x86: hibernation: document __save_processor_state() on x86

Document the fact that __save_processor_state() has to save all CPU
registers referred to by the kernel in case a different kernel is
used to load and restore a hibernation image containing it.

Sigend-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/include/asm-x86/suspend_64.h b/include/asm-x86/suspend_64.h
index c505a76bcf6e..4404668f9aa4 100644
--- a/include/asm-x86/suspend_64.h
+++ b/include/asm-x86/suspend_64.h
@@ -15,7 +15,14 @@ arch_prepare_suspend(void)
         return 0;
 }
 
-/* Image of the saved processor state. If you touch this, fix acpi/wakeup.S. */
+/*
+ * Image of the saved processor state, used by the low level ACPI suspend to
+ * RAM code and by the low level hibernation code.
+ *
+ * If you modify it, fix arch/x86/kernel/acpi/wakeup_64.S and make sure that
+ * __save/__restore_processor_state(), defined in arch/x86/kernel/suspend_64.c,
+ * still work as required.
+ */
 struct saved_context {
         struct pt_regs regs;
         u16 ds, es, fs, gs, ss;