x86: apic - unify smp_apic_timer_interrupt

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / x86 / kernel / apic_32.c

/*
 *      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/cpu.h>
#include <linux/clockchips.h>
#include <linux/acpi_pmtmr.h>
#include <linux/module.h>
#include <linux/dmi.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/i8253.h>
#include <asm/nmi.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

unsigned long mp_lapic_addr;

/*
 * Knob to control our willingness to enable the local APIC.
 *
 * +1=force-enable
 */
static int force_enable_local_apic;
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);

/* Local APIC was disabled by the BIOS and enabled by the kernel */
static int enabled_via_apicbase;

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);

/**
 * 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);
}

/**
 * get_physical_broadcast - Get number of physical broadcast IDs
 */
int get_physical_broadcast(void)
{
        return modern_apic() ? 0xff : 0xf;
}

/**
 * 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);
}

/*
 * 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;
}

/*
 * 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();
}

/*
 * 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;
}

/**
 * init_apic_mappings - initialize APIC mappings
 */
void __init init_apic_mappings(void)
{
        /*
         * 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);
        printk(KERN_DEBUG "mapped APIC to %08lx (%08lx)\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)
{
        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;
        }

        verify_local_APIC();

        connect_bsp_APIC();

        /*
         * 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
        physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);

        setup_local_APIC();

#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)
                if (!skip_ioapic_setup && nr_ioapics)
                        setup_IO_APIC();
#endif
        setup_boot_clock();

        return 0;
}

/*
 * Local APIC interrupts
 */

/*
 * This interrupt should _never_ happen with our APIC/SMP architecture
 */
void smp_spurious_interrupt(struct pt_regs *regs)
{
        unsigned long v;

        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();

        /* 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++;
        irq_exit();
}

/*
 * This interrupt should never happen with our APIC/SMP architecture
 */
void smp_error_interrupt(struct pt_regs *regs)
{
        unsigned long v, v1;

        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: %02lx(%02lx)\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);
}

/*
 * 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 CONFIG_X86_64
        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 */

/*
 * APIC command line parameters
 */
static int __init parse_lapic(char *arg)
{
        force_enable_local_apic = 1;
        return 0;
}
early_param("lapic", parse_lapic);

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);

#ifdef CONFIG_X86_64
static __init int setup_apicpmtimer(char *s)
{
        apic_calibrate_pmtmr = 1;
        notsc_setup(NULL);
        return 0;
}
__setup("apicpmtimer", setup_apicpmtimer);
#endif

static int __init apic_set_verbosity(char *arg)
{
        if (!arg)  {
#ifdef CONFIG_X86_64
                skip_ioapic_setup = 0;
                ioapic_force = 1;
                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);