lguest: documentation update

Went through the documentation doing typo and content fixes.  This
patch contains only comment and whitespace changes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 30 insertions, 26 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index a0179fc6b791..a55b0902f9d3 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -99,7 +99,7 @@ static cycle_t clock_base;
  * When lazy_mode is set, it means we're allowed to defer all hypercalls and do
  * them as a batch when lazy_mode is eventually turned off.  Because hypercalls
  * are reasonably expensive, batching them up makes sense.  For example, a
- * large mmap might update dozens of page table entries: that code calls
+ * large munmap might update dozens of page table entries: that code calls
  * paravirt_enter_lazy_mmu(), does the dozen updates, then calls
  * lguest_leave_lazy_mode().
  *
@@ -164,8 +164,8 @@ void async_hcall(unsigned long call,
 /*:*/
 
 /*G:033
- * Here are our first native-instruction replacements: four functions for
- * interrupt control.
+ * After that diversion we return to our first native-instruction
+ * replacements: four functions for interrupt control.
  *
  * The simplest way of implementing these would be to have "turn interrupts
  * off" and "turn interrupts on" hypercalls.  Unfortunately, this is too slow:
@@ -184,7 +184,7 @@ static unsigned long save_fl(void)
         return lguest_data.irq_enabled;
 }
 
-/* "restore_flags" just sets the flags back to the value given. */
+/* restore_flags() just sets the flags back to the value given. */
 static void restore_fl(unsigned long flags)
 {
         lguest_data.irq_enabled = flags;
@@ -357,7 +357,7 @@ static void lguest_cpuid(unsigned int *eax, unsigned int *ebx,
  * it.  The Host needs to know when the Guest wants to change them, so we have
  * a whole series of functions like read_cr0() and write_cr0().
  *
- * We start with CR0.  CR0 allows you to turn on and off all kinds of basic
+ * We start with cr0.  cr0 allows you to turn on and off all kinds of basic
  * features, but Linux only really cares about one: the horrifically-named Task
  * Switched (TS) bit at bit 3 (ie. 8)
  *
@@ -390,7 +390,7 @@ static void lguest_clts(void)
         current_cr0 &= ~X86_CR0_TS;
 }
 
-/* CR2 is the virtual address of the last page fault, which the Guest only ever
+/* cr2 is the virtual address of the last page fault, which the Guest only ever
  * reads.  The Host kindly writes this into our "struct lguest_data", so we
  * just read it out of there. */
 static unsigned long lguest_read_cr2(void)
@@ -398,7 +398,7 @@ static unsigned long lguest_read_cr2(void)
         return lguest_data.cr2;
 }
 
-/* CR3 is the current toplevel pagetable page: the principle is the same as
+/* 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. */
 static void lguest_write_cr3(unsigned long cr3)
 {
@@ -411,7 +411,7 @@ static unsigned long lguest_read_cr3(void)
         return current_cr3;
 }
 
-/* CR4 is used to enable and disable PGE, but we don't care. */
+/* cr4 is used to enable and disable PGE, but we don't care. */
 static unsigned long lguest_read_cr4(void)
 {
         return 0;
@@ -432,7 +432,7 @@ static void lguest_write_cr4(unsigned long val)
  * maps virtual addresses to physical addresses using "page tables".  We could
  * use one huge index of 1 million entries: each address is 4 bytes, so that's
  * 1024 pages just to hold the page tables.   But since most virtual addresses
- * are unused, we use a two level index which saves space.  The CR3 register
+ * are unused, we use a two level index which saves space.  The cr3 register
  * contains the physical address of the top level "page directory" page, which
  * contains physical addresses of up to 1024 second-level pages.  Each of these
  * second level pages contains up to 1024 physical addresses of actual pages,
@@ -440,7 +440,7 @@ static void lguest_write_cr4(unsigned long val)
  *
  * Here's a diagram, where arrows indicate physical addresses:
  *
- * CR3 ---> +---------+
+ * cr3 ---> +---------+
  *          |      --------->+---------+
  *          |         |      | PADDR1  |
  *        Top-level   |      | PADDR2  |
@@ -498,8 +498,7 @@ static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
  *
  * ... 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.
- */
+ * anything changed until we've done the first page table switch. */
 static void lguest_set_pte(pte_t *ptep, pte_t pteval)
 {
         *ptep = pteval;
@@ -720,10 +719,10 @@ static void lguest_time_init(void)
         /* Set up the timer interrupt (0) to go to our simple timer routine */
         set_irq_handler(0, lguest_time_irq);
 
-        /* Our clock structure look like arch/i386/kernel/tsc.c if we can use
-         * the TSC, otherwise it's a dumb nanosecond-resolution clock.  Either
-         * way, the "rating" is initialized so high that it's always chosen
-         * over any other clocksource. */
+        /* 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);
@@ -749,7 +748,7 @@ static void lguest_time_init(void)
  * to work.  They're pretty simple.
  */
 
-/* The Guest needs to tell the host what stack it expects traps to use.  For
+/* The Guest needs to tell the Host what stack it expects traps to use.  For
  * native hardware, this is part of the Task State Segment mentioned above in
  * lguest_load_tr_desc(), but to help hypervisors there's this special call.
  *
@@ -850,13 +849,16 @@ static __init char *lguest_memory_setup(void)
         return "LGUEST";
 }
 
-/* Before virtqueues are set up, we use LHCALL_NOTIFY on normal memory to
- * produce console output. */
+/* We will eventually use the virtio console device to produce console output,
+ * but before that is set up we use LHCALL_NOTIFY on normal memory to produce
+ * console output. */
 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 {
         char scratch[17];
         unsigned int len = count;
 
+        /* We use a nul-terminated string, so we have to make a copy.  Icky,
+         * huh? */
         if (len > sizeof(scratch) - 1)
                 len = sizeof(scratch) - 1;
         scratch[len] = '\0';
@@ -883,7 +885,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count)
  * Our current solution is to allow the paravirt back end to optionally patch
  * over the indirect calls to replace them with something more efficient.  We
  * patch the four most commonly called functions: disable interrupts, enable
- * interrupts, restore interrupts and save interrupts.  We usually have 10
+ * interrupts, restore interrupts and save interrupts.  We usually have 6 or 10
  * bytes to patch into: the Guest versions of these operations are small enough
  * that we can fit comfortably.
  *
@@ -1015,7 +1017,7 @@ __init void lguest_init(void)
         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 much it needs in
+         * Host<->Guest Switcher, and it tells us how big that is in
          * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */
         reserve_top_address(lguest_data.reserve_mem);
 
@@ -1065,6 +1067,6 @@ __init void lguest_init(void)
 /*
  * This marks the end of stage II of our journey, The Guest.
  *
- * It is now time for us to explore the nooks and crannies of the three Guest
- * devices and complete our understanding of the Guest in "make Drivers".
+ * It is now time for us to explore the layer of virtual drivers and complete
+ * our understanding of the Guest in "make Drivers".
  */
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S
index ebc6ac733899..95b6fbcded63 100644
--- a/arch/x86/lguest/i386_head.S
+++ b/arch/x86/lguest/i386_head.S
@@ -6,7 +6,7 @@
 #include <asm/processor-flags.h>
 
 /*G:020 This is where we begin: head.S notes that the boot header's platform
- * type field is "1" (lguest), so calls us here.  The boot header is in %esi.
+ * type field is "1" (lguest), so calls us here.
  *
  * WARNING: be very careful here!  We're running at addresses equal to physical
  * addesses (around 0), not above PAGE_OFFSET as most code expectes
@@ -17,13 +17,15 @@
  * boot. */
 .section .init.text, "ax", @progbits
 ENTRY(lguest_entry)
-        /* Make initial hypercall now, so we can set up the pagetables. */
+        /* We make the "initialization" hypercall now to tell the Host about
+         * us, and also find out where it put our page tables. */
         movl $LHCALL_LGUEST_INIT, %eax
         movl $lguest_data - __PAGE_OFFSET, %edx
         int $LGUEST_TRAP_ENTRY
 
         /* The Host put the toplevel pagetable in lguest_data.pgdir.  The movsl
-         * instruction uses %esi implicitly. */
+         * instruction uses %esi implicitly as the source for the copy we'
+         * about to do. */
         movl lguest_data - __PAGE_OFFSET + LGUEST_DATA_pgdir, %esi
 
         /* Copy first 32 entries of page directory to __PAGE_OFFSET entries.