* (such as the example in Documentation/lguest/lguest.c) is called the
* Launcher.
*
- * Secondly, we only run specially modified Guests, not normal kernels. When
- * you set CONFIG_LGUEST to 'y' or 'm', this automatically sets
- * CONFIG_LGUEST_GUEST=y, which compiles this file into the kernel so it knows
- * how to be a Guest. This means that you can use the same kernel you boot
- * normally (ie. as a Host) as a Guest.
+ * Secondly, we only run specially modified Guests, not normal kernels: setting
+ * CONFIG_LGUEST_GUEST to "y" compiles this file into the kernel so it knows
+ * how to be a Guest at boot time. This means that you can use the same kernel
+ * you boot normally (ie. as a Host) as a Guest.
*
* These Guests know that they cannot do privileged operations, such as disable
* interrupts, and that they have to ask the Host to do such things explicitly.
* This file consists of all the replacements for such low-level native
* hardware operations: these special Guest versions call the Host.
*
- * So how does the kernel know it's a Guest? The Guest starts at a special
- * entry point marked with a magic string, which sets up a few things then
- * calls here. We replace the native functions various "paravirt" structures
- * with our Guest versions, then boot like normal. :*/
+ * So how does the kernel know it's a Guest? We'll see that later, but let's
+ * just say that we end up here where we replace the native functions various
+ * "paravirt" structures with our Guest versions, then boot like normal. :*/
/*
* Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
#include <linux/lguest_launcher.h>
#include <linux/virtio_console.h>
#include <linux/pm.h>
+#include <asm/apic.h>
+#include <asm/lguest.h>
#include <asm/paravirt.h>
#include <asm/param.h>
#include <asm/page.h>
#include <asm/mce.h>
#include <asm/io.h>
#include <asm/i387.h>
+#include <asm/reboot.h> /* for struct machine_ops */
/*G:010 Welcome to the Guest!
*
* behaving in simplified but equivalent ways. In particular, the Guest is the
* same kernel as the Host (or at least, built from the same source code). :*/
-/* Declarations for definitions in lguest_guest.S */
-extern char lguest_noirq_start[], lguest_noirq_end[];
-extern const char lgstart_cli[], lgend_cli[];
-extern const char lgstart_sti[], lgend_sti[];
-extern const char lgstart_popf[], lgend_popf[];
-extern const char lgstart_pushf[], lgend_pushf[];
-extern const char lgstart_iret[], lgend_iret[];
-extern void lguest_iret(void);
-
struct lguest_data lguest_data = {
.hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
.noirq_start = (u32)lguest_noirq_start,
.blocked_interrupts = { 1 }, /* Block timer interrupts */
.syscall_vec = SYSCALL_VECTOR,
};
-static cycle_t clock_base;
/*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a
* ring buffer of stored hypercalls which the Host will run though next time we
* lguest_leave_lazy_mode().
*
* So, when we're in lazy mode, we call async_hcall() to store the call for
- * future processing. */
+ * future processing: */
static void lazy_hcall(unsigned long call,
unsigned long arg1,
unsigned long arg2,
}
/* When lazy mode is turned off reset the per-cpu lazy mode variable and then
- * issue a hypercall to flush any stored calls. */
+ * issue the do-nothing hypercall to flush any stored calls. */
static void lguest_leave_lazy_mode(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
*
* So instead we keep an "irq_enabled" field inside our "struct lguest_data",
* which the Guest can update with a single instruction. The Host knows to
- * check there when it wants to deliver an interrupt.
+ * check there before it tries to deliver an interrupt.
*/
/* save_flags() is expected to return the processor state (ie. "flags"). The
/*M:003 Note that we don't check for outstanding interrupts when we re-enable
* them (or when we unmask an interrupt). This seems to work for the moment,
* since interrupts are rare and we'll just get the interrupt on the next timer
- * tick, but when we turn on CONFIG_NO_HZ, we should revisit this. One way
+ * tick, but now we can run with CONFIG_NO_HZ, we should revisit this. One way
* would be to put the "irq_enabled" field in a page by itself, and have the
* Host write-protect it when an interrupt comes in when irqs are disabled.
- * There will then be a page fault as soon as interrupts are re-enabled. :*/
+ * There will then be a page fault as soon as interrupts are re-enabled.
+ *
+ * A better method is to implement soft interrupt disable generally for x86:
+ * instead of disabling interrupts, we set a flag. If an interrupt does come
+ * in, we then disable them for real. This is uncommon, so we could simply use
+ * a hypercall for interrupt control and not worry about efficiency. :*/
/*G:034
* The Interrupt Descriptor Table (IDT).
* address of the handler, and... well, who cares? The Guest just asks the
* Host to make the change anyway, because the Host controls the real IDT.
*/
-static void lguest_write_idt_entry(struct desc_struct *dt,
- int entrynum, u32 low, u32 high)
+static void lguest_write_idt_entry(gate_desc *dt,
+ int entrynum, const gate_desc *g)
{
+ /* The gate_desc structure is 8 bytes long: we hand it to the Host in
+ * two 32-bit chunks. The whole 32-bit kernel used to hand descriptors
+ * around like this; typesafety wasn't a big concern in Linux's early
+ * years. */
+ u32 *desc = (u32 *)g;
/* Keep the local copy up to date. */
- write_dt_entry(dt, entrynum, low, high);
+ native_write_idt_entry(dt, entrynum, g);
/* Tell Host about this new entry. */
- hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high);
+ hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]);
}
/* Changing to a different IDT is very rare: we keep the IDT up-to-date every
* time it is written, so we can simply loop through all entries and tell the
* Host about them. */
-static void lguest_load_idt(const struct Xgt_desc_struct *desc)
+static void lguest_load_idt(const struct desc_ptr *desc)
{
unsigned int i;
struct desc_struct *idt = (void *)desc->address;
*
* This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY
* hypercall and use that repeatedly to load a new IDT. I don't think it
- * really matters, but wouldn't it be nice if they were the same?
+ * really matters, but wouldn't it be nice if they were the same? Wouldn't
+ * it be even better if you were the one to send the patch to fix it?
*/
-static void lguest_load_gdt(const struct Xgt_desc_struct *desc)
+static void lguest_load_gdt(const struct desc_ptr *desc)
{
BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
* then tell the Host to reload the entire thing. This operation is so rare
* that this naive implementation is reasonable. */
-static void lguest_write_gdt_entry(struct desc_struct *dt,
- int entrynum, u32 low, u32 high)
+static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
+ const void *desc, int type)
{
- write_dt_entry(dt, entrynum, low, high);
+ native_write_gdt_entry(dt, entrynum, desc, type);
hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
}
/* The "cpuid" instruction is a way of querying both the CPU identity
* (manufacturer, model, etc) and its features. It was introduced before the
- * Pentium in 1993 and keeps getting extended by both Intel and AMD. As you
- * might imagine, after a decade and a half this treatment, it is now a giant
- * ball of hair. Its entry in the current Intel manual runs to 28 pages.
+ * Pentium in 1993 and keeps getting extended by both Intel, AMD and others.
+ * As you might imagine, after a decade and a half this treatment, it is now a
+ * giant ball of hair. Its entry in the current Intel manual runs to 28 pages.
*
* This instruction even it has its own Wikipedia entry. The Wikipedia entry
* has been translated into 4 languages. I am not making this up!
case 1: /* Basic feature request. */
/* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
*cx &= 0x00002201;
- /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */
- *dx &= 0x07808101;
+ /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU. */
+ *dx &= 0x07808111;
/* The Host can do a nice optimization if it knows that the
* kernel mappings (addresses above 0xC0000000 or whatever
* PAGE_OFFSET is set to) haven't changed. But Linux calls
* flush_tlb_user() for both user and kernel mappings unless
* the Page Global Enable (PGE) feature bit is set. */
*dx |= 0x00002000;
+ /* We also lie, and say we're family id 5. 6 or greater
+ * leads to a rdmsr in early_init_intel which we can't handle.
+ * Family ID is returned as bits 8-12 in ax. */
+ *ax &= 0xFFFFF0FF;
+ *ax |= 0x00000500;
break;
case 0x80000000:
/* Futureproof this a little: if they ask how much extended
* lazily after a task switch, and Linux uses that gratefully, but wouldn't a
* name like "FPUTRAP bit" be a little less cryptic?
*
- * We store cr0 (and cr3) locally, because the Host never changes it. The
- * Guest sometimes wants to read it and we'd prefer not to bother the Host
- * unnecessarily. */
-static unsigned long current_cr0, current_cr3;
+ * We store cr0 locally because the Host never changes it. The Guest sometimes
+ * wants to read it and we'd prefer not to bother the Host unnecessarily. */
+static unsigned long current_cr0;
static void lguest_write_cr0(unsigned long val)
{
lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0);
return lguest_data.cr2;
}
+/* See lguest_set_pte() below. */
+static bool cr3_changed = false;
+
/* cr3 is the current toplevel pagetable page: the principle is the same as
- * cr0. Keep a local copy, and tell the Host when it changes. */
+ * cr0. Keep a local copy, and tell the Host when it changes. The only
+ * difference is that our local copy is in lguest_data because the Host needs
+ * to set it upon our initial hypercall. */
static void lguest_write_cr3(unsigned long cr3)
{
+ lguest_data.pgdir = cr3;
lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
- current_cr3 = cr3;
+ cr3_changed = true;
}
static unsigned long lguest_read_cr3(void)
{
- return current_cr3;
+ return lguest_data.pgdir;
}
/* cr4 is used to enable and disable PGE, but we don't care. */
* to forget all of them. Fortunately, this is very rare.
*
* ... except in early boot when the kernel sets up the initial pagetables,
- * which makes booting astonishingly slow. So we don't even tell the Host
- * anything changed until we've done the first page table switch. */
+ * which makes booting astonishingly slow: 1.83 seconds! So we don't even tell
+ * the Host anything changed until we've done the first page table switch,
+ * which brings boot back to 0.25 seconds. */
static void lguest_set_pte(pte_t *ptep, pte_t pteval)
{
*ptep = pteval;
- /* Don't bother with hypercall before initial setup. */
- if (current_cr3)
+ if (cr3_changed)
lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
}
static void lguest_flush_tlb_single(unsigned long addr)
{
/* Simply set it to zero: if it was not, it will fault back in. */
- lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0);
+ lazy_hcall(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
}
/* This is what happens after the Guest has removed a large number of entries.
for (i = 0; i < LGUEST_IRQS; i++) {
int vector = FIRST_EXTERNAL_VECTOR + i;
- if (vector != SYSCALL_VECTOR) {
+ /* Some systems map "vectors" to interrupts weirdly. Lguest has
+ * a straightforward 1 to 1 mapping, so force that here. */
+ __get_cpu_var(vector_irq)[vector] = i;
+ if (vector != SYSCALL_VECTOR)
set_intr_gate(vector, interrupt[i]);
- set_irq_chip_and_handler(i, &lguest_irq_controller,
- handle_level_irq);
- }
}
/* This call is required to set up for 4k stacks, where we have
* separate stacks for hard and soft interrupts. */
irq_ctx_init(smp_processor_id());
}
+void lguest_setup_irq(unsigned int irq)
+{
+ irq_to_desc_alloc_cpu(irq, 0);
+ set_irq_chip_and_handler_name(irq, &lguest_irq_controller,
+ handle_level_irq, "level");
+}
+
/*
* Time.
*
return lguest_data.time.tv_sec;
}
+/* The TSC is an Intel thing called the Time Stamp Counter. The Host tells us
+ * what speed it runs at, or 0 if it's unusable as a reliable clock source.
+ * This matches what we want here: if we return 0 from this function, the x86
+ * TSC clock will give up and not register itself. */
+static unsigned long lguest_tsc_khz(void)
+{
+ return lguest_data.tsc_khz;
+}
+
+/* If we can't use the TSC, the kernel falls back to our lower-priority
+ * "lguest_clock", where we read the time value given to us by the Host. */
static cycle_t lguest_clock_read(void)
{
unsigned long sec, nsec;
- /* If the Host tells the TSC speed, we can trust that. */
- if (lguest_data.tsc_khz)
- return native_read_tsc();
-
- /* If we can't use the TSC, we read the time value written by the Host.
- * Since it's in two parts (seconds and nanoseconds), we risk reading
- * it just as it's changing from 99 & 0.999999999 to 100 and 0, and
- * getting 99 and 0. As Linux tends to come apart under the stress of
- * time travel, we must be careful: */
+ /* Since the time is in two parts (seconds and nanoseconds), we risk
+ * reading it just as it's changing from 99 & 0.999999999 to 100 and 0,
+ * and getting 99 and 0. As Linux tends to come apart under the stress
+ * of time travel, we must be careful: */
do {
/* First we read the seconds part. */
sec = lguest_data.time.tv_sec;
/* Now if the seconds part has changed, try again. */
} while (unlikely(lguest_data.time.tv_sec != sec));
- /* Our non-TSC clock is in real nanoseconds. */
+ /* Our lguest clock is in real nanoseconds. */
return sec*1000000000ULL + nsec;
}
-/* This is what we tell the kernel is our clocksource. */
+/* This is the fallback clocksource: lower priority than the TSC clocksource. */
static struct clocksource lguest_clock = {
.name = "lguest",
- .rating = 400,
+ .rating = 200,
.read = lguest_clock_read,
.mask = CLOCKSOURCE_MASK(64),
.mult = 1 << 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
-/* The "scheduler clock" is just our real clock, adjusted to start at zero */
-static unsigned long long lguest_sched_clock(void)
-{
- return cyc2ns(&lguest_clock, lguest_clock_read() - clock_base);
-}
-
/* We also need a "struct clock_event_device": Linux asks us to set it to go
* off some time in the future. Actually, James Morris figured all this out, I
* just applied the patch. */
static int lguest_clockevent_set_next_event(unsigned long delta,
struct clock_event_device *evt)
{
+ /* FIXME: I don't think this can ever happen, but James tells me he had
+ * to put this code in. Maybe we should remove it now. Anyone? */
if (delta < LG_CLOCK_MIN_DELTA) {
if (printk_ratelimit())
printk(KERN_DEBUG "%s: small delta %lu ns\n",
- __FUNCTION__, delta);
+ __func__, delta);
return -ETIME;
}
+
+ /* Please wake us this far in the future. */
hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
return 0;
}
/* Set up the timer interrupt (0) to go to our simple timer routine */
set_irq_handler(0, lguest_time_irq);
- /* Our clock structure looks like arch/x86/kernel/tsc_32.c if we can
- * use the TSC, otherwise it's a dumb nanosecond-resolution clock.
- * Either way, the "rating" is set so high that it's always chosen over
- * any other clocksource. */
- if (lguest_data.tsc_khz)
- lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
- lguest_clock.shift);
- clock_base = lguest_clock_read();
clocksource_register(&lguest_clock);
- /* Now we've set up our clock, we can use it as the scheduler clock */
- pv_time_ops.sched_clock = lguest_sched_clock;
-
/* We can't set cpumask in the initializer: damn C limitations! Set it
* here and register our timer device. */
- lguest_clockevent.cpumask = cpumask_of_cpu(0);
+ lguest_clockevent.cpumask = cpumask_of(0);
clockevents_register_device(&lguest_clockevent);
/* Finally, we unblock the timer interrupt. */
* will not tolerate us trying to use that), the stack pointer, and the number
* of pages in the stack. */
static void lguest_load_sp0(struct tss_struct *tss,
- struct thread_struct *thread)
+ struct thread_struct *thread)
{
lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->sp0,
THREAD_SIZE/PAGE_SIZE);
* code qualifies for Advanced. It will also never interrupt anything. It
* does, however, allow us to get through the Linux boot code. */
#ifdef CONFIG_X86_LOCAL_APIC
-static void lguest_apic_write(unsigned long reg, u32 v)
+static void lguest_apic_write(u32 reg, u32 v)
{
}
-static u32 lguest_apic_read(unsigned long reg)
+static u32 lguest_apic_read(u32 reg)
{
return 0;
}
+
+static u64 lguest_apic_icr_read(void)
+{
+ return 0;
+}
+
+static void lguest_apic_icr_write(u32 low, u32 id)
+{
+ /* Warn to see if there's any stray references */
+ WARN_ON(1);
+}
+
+static void lguest_apic_wait_icr_idle(void)
+{
+ return;
+}
+
+static u32 lguest_apic_safe_wait_icr_idle(void)
+{
+ return 0;
+}
+
+static struct apic_ops lguest_basic_apic_ops = {
+ .read = lguest_apic_read,
+ .write = lguest_apic_write,
+ .icr_read = lguest_apic_icr_read,
+ .icr_write = lguest_apic_icr_write,
+ .wait_icr_idle = lguest_apic_wait_icr_idle,
+ .safe_wait_icr_idle = lguest_apic_safe_wait_icr_idle,
+};
#endif
/* STOP! Until an interrupt comes in. */
hcall(LHCALL_HALT, 0, 0, 0);
}
-/* Perhaps CRASH isn't the best name for this hypercall, but we use it to get a
- * message out when we're crashing as well as elegant termination like powering
- * off.
+/* The SHUTDOWN hypercall takes a string to describe what's happening, and
+ * an argument which says whether this to restart (reboot) the Guest or not.
*
* Note that the Host always prefers that the Guest speak in physical addresses
* rather than virtual addresses, so we use __pa() here. */
static void lguest_power_off(void)
{
- hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
+ hcall(LHCALL_SHUTDOWN, __pa("Power down"), LGUEST_SHUTDOWN_POWEROFF, 0);
}
/*
*/
static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
{
- hcall(LHCALL_CRASH, __pa(p), 0, 0);
+ hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0);
/* The hcall won't return, but to keep gcc happy, we're "done". */
return NOTIFY_DONE;
}
/* Setting up memory is fairly easy. */
static __init char *lguest_memory_setup(void)
{
- /* We do this here and not earlier because lockcheck barfs if we do it
- * before start_kernel() */
+ /* We do this here and not earlier because lockcheck used to barf if we
+ * did it before start_kernel(). I think we fixed that, so it'd be
+ * nice to move it back to lguest_init. Patch welcome... */
atomic_notifier_chain_register(&panic_notifier_list, &paniced);
/* The Linux bootloader header contains an "e820" memory map: the
* Launcher populated the first entry with our memory limit. */
- add_memory_region(boot_params.e820_map[0].addr,
+ e820_add_region(boot_params.e820_map[0].addr,
boot_params.e820_map[0].size,
boot_params.e820_map[0].type);
return len;
}
+/* Rebooting also tells the Host we're finished, but the RESTART flag tells the
+ * Launcher to reboot us. */
+static void lguest_restart(char *reason)
+{
+ hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0);
+}
+
/*G:050
* Patching (Powerfully Placating Performance Pedants)
*
- * We have already seen that pv_ops structures let us replace simple
- * native instructions with calls to the appropriate back end all throughout
- * the kernel. This allows the same kernel to run as a Guest and as a native
+ * We have already seen that pv_ops structures let us replace simple native
+ * instructions with calls to the appropriate back end all throughout the
+ * kernel. This allows the same kernel to run as a Guest and as a native
* kernel, but it's slow because of all the indirect branches.
*
* Remember that David Wheeler quote about "Any problem in computer science can
* that we can fit comfortably.
*
* First we need assembly templates of each of the patchable Guest operations,
- * and these are in lguest_asm.S. */
+ * and these are in i386_head.S. */
/*G:060 We construct a table from the assembler templates: */
static const struct lguest_insns
return insn_len;
}
-/*G:030 Once we get to lguest_init(), we know we're a Guest. The pv_ops
- * structures in the kernel provide points for (almost) every routine we have
- * to override to avoid privileged instructions. */
+/*G:030 Once we get to lguest_init(), we know we're a Guest. The various
+ * pv_ops structures in the kernel provide points for (almost) every routine we
+ * have to override to avoid privileged instructions. */
__init void lguest_init(void)
{
/* We're under lguest, paravirt is enabled, and we're running at
#ifdef CONFIG_X86_LOCAL_APIC
/* apic read/write intercepts */
- pv_apic_ops.apic_write = lguest_apic_write;
- pv_apic_ops.apic_write_atomic = lguest_apic_write;
- pv_apic_ops.apic_read = lguest_apic_read;
+ apic_ops = &lguest_basic_apic_ops;
#endif
/* time operations */
pv_time_ops.get_wallclock = lguest_get_wallclock;
pv_time_ops.time_init = lguest_time_init;
+ pv_time_ops.get_tsc_khz = lguest_tsc_khz;
/* Now is a good time to look at the implementations of these functions
* before returning to the rest of lguest_init(). */
* clobbered. The Launcher places our initial pagetables somewhere at
* the top of our physical memory, so we don't need extra space: set
* init_pg_tables_end to the end of the kernel. */
+ init_pg_tables_start = __pa(pg0);
init_pg_tables_end = __pa(pg0);
+ /* As described in head_32.S, we map the first 128M of memory. */
+ max_pfn_mapped = (128*1024*1024) >> PAGE_SHIFT;
+
/* Load the %fs segment register (the per-cpu segment register) with
* the normal data segment to get through booting. */
asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
- /* The Host uses the top of the Guest's virtual address space for the
- * Host<->Guest Switcher, and it tells us how big that is in
- * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */
+ /* The Host<->Guest Switcher lives at the top of our address space, and
+ * the Host told us how big it is when we made LGUEST_INIT hypercall:
+ * it put the answer in lguest_data.reserve_mem */
reserve_top_address(lguest_data.reserve_mem);
/* If we don't initialize the lock dependency checker now, it crashes
/* Math is always hard! */
new_cpu_data.hard_math = 1;
+ /* We don't have features. We have puppies! Puppies! */
#ifdef CONFIG_X86_MCE
mce_disabled = 1;
#endif
acpi_ht = 0;
#endif
- /* We set the perferred console to "hvc". This is the "hypervisor
+ /* We set the preferred console to "hvc". This is the "hypervisor
* virtual console" driver written by the PowerPC people, which we also
* adapted for lguest's use. */
add_preferred_console("hvc", 0, NULL);
virtio_cons_early_init(early_put_chars);
/* Last of all, we set the power management poweroff hook to point to
- * the Guest routine to power off. */
+ * the Guest routine to power off, and the reboot hook to our restart
+ * routine. */
pm_power_off = lguest_power_off;
+ machine_ops.restart = lguest_restart;
- /* Now we're set up, call start_kernel() in init/main.c and we proceed
+ /* Now we're set up, call i386_start_kernel() in head32.c and we proceed
* to boot as normal. It never returns. */
- start_kernel();
+ i386_start_kernel();
}
/*
* This marks the end of stage II of our journey, The Guest.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff