Re: [PATCH] x86: Construct 32 bit boot time page tables in native format.

Rafael J. Wysocki
2008-02-01T14:30:33Z

On Friday, 1 of February 2008, Ingo Molnar wrote:
>
> * Rafael J. Wysocki <rjw@sisk.pl> wrote:
>
> > > arch/x86/kernel/built-in.o: In function `wakeup_start':
> > > : undefined reference to `swsusp_pg_dir'
> > >
> > > config attached.
> >
> > I see. CONFIG_HIBERNATION && CONFIG_ACPI -> CONFIG_ACPI_SLEEP and the
> > Makefile in arch/x86/kernel/acpi/ wants to build wakeup.S, which is
> > not necessary. Hmm.
> >
> > We can do a couple of things:
> > (1) make wakeup_$(BITS).o depend on CONFIG_SUSPEND (alone)
> > This will build it if CONFIG_SUSPEND is set, but CONFIG_ACPI is not
> > (still, that's consistent with the change in question).
> > (2) make wakeup_$(BITS).o depend on CONFIG_SUSPEND and CONFIG_ACPI
> > (3) define CONFIG_ACPI_SUSPEND depending on ACPI and SUSPEND and
> > make wakeup_$(BITS).o as well as swsusp_pg_dir depend on that (most
> > elegant)
> >
> > Which one do you prefer?
>
> no strong preference here - pick the one you like best and send a patch
> please :-)

Here you go, but I think it falls into the ACPI category.

---
From: Rafael J. Wysocki <rjw@sisk.pl>

Since hibernation uses its own temporary page tables for restoring
the image kernel, swsusp_pg_dir is only needed for ACPI resume from
RAM. Also, some files under arch/x86/kernel/acpi need only be compiled
if ACPI suspend to RAM is going to be used.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
arch/x86/kernel/acpi/Makefile | 2 +-
arch/x86/mm/init_32.c | 10 +++++-----
drivers/acpi/Kconfig | 5 +++++
3 files changed, 11 insertions(+), 6 deletions(-)

Index: linux-2.6/arch/x86/mm/init_32.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_32.c
+++ linux-2.6/arch/x86/mm/init_32.c
@@ -423,23 +423,23 @@ static void __init pagetable_init(void)
paravirt_pagetable_setup_done(pgd_base);
}

-#if defined(CONFIG_HIBERNATION) || defined(CONFIG_ACPI)
+#ifdef CONFIG_ACPI_SUSPEND
/*
- * Swap suspend & friends need this for resume because things like the intel-agp
+ * ACPI suspend needs this for resume, because things like the intel-agp
* driver might have split up a kernel 4MB mapping.
*/
-char __nosavedata swsusp_pg_dir[PAGE_SIZE]
+char swsusp_pg_dir[PAGE_SIZE]
__attribute__ ((aligned(PAGE_SIZE)));

static inline void save_pg_dir(void)
{
memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
}
-#else
+#else /* !CONFIG_ACPI_SUSPEND */
static inline void save_pg_dir(void)
{
}
-#endif
+#endif /* !CONFIG_ACPI_SUSPEND */

void zap_low_mappings(void)
{
Index: linux-2.6/drivers/acpi/Kconfig
===================================================================
--- linux-2.6.orig/drivers/acpi/Kconfig
+++ linux-2.6/drivers/acpi/Kconfig
@@ -42,6 +42,11 @@ menuconfig ACPI

if ACPI

+config ACPI_SUSPEND
+ bool
+ depends on SUSPEND
+ default y
+
config ACPI_SLEEP
bool
depends on PM_SLEEP
Index: linux-2.6/arch/x86/kernel/acpi/Makefile
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/Makefile
+++ linux-2.6/arch/x86/kernel/acpi/Makefile
@@ -1,5 +1,5 @@
obj-$(CONFIG_ACPI) += boot.o
-obj-$(CONFIG_ACPI_SLEEP) += sleep.o wakeup_$(BITS).o
+obj-$(CONFIG_ACPI_SUSPEND) += sleep.o wakeup_$(BITS).o

ifneq ($(CONFIG_ACPI_PROCESSOR),)
obj-y += cstate.o processor.o