On Sunday, 30 of December 2007, Pavel Machek wrote: > Hi! > > > From: Rafael J. Wysocki <rjw@xxxxxxx> > > > > 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@xxxxxxx> > > --- > > arch/x86/kernel/suspend_64.c | 20 ++++++++++++++++++++ > > 1 file changed, 20 insertions(+) > > > > Index: linux-2.6/arch/x86/kernel/suspend_64.c > > =================================================================== > > --- linux-2.6.orig/arch/x86/kernel/suspend_64.c > > +++ linux-2.6/arch/x86/kernel/suspend_64.c > > @@ -19,6 +19,21 @@ extern const void __nosave_begin, __nosa > > > > struct saved_context saved_context; > > > > +/** > > + * __save_processor_state - save CPU registers before creating a > > + * hibernation image and before restoring the memory state from it > > + * @ctxt - structure to store the registers contents in > > + * > > + * NOTE: If there is a CPU register the modification of which by the > > + * boot kernel (ie. the kernel used for loading the hibernation image) > > + * might affect the operations of the restored target kernel (ie. the one > > + * saved in the hibernation image), then its contents must be saved by this > > + * function. In other words, if kernel A is hibernated and different > > + * kernel B is used for loading the hibernation image into memory, the > > + * kernel A's __save_processor_state() function must save all registers > > + * needed by kernel A, so that it can operate correctly after the resume > > + * regardless of what kernel B does in the meantime. > > + */ > > Maybe this warning should be appended to struct saved_context > definition? Reordering its fields (etc) would be bad news, too, Hmm, I think they can be reordered without any problem. It's always the same kernel using them, although at different times. > and documentation near data structures is easier to find... Well, I'll add a coment next to the definition of struct saved_context to explain what it's for, but IMO the behavior of __save_processor_state() is what _really_ matters (ie. it doesn't matter how and where exactly it saves the registers as long as __restore_processor_state() can restore their "old" values). Greetings, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
