Re: [PATCH -mm 2/2] Hibernation: Arbitrary boot kernel support on x86_64

Rafael J. Wysocki
2007-08-25T20:32:42Z

On Saturday, 25 August 2007 01:23, Andrew Morton wrote:
> On Fri, 24 Aug 2007 12:11:54 +0200
> "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
>
> > Index: linux-2.6.23-rc3/include/asm-x86_64/suspend.h
> > ===================================================================
> > --- linux-2.6.23-rc3.orig/include/asm-x86_64/suspend.h 2007-08-21 20:36:49.000000000 +0200
> > +++ linux-2.6.23-rc3/include/asm-x86_64/suspend.h 2007-08-21 20:37:47.000000000 +0200
> > @@ -43,4 +43,10 @@ extern void fix_processor_context(void);
> > /* routines for saving/restoring kernel state */
> > extern int acpi_save_state_mem(void);
> >
> > +#define ARCH_HAS_HIBERNATION_HEADER
>
> The preferred way of doing this is via Kconfig, please. ie: add a
> CONFIG_HIBERNATION_HEADER to arch/x86_64/Kconfig.

OK

> > +
> > +/* arch/x86_64/kernel/suspend.c */
> > +extern int arch_hibernation_header_save(void *addr, unsigned int max_size);
> > +extern int arch_hibernation_header_restore(void *addr);
>
> Given that these are called from non-arch-specific code, they must have the
> same signature across all architectures. So there's no point in putting
> the prototypes into an arch-specific header file.
>
> It would be better to do something like this in (say) suspend.h:
>
> #ifdef CONFIG_HIBERNATION_HEADER
> extern int arch_hibernation_header_save(void *addr, unsigned int max_size);
> extern int arch_hibernation_header_restore(void *addr);
> #else
> static inline int arch_hibernation_header_save(void *addr,
> unsigned int max_size)
> {
> return 0;
> }
>
> static inline int arch_hibernation_header_restore(void *addr)
> {
> return 0;
> }
> #endif
>
> then go nuke some ifdefs from the .c files.

The ifdefs in snapshot.c are necessary anyway, because they are around some
code that is only compiled when the CONFIG_HIBERNATION_HEADER is undefined.

I'll post the reworked patches in a new thread once again after the other issue
raised by Pavel gets settled.