[patch 8/8] kvmctl: time testcase

From: Marcelo Tosatti <mtosatti@redhat.com>
To: kvm@vger.kernel.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Subject: [patch 8/8] kvmctl: time testcase
Date: Sun, 05 Jul 2009 22:55:19 -0300	[thread overview]
Message-ID: <20090706015813.217787023@localhost.localdomain> (raw)
In-Reply-To: 20090706015511.923596553@localhost.localdomain

[-- Attachment #1: timer-testcase --]
[-- Type: text/plain, Size: 19119 bytes --]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

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
@@ -56,6 +56,9 @@ $(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)/irq.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 +1,766 @@
+#include "libcflat.h"
+#include "apic.h"
+#include "vm.h"
+#include "io.h"
+
+#ifndef NULL
+#define NULL ((void*)0)
+#endif
+
+static void *g_apic;
+static void *g_ioapic;
+
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned u32;
+typedef unsigned long ulong;
+typedef unsigned long long u64;
+
+typedef u64 ns_t;
+
+#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 u32 apic_read(unsigned reg)
+{
+    return *(volatile u32 *)(g_apic + reg);
+}
+
+static void apic_write(unsigned reg, u32 val)
+{
+    *(volatile u32 *)(g_apic + reg) = val;
+}
+
+static void test_lapic_existence(void)
+{
+    u32 lvr;
+
+    lvr = apic_read(APIC_LVR);
+    printf("apic version: %x\n", lvr);
+    report("apic existence", (u16)lvr == 0x14);
+}
+
+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 ioapic_write_reg(unsigned reg, u32 value)
+{
+    *(volatile u32 *)g_ioapic = reg;
+    *(volatile u32 *)(g_ioapic + 0x10) = value;
+}
+
+typedef struct {
+    u8 vector;
+    u8 delivery_mode:3;
+    u8 dest_mode:1;
+    u8 delivery_status:1;
+    u8 polarity:1;
+    u8 remote_irr:1;
+    u8 trig_mode:1;
+    u8 mask:1;
+    u8 reserve:7;
+    u8 reserved[4];
+    u8 dest_id;
+} ioapic_redir_entry_t;
+
+static void ioapic_write_redir(unsigned line, ioapic_redir_entry_t e)
+{
+    ioapic_write_reg(0x10 + line * 2 + 0, ((u32 *)&e)[0]);
+    ioapic_write_reg(0x10 + line * 2 + 1, ((u32 *)&e)[1]);
+}
+
+static void set_ioapic_redir(unsigned line, unsigned vec)
+{
+    ioapic_redir_entry_t e = {
+        .vector = vec,
+        .delivery_mode = 0,
+        .trig_mode = 0,
+    };
+
+    ioapic_write_redir(line, e);
+}
+
+static void enable_apic(void)
+{
+    apic_write(0xf0, 0x1ff); /* spurious vector register */
+}
+
+/* interrupt handlers */
+
+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 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 ns_to_ms(x) (x / 1000000)
+
+#define udelay(n) nsdelay(us_to_ns(n))
+#define mdelay(n) nsdelay(ms_to_ns(n))
+#define sdelay(n) nsdelay(s_to_ns(n))
+
+u64 cpu_hz;
+
+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 = (val * NS_FREQ) / clock->freq;
+    return val;
+}
+
+enum clockevt_type { CLOCKEVT_PERIODIC, CLOCKEVT_ONESHOT, };
+
+struct clockevent {
+    char *name;
+    u64 (*init) (int vec);
+    int (*arm) (u64 count, enum clockevt_type);
+    void (*cancel)(void);
+    u64 (*remain) (void);
+
+    u64 freq;
+    unsigned vec;
+};
+
+void clock_arm(struct clockevent *clockevt, enum clockevt_type type,
+               u64 period)
+{
+    u64 count = (period * clockevt->freq) / NS_FREQ;
+
+    clockevt->arm(count, 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
+
+int acpi_init(void) { printf("%s\n", __func__); return 0; }
+u64 acpi_read(void) { return inl(ACPI_PORT); }
+
+struct clocksource acpi = {
+    .name = "acpi",
+    .init = acpi_init,
+    .read = acpi_read,
+    .freq = ACPI_FREQ,
+};
+
+//struct clocksource *clocksources[] = { &tsc, &acpi, };
+struct clocksource *clocksources[] = { &tsc };
+
+/* --------- LAPIC clockevent ---------- */
+
+#define aprint(reg)  printf("%s = %x\n", #reg , apic_read(reg))
+
+static void dummy(void *irq_priv)
+{
+}
+
+u64 lapic_timer_init(int vec)
+{
+    u64 hz;
+
+    set_irq_handler(vec, dummy, NULL);
+    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, enum clockevt_type type)
+{
+    if (type == CLOCKEVT_PERIODIC)
+        apic_write(APIC_LVTT, apic_read(APIC_LVTT) | 1 << 17);
+    /* divide count */
+    apic_write(APIC_TDCR, 0xB);
+    /* 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,
+};
+
+/* ---------- 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(0, vec);
+    /* mask LINT0, int is coming through IO-APIC */
+    apic_write(APIC_LVT0, 1 << 16);
+    return PIT_FREQ;
+}
+
+int pit_timer_arm(u64 period, enum clockevt_type type)
+{
+    unsigned char ctrl_word = 0x30;
+
+    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 clockevent pit_timer = {
+    .name = "pit",
+    .init = pit_timer_init,
+    .arm = pit_timer_arm,
+    .cancel = pit_timer_cancel,
+    .remain = pit_timer_remain,
+};
+
+
+#define NR_CLOCKEVENTS 2
+
+/* clockevent initialization */
+struct clockevent *clockevents[NR_CLOCKEVENTS] = {
+    &pit_timer, &lapic_timer,
+};
+
+decl_irq_handler(0)
+decl_irq_handler(1)
+
+static struct int_table int_handlers[NR_CLOCKEVENTS] = {
+    { .func = timer_int_0 }, { .func = timer_int_1 },
+};
+
+#define TIMER_VEC_BASE 0x90
+
+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)
+        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; 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;
+}
+
+/*
+ *
+ * TODO:
+ * 1. test every divisor possible
+ * 3. monotonicity of clocksources
+ * 4. tests to mimic Linux calibration sites
+ * 5. SMP
+ *
+ */
+
+/* actual tests */
+
+#define TIME_TABLE_SZ 100
+struct time_table {
+    u64 val[TIME_TABLE_SZ];
+    int idx;
+    struct clocksource *source;
+    u64 period;
+};
+
+void time_table_record(struct time_table *t)
+{
+    t->val[t->idx] = clocksource_read(t->source);
+    t->idx++;
+    if (t->idx >= TIME_TABLE_SZ)
+        t->idx = 0;
+}
+
+void inspect_table(struct time_table *t)
+{
+    int i;
+    int percent_avg = 0;
+
+    for (i = 1; i < t->idx; i++) {
+	u64 fire_period = t->val[i] - t->val[i-1];
+        /* FIXME: handle clock wraparound */
+        if (t->val[i] < t->val[i-1])
+            break;
+        percent_avg += (fire_period*100) / t->period;
+    }
+
+    percent_avg /= t->idx-1;
+    printf(" %d ms percent_off_avg = %d\n", ns_to_ms(t->period), percent_avg);
+
+}
+
+static void timer_int_record(void *irq_priv)
+{
+    time_table_record(irq_priv);
+}
+
+void test_periodic_one_clock(struct clockevent *clockevt,
+                             struct clocksource *source, u64 period)
+{
+    int i;
+    struct time_table *t = vmalloc(sizeof(struct time_table));
+
+    t->idx = 0;
+    t->period = period;
+    t->source = source;
+
+    clockevt->cancel();
+    set_irq_handler(clockevt->vec, timer_int_record, t);
+
+    clock_arm(clockevt, CLOCKEVT_PERIODIC, period);
+
+    for (i=0;i<50;i++)
+        hlt();
+
+    clockevt->cancel();
+    inspect_table(t);
+    vfree(t);
+}
+
+static int periodic_freqs[] = { 1, 2, 10, 15, 20, 50, 100, 200 };
+
+void test_periodic_events(void)
+{
+    int i, n, 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];
+
+            printf("clockevent = %s clocksource = %s\n", clockevt->name,
+                   clocksource->name);
+
+            for (n = 0; n < ARRAY_SIZE(periodic_freqs); n++)
+                test_periodic_one_clock(clockevt, clocksource,
+                                        ms_to_ns(periodic_freqs[n]));
+        }
+    }
+}
+
+static void int_handler_reinject(void *irq_priv)
+{
+    int *ints = (int *)irq_priv;
+    *ints += 1;
+}
+
+void test_reinjection(void)
+{
+    int i;
+    u64 period = ms_to_ns(1);
+
+    for (i = 0; i < ARRAY_SIZE(clockevents); i++) {
+        struct clockevent *clockevt = clockevents[i];
+        int ints = 0;
+
+        printf("clockevent = %s\n", clockevt->name);
+
+        clockevt->cancel();
+        set_irq_handler(clockevt->vec, int_handler_reinject, &ints);
+
+        clock_arm(clockevt, CLOCKEVT_PERIODIC, period);
+        irq_disable();
+        mdelay(100);
+        irq_enable();
+        printf("irqoff delay=100 ints=%d\n", ints);
+
+        clockevt->cancel();
+    }
+}
+
+/* early calibration with PIT to detect TSC frequency, which is necessary
+ * to find lapic frequency.
+ */
+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;
+    t1 = rdtsc();
+    do {
+        pit_timer.arm(0xffff, CLOCKEVT_ONESHOT);
+        __asm__ volatile ("hlt");
+    } while (timer_isr < ints_per_sec);
+    t2 = rdtsc();
+    cpu_hz = t2 - t1;
+    printf("detected %lld MHz cpu\n", cpu_hz);
+    tsc.freq = cpu_hz;
+}
+
+void early_calibrate(void)
+{
+    pit_timer.init(TIMER_VEC_BASE);
+    set_irq_handler(TIMER_VEC_BASE, timer_int_handler, NULL);
+    early_calibrate_cpu_hz();
+}
+
+int main()
+{
+    setup_vm();
+    init_interrupts();
+
+    g_apic = vmap(0xfee00000, 0x1000);
+    g_ioapic = vmap(0xfec00000, 0x1000);
+
+    test_lapic_existence();
+
+    enable_apic();
+    init_idt();
+
+    test_self_ipi();
+
+    early_calibrate();
+    init_clockevents();
+
+    test_reinjection();
+    test_periodic_events();
+
+    return g_fail != 0;
+}
+
+
+#if 0
+void calibrate(struct clocksource *csource, struct clockevent *cevent)
+{
+    u64 t1, t2;
+    int ints_per_sec = (cevent->freq / c
+
+    csource->wait();
+    t1 = clocksource_read(csource);
+    do {
+        cevent->arm(count, CLOCKEVT_ONESHOT);
+        __asm__ volatile ("hlt");
+    } while (timer_isr < ints_per_sec);
+    t2 = clocksource_read(csource);
+
+    printf("");
+}
+#endif
+

-- 

