifdef CONFIG_X86_32
+/**
+ * get_physical_broadcast - Get number of physical broadcast IDs
+ */
+int get_physical_broadcast(void)
+{
+	return modern_apic() ? 0xff : 0xf;
+}
+#endif
+
+/**
+ * lapic_get_maxlvt - get the maximum number of local vector table entries
+ */
+int lapic_get_maxlvt(void)
+{
+	unsigned int v;
+
+	v = apic_read(APIC_LVR);
+	/*
+	 * - we always have APIC integrated on 64bit mode
+	 * - 82489DXs do not report # of LVT entries
+	 */
+	return APIC_INTEGRATED(GET_APIC_VERSION(v)) ? GET_APIC_MAXLVT(v) : 2;
+}
+
+/*
+ * Local APIC timer
+ */
+
+/* Clock divisor */
+#ifdef CONFG_X86_64
+#define APIC_DIVISOR 1
+#else
+#define APIC_DIVISOR 16
+#endif
+
+/*
+ * This function sets up the local APIC timer, with a timeout of
+ * 'clocks' APIC bus clock. During calibration we actually call
+ * this function twice on the boot CPU, once with a bogus timeout
+ * value, second time for real. The other (noncalibrating) CPUs
+ * call this function only once, with the real, calibrated value.
+ *
+ * We do reads before writes even if unnecessary, to get around the
+ * P5 APIC double write bug.
+ */
+static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
+{
+	unsigned int lvtt_value, tmp_value;
+
+	lvtt_value = LOCAL_TIMER_VECTOR;
+	if (!oneshot)
+		lvtt_value |= APIC_LVT_TIMER_PERIODIC;
+	if (!lapic_is_integrated())
+		lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);
+
+	if (!irqen)
+		lvtt_value |= APIC_LVT_MASKED;
+
+	apic_write(APIC_LVTT, lvtt_value);
+
+	/*
+	 * Divide PICLK by 16
+	 */
+	tmp_value = apic_read(APIC_TDCR);
+	apic_write(APIC_TDCR,
+		(tmp_value & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) |
+		APIC_TDR_DIV_16);
+
+	if (!oneshot)
+		apic_write(APIC_TMICT, clocks / APIC_DIVISOR);
+}
+
+/*
+ * Setup extended LVT, AMD specific (K8, family 10h)
+ *
+ * Vector mappings are hard coded. On K8 only offset 0 (APIC500) and
+ * MCE interrupts are supported. Thus MCE offset must be set to 0.
+ *
+ * If mask=1, the LVT entry does not generate interrupts while mask=0
+ * enables the vector. See also the BKDGs.
+ */
+
+#define APIC_EILVT_LVTOFF_MCE 0
+#define APIC_EILVT_LVTOFF_IBS 1
+
+static void setup_APIC_eilvt(u8 lvt_off, u8 vector, u8 msg_type, u8 mask)
+{
+	unsigned long reg = (lvt_off << 4) + APIC_EILVT0;
+	unsigned int  v   = (mask << 16) | (msg_type << 8) | vector;
+
+	apic_write(reg, v);
+}
+
+u8 setup_APIC_eilvt_mce(u8 vector, u8 msg_type, u8 mask)
+{
+	setup_APIC_eilvt(APIC_EILVT_LVTOFF_MCE, vector, msg_type, mask);
+	return APIC_EILVT_LVTOFF_MCE;
+}
+
+u8 setup_APIC_eilvt_ibs(u8 vector, u8 msg_type, u8 mask)
+{
+	setup_APIC_eilvt(APIC_EILVT_LVTOFF_IBS, vector, msg_type, mask);
+	return APIC_EILVT_LVTOFF_IBS;
+}
+EXPORT_SYMBOL_GPL(setup_APIC_eilvt_ibs);
+
+/*
+ * Program the next event, relative to now
+ */
+static int lapic_next_event(unsigned long delta,
+			    struct clock_event_device *evt)
+{
+	apic_write(APIC_TMICT, delta);
+	return 0;
+}
+
+/*
+ * Setup the lapic timer in periodic or oneshot mode
+ */
+static void lapic_timer_setup(enum clock_event_mode mode,
+			      struct clock_event_device *evt)
+{
+	unsigned long flags;
+	unsigned int v;
+
+	/* Lapic used as dummy for broadcast ? */
+	if (evt->features & CLOCK_EVT_FEAT_DUMMY)
+		return;
+
+	local_irq_save(flags);
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+	case CLOCK_EVT_MODE_ONESHOT:
+		__setup_APIC_LVTT(calibration_result,
+				  mode != CLOCK_EVT_MODE_PERIODIC, 1);
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		v = apic_read(APIC_LVTT);
+		v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
+		apic_write(APIC_LVTT, v);
+		break;
+	case CLOCK_EVT_MODE_RESUME:
+		/* Nothing to do here */
+		break;
+	}
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Local APIC timer broadcast function
+ */
+static void lapic_timer_broadcast(cpumask_t mask)
+{
+#ifdef CONFIG_SMP
+	send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
+#endif
+}
+
+/*
+ * Setup the local APIC timer for this CPU. Copy the initilized values
+ * of the boot CPU and register the clock event in the framework.
+ */
+static void __cpuinit setup_APIC_timer(void)
+{
+	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
+
+	memcpy(levt, &lapic_clockevent, sizeof(*levt));
+	levt->cpumask = cpumask_of_cpu(smp_processor_id());
+
+	clockevents_register_device(levt);
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * In this function we calibrate APIC bus clocks to the external
+ * timer. Unfortunately we cannot use jiffies and the timer irq
+ * to calibrate, since some later bootup code depends on getting
+ * the first irq? Ugh.
+ *
+ * We want to do the calibration only once since we
+ * want to have local timer irqs syncron. CPUs connected
+ * by the same APIC bus have the very same bus frequency.
+ * And we want to have irqs off anyways, no accidental
+ * APIC irq that way.
+ */
+
+#define TICK_COUNT 100000000
+
+static int __init calibrate_APIC_clock(void)
+{
+	unsigned apic, apic_start;
+	unsigned long tsc, tsc_start;
+	int result;
+
+	local_irq_disable();
+
+	/*
+	 * Put whatever arbitrary (but long enough) timeout
+	 * value into the APIC clock, we just want to get the
+	 * counter running for calibration.
+	 *
+	 * No interrupt enable !
+	 */
+	__setup_APIC_LVTT(250000000, 0, 0);
+
+	apic_start = apic_read(APIC_TMCCT);
+#ifdef CONFIG_X86_PM_TIMER
+	if (apic_calibrate_pmtmr && pmtmr_ioport) {
+		pmtimer_wait(5000);  /* 5ms wait */
+		apic = apic_read(APIC_TMCCT);
+		result = (apic_start - apic) * 1000L / 5;
+	} else
+#endif
+	{
+		rdtscll(tsc_start);
+
+		do {
+			apic = apic_read(APIC_TMCCT);
+			rdtscll(tsc);
+		} while ((tsc - tsc_start) < TICK_COUNT &&
+				(apic_start - apic) < TICK_COUNT);
+
+		result = (apic_start - apic) * 1000L * tsc_khz /
+					(tsc - tsc_start);
+	}
+
+	local_irq_enable();
+
+	printk(KERN_DEBUG "APIC timer calibration result %d\n", result);
+
+	printk(KERN_INFO "Detected %d.%03d MHz APIC timer.\n",
+		result / 1000 / 1000, result / 1000 % 1000);
+
+	/* Calculate the scaled math multiplication factor */
+	lapic_clockevent.mult = div_sc(result, NSEC_PER_SEC,
+				       lapic_clockevent.shift);
+	lapic_clockevent.max_delta_ns =
+		clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
+	lapic_clockevent.min_delta_ns =
+		clockevent_delta2ns(0xF, &lapic_clockevent);
+
+	calibration_result = (result * APIC_DIVISOR) / HZ;
+
+	/*
+	 * Do a sanity check on the APIC calibration result
+	 */
+	if (calibration_result < (1000000 / HZ)) {
+		printk(KERN_WARNING
+			"APIC frequency too slow, disabling apic timer\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+#else
+/*
+ * In this functions we calibrate APIC bus clocks to the external timer.
+ *
+ * We want to do the calibration only once since we want to have local timer
+ * irqs syncron. CPUs connected by the same APIC bus have the very same bus
+ * frequency.
+ *
+ * This was previously done by reading the PIT/HPET and waiting for a wrap
+ * around to find out, that a tick has elapsed. I have a box, where the PIT
+ * readout is broken, so it never gets out of the wait loop again. This was
+ * also reported by others.
+ *
+ * Monitoring the jiffies value is inaccurate and the clockevents
+ * infrastructure allows us to do a simple substitution of the interrupt
+ * handler.
+ *
+ * The calibration routine also uses the pm_timer when possible, as the PIT
+ * happens to run way too slow (factor 2.3 on my VAIO CoreDuo, which goes
+ * back to normal later in the boot process).
+ */
+
+#define LAPIC_CAL_LOOPS		(HZ/10)
+
+static __initdata int lapic_cal_loops = -1;
+static __initdata long lapic_cal_t1, lapic_cal_t2;
+static __initdata unsigned long long lapic_cal_tsc1, lapic_cal_tsc2;
+static __initdata unsigned long lapic_cal_pm1, lapic_cal_pm2;
+static __initdata unsigned long lapic_cal_j1, lapic_cal_j2;
+
+/*
+ * Temporary interrupt handler.
+ */
+static void __init lapic_cal_handler(struct clock_event_device *dev)
+{
+	unsigned long long tsc = 0;
+	long tapic = apic_read(APIC_TMCCT);
+	unsigned long pm = acpi_pm_read_early();
+
+	if (cpu_has_tsc)
+		rdtscll(tsc);
+
+	switch (lapic_cal_loops++) {
+	case 0:
+		lapic_cal_t1 = tapic;
+		lapic_cal_tsc1 = tsc;
+		lapic_cal_pm1 = pm;
+		lapic_cal_j1 = jiffies;
+		break;
+
+	case LAPIC_CAL_LOOPS:
+		lapic_cal_t2 = tapic;
+		lapic_cal_tsc2 = tsc;
+		if (pm < lapic_cal_pm1)
+			pm += ACPI_PM_OVRRUN;
+		lapic_cal_pm2 = pm;
+		lapic_cal_j2 = jiffies;
+		break;
+	}
+}
+
+static int __init calibrate_APIC_clock(void)
+{
+	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
+	const long pm_100ms = PMTMR_TICKS_PER_SEC/10;
+	const long pm_thresh = pm_100ms/100;
+	void (*real_handler)(struct clock_event_device *dev);
+	unsigned long deltaj;
+	long delta, deltapm;
+	int pm_referenced = 0;
+
+	local_irq_disable();
+
+	/* Replace the global interrupt handler */
+	real_handler = global_clock_event->event_handler;
+	global_clock_event->event_handler = lapic_cal_handler;
+
+	/*
+	 * Setup the APIC counter to 1e9. There is no way the lapic
+	 * can underflow in the 100ms detection time frame
+	 */
+	__setup_APIC_LVTT(1000000000, 0, 0);
+
+	/* Let the interrupts run */
+	local_irq_enable();
+
+	while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
+		cpu_relax();
+
+	local_irq_disable();
+
+	/* Restore the real event handler */
+	global_clock_event->event_handler = real_handler;
+
+	/* Build delta t1-t2 as apic timer counts down */
+	delta = lapic_cal_t1 - lapic_cal_t2;
+	apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);
+
+	/* Check, if the PM timer is available */
+	deltapm = lapic_cal_pm2 - lapic_cal_pm1;
+	apic_printk(APIC_VERBOSE, "... PM timer delta = %ld\n", deltapm);
+
+	if (deltapm) {
+		unsigned long mult;
+		u64 res;
+
+		mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22);
+
+		if (deltapm > (pm_100ms - pm_thresh) &&
+		    deltapm < (pm_100ms + pm_thresh)) {
+			apic_printk(APIC_VERBOSE, "... PM timer result ok\n");
+		} else {
+			res = (((u64) deltapm) *  mult) >> 22;
+			do_div(res, 1000000);
+			printk(KERN_WARNING "APIC calibration not consistent "
+			       "with PM Timer: %ldms instead of 100ms\n",
+			       (long)res);
+			/* Correct the lapic counter value */
+			res = (((u64) delta) * pm_100ms);
+			do_div(res, deltapm);
+			printk(KERN_INFO "APIC delta adjusted to PM-Timer: "
+			       "%lu (%ld)\n", (unsigned long) res, delta);
+			delta = (long) res;
+		}
+		pm_referenced = 1;
+	}
+
+	/* Calculate the scaled math multiplication factor */
+	lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
+				       lapic_clockevent.shift);
+	lapic_clockevent.max_delta_ns =
+		clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
+	lapic_clockevent.min_delta_ns =
+		clockevent_delta2ns(0xF, &lapic_clockevent);
+
+	calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
+
+	apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
+	apic_printk(APIC_VERBOSE, "..... mult: %ld\n", lapic_clockevent.mult);
+	apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
+		    calibration_result);
+
+	if (cpu_has_tsc) {
+		delta = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);
+		apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
+			    "%ld.%04ld MHz.\n",
+			    (delta / LAPIC_CAL_LOOPS) / (1000000 / HZ),
+			    (delta / LAPIC_CAL_LOOPS) % (1000000 / HZ));
+	}
+
+	apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
+		    "%u.%04u MHz.\n",
+		    calibration_result / (1000000 / HZ),
+		    calibration_result % (1000000 / HZ));
+
+	/*
+	 * Do a sanity check on the APIC calibration result
+	 */
+	if (calibration_result < (1000000 / HZ)) {
+		local_irq_enable();
+		printk(KERN_WARNING
+		       "APIC frequency too slow, disabling apic timer\n");
+		return -1;
+	}
+
+	levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
+
+	/* We trust the pm timer based calibration */
+	if (!pm_referenced) {
+		apic_printk(APIC_VERBOSE, "... verify APIC timer\n");
+
+		/*
+		 * Setup the apic timer manually
+		 */
+		levt->event_handler = lapic_cal_handler;
+		lapic_timer_setup(CLOCK_EVT_MODE_PERIODIC, levt);
+		lapic_cal_loops = -1;
+
+		/* Let the interrupts run */
+		local_irq_enable();
+
+		while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
+			cpu_relax();
+
+		local_irq_disable();
+
+		/* Stop the lapic timer */
+		lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, levt);
+
+		local_irq_enable();
+
+		/* Jiffies delta */
+		deltaj = lapic_cal_j2 - lapic_cal_j1;
+		apic_printk(APIC_VERBOSE, "... jiffies delta = %lu\n", deltaj);
+
+		/* Check, if the jiffies result is consistent */
+		if (deltaj >= LAPIC_CAL_LOOPS-2 && deltaj <= LAPIC_CAL_LOOPS+2)
+			apic_printk(APIC_VERBOSE, "... jiffies result ok\n");
+		else
+			levt->features |= CLOCK_EVT_FEAT_DUMMY;
+	} else
+		local_irq_enable();
+
+	if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
+		printk(KERN_WARNING
+		       "APIC timer disabled due to verification failure.\n");
+			return -1;
+	}
+
+	return 0;
+}
+
+#endif
+
+/*
+ * Setup the boot APIC
+ *
+ * Calibrate and verify the result.
+ */
+void __init setup_boot_APIC_clock(void)
+{
+	/*
+	 * The local apic timer can be disabled via the kernel
+	 * commandline or from the CPU detection code. Register the lapic
+	 * timer as a dummy clock event source on SMP systems, so the
+	 * broadcast mechanism is used. On UP systems simply ignore it.
+	 */
+	if (disable_apic_timer) {
+		printk(KERN_INFO "Disabling APIC timer\n");
+		/* No broadcast on UP ! */
+		if (num_possible_cpus() > 1) {
+			lapic_clockevent.mult = 1;
+			setup_APIC_timer();
+		}
+		return;
+	}
+
+	apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
+		    "calibrating APIC timer ...\n");
+
+	if (calibrate_APIC_clock()) {
+		/* No broadcast on UP ! */
+		if (num_possible_cpus() > 1)
+			setup_APIC_timer();
+		return;
+	}
+
+	/*
+	 * If nmi_watchdog is set to IO_APIC, we need the
+	 * PIT/HPET going.  Otherwise register lapic as a dummy
+	 * device.
+	 */
+	if (nmi_watchdog != NMI_IO_APIC)
+		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
+	else
+		printk(KERN_WARNING "APIC timer registered as dummy,"
+			" due to nmi_watchdog=%d!\n", nmi_watchdog);
+
+	/* Setup the lapic or request the broadcast */
+	setup_APIC_timer();
+}
+
+void __cpuinit setup_secondary_APIC_clock(void)
+{
+	setup_APIC_timer();
+}
+
+/*
+ * The guts of the apic timer interrupt
+ */
+static void local_apic_timer_interrupt(void)
+{
+	int cpu = smp_processor_id();
+	struct clock_event_device *evt = &per_cpu(lapic_events, cpu);
+
+	/*
+	 * Normally we should not be here till LAPIC has been initialized but
+	 * in some cases like kdump, its possible that there is a pending LAPIC
+	 * timer interrupt from previous kernel's context and is delivered in
+	 * new kernel the moment interrupts are enabled.
+	 *
+	 * Interrupts are enabled early and LAPIC is setup much later, hence
+	 * its possible that when we get here evt->event_handler is NULL.
+	 * Check for event_handler being NULL and discard the interrupt as
+	 * spurious.
+	 */
+	if (!evt->event_handler) {
+		printk(KERN_WARNING
+		       "Spurious LAPIC timer interrupt on cpu %d\n", cpu);
+		/* Switch it off */
+		lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, evt);
+		return;
+	}
+
+	/*
+	 * the NMI deadlock-detector uses this.
+	 */
+#ifdef CONFIG_X86_64
+	add_pda(apic_timer_irqs, 1);
+#else
+	per_cpu(irq_stat, cpu).apic_timer_irqs++;
+#endif
+
+	evt->event_handler(evt);
+}
+
+/*
+ * Local APIC timer interrupt. This is the most natural way for doing
+ * local interrupts, but local timer interrupts can be emulated by
+ * broadcast interrupts too. [in case the hw doesn't support APIC timers]
+ *
+ * [ if a single-CPU system runs an SMP kernel then we call the local
+ *   interrupt as well. Thus we cannot inline the local irq ... ]
+ */
+void smp_apic_timer_interrupt(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	/*
+	 * NOTE! We'd better ACK the irq immediately,
+	 * because timer handling can be slow.
+	 */
+	ack_APIC_irq();
+	/*
+	 * update_process_times() expects us to have done irq_enter().
+	 * Besides, if we don't timer interrupts ignore the global
+	 * interrupt lock, which is the WrongThing (tm) to do.
+	 */
+#ifdef CONFIG_X86_64
+	exit_idle();
+#endif
+	irq_enter();
+	local_apic_timer_interrupt();
+	irq_exit();
+
+	set_irq_regs(old_regs);
+}
+
+int setup_profiling_timer(unsigned int multiplier)
+{
+	return -EINVAL;
+}
+
+/*
+ * Local APIC start and shutdown
+ */
+
+/**
+ * clear_local_APIC - shutdown the local APIC
+ *
+ * This is called, when a CPU is disabled and before rebooting, so the state of
+ * the local APIC has no dangling leftovers. Also used to cleanout any BIOS
+ * leftovers during boot.
+ */
+void clear_local_APIC(void)
+{
+	int maxlvt;
+	u32 v;
+
+	/* APIC hasn't been mapped yet */
+	if (!apic_phys)
+		return;
+
+	maxlvt = lapic_get_maxlvt();
+	/*
+	 * Masking an LVT entry can trigger a local APIC error
+	 * if the vector is zero. Mask LVTERR first to prevent this.
+	 */
+	if (maxlvt >= 3) {
+		v = ERROR_APIC_VECTOR; /* any non-zero vector will do */
+		apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
+	}
+	/*
+	 * Careful: we have to set masks only first to deassert
+	 * any level-triggered sources.
+	 */
+	v = apic_read(APIC_LVTT);
+	apic_write(APIC_LVTT, v | APIC_LVT_MASKED);
+	v = apic_read(APIC_LVT0);
+	apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
+	v = apic_read(APIC_LVT1);
+	apic_write(APIC_LVT1, v | APIC_LVT_MASKED);
+	if (maxlvt >= 4) {
+		v = apic_read(APIC_LVTPC);
+		apic_write(APIC_LVTPC, v | APIC_LVT_MASKED);
+	}
+
+	/* lets not touch this if we didn't frob it */
+#if defined(CONFIG_X86_MCE_P4THERMAL) || defined(X86_MCE_INTEL)
+	if (maxlvt >= 5) {
+		v = apic_read(APIC_LVTTHMR);
+		apic_write(APIC_LVTTHMR, v | APIC_LVT_MASKED);
+	}
+#endif
+	/*
+	 * Clean APIC state for other OSs:
+	 */
+	apic_write(APIC_LVTT, APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, APIC_LVT_MASKED);
+	apic_write(APIC_LVT1, APIC_LVT_MASKED);
+	if (maxlvt >= 3)
+		apic_write(APIC_LVTERR, APIC_LVT_MASKED);
+	if (maxlvt >= 4)
+		apic_write(APIC_LVTPC, APIC_LVT_MASKED);
+
+	/* Integrated APIC (!82489DX) ? */
+	if (lapic_is_integrated()) {
+		if (maxlvt > 3)
+			/* Clear ESR due to Pentium errata 3AP and 11AP */
+			apic_write(APIC_ESR, 0);
+		apic_read(APIC_ESR);
+	}
+}
+
+/**
+ * disable_local_APIC - clear and disable the local APIC
+ */
+void disable_local_APIC(void)
+{
+	unsigned int value;
+
+	clear_local_APIC();
+
+	/*
+	 * Disable APIC (implies clearing of registers
+	 * for 82489DX!).
+	 */
+	value = apic_read(APIC_SPIV);
+	value &= ~APIC_SPIV_APIC_ENABLED;
+	apic_write(APIC_SPIV, value);
+
+#ifdef CONFIG_X86_32
+	/*
+	 * When LAPIC was disabled by the BIOS and enabled by the kernel,
+	 * restore the disabled state.
+	 */
+	if (enabled_via_apicbase) {
+		unsigned int l, h;
+
+		rdmsr(MSR_IA32_APICBASE, l, h);
+		l &= ~MSR_IA32_APICBASE_ENABLE;
+		wrmsr(MSR_IA32_APICBASE, l, h);
+	}
+#endif
+}
+
+/*
+ * If Linux enabled the LAPIC against the BIOS default disable it down before
+ * re-entering the BIOS on shutdown.  Otherwise the BIOS may get confused and
+ * not power-off.  Additionally clear all LVT entries before disable_local_APIC
+ * for the case where Linux didn't enable the LAPIC.
+ */
+void lapic_shutdown(void)
+{
+	unsigned long flags;
+
+	if (!cpu_has_apic)
+		return;
+
+	local_irq_save(flags);
+
+#ifdef CONFIG_X86_32
+	if (!enabled_via_apicbase)
+		clear_local_APIC();
+	else
+#endif
+		disable_local_APIC();
+
+
+	local_irq_restore(flags);
+}
+
+/*
+ * This is to verify that we're looking at a real local APIC.
+ * Check these against your board if the CPUs aren't getting
+ * started for no apparent reason.
+ */
+int __init verify_local_APIC(void)
+{
+	unsigned int reg0, reg1;
+
+	/*
+	 * The version register is read-only in a real APIC.
+	 */
+	reg0 = apic_read(APIC_LVR);
+	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg0);
+	apic_write(APIC_LVR, reg0 ^ APIC_LVR_MASK);
+	reg1 = apic_read(APIC_LVR);
+	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg1);
+
+	/*
+	 * The two version reads above should print the same
+	 * numbers.  If the second one is different, then we
+	 * poke at a non-APIC.
+	 */
+	if (reg1 != reg0)
+		return 0;
+
+	/*
+	 * Check if the version looks reasonably.
+	 */
+	reg1 = GET_APIC_VERSION(reg0);
+	if (reg1 == 0x00 || reg1 == 0xff)
+		return 0;
+	reg1 = lapic_get_maxlvt();
+	if (reg1 < 0x02 || reg1 == 0xff)
+		return 0;
+
+	/*
+	 * The ID register is read/write in a real APIC.
+	 */
+	reg0 = apic_read(APIC_ID);
+	apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0);
+	apic_write(APIC_ID, reg0 ^ APIC_ID_MASK);
+	reg1 = apic_read(APIC_ID);
+	apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg1);
+	apic_write(APIC_ID, reg0);
+	if (reg1 != (reg0 ^ APIC_ID_MASK))
+		return 0;
+
+	/*
+	 * The next two are just to see if we have sane values.
+	 * They're only really relevant if we're in Virtual Wire
+	 * compatibility mode, but most boxes are anymore.
+	 */
+	reg0 = apic_read(APIC_LVT0);
+	apic_printk(APIC_DEBUG, "Getting LVT0: %x\n", reg0);
+	reg1 = apic_read(APIC_LVT1);
+	apic_printk(APIC_DEBUG, "Getting LVT1: %x\n", reg1);
+
+	return 1;
+}
+
+/**
+ * sync_Arb_IDs - synchronize APIC bus arbitration IDs
+ */
+void __init sync_Arb_IDs(void)
+{
+	/*
+	 * Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1 And not
+	 * needed on AMD.
+	 */
+	if (modern_apic() || boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+		return;
+
+	/*
+	 * Wait for idle.
+	 */
+	apic_wait_icr_idle();
+
+	apic_printk(APIC_DEBUG, "Synchronizing Arb IDs.\n");
+	apic_write(APIC_ICR, APIC_DEST_ALLINC |
+			APIC_INT_LEVELTRIG | APIC_DM_INIT);
+}
+
+/*
+ * An initial setup of the virtual wire mode.
+ */
+void __init init_bsp_APIC(void)
+{
+	unsigned int value;
+
+	/*
+	 * Don't do the setup now if we have a SMP BIOS as the
+	 * through-I/O-APIC virtual wire mode might be active.
+	 */
+	if (smp_found_config || !cpu_has_apic)
+		return;
+
+	/*
+	 * Do not trust the local APIC being empty at bootup.
+	 */
+	clear_local_APIC();
+
+	/*
+	 * Enable APIC.
+	 */
+	value = apic_read(APIC_SPIV);
+	value &= ~APIC_VECTOR_MASK;
+	value |= APIC_SPIV_APIC_ENABLED;
+
+#ifdef CONFIG_X86_32
+	/* This bit is reserved on P4/Xeon and should be cleared */
+	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
+	    (boot_cpu_data.x86 == 15))
+		value &= ~APIC_SPIV_FOCUS_DISABLED;
+	else
+#endif
+		value |= APIC_SPIV_FOCUS_DISABLED;
+	value |= SPURIOUS_APIC_VECTOR;
+	apic_write(APIC_SPIV, value);
+
+	/*
+	 * Set up the virtual wire mode.
+	 */
+	apic_write(APIC_LVT0, APIC_DM_EXTINT);
+	value = APIC_DM_NMI;
+	if (!lapic_is_integrated())		/* 82489DX */
+		value |= APIC_LVT_LEVEL_TRIGGER;
+	apic_write(APIC_LVT1, value);
+}
+
+static void __cpuinit lapic_setup_esr(void)
+{
+	unsigned long oldvalue, value, maxlvt;
+	if (lapic_is_integrated() && !esr_disable) {
+		if (esr_disable) {
+			/*
+			 * Something untraceable is creating bad interrupts on
+			 * secondary quads ... for the moment, just leave the
+			 * ESR disabled - we can't do anything useful with the
+			 * errors anyway - mbligh
+			 */
+			printk(KERN_INFO "Leaving ESR disabled.\n");
+			return;
+		}
+		/* !82489DX */
+		maxlvt = lapic_get_maxlvt();
+		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP. */
+			apic_write(APIC_ESR, 0);
+		oldvalue = apic_read(APIC_ESR);
+
+		/* enables sending errors */
+		value = ERROR_APIC_VECTOR;
+		apic_write(APIC_LVTERR, value);
+		/*
+		 * spec says clear errors after enabling vector.
+		 */
+		if (maxlvt > 3)
+			apic_write(APIC_ESR, 0);
+		value = apic_read(APIC_ESR);
+		if (value != oldvalue)
+			apic_printk(APIC_VERBOSE, "ESR value before enabling "
+				"vector: 0x%08lx  after: 0x%08lx\n",
+				oldvalue, value);
+	} else {
+		printk(KERN_INFO "No ESR for 82489DX.\n");
+	}
+}
+
+
+/**
+ * setup_local_APIC - setup the local APIC
+ */
+void __cpuinit setup_local_APIC(void)
+{
+	unsigned int value;
+	int i, j;
+
+#ifdef CONFIG_X86_32
+	/* Pound the ESR really hard over the head with a big hammer - mbligh */
+	if (esr_disable) {
+		apic_write(APIC_ESR, 0);
+		apic_write(APIC_ESR, 0);
+		apic_write(APIC_ESR, 0);
+		apic_write(APIC_ESR, 0);
+	}
+#endif
+
+	preempt_disable();
+
+	/*
+	 * Double-check whether this APIC is really registered.
+	 * This is meaningless in clustered apic mode, so we skip it.
+	 */
+	if (!apic_id_registered())
+		BUG();
+
+	/*
+	 * Intel recommends to set DFR, LDR and TPR before enabling
+	 * an APIC.  See e.g. "AP-388 82489DX User's Manual" (Intel
+	 * document number 292116).  So here it goes...
+	 */
+	init_apic_ldr();
+
+	/*
+	 * Set Task Priority to 'accept all'. We never change this
+	 * later on.
+	 */
+	value = apic_read(APIC_TASKPRI);
+	value &= ~APIC_TPRI_MASK;
+	apic_write(APIC_TASKPRI, value);
+
+	/*
+	 * After a crash, we no longer service the interrupts and a pending
+	 * interrupt from previous kernel might still have ISR bit set.
+	 *
+	 * Most probably by now CPU has serviced that pending interrupt and
+	 * it might not have done the ack_APIC_irq() because it thought,
+	 * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
+	 * does not clear the ISR bit and cpu thinks it has already serivced
+	 * the interrupt. Hence a vector might get locked. It was noticed
+	 * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
+	 */
+	for (i = APIC_ISR_NR - 1; i >= 0; i--) {
+		value = apic_read(APIC_ISR + i*0x10);
+		for (j = 31; j >= 0; j--) {
+			if (value & (1<<j))
+				ack_APIC_irq();
+		}
+	}
+
+	/*
+	 * Now that we are all set up, enable the APIC
+	 */
+	value = apic_read(APIC_SPIV);
+	value &= ~APIC_VECTOR_MASK;
+	/*
+	 * Enable APIC
+	 */
+	value |= APIC_SPIV_APIC_ENABLED;
+
+#ifdef CONFIG_X86_32
+	/*
+	 * Some unknown Intel IO/APIC (or APIC) errata is biting us with
+	 * certain networking cards. If high frequency interrupts are
+	 * happening on a particular IOAPIC pin, plus the IOAPIC routing
+	 * entry is masked/unmasked at a high rate as well then sooner or
+	 * later IOAPIC line gets 'stuck', no more interrupts are received
+	 * from the device. If focus CPU is disabled then the hang goes
+	 * away, oh well :-(
+	 *
+	 * [ This bug can be reproduced easily with a level-triggered
+	 *   PCI Ne2000 networking cards and PII/PIII processors, dual
+	 *   BX chipset. ]
+	 */
+	/*
+	 * Actually disabling the focus CPU check just makes the hang less
+	 * frequent as it makes the interrupt distributon model be more
+	 * like LRU than MRU (the short-term load is more even across CPUs).
+	 * See also the comment in end_level_ioapic_irq().  --macro
+	 */
+
+	/*
+	 * - enable focus processor (bit==0)
+	 * - 64bit mode always use processor focus
+	 *   so no need to set it
+	 */
+	value &= ~APIC_SPIV_FOCUS_DISABLED;
+#endif
+
+	/*
+	 * Set spurious IRQ vector
+	 */
+	value |= SPURIOUS_APIC_VECTOR;
+	apic_write(APIC_SPIV, value);
+
+	/*
+	 * Set up LVT0, LVT1:
+	 *
+	 * set up through-local-APIC on the BP's LINT0. This is not
+	 * strictly necessary in pure symmetric-IO mode, but sometimes
+	 * we delegate interrupts to the 8259A.
+	 */
+	/*
+	 * TODO: set up through-local-APIC from through-I/O-APIC? --macro
+	 */
+	value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
+	if (!smp_processor_id() && (pic_mode || !value)) {
+		value = APIC_DM_EXTINT;
+		apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n",
+				smp_processor_id());
+	} else {
+		value = APIC_DM_EXTINT | APIC_LVT_MASKED;
+		apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n",
+				smp_processor_id());
+	}
+	apic_write(APIC_LVT0, value);
+
+	/*
+	 * only the BP should see the LINT1 NMI signal, obviously.
+	 */
+	if (!smp_processor_id())
+		value = APIC_DM_NMI;
+	else
+		value = APIC_DM_NMI | APIC_LVT_MASKED;
+	if (!lapic_is_integrated())		/* 82489DX */
+		value |= APIC_LVT_LEVEL_TRIGGER;
+	apic_write(APIC_LVT1, value);
+
+	preempt_enable();
+}
+
+void __cpuinit end_local_APIC_setup(void)
+{
+	lapic_setup_esr();
+
+#ifdef CONFIG_X86_32
+	{
+		unsigned int value;
+		/* Disable the local apic timer */
+		value = apic_read(APIC_LVTT);
+		value |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
+		apic_write(APIC_LVTT, value);
+	}
+#endif
+
+	setup_apic_nmi_watchdog(NULL);
+	apic_pm_activate();
+}
+
+#ifdef HAVE_X2APIC
+void check_x2apic(void)
+{
+	int msr, msr2;
+
+	rdmsr(MSR_IA32_APICBASE, msr, msr2);
+
+	if (msr & X2APIC_ENABLE) {
+		printk("x2apic enabled by BIOS, switching to x2apic ops\n");
+		x2apic_preenabled = x2apic = 1;
+		apic_ops = &x2apic_ops;
+	}
+}
+
+void enable_x2apic(void)
+{
+	int msr, msr2;
+
+	rdmsr(MSR_IA32_APICBASE, msr, msr2);
+	if (!(msr & X2APIC_ENABLE)) {
+		printk("Enabling x2apic\n");
+		wrmsr(MSR_IA32_APICBASE, msr | X2APIC_ENABLE, 0);
+	}
+}
+
+void enable_IR_x2apic(void)
+{
+#ifdef CONFIG_INTR_REMAP
+	int ret;
+	unsigned long flags;
+
+	if (!cpu_has_x2apic)
+		return;
+
+	if (!x2apic_preenabled && disable_x2apic) {
+		printk(KERN_INFO
+		       "Skipped enabling x2apic and Interrupt-remapping "
+		       "because of nox2apic\n");
+		return;
+	}
+
+	if (x2apic_preenabled && disable_x2apic)
+		panic("Bios already enabled x2apic, can't enforce nox2apic");
+
+	if (!x2apic_preenabled && skip_ioapic_setup) {
+		printk(KERN_INFO
+		       "Skipped enabling x2apic and Interrupt-remapping "
+		       "because of skipping io-apic setup\n");
+		return;
+	}
+
+	ret = dmar_table_init();
+	if (ret) {
+		printk(KERN_INFO
+		       "dmar_table_init() failed with %d:\n", ret);
+
+		if (x2apic_preenabled)
+			panic("x2apic enabled by bios. But IR enabling failed");
+		else
+			printk(KERN_INFO
+			       "Not enabling x2apic,Intr-remapping\n");
+		return;
+	}
+
+	local_irq_save(flags);
+	mask_8259A();
+	save_mask_IO_APIC_setup();
+
+	ret = enable_intr_remapping(1);
+
+	if (ret && x2apic_preenabled) {
+		local_irq_restore(flags);
+		panic("x2apic enabled by bios. But IR enabling failed");
+	}
+
+	if (ret)
+		goto end;
+
+	if (!x2apic) {
+		x2apic = 1;
+		apic_ops = &x2apic_ops;
+		enable_x2apic();
+	}
+end:
+	if (ret)
+		/*
+		 * IR enabling failed
+		 */
+		restore_IO_APIC_setup();
+	else
+		reinit_intr_remapped_IO_APIC(x2apic_preenabled);
+
+	unmask_8259A();
+	local_irq_restore(flags);
+
+	if (!ret) {
+		if (!x2apic_preenabled)
+			printk(KERN_INFO
+			       "Enabled x2apic and interrupt-remapping\n");
+		else
+			printk(KERN_INFO
+			       "Enabled Interrupt-remapping\n");
+	} else
+		printk(KERN_ERR
+		       "Failed to enable Interrupt-remapping and x2apic\n");
+#else
+	if (!cpu_has_x2apic)
+		return;
+
+	if (x2apic_preenabled)
+		panic("x2apic enabled prior OS handover,"
+		      " enable CONFIG_INTR_REMAP");
+
+	printk(KERN_INFO "Enable CONFIG_INTR_REMAP for enabling intr-remapping "
+	       " and x2apic\n");
+#endif
+
+	return;
+}
+#endif /* HAVE_X2APIC */
+
+#ifdef CONFIG_X86_64
+/*
+ * Detect and enable local APICs on non-SMP boards.
+ * Original code written by Keir Fraser.
+ * On AMD64 we trust the BIOS - if it says no APIC it is likely
+ * not correctly set up (usually the APIC timer won't work etc.)
+ */
+static int __init detect_init_APIC(void)
+{
+	if (!cpu_has_apic) {
+		printk(KERN_INFO "No local APIC present\n");
+		return -1;
+	}
+
+	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
+	boot_cpu_physical_apicid = 0;
+	return 0;
+}
+#else
+/*
+ * Detect and initialize APIC
+ */
+static int __init detect_init_APIC(void)
+{
+	u32 h, l, features;
+
+	/* Disabled by kernel option? */
+	if (disable_apic)
+		return -1;
+
+	switch (boot_cpu_data.x86_vendor) {
+	case X86_VENDOR_AMD:
+		if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model > 1) ||
+		    (boot_cpu_data.x86 == 15))
+			break;
+		goto no_apic;
+	case X86_VENDOR_INTEL:
+		if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 ||
+		    (boot_cpu_data.x86 == 5 && cpu_has_apic))
+			break;
+		goto no_apic;
+	default:
+		goto no_apic;
+	}
+
+	if (!cpu_has_apic) {
+		/*
+		 * Over-ride BIOS and try to enable the local APIC only if
+		 * "lapic" specified.
+		 */
+		if (!force_enable_local_apic) {
+			printk(KERN_INFO "Local APIC disabled by BIOS -- "
+			       "you can enable it with \"lapic\"\n");
+			return -1;
+		}
+		/*
+		 * Some BIOSes disable the local APIC in the APIC_BASE
+		 * MSR. This can only be done in software for Intel P6 or later
+		 * and AMD K7 (Model > 1) or later.
+		 */
+		rdmsr(MSR_IA32_APICBASE, l, h);
+		if (!(l & MSR_IA32_APICBASE_ENABLE)) {
+			printk(KERN_INFO
+			       "Local APIC disabled by BIOS -- reenabling.\n");
+			l &= ~MSR_IA32_APICBASE_BASE;
+			l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
+			wrmsr(MSR_IA32_APICBASE, l, h);
+			enabled_via_apicbase = 1;
+		}
+	}
+	/*
+	 * The APIC feature bit should now be enabled
+	 * in `cpuid'
+	 */
+	features = cpuid_edx(1);
+	if (!(features & (1 << X86_FEATURE_APIC))) {
+		printk(KERN_WARNING "Could not enable APIC!\n");
+		return -1;
+	}
+	set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
+	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
+
+	/* The BIOS may have set up the APIC at some other address */
+	rdmsr(MSR_IA32_APICBASE, l, h);
+	if (l & MSR_IA32_APICBASE_ENABLE)
+		mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
+
+	printk(KERN_INFO "Found and enabled local APIC!\n");
+
+	apic_pm_activate();
+
+	return 0;
+
+no_apic:
+	printk(KERN_INFO "No local APIC present or hardware disabled\n");
+	return -1;
+}
+#endif
+
+#ifdef CONFIG_X86_64
+void __init early_init_lapic_mapping(void)
+{
+	unsigned long phys_addr;
+
+	/*
+	 * If no local APIC can be found then go out
+	 * : it means there is no mpatable and MADT
+	 */
+	if (!smp_found_config)
+		return;
+
+	phys_addr = mp_lapic_addr;
+
+	set_fixmap_nocache(FIX_APIC_BASE, phys_addr);
+	apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
+		    APIC_BASE, phys_addr);
+
+	/*
+	 * Fetch the APIC ID of the BSP in case we have a
+	 * default configuration (or the MP table is broken).
+	 */
+	boot_cpu_physical_apicid = read_apic_id();
+}
+#endif
+
+/**
+ * init_apic_mappings - initialize APIC mappings
+ */
+void __init init_apic_mappings(void)
+{
+#ifdef HAVE_X2APIC
+	if (x2apic) {
+		boot_cpu_physical_apicid = read_apic_id();
+		return;
+	}
+#endif
+
+	/*
+	 * If no local APIC can be found then set up a fake all
+	 * zeroes page to simulate the local APIC and another
+	 * one for the IO-APIC.
+	 */
+	if (!smp_found_config && detect_init_APIC()) {
+		apic_phys = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
+		apic_phys = __pa(apic_phys);
+	} else
+		apic_phys = mp_lapic_addr;
+
+	set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
+	apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
+				APIC_BASE, apic_phys);
+
+	/*
+	 * Fetch the APIC ID of the BSP in case we have a
+	 * default configuration (or the MP table is broken).
+	 */
+	if (boot_cpu_physical_apicid == -1U)
+		boot_cpu_physical_apicid = read_apic_id();
+}
+
+/*
+ * This initializes the IO-APIC and APIC hardware if this is
+ * a UP kernel.
+ */
+int apic_version[MAX_APICS];
+
+int __init APIC_init_uniprocessor(void)
+{
+#ifdef CONFIG_X86_64
+	if (disable_apic) {
+		printk(KERN_INFO "Apic disabled\n");
+		return -1;
+	}
+	if (!cpu_has_apic) {
+		disable_apic = 1;
+		printk(KERN_INFO "Apic disabled by BIOS\n");
+		return -1;
+	}
+#else
+	if (!smp_found_config && !cpu_has_apic)
+		return -1;
+
+	/*
+	 * Complain if the BIOS pretends there is one.
+	 */
+	if (!cpu_has_apic &&
+	    APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+		printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
+		       boot_cpu_physical_apicid);
+		clear_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
+		return -1;
+	}
+#endif
+
+#ifdef HAVE_X2APIC
+	enable_IR_x2apic();
+#endif
+#ifdef CONFIG_X86_64
+	setup_apic_routing();
+#endif
+
+	verify_local_APIC();
+	connect_bsp_APIC();
+
+#ifdef CONFIG_X86_64
+	apic_write(APIC_ID, SET_APIC_ID(boot_cpu_physical_apicid));
+#else
+	/*
+	 * Hack: In case of kdump, after a crash, kernel might be booting
+	 * on a cpu with non-zero lapic id. But boot_cpu_physical_apicid
+	 * might be zero if read from MP tables. Get it from LAPIC.
+	 */
+# ifdef CONFIG_CRASH_DUMP
+	boot_cpu_physical_apicid = read_apic_id();
+# endif
+#endif
+	physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
+	setup_local_APIC();
+
+#ifdef CONFIG_X86_64
+	/*
+	 * Now enable IO-APICs, actually call clear_IO_APIC
+	 * We need clear_IO_APIC before enabling vector on BP
+	 */
+	if (!skip_ioapic_setup && nr_ioapics)
+		enable_IO_APIC();
+#endif
+
+#ifdef CONFIG_X86_IO_APIC
+	if (!smp_found_config || skip_ioapic_setup || !nr_ioapics)
+#endif
+		localise_nmi_watchdog();
+	end_local_APIC_setup();
+
+#ifdef CONFIG_X86_IO_APIC
+	if (smp_found_config && !skip_ioapic_setup && nr_ioapics)
+		setup_IO_APIC();
+# ifdef CONFIG_X86_64
+	else
+		nr_ioapics = 0;
+# endif
+#endif
+
+#ifdef CONFIG_X86_64
+	setup_boot_APIC_clock();
+	check_nmi_watchdog();
+#else
+	setup_boot_clock();
+#endif
+
+	return 0;
+}
+
+/*
+ * Local APIC interrupts
+ */
+
+/*
+ * This interrupt should _never_ happen with our APIC/SMP architecture
+ */
+#ifdef CONFIG_X86_64
+asmlinkage void smp_spurious_interrupt(void)
+#else
+void smp_spurious_interrupt(struct pt_regs *regs)
+#endif
+{
+	u32 v;
+
+#ifdef CONFIG_X86_64
+	exit_idle();
+#endif
+	irq_enter();
+	/*
+	 * Check if this really is a spurious interrupt and ACK it
+	 * if it is a vectored one.  Just in case...
+	 * Spurious interrupts should not be ACKed.
+	 */
+	v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
+	if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
+		ack_APIC_irq();
+
+#ifdef CONFIG_X86_64
+	add_pda(irq_spurious_count, 1);
+#else
+	/* see sw-dev-man vol 3, chapter 7.4.13.5 */
+	printk(KERN_INFO "spurious APIC interrupt on CPU#%d, "
+	       "should never happen.\n", smp_processor_id());
+	__get_cpu_var(irq_stat).irq_spurious_count++;
+#endif
+	irq_exit();
+}
+
+/*
+ * This interrupt should never happen with our APIC/SMP architecture
+ */
+#ifdef CONFIG_X86_64
+asmlinkage void smp_error_interrupt(void)
+#else
+void smp_error_interrupt(struct pt_regs *regs)
+#endif
+{
+	u32 v, v1;
+
+#ifdef CONFIG_X86_64
+	exit_idle();
+#endif
+	irq_enter();
+	/* First tickle the hardware, only then report what went on. -- REW */
+	v = apic_read(APIC_ESR);
+	apic_write(APIC_ESR, 0);
+	v1 = apic_read(APIC_ESR);
+	ack_APIC_irq();
+	atomic_inc(&irq_err_count);
+
+	/* Here is what the APIC error bits mean:
+	   0: Send CS error
+	   1: Receive CS error
+	   2: Send accept error
+	   3: Receive accept error
+	   4: Reserved
+	   5: Send illegal vector
+	   6: Received illegal vector
+	   7: Illegal register address
+	*/
+	printk(KERN_DEBUG "APIC error on CPU%d: %02x(%02x)\n",
+		smp_processor_id(), v , v1);
+	irq_exit();
+}
+
+/**
+ * connect_bsp_APIC - attach the APIC to the interrupt system
+ */
+void __init connect_bsp_APIC(void)
+{
+#ifdef CONFIG_X86_32
+	if (pic_mode) {
+		/*
+		 * Do not trust the local APIC being empty at bootup.
+		 */
+		clear_local_APIC();
+		/*
+		 * PIC mode, enable APIC mode in the IMCR, i.e.  connect BSP's
+		 * local APIC to INT and NMI lines.
+		 */
+		apic_printk(APIC_VERBOSE, "leaving PIC mode, "
+				"enabling APIC mode.\n");
+		outb(0x70, 0x22);
+		outb(0x01, 0x23);
+	}
+#endif
+	enable_apic_mode();
+}
+
+/**
+ * disconnect_bsp_APIC - detach the APIC from the interrupt system
+ * @virt_wire_setup:	indicates, whether virtual wire mode is selected
+ *
+ * Virtual wire mode is necessary to deliver legacy interrupts even when the
+ * APIC is disabled.
+ */
+void disconnect_bsp_APIC(int virt_wire_setup)
+{
+	unsigned int value;
+
+#ifdef CONFIG_X86_32
+	if (pic_mode) {
+		/*
+		 * Put the board back into PIC mode (has an effect only on
+		 * certain older boards).  Note that APIC interrupts, including
+		 * IPIs, won't work beyond this point!  The only exception are
+		 * INIT IPIs.
+		 */
+		apic_printk(APIC_VERBOSE, "disabling APIC mode, "
+				"entering PIC mode.\n");
+		outb(0x70, 0x22);
+		outb(0x00, 0x23);
+		return;
+	}
+#endif
+
+	/* Go back to Virtual Wire compatibility mode */
+
+	/* For the spurious interrupt use vector F, and enable it */
+	value = apic_read(APIC_SPIV);
+	value &= ~APIC_VECTOR_MASK;
+	value |= APIC_SPIV_APIC_ENABLED;
+	value |= 0xf;
+	apic_write(APIC_SPIV, value);
+
+	if (!virt_wire_setup) {
+		/*
+		 * For LVT0 make it edge triggered, active high,
+		 * external and enabled
+		 */
+		value = apic_read(APIC_LVT0);
+		value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
+			APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
+			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
+		value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
+		value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXTINT);
+		apic_write(APIC_LVT0, value);
+	} else {
+		/* Disable LVT0 */
+		apic_write(APIC_LVT0, APIC_LVT_MASKED);
+	}
+
+	/*
+	 * For LVT1 make it edge triggered, active high,
+	 * nmi and enabled
+	 */
+	value = apic_read(APIC_LVT1);
+	value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
+			APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
+			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
+	value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
+	value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
+	apic_write(APIC_LVT1, value);
+}
+
+void __cpuinit generic_processor_info(int apicid, int version)
+{
+	int cpu;
+	cpumask_t tmp_map;
+
+	/*
+	 * Validate version
+	 */
+	if (version == 0x0) {
+		printk(KERN_WARNING "BIOS bug, APIC version is 0 for CPU#%d! "
+				"fixing up to 0x10. (tell your hw vendor)\n",
+				version);
+		version = 0x10;
+	}
+	apic_version[apicid] = version;
+
+	if (num_processors >= NR_CPUS) {
+		printk(KERN_WARNING "WARNING: NR_CPUS limit of %i reached."
+			"  Processor ignored.\n", NR_CPUS);
+		return;
+	}
+
+	num_processors++;
+	cpus_complement(tmp_map, cpu_present_map);
+	cpu = first_cpu(tmp_map);
+
+	physid_set(apicid, phys_cpu_present_map);
+	if (apicid == boot_cpu_physical_apicid) {
+		/*
+		 * x86_bios_cpu_apicid is required to have processors listed
+		 * in same order as logical cpu numbers. Hence the first
+		 * entry is BSP, and so on.
+		 */
+		cpu = 0;
+	}
+	if (apicid > max_physical_apicid)
+		max_physical_apicid = apicid;
+
+#ifdef CONFIG_X86_32
+	/*
+	 * Would be preferable to switch to bigsmp when CONFIG_HOTPLUG_CPU=y
+	 * but we need to work other dependencies like SMP_SUSPEND etc
+	 * before this can be done without some confusion.
+	 * if (CPU_HOTPLUG_ENABLED || num_processors > 8)
+	 *       - Ashok Raj <ashok.raj@intel.com>
+	 */
+	if (max_physical_apicid >= 8) {
+		switch (boot_cpu_data.x86_vendor) {
+		case X86_VENDOR_INTEL:
+			if (!APIC_XAPIC(version)) {
+				def_to_bigsmp = 0;
+				break;
+			}
+			/* If P4 and above fall through */
+		case X86_VENDOR_AMD:
+			def_to_bigsmp = 1;
+		}
+	}
+#endif
+
+#if defined(CONFIG_X86_SMP) || defined(CONFIG_X86_64)
+	/* are we being called early in kernel startup? */
+	if (early_per_cpu_ptr(x86_cpu_to_apicid)) {
+		u16 *cpu_to_apicid = early_per_cpu_ptr(x86_cpu_to_apicid);
+		u16 *bios_cpu_apicid = early_per_cpu_ptr(x86_bios_cpu_apicid);
+
+		cpu_to_apicid[cpu] = apicid;
+		bios_cpu_apicid[cpu] = apicid;
+	} else {
+		per_cpu(x86_cpu_to_apicid, cpu) = apicid;
+		per_cpu(x86_bios_cpu_apicid, cpu) = apicid;
+	}
+#endif
+
+	cpu_set(cpu, cpu_possible_map);
+	cpu_set(cpu, cpu_present_map);
+}
+
+#ifdef CONFIG_X86_64
+int hard_smp_processor_id(void)
+{
+	return read_apic_id();
+}
+#endif
+
+/*
+ * Power management
+ */
+#ifdef CONFIG_PM
+
+static struct {
+	/*
+	 * 'active' is true if the local APIC was enabled by us and
+	 * not the BIOS; this signifies that we are also responsible
+	 * for disabling it before entering apm/acpi suspend
+	 */
+	int active;
+	/* r/w apic fields */
+	unsigned int apic_id;
+	unsigned int apic_taskpri;
+	unsigned int apic_ldr;
+	unsigned int apic_dfr;
+	unsigned int apic_spiv;
+	unsigned int apic_lvtt;
+	unsigned int apic_lvtpc;
+	unsigned int apic_lvt0;
+	unsigned int apic_lvt1;
+	unsigned int apic_lvterr;
+	unsigned int apic_tmict;
+	unsigned int apic_tdcr;
+	unsigned int apic_thmr;
+} apic_pm_state;
+
+static int lapic_suspend(struct sys_device *dev, pm_message_t state)
+{
+	unsigned long flags;
+	int maxlvt;
+
+	if (!apic_pm_state.active)
+		return 0;
+
+	maxlvt = lapic_get_maxlvt();
+
+	apic_pm_state.apic_id = apic_read(APIC_ID);
+	apic_pm_state.apic_taskpri = apic_read(APIC_TASKPRI);
+	apic_pm_state.apic_ldr = apic_read(APIC_LDR);
+	apic_pm_state.apic_dfr = apic_read(APIC_DFR);
+	apic_pm_state.apic_spiv = apic_read(APIC_SPIV);
+	apic_pm_state.apic_lvtt = apic_read(APIC_LVTT);
+	if (maxlvt >= 4)
+		apic_pm_state.apic_lvtpc = apic_read(APIC_LVTPC);
+	apic_pm_state.apic_lvt0 = apic_read(APIC_LVT0);
+	apic_pm_state.apic_lvt1 = apic_read(APIC_LVT1);
+	apic_pm_state.apic_lvterr = apic_read(APIC_LVTERR);
+	apic_pm_state.apic_tmict = apic_read(APIC_TMICT);
+	apic_pm_state.apic_tdcr = apic_read(APIC_TDCR);
+#if defined(CONFIG_X86_MCE_P4THERMAL) || defined(CONFIG_X86_MCE_INTEL)
+	if (maxlvt >= 5)
+		apic_pm_state.apic_thmr = apic_read(APIC_LVTTHMR);
+#endif
+
+	local_irq_save(flags);
+	disable_local_APIC();
+	local_irq_restore(flags);
+	return 0;
+}
+
+static int lapic_resume(struct sys_device *dev)
+{
+	unsigned int l, h;
+	unsigned long flags;
+	int maxlvt;
+
+	if (!apic_pm_state.active)
+		return 0;
+
+	maxlvt = lapic_get_maxlvt();
+
+	local_irq_save(flags);
+
+#ifdef HAVE_X2APIC
+	if (x2apic)
+		enable_x2apic();
+	else
+#endif
+	{
+		/*
+		 * Make sure the APICBASE points to the right address
+		 *
+		 * FIXME! This will be wrong if we ever support suspend on
+		 * SMP! We'll need to do this as part of the CPU restore!
+		 */
+		rdmsr(MSR_IA32_APICBASE, l, h);
+		l &= ~MSR_IA32_APICBASE_BASE;
+		l |= MSR_IA32_APICBASE_ENABLE | mp_lapic_addr;
+		wrmsr(MSR_IA32_APICBASE, l, h);
+	}
+
+	apic_write(APIC_LVTERR, ERROR_APIC_VECTOR | APIC_LVT_MASKED);
+	apic_write(APIC_ID, apic_pm_state.apic_id);
+	apic_write(APIC_DFR, apic_pm_state.apic_dfr);
+	apic_write(APIC_LDR, apic_pm_state.apic_ldr);
+	apic_write(APIC_TASKPRI, apic_pm_state.apic_taskpri);
+	apic_write(APIC_SPIV, apic_pm_state.apic_spiv);
+	apic_write(APIC_LVT0, apic_pm_state.apic_lvt0);
+	apic_write(APIC_LVT1, apic_pm_state.apic_lvt1);
+#if defined(CONFIG_X86_MCE_P4THERMAL) || defined(CONFIG_X86_MCE_INTEL)
+	if (maxlvt >= 5)
+		apic_write(APIC_LVTTHMR, apic_pm_state.apic_thmr);
+#endif
+	if (maxlvt >= 4)
+		apic_write(APIC_LVTPC, apic_pm_state.apic_lvtpc);
+	apic_write(APIC_LVTT, apic_pm_state.apic_lvtt);
+	apic_write(APIC_TDCR, apic_pm_state.apic_tdcr);
+	apic_write(APIC_TMICT, apic_pm_state.apic_tmict);
+	apic_write(APIC_ESR, 0);
+	apic_read(APIC_ESR);
+	apic_write(APIC_LVTERR, apic_pm_state.apic_lvterr);
+	apic_write(APIC_ESR, 0);
+	apic_read(APIC_ESR);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/*
+ * This device has no shutdown method - fully functioning local APICs
+ * are needed on every CPU up until machine_halt/restart/poweroff.
+ */
+
+static struct sysdev_class lapic_sysclass = {
+	.name		= "lapic",
+	.resume		= lapic_resume,
+	.suspend	= lapic_suspend,
+};
+
+static struct sys_device device_lapic = {
+	.id	= 0,
+	.cls	= &lapic_sysclass,
+};
+
+static void __cpuinit apic_pm_activate(void)
+{
+	apic_pm_state.active = 1;
+}
+
+static int __init init_lapic_sysfs(void)
+{
+	int error;
+
+	if (!cpu_has_apic)
+		return 0;
+	/* XXX: remove suspend/resume procs if !apic_pm_state.active? */
+
+	error = sysdev_class_register(&lapic_sysclass);
+	if (!error)
+		error = sysdev_register(&device_lapic);
+	return error;
+}
+device_initcall(init_lapic_sysfs);
+
+#else	/* CONFIG_PM */
+
+static void apic_pm_activate(void) { }
+
+#endif	/* CONFIG_PM */
+
+#ifdef CONFIG_X86_64
+/*
+ * apic_is_clustered_box() -- Check if we can expect good TSC
+ *
+ * Thus far, the major user of this is IBM's Summit2 series:
+ *
+ * Clustered boxes may have unsynced TSC problems if they are
+ * multi-chassis. Use available data to take a good guess.
+ * If in doubt, go HPET.
+ */
+__cpuinit int apic_is_clustered_box(void)
+{
+	int i, clusters, zeros;
+	unsigned id;
+	u16 *bios_cpu_apicid;
+	DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
+
+	/*
+	 * there is not this kind of box with AMD CPU yet.
+	 * Some AMD box with quadcore cpu and 8 sockets apicid
+	 * will be [4, 0x23] or [8, 0x27] could be thought to
+	 * vsmp box still need checking...
+	 */
+	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && !is_vsmp_box())
+		return 0;
+
+	bios_cpu_apicid = early_per_cpu_ptr(x86_bios_cpu_apicid);
+	bitmap_zero(clustermap, NUM_APIC_CLUSTERS);
+
+	for (i = 0; i < NR_CPUS; i++) {
+		/* are we being called early in kernel startup? */
+		if (bios_cpu_apicid) {
+			id = bios_cpu_apicid[i];
+		}
+		else if (i < nr_cpu_ids) {
+			if (cpu_present(i))
+				id = per_cpu(x86_bios_cpu_apicid, i);
+			else
+				continue;
+		}
+		else
+			break;
+
+		if (id != BAD_APICID)
+			__set_bit(APIC_CLUSTERID(id), clustermap);
+	}
+
+	/* Problem:  Partially populated chassis may not have CPUs in some of
+	 * the APIC clusters they have been allocated.  Only present CPUs have
+	 * x86_bios_cpu_apicid entries, thus causing zeroes in the bitmap.
+	 * Since clusters are allocated sequentially, count zeros only if
+	 * they are bounded by ones.
+	 */
+	clusters = 0;
+	zeros = 0;
+	for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
+		if (test_bit(i, clustermap)) {
+			clusters += 1 + zeros;
+			zeros = 0;
+		} else
+			++zeros;
+	}
+
+	/* ScaleMP vSMPowered boxes have one cluster per board and TSCs are
+	 * not guaranteed to be synced between boards
+	 */
+	if (is_vsmp_box() && clusters > 1)
+		return 1;
+
+	/*
+	 * If clusters > 2, then should be multi-chassis.
+	 * May have to revisit this when multi-core + hyperthreaded CPUs come
+	 * out, but AFAIK this will work even for them.
+	 */
+	return (clusters > 2);
+}
+#endif
+
+/*
+ * APIC command line parameters
+ */
+static int __init setup_disableapic(char *arg)
+{
+	disable_apic = 1;
+	setup_clear_cpu_cap(X86_FEATURE_APIC);
+	return 0;
+}
+early_param("disableapic", setup_disableapic);
+
+/* same as disableapic, for compatibility */
+static int __init setup_nolapic(char *arg)
+{
+	return setup_disableapic(arg);
+}
+early_param("nolapic", setup_nolapic);
+
+static int __init parse_lapic_timer_c2_ok(char *arg)
+{
+	local_apic_timer_c2_ok = 1;
+	return 0;
+}
+early_param("lapic_timer_c2_ok", parse_lapic_timer_c2_ok);
+
+static int __init parse_disable_apic_timer(char *arg)
+{
+	disable_apic_timer = 1;
+	return 0;
+}
+early_param("noapictimer", parse_disable_apic_timer);
+
+static int __init parse_nolapic_timer(char *arg)
+{
+	disable_apic_timer = 1;
+	return 0;
+}
+early_param("nolapic_timer", parse_nolapic_timer);
+
+static int __init apic_set_verbosity(char *arg)
+{
+	if (!arg)  {
+#ifdef CONFIG_X86_64
+		skip_ioapic_setup = 0;
+		return 0;
+#endif
+		return -EINVAL;
+	}
+
+	if (strcmp("debug", arg) == 0)
+		apic_verbosity = APIC_DEBUG;
+	else if (strcmp("verbose", arg) == 0)
+		apic_verbosity = APIC_VERBOSE;
+	else {
+		printk(KERN_WARNING "APIC Verbosity level %s not recognised"
+			" use apic=verbose or apic=debug\n", arg);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+early_param("apic", apic_set_verbosity);
+
+static int __init lapic_insert_resource(void)
+{
+	if (!apic_phys)
+		return -1;
+
+	/* Put local APIC into the resource map. */
+	lapic_resource.start = apic_phys;
+	lapic_resource.end = lapic_resource.start + PAGE_SIZE - 1;
+	insert_resource(&iomem_resource, &lapic_resource);
+
+	return 0;
+}
+
+/*
+ * need call insert after e820_reserve_resources()
+ * that is using request_resource
+ */
+late_initcall(lapic_insert_resource);