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lguest: comment documentation update.

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Took some cycles to re-read the Lguest Journey end-to-end, fix some
rot and tighten some phrases.

Only comments change.  No new jokes, but a couple of recycled old jokes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2008-03-28 11:05:53 -05:00
parent e18b094f0f
commit a6bd8e1303
13 changed files with 208 additions and 142 deletions
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30
drivers/lguest/lguest_user.c
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@@ -73,7 +73,7 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
if (current != cpu->tsk)
return -EPERM;
/* If the guest is already dead, we indicate why */
/* If the Guest is already dead, we indicate why */
if (lg->dead) {
size_t len;
@@ -88,7 +88,7 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
return len;
}
/* If we returned from read() last time because the Guest notified,
/* If we returned from read() last time because the Guest sent I/O,
* clear the flag. */
if (cpu->pending_notify)
cpu->pending_notify = 0;
@@ -97,14 +97,20 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
return run_guest(cpu, (unsigned long __user *)user);
}
/*L:025 This actually initializes a CPU. For the moment, a Guest is only
* uniprocessor, so "id" is always 0. */
static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
{
/* We have a limited number the number of CPUs in the lguest struct. */
if (id >= NR_CPUS)
return -EINVAL;
/* Set up this CPU's id, and pointer back to the lguest struct. */
cpu->id = id;
cpu->lg = container_of((cpu - id), struct lguest, cpus[0]);
cpu->lg->nr_cpus++;
/* Each CPU has a timer it can set. */
init_clockdev(cpu);
/* We need a complete page for the Guest registers: they are accessible
@@ -120,11 +126,11 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
* address. */
lguest_arch_setup_regs(cpu, start_ip);
/* Initialize the queue for the waker to wait on */
/* Initialize the queue for the Waker to wait on */
init_waitqueue_head(&cpu->break_wq);
/* We keep a pointer to the Launcher task (ie. current task) for when
* other Guests want to wake this one (inter-Guest I/O). */
* other Guests want to wake this one (eg. console input). */
cpu->tsk = current;
/* We need to keep a pointer to the Launcher's memory map, because if
@@ -136,6 +142,7 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
* when the same Guest runs on the same CPU twice. */
cpu->last_pages = NULL;
/* No error == success. */
return 0;
}
@@ -185,14 +192,13 @@ static int initialize(struct file *file, const unsigned long __user *input)
lg->mem_base = (void __user *)(long)args[0];
lg->pfn_limit = args[1];
/* This is the first cpu */
/* This is the first cpu (cpu 0) and it will start booting at args[3] */
err = lg_cpu_start(&lg->cpus[0], 0, args[3]);
if (err)
goto release_guest;
/* Initialize the Guest's shadow page tables, using the toplevel
* address the Launcher gave us. This allocates memory, so can
* fail. */
* address the Launcher gave us. This allocates memory, so can fail. */
err = init_guest_pagetable(lg, args[2]);
if (err)
goto free_regs;
@@ -218,11 +224,16 @@ unlock:
/*L:010 The first operation the Launcher does must be a write. All writes
* start with an unsigned long number: for the first write this must be
* LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
* writes of other values to send interrupts. */
* writes of other values to send interrupts.
*
* Note that we overload the "offset" in the /dev/lguest file to indicate what
* CPU number we're dealing with. Currently this is always 0, since we only
* support uniprocessor Guests, but you can see the beginnings of SMP support
* here. */
static ssize_t write(struct file *file, const char __user *in,
size_t size, loff_t *off)
{
/* Once the guest is initialized, we hold the "struct lguest" in the
/* Once the Guest is initialized, we hold the "struct lguest" in the
* file private data. */
struct lguest *lg = file->private_data;
const unsigned long __user *input = (const unsigned long __user *)in;
@@ -230,6 +241,7 @@ static ssize_t write(struct file *file, const char __user *in,
struct lg_cpu *uninitialized_var(cpu);
unsigned int cpu_id = *off;
/* The first value tells us what this request is. */
if (get_user(req, input) != 0)
return -EFAULT;
input++;