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authorRusty Russell <rusty@rustcorp.com.au>2011-07-22 14:39:50 +0930
committerRusty Russell <rusty@rustcorp.com.au>2011-07-22 14:39:50 +0930
commit9f54288def3f92b7805eb6d4b1ddcd73ecf6e889 (patch)
treebb46242a92e47112c2967354b3be0c6daecae7a7 /arch/x86/lguest
parent3c3ed482dc077a67903a58c9e1aedba1bb18c18a (diff)
lguest: update comments
Also removes a long-unused #define and an extraneous semicolon. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'arch/x86/lguest')
-rw-r--r--arch/x86/lguest/boot.c21
-rw-r--r--arch/x86/lguest/i386_head.S18
2 files changed, 26 insertions, 13 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 719a32c60516..74279907bc1a 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -71,7 +71,8 @@
#include <asm/stackprotector.h>
#include <asm/reboot.h> /* for struct machine_ops */
-/*G:010 Welcome to the Guest!
+/*G:010
+ * Welcome to the Guest!
*
* The Guest in our tale is a simple creature: identical to the Host but
* behaving in simplified but equivalent ways. In particular, the Guest is the
@@ -190,15 +191,23 @@ static void lazy_hcall4(unsigned long call,
#endif
/*G:036
- * When lazy mode is turned off reset the per-cpu lazy mode variable and then
- * issue the do-nothing hypercall to flush any stored calls.
-:*/
+ * When lazy mode is turned off, we issue the do-nothing hypercall to
+ * flush any stored calls, and call the generic helper to reset the
+ * per-cpu lazy mode variable.
+ */
static void lguest_leave_lazy_mmu_mode(void)
{
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
paravirt_leave_lazy_mmu();
}
+/*
+ * We also catch the end of context switch; we enter lazy mode for much of
+ * that too, so again we need to flush here.
+ *
+ * (Technically, this is lazy CPU mode, and normally we're in lazy MMU
+ * mode, but unlike Xen, lguest doesn't care about the difference).
+ */
static void lguest_end_context_switch(struct task_struct *next)
{
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
@@ -640,7 +649,7 @@ static void lguest_write_cr4(unsigned long val)
/*
* The Guest calls this after it has set a second-level entry (pte), ie. to map
- * a page into a process' address space. Wetell the Host the toplevel and
+ * a page into a process' address space. We tell the Host the toplevel and
* address this corresponds to. The Guest uses one pagetable per process, so
* we need to tell the Host which one we're changing (mm->pgd).
*/
@@ -1139,7 +1148,7 @@ static struct notifier_block paniced = {
static __init char *lguest_memory_setup(void)
{
/*
- *The Linux bootloader header contains an "e820" memory map: the
+ * The Linux bootloader header contains an "e820" memory map: the
* Launcher populated the first entry with our memory limit.
*/
e820_add_region(boot_params.e820_map[0].addr,
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S
index c8c95e575c1e..cfa23e37ec5c 100644
--- a/arch/x86/lguest/i386_head.S
+++ b/arch/x86/lguest/i386_head.S
@@ -6,18 +6,22 @@
#include <asm/processor-flags.h>
/*G:020
- * Our story starts with the kernel booting into startup_32 in
- * arch/x86/kernel/head_32.S. It expects a boot header, which is created by
- * the bootloader (the Launcher in our case).
+
+ * Our story starts with the bzImage: booting starts at startup_32 in
+ * arch/x86/boot/compressed/head_32.S. This merely uncompresses the real
+ * kernel in place and then jumps into it: startup_32 in
+ * arch/x86/kernel/head_32.S. Both routines expects a boot header in the %esi
+ * register, which is created by the bootloader (the Launcher in our case).
*
* The startup_32 function does very little: it clears the uninitialized global
* C variables which we expect to be zero (ie. BSS) and then copies the boot
- * header and kernel command line somewhere safe. Finally it checks the
- * 'hardware_subarch' field. This was introduced in 2.6.24 for lguest and Xen:
- * if it's set to '1' (lguest's assigned number), then it calls us here.
+ * header and kernel command line somewhere safe, and populates some initial
+ * page tables. Finally it checks the 'hardware_subarch' field. This was
+ * introduced in 2.6.24 for lguest and Xen: if it's set to '1' (lguest's
+ * assigned number), then it 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
+ * addesses (around 0), not above PAGE_OFFSET as most code expects
* (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any
* data without remembering to subtract __PAGE_OFFSET!
*

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