Index: qemu-kvm/kvm/user/config-x86-common.mak
===================================================================
--- qemu-kvm.orig/kvm/user/config-x86-common.mak
+++ qemu-kvm/kvm/user/config-x86-common.mak
@@ -58,6 +58,9 @@ $(TEST_DIR)/tsc.flat: $(cstart.o) $(TEST
 $(TEST_DIR)/apic.flat: $(cstart.o) $(TEST_DIR)/apic.o $(TEST_DIR)/vm.o \
 		       $(TEST_DIR)/print.o 
 
+$(TEST_DIR)/time.flat: $(cstart.o) $(TEST_DIR)/time.o $(TEST_DIR)/vm.o \
+		       $(TEST_DIR)/print.o
+
 $(TEST_DIR)/realmode.flat: $(TEST_DIR)/realmode.o
 	$(CC) -m32 -nostdlib -o $@ -Wl,-T,$(TEST_DIR)/realmode.lds $^
 
Index: qemu-kvm/kvm/user/config-x86_64.mak
===================================================================
--- qemu-kvm.orig/kvm/user/config-x86_64.mak
+++ qemu-kvm/kvm/user/config-x86_64.mak
@@ -7,6 +7,7 @@ CFLAGS += -D__x86_64__
 tests = $(TEST_DIR)/access.flat $(TEST_DIR)/sieve.flat \
       $(TEST_DIR)/simple.flat $(TEST_DIR)/stringio.flat \
       $(TEST_DIR)/memtest1.flat $(TEST_DIR)/emulator.flat \
-      $(TEST_DIR)/hypercall.flat $(TEST_DIR)/apic.flat
+      $(TEST_DIR)/hypercall.flat $(TEST_DIR)/apic.flat \
+      $(TEST_DIR)/time.flat
 
 include config-x86-common.mak
Index: qemu-kvm/kvm/user/test/x86/io.h
===================================================================
--- /dev/null
+++ qemu-kvm/kvm/user/test/x86/io.h
@@ -0,0 +1,35 @@
+static inline void outb(unsigned char val, unsigned short port)
+{
+	asm volatile("outb %0, %w1": : "a"(val), "Nd" (port));
+}
+
+static inline void outw(unsigned short val, unsigned short port)
+{
+	asm volatile("outw %0, %w1": : "a"(val), "Nd" (port));
+}
+
+static inline void outl(unsigned long val, unsigned short port)
+{
+	asm volatile("outl %0, %w1": : "a"(val), "Nd" (port));
+}
+
+static inline unsigned char inb(unsigned short port)
+{
+	unsigned char val;
+	asm volatile("inb %w1, %0": "=a"(val) : "Nd" (port));
+	return val;
+}
+
+static inline short inw(unsigned short port)
+{
+	short val;
+	asm volatile("inw %w1, %0": "=a"(val) : "Nd" (port));
+	return val;
+}
+
+static inline unsigned int inl(unsigned short port)
+{
+	unsigned int val;
+	asm volatile("inl %w1, %0": "=a"(val) : "Nd" (port));
+	return val;
+}
Index: qemu-kvm/kvm/user/test/x86/time.c
===================================================================
--- /dev/null
+++ qemu-kvm/kvm/user/test/x86/time.c
@@ -0,0 +1,1010 @@
+#include "libcflat.h"
+#include "apic.h"
+#include "vm.h"
+#include "io.h"
+
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned u32;
+typedef unsigned long ulong;
+typedef unsigned long long u64;
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+typedef struct {
+    unsigned short offset0;
+    unsigned short selector;
+    unsigned short ist : 3;
+    unsigned short : 5;
+    unsigned short type : 4;
+    unsigned short : 1;
+    unsigned short dpl : 2;
+    unsigned short p : 1;
+    unsigned short offset1;
+#ifdef __x86_64__
+    unsigned offset2;
+    unsigned reserved;
+#endif
+} idt_entry_t;
+
+typedef struct {
+    ulong rflags;
+    ulong cs;
+    ulong rip;
+    ulong func;
+    ulong regs[sizeof(ulong)*2];
+} isr_regs_t;
+
+#ifdef __x86_64__
+#  define R "r"
+#else
+#  define R "e"
+#endif
+
+extern char isr_entry_point[];
+
+asm (
+    "isr_entry_point: \n"
+#ifdef __x86_64__
+    "push %r15 \n\t"
+    "push %r14 \n\t"
+    "push %r13 \n\t"
+    "push %r12 \n\t"
+    "push %r11 \n\t"
+    "push %r10 \n\t"
+    "push %r9  \n\t"
+    "push %r8  \n\t"
+#endif
+    "push %"R "di \n\t"
+    "push %"R "si \n\t"
+    "push %"R "bp \n\t"
+    "push %"R "sp \n\t"
+    "push %"R "bx \n\t"
+    "push %"R "dx \n\t"
+    "push %"R "cx \n\t"
+    "push %"R "ax \n\t"
+#ifdef __x86_64__
+    "mov %rsp, %rdi \n\t"
+    "callq *8*16(%rsp) \n\t"
+#else
+    "push %esp \n\t"
+    "calll *4+4*8(%esp) \n\t"
+    "add $4, %esp \n\t"
+#endif
+    "pop %"R "ax \n\t"
+    "pop %"R "cx \n\t"
+    "pop %"R "dx \n\t"
+    "pop %"R "bx \n\t"
+    "pop %"R "bp \n\t"
+    "pop %"R "bp \n\t"
+    "pop %"R "si \n\t"
+    "pop %"R "di \n\t"
+#ifdef __x86_64__
+    "pop %r8  \n\t"
+    "pop %r9  \n\t"
+    "pop %r10 \n\t"
+    "pop %r11 \n\t"
+    "pop %r12 \n\t"
+    "pop %r13 \n\t"
+    "pop %r14 \n\t"
+    "pop %r15 \n\t"
+#endif
+#ifdef __x86_64__
+    "add $8, %rsp \n\t"
+    "iretq \n\t"
+#else
+    "add $4, %esp \n\t"
+    "iretl \n\t"
+#endif
+    );
+
+static idt_entry_t idt[256];
+
+static int g_fail;
+static int g_tests;
+
+static void report(const char *msg, int pass)
+{
+    ++g_tests;
+    printf("%s: %s\n", msg, (pass ? "PASS" : "FAIL"));
+    if (!pass)
+        ++g_fail;
+}
+
+static u16 read_cs(void)
+{
+    u16 v;
+
+    asm("mov %%cs, %0" : "=rm"(v));
+    return v;
+}
+
+static void init_idt(void)
+{
+    struct {
+        u16 limit;
+        ulong idt;
+    } __attribute__((packed)) idt_ptr = {
+        sizeof(idt_entry_t) * 256 - 1,
+        (ulong)&idt,
+    };
+
+    asm volatile("lidt %0" : : "m"(idt_ptr));
+}
+
+static void set_idt_entry(unsigned vec, void (*func)(isr_regs_t *regs))
+{
+    u8 *thunk = vmalloc(50);
+    ulong ptr = (ulong)thunk;
+    idt_entry_t ent = {
+        .offset0 = ptr,
+        .selector = read_cs(),
+        .ist = 0,
+        .type = 14,
+        .dpl = 0,
+        .p = 1,
+        .offset1 = ptr >> 16,
+#ifdef __x86_64__
+        .offset2 = ptr >> 32,
+#endif
+    };
+#ifdef __x86_64__
+    /* sub $8, %rsp */
+    *thunk++ = 0x48; *thunk++ = 0x83; *thunk++ = 0xec; *thunk++ = 0x08;
+    /* mov $func_low, %(rsp) */
+    *thunk++ = 0xc7; *thunk++ = 0x04; *thunk++ = 0x24;
+    *(u32 *)thunk = (ulong)func; thunk += 4;
+    /* mov $func_high, %(rsp+4) */
+    *thunk++ = 0xc7; *thunk++ = 0x44; *thunk++ = 0x24; *thunk++ = 0x04;
+    *(u32 *)thunk = (ulong)func >> 32; thunk += 4;
+    /* jmp isr_entry_point */
+    *thunk ++ = 0xe9;
+    *(u32 *)thunk = (ulong)isr_entry_point - (ulong)(thunk + 4);
+#else
+    /* push $func */
+    *thunk++ = 0x68;
+    *(u32 *)thunk = (ulong)func;
+    /* jmp isr_entry_point */
+    *thunk ++ = 0xe9;
+    *(u32 *)thunk = (ulong)isr_entry_point - (ulong)(thunk + 4);
+#endif
+    idt[vec] = ent;
+}
+
+static void irq_disable(void)
+{
+    asm volatile("cli");
+}
+
+static void irq_enable(void)
+{
+    asm volatile("sti");
+}
+
+static void eoi(void)
+{
+    apic_write(APIC_EOI, 0);
+}
+
+static int ipi_count;
+
+static void self_ipi_isr(isr_regs_t *regs)
+{
+    ++ipi_count;
+    eoi();
+}
+
+static void test_self_ipi(void)
+{
+    int vec = 0xf1;
+
+    set_idt_entry(vec, self_ipi_isr);
+    irq_enable();
+    apic_write(APIC_ICR,
+               APIC_DEST_SELF | APIC_DEST_PHYSICAL | APIC_DM_FIXED | vec);
+    asm volatile ("nop");
+    report("self ipi", ipi_count == 1);
+}
+
+static void set_ioapic_redir(unsigned line, unsigned vec, unsigned trig_mode)
+{
+    ioapic_redir_entry_t e = {
+        .vector = vec,
+        .delivery_mode = 0,
+        .trig_mode = trig_mode,
+    };
+
+    ioapic_write_redir(line, e);
+}
+
+/* interrupt handlers */
+
+#define TIMER_VEC_BASE 0x90
+
+struct int_table {
+    void (*func)(isr_regs_t *regs);
+    void (*irq_handler)(void *irq_priv);
+    void *irq_priv;
+};
+
+static struct int_table int_handlers[];
+
+#define decl_irq_handler(N)                         \
+static void timer_int_##N(isr_regs_t *regs) {       \
+    struct int_table *t = &int_handlers[N];         \
+    t->irq_handler(t->irq_priv);                    \
+    eoi();                                          \
+}
+
+void set_irq_handler(int vec, void (*func)(void *irq_priv), void *irq_priv);
+
+void hlt(void) { asm volatile("hlt"); }
+
+#define NS_FREQ 1000000000ULL
+#define US_FREQ 1000000ULL
+
+#define ns2cyc(ns) (ns*cpu_hz)/NS_FREQ
+#define cyc2ns(cyc) (cyc*NS_FREQ)/cpu_hz
+
+#define us_to_ns(n) (1000*n)
+#define ms_to_ns(n) (1000000*n)
+#define s_to_ns(n)  (1000000000*n)
+
+#define sdelay(n) nsdelay(s_to_ns(n))
+
+u64 cpu_hz;
+
+static inline int fls(int x)
+{
+        int r;
+        asm("bsrl %1,%0\n\t"
+            "jnz 1f\n\t"
+            "movl $-1,%0\n"
+            "1:" : "=r" (r) : "rm" (x));
+        return r + 1;
+}
+
+# define do_div(n,base) ({                                      \
+        uint32_t __base = (base);                               \
+        uint32_t __rem;                                         \
+        __rem = ((uint64_t)(n)) % __base;                       \
+        (n) = ((uint64_t)(n)) / __base;                         \
+        __rem;                                                  \
+ })
+
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+        *remainder = dividend % divisor;
+        return dividend / divisor;
+}
+
+static inline u64 div_u64(u64 dividend, u32 divisor)
+{
+        u32 remainder;
+        return div_u64_rem(dividend, divisor, &remainder);
+}
+
+#ifdef CONFIG_32BITS
+#define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
+#else
+#define mod_64(x, y) ((x) % (y))
+#endif
+
+/* 64bit divisor, dividend and result. dynamic precision */
+u64 div64_u64(u64 dividend, u64 divisor)
+{
+        u32 high, d;
+
+        high = divisor >> 32;
+        if (high) {
+                unsigned int shift = fls(high);
+
+                d = divisor >> shift;
+                dividend >>= shift;
+        } else
+                d = divisor;
+
+        return div_u64(dividend, d);
+}
+
+static u64 muldiv64(u64 a, u32 b, u32 c)
+{
+        union {
+                u64 ll;
+                struct {
+                        u32 low, high;
+                } l;
+        } u, res;
+        u64 rl, rh;
+
+        u.ll = a;
+        rl = (u64)u.l.low * (u64)b;
+        rh = (u64)u.l.high * (u64)b;
+        rh += (rl >> 32);
+        res.l.high = div64_u64(rh, c);
+        res.l.low = div64_u64(((mod_64(rh, c) << 32) + (rl & 0xffffffff)), c);
+        return res.ll;
+}
+
+
+u64 rdtsc(void)
+{
+        unsigned a, d;
+
+        asm volatile("rdtsc" : "=a"(a), "=d"(d));
+        return a | (u64)d << 32;
+}
+
+void wrtsc(u64 tsc)
+{
+        unsigned a = tsc, d = tsc >> 32;
+
+        asm volatile("wrmsr" : : "a"(a), "d"(d), "c"(0x10));
+}
+
+void nsdelay(u64 ns)
+{
+    u64 entry = cyc2ns(rdtsc());
+
+    do {
+        __asm__ volatile ("nop");
+    } while (cyc2ns(rdtsc()) - entry < ns);
+}
+
+struct clocksource {
+    char *name;
+    int (*init) (void);
+    u64 (*read) (void);
+    u64 freq;
+};
+
+/* return count in nanoseconds */
+u64 clocksource_read(struct clocksource *clock)
+{
+    u64 val = clock->read();
+
+    val = muldiv64(val, NS_FREQ, clock->freq);
+
+    return val;
+}
+
+struct freq_divisor {
+    unsigned int divisor;
+    unsigned int program_value;
+};
+
+enum clockevt_type { CLOCKEVT_PERIODIC, CLOCKEVT_ONESHOT, };
+
+struct clockevent {
+    char *name;
+    u64 (*init) (int vec);
+    int (*arm) (u64 count, u64 divisor, enum clockevt_type);
+    void (*cancel)(void);
+    u64 (*remain) (void);
+
+    u64 max_count;
+    u64 freq;
+    struct freq_divisor *divisors;
+
+    unsigned vec;
+};
+
+void clock_arm(struct clockevent *clockevt, enum clockevt_type type,
+               u64 period, u64 divisor)
+{
+    u64 count = (period * clockevt->freq) / NS_FREQ;
+
+    if (count > clockevt->max_count)
+        printf("ERROR clock_arm: %s invalid count %ld (max_count=%ld)\n",
+                clockevt->name, period, clockevt->max_count);
+
+    clockevt->arm(count, divisor, type);
+}
+
+void clock_arm_raw(struct clockevent *clockevt, enum clockevt_type type,
+               u64 count, u64 divisor)
+{
+    if (count > clockevt->max_count)
+        printf("ERROR clock_arm: %s invalid count %ld (max_count=%ld)\n",
+                clockevt->name, count, clockevt->max_count);
+
+    clockevt->arm(count, divisor, type);
+}
+
+
+/* -------- TSC clocksource ------------- */
+
+int tsc_init(void) { printf("%s\n", __func__); return 0; }
+u64 tsc_read(void) { return rdtsc(); }
+
+struct clocksource tsc = {
+    .name = "tsc",
+    .init = tsc_init,
+    .read = tsc_read,
+};
+
+/* --------- ACPI clocksource ----------- */
+
+#define ACPI_PORT 0xb008
+#define ACPI_FREQ 3579545
+
+u64 acpi_time_base;
+
+static void acpi_ovf(void *irq_priv)
+{
+    static int flip = 1;
+
+    outw(1, 0xb000);
+    if (flip)
+        acpi_time_base += 0xffffff;
+    flip ^= 1;
+}
+
+int acpi_init(void)
+{
+    outb(0xf1, 0xb2);
+    outw(1, 0xb002);
+
+    /* wait to synchronize flip above with bit 23 going 1->0 */
+    while (inl(ACPI_PORT) > 0x100);
+
+    set_irq_handler(TIMER_VEC_BASE+3, acpi_ovf, 0);
+    set_ioapic_redir(9, TIMER_VEC_BASE+3, 1);
+
+    return 0;
+}
+
+u64 acpi_read(void)
+{
+    u64 val;
+
+    irq_disable();
+    val = acpi_time_base + inl(ACPI_PORT);
+    irq_enable();
+
+    return val;
+}
+
+struct clocksource acpi = {
+    .name = "acpi",
+    .init = acpi_init,
+    .read = acpi_read,
+    .freq = ACPI_FREQ,
+};
+
+struct clocksource *clocksources[] = { &tsc, &acpi, };
+
+/* --------- HPET clockevent  ---------- */
+
+#define HPET_CFG                0x010
+#define HPET_COUNTER            0x0f0
+
+#define HPET_Tn_CFG(n)          (0x100 + 0x20 * n)
+#define HPET_Tn_CMP(n)          (0x108 + 0x20 * n)
+
+static void *hpet_addr = (void *)0xfed00000;
+
+static unsigned long hpet_readl(unsigned reg)
+{
+    return *(volatile unsigned long *)(hpet_addr + reg);
+}
+
+static void hpet_writel(unsigned reg, unsigned long val)
+{
+    *(volatile unsigned long *)(hpet_addr + reg) = val;
+}
+
+struct freq_divisor hpet_divisors[] = {
+    {1, 1},
+    {-1, -1},
+};
+
+int hpet_vec;
+
+u64 hpet_timer_init(int vec)
+{
+    u64 val;
+
+    hpet_writel(HPET_CFG, hpet_readl(HPET_CFG)|0x3);
+
+    val = hpet_readl(HPET_COUNTER);
+    sdelay(1);
+    val = hpet_readl(HPET_COUNTER) - val;
+    printf("%s: detected %lld Hz timer\n", __func__, val);
+    hpet_vec = vec;
+
+    return val;
+}
+
+int hpet_timer_arm(u64 period, u64 divisor, enum clockevt_type type)
+{
+    u64 cfg = 0x4;
+
+    set_ioapic_redir(8, hpet_vec, 0);
+    if (type == CLOCKEVT_PERIODIC)
+        cfg |= 0x8;
+
+    hpet_writel(HPET_Tn_CFG(1), cfg);
+    hpet_writel(HPET_COUNTER, 0);
+    hpet_writel(HPET_CFG, hpet_readl(HPET_CFG)|0x3); /* enable HPET */
+    hpet_writel(HPET_Tn_CMP(1), period);
+
+    return 0;
+}
+
+void hpet_timer_cancel(void)
+{
+    hpet_writel(HPET_Tn_CFG(1), 0);
+    hpet_writel(HPET_CFG, hpet_readl(HPET_CFG) & ~(0x3));
+}
+
+u64 hpet_timer_remain(void)
+{
+    return hpet_readl(HPET_Tn_CMP(1)) - hpet_readl(HPET_COUNTER);
+}
+
+struct clockevent hpet_timer = {
+    .name = "hpet",
+    .init = hpet_timer_init,
+    .arm = hpet_timer_arm,
+    .cancel = hpet_timer_cancel,
+    .remain = hpet_timer_remain,
+    .max_count = 0xffffffff,
+    .divisors = hpet_divisors,
+};
+
+/* --------- LAPIC clockevent ---------- */
+
+static void dummy(void *irq_priv)
+{
+}
+
+struct freq_divisor lapic_divisors[] = {
+    {1, 0xB},
+    {2, 0x0},
+    {4, 0x1},
+    {8, 0x2},
+    {16, 0x3},
+    {32, 0x8},
+    {64, 0x9},
+    {128, 0xA},
+    {-1, -1},
+};
+
+u64 lapic_timer_init(int vec)
+{
+    u64 hz;
+
+    set_irq_handler(vec, dummy, 0);
+    apic_write(APIC_LVTT, vec);
+    apic_write(APIC_TDCR, 0xB); /* divide by 1 */
+    apic_write(APIC_TMICT, 0xffffffff);
+    sdelay(1);
+    hz = 0xffffffff - apic_read(APIC_TMCCT);
+    printf("%s: detected %d Hz timer\n", __func__, hz);
+    return hz;
+}
+
+int lapic_timer_arm(u64 period, u64 divisor, enum clockevt_type type)
+{
+    if (type == CLOCKEVT_PERIODIC)
+        apic_write(APIC_LVTT, apic_read(APIC_LVTT) | 1 << 17);
+    /* divide count */
+    apic_write(APIC_TDCR, divisor);
+    /* initial count */
+    apic_write(APIC_TMICT, period);
+    return 0;
+}
+
+void lapic_timer_cancel(void)
+{
+    apic_write(APIC_LVTT, apic_read(APIC_LVTT) & ~(1 << 17)); /* one-shot */
+    apic_write(APIC_TMICT, 0);
+}
+
+u64 lapic_timer_remain(void)
+{
+    return apic_read(APIC_TMCCT);
+}
+
+struct clockevent lapic_timer = {
+    .name = "lapic",
+    .init = lapic_timer_init,
+    .arm = lapic_timer_arm,
+    .cancel = lapic_timer_cancel,
+    .remain = lapic_timer_remain,
+    .max_count = 0xffffffff,
+    .divisors = lapic_divisors,
+};
+
+/* ---------- PIT clockevent --------- */
+
+#define PIT_FREQ 1193181
+#define PIT_CNT_0 0x40
+#define PIT_CNT_1 0x41
+#define PIT_CNT_2 0x42
+#define PIT_TCW 0x43
+
+u64 pit_timer_remain(void)
+{
+    	outb(0xf0, PIT_TCW);
+        return inb(PIT_CNT_0) | inb(PIT_CNT_0) << 8;
+}
+
+u64 pit_timer_init(int vec)
+{
+    set_ioapic_redir(2, vec, 0);
+    /* mask LINT0, int is coming through IO-APIC */
+    apic_write(APIC_LVT0, 1 << 16);
+    return PIT_FREQ;
+}
+
+int pit_timer_arm(u64 period, u64 divisor, enum clockevt_type type)
+{
+    unsigned char ctrl_word = 0x30;
+
+    hpet_writel(HPET_CFG, hpet_readl(HPET_CFG) & ~(0x3)); /* disable HPET */
+    if (type == CLOCKEVT_PERIODIC)
+        ctrl_word |= 0x4;
+    outb(ctrl_word, PIT_TCW);
+    outb(period & 0xff, PIT_CNT_0);
+    outb((period & 0xff00) >> 8, PIT_CNT_0);
+    return 0;
+}
+
+void pit_timer_cancel(void)
+{
+    unsigned char ctrl_word = 0x30;
+    outb(ctrl_word, PIT_TCW);
+    outb(0, PIT_CNT_0);
+    outb(0, PIT_CNT_0);
+}
+
+struct freq_divisor pit_divisors[] = {
+    {1, 1},
+    {-1, -1},
+};
+
+struct clockevent pit_timer = {
+    .name = "pit",
+    .init = pit_timer_init,
+    .arm = pit_timer_arm,
+    .cancel = pit_timer_cancel,
+    .remain = pit_timer_remain,
+    .divisors = pit_divisors,
+    .max_count = 0xffff,
+};
+
+
+#define NR_CLOCKEVENTS 3
+
+/* clockevent initialization */
+struct clockevent *clockevents[NR_CLOCKEVENTS] = {
+     &pit_timer, &lapic_timer, &hpet_timer,
+};
+
+decl_irq_handler(0) /* PIT */
+decl_irq_handler(1) /* LAPIC */
+decl_irq_handler(2) /* HPET */
+decl_irq_handler(3) /* ACPI OVF */
+
+static struct int_table int_handlers[NR_CLOCKEVENTS+1] = {
+    { .func = timer_int_0 },
+    { .func = timer_int_1 },
+    { .func = timer_int_2 },
+    { .func = timer_int_3 },
+};
+
+void set_irq_handler(int vec, void (*func)(void *irq_priv), void *irq_priv)
+{
+    int int_table_idx = vec - TIMER_VEC_BASE;
+
+    if (int_table_idx >= NR_CLOCKEVENTS+1)
+        printf("%s invalid vec\n", __func__);
+
+    int_handlers[int_table_idx].irq_handler = func;
+    int_handlers[int_table_idx].irq_priv = irq_priv;
+}
+
+void init_interrupts(void)
+{
+    int i;
+
+    for (i = 0; i < NR_CLOCKEVENTS+1; i++) {
+        int vec = TIMER_VEC_BASE+i;
+
+        set_idt_entry(vec, int_handlers[i].func);
+    }
+}
+
+int init_clockevents(void)
+{
+    int i;
+    int vec = TIMER_VEC_BASE;
+
+    for (i=0; i < ARRAY_SIZE(clockevents); i++) {
+        u64 freq = clockevents[i]->init(vec);
+        clockevents[i]->freq = freq;
+        clockevents[i]->vec = vec;
+        vec++;
+    }
+    return 0;
+}
+
+void init_clocksources(void)
+{
+    int i;
+
+    for(i=0; i < ARRAY_SIZE(clocksources); i++)
+        clocksources[i]->init();
+}
+
+/* actual tests */
+
+#define TIME_TABLE_SZ 70
+struct time_table {
+    int idx;
+    struct clocksource *source;
+    struct clockevent *event;
+    u64 period;
+    u64 count;
+    u32 freq_divider;
+    unsigned long int val[TIME_TABLE_SZ];
+    unsigned long int remain[TIME_TABLE_SZ];
+};
+
+void time_table_record(struct time_table *t)
+{
+    t->remain[t->idx] = t->event->remain();
+    t->val[t->idx] = clocksource_read(t->source);
+    t->idx++;
+    if (t->idx >= TIME_TABLE_SZ/2)
+        t->idx = 0;
+}
+
+void dump_time_table(struct time_table *t)
+{
+    int i;
+
+    for (i = 1; i < t->idx; i++)
+        printf("i=%d    %lld - %lld = %lld (expect %lld) %% %d off\n", i,
+                t->val[i], t->val[i-1], t->val[i] - t->val[i-1], t->period,
+                100 - ((t->val[i] - t->val[i-1])*100 / t->period));
+}
+
+/* Tunables
+ *
+ * pct_delta_threshold: percentage of correctness before declaring failure
+ * pct_remain_threshold: "" for remain (read from clockevent on interrupt)
+ * nr_periods_per_clock: test periodic clocks in the
+ * <0...max_count>/nr_periods_per_clock range.
+ *
+ */
+
+int pct_delta_threshold = 10;
+int pct_remain_threshold = 20;
+int nr_periods_per_clock = 4;
+
+void inspect_table(struct time_table *t)
+{
+    int i;
+    u64 percent_avg = 0;
+    int dump_table = 0;
+
+    if (t->idx <= 1 || t->period == 0) {
+        printf("failure\n");
+        return;
+    }
+
+    /* first entry can be little of if programming is slow (eg hpet) */
+    for (i = 2; i < t->idx; i++) {
+	u64 fire_period = t->val[i] - t->val[i-1];
+        u64 percent_off = (fire_period*100) / t->period;
+
+        percent_avg += percent_off;
+        if (percent_off < 100-pct_delta_threshold ||
+            percent_off > 100+pct_delta_threshold)
+            dump_table = 1;
+    }
+
+    percent_avg /= t->idx-1;
+
+    if (dump_table) {
+        printf("%s vs %s (period=%lld divider=%d) ", t->source->name,
+            t->event->name, t->period, t->freq_divider);
+        printf("correctness = %d %% off\n", percent_avg-100);
+        dump_time_table(t);
+    }
+}
+
+void inspect_table_remain(struct time_table *t)
+{
+    int i;
+    int dump_table = 0;
+
+    for (i = 2; i < t->idx; i++) {
+        u64 percent_off = (t->remain[i]*100) / t->count;
+        if (percent_off < 100-pct_remain_threshold ||
+            percent_off > 100+pct_remain_threshold)
+            dump_table = 1;
+    }
+
+    if (dump_table) {
+        printf("%s vs %s (period=%lld divider=%d)\n", t->source->name,
+            t->event->name, t->period, t->freq_divider);
+        for (i = 0; i < t->idx; i++)
+            printf("remain i=%d %lld (expect %lld) %d %% off\n", i,
+                    t->remain[i], t->count,
+                    ((t->remain[i]*100) / t->count)-100);
+    }
+}
+
+static void timer_int_record(void *irq_priv)
+{
+    time_table_record(irq_priv);
+}
+
+#define NR_TABLE_RECORD 30
+
+void __test_periodic_one_clock(struct clockevent *clockevt,
+                             struct clocksource *source, u64 count,
+                             u64 freq_divider, u64 freq_divider_value)
+{
+    u64 period;
+    struct time_table *t = vmalloc(sizeof(struct time_table));
+
+    period = muldiv64(count, NS_FREQ, clockevt->freq);
+
+    t->idx = 0;
+    t->period = period;
+    t->count = count / freq_divider;
+    t->source = source;
+    t->event = clockevt;
+    t->freq_divider = freq_divider;
+
+    clockevt->cancel();
+    set_irq_handler(clockevt->vec, timer_int_record, t);
+
+    clock_arm_raw(clockevt, CLOCKEVT_PERIODIC, count/freq_divider, freq_divider_value);
+
+    while (t->idx <= NR_TABLE_RECORD)
+        hlt();
+
+    clockevt->cancel();
+    inspect_table(t);
+    inspect_table_remain(t);
+    vfree(t);
+}
+
+void test_periodic_one_clock(struct clockevent *clockevt,
+                             struct clocksource *source, u64 count)
+{
+    struct freq_divisor *entry = clockevt->divisors;
+
+    while (entry && entry->divisor != -1) {
+        if (count < entry->divisor)
+            break;
+        __test_periodic_one_clock(clockevt, source, count, entry->divisor,
+                                  entry->program_value);
+        entry++;
+    }
+}
+
+void test_periodic_one_clock2(struct clockevent *clockevt,
+                             struct clocksource *source, u64 count)
+{
+    struct freq_divisor *entry = clockevt->divisors;
+
+    while (entry && entry->divisor != -1) {
+        __test_periodic_one_clock(clockevt, source, count*entry->divisor,
+                                  entry->divisor, entry->program_value);
+        entry++;
+    }
+}
+
+void test_periodic_events(void)
+{
+    int i, x;
+
+    for (x = 0; x < ARRAY_SIZE(clocksources); x++) {
+        struct clocksource *clocksource = clocksources[x];
+
+        for (i = 0; i < ARRAY_SIZE(clockevents); i++) {
+            struct clockevent *clockevt = clockevents[i];
+            u64 count, inc;
+
+            printf("clockevent = %s clocksource = %s\n", clockevt->name,
+                   clocksource->name);
+
+            inc = clockevt->max_count / nr_periods_per_clock;
+            for (count = inc; count < clockevt->max_count;
+                count += inc)
+                    test_periodic_one_clock(clockevt, clocksource, count);
+
+            test_periodic_one_clock(clockevt, clocksource, 10);
+            test_periodic_one_clock2(clockevt, clocksource,
+                                     clockevt->max_count);
+        }
+    }
+}
+
+u64 static_periods[] = { 1, 2, 5, 10, 20};
+
+void test_periodic_events_short(void)
+{
+    int i, x, n;
+
+    for (x = 0; x < ARRAY_SIZE(clocksources); x++) {
+        struct clocksource *clocksource = clocksources[x];
+
+        for (i = 0; i < ARRAY_SIZE(clockevents); i++) {
+            struct clockevent *clockevt = clockevents[i];
+
+
+            for (n = 0; n < ARRAY_SIZE(static_periods); n++) {
+                printf("clockevent = %s clocksource = %s period = %dms\n",
+                        clockevt->name, clocksource->name, static_periods[n]);
+                test_periodic_one_clock(clockevt, clocksource,
+                                        muldiv64(ms_to_ns(static_periods[n]),
+                                                clockevt->freq, NS_FREQ));
+            }
+        }
+    }
+}
+
+/* early calibration with PIT to detect TSC frequency, which is necessary
+ * to find lapic frequency.
+ */
+volatile int timer_isr;
+static void timer_int_handler(void *irq_priv)
+{
+    timer_isr++;
+}
+
+void early_calibrate_cpu_hz(void)
+{
+    u64 t1, t2;
+    int ints_per_sec = (PIT_FREQ/0xffff)+1;
+
+    timer_isr = 0;
+
+    pit_timer.arm(0xffff, 1, CLOCKEVT_PERIODIC);
+    t1 = rdtsc();
+    do {
+        hlt();
+    } while (timer_isr < ints_per_sec);
+    t2 = rdtsc();
+    cpu_hz = t2 - t1;
+    printf("detected %lld MHz cpu\n", cpu_hz/1000/1000);
+    tsc.freq = cpu_hz;
+}
+
+void early_calibrate(void)
+{
+    pit_timer.init(TIMER_VEC_BASE);
+    set_irq_handler(TIMER_VEC_BASE, timer_int_handler, 0);
+    early_calibrate_cpu_hz();
+}
+
+int main()
+{
+    setup_vm();
+    init_interrupts();
+
+    init_idt();
+
+    test_self_ipi();
+
+    early_calibrate();
+    init_clocksources();
+    init_clockevents();
+
+    test_periodic_events_short();
+    // full test is slow since it uses maximum count and dividers
+    // test_periodic_events();
+
+    return g_fail != 0;
+}
+
