[PATCH] x86_64 genapic update

x86_64 genapic mechanism should be aware of machines that use physical APIC
mode regardless of how many clusters/processors are detected.

ACPI 3.0 FADT makes this determination very simple by providing a feature
flag "force_apic_physical_destination_mode" to state whether the machine
unconditionally uses physical APIC mode.

Unisys' next generation x86_64 ES7000 will need to utilize this FADT
feature flag in order to boot the x86_64 kernel in the correct APIC mode. 
This patch has been tested on both x86_64 commodity and ES7000 boxes.

Signed-off-by: Jason Davis <jason.davis@unisys.com>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/i386/kernel/acpi/boot.c b/arch/i386/kernel/acpi/boot.c
index 9ba0b957d11f..040451e90a04 100644
--- a/arch/i386/kernel/acpi/boot.c
+++ b/arch/i386/kernel/acpi/boot.c
@@ -608,6 +608,10 @@ static int __init acpi_parse_fadt(unsigned long phys, unsigned long size)
         acpi_fadt.sci_int = fadt->sci_int;
 #endif
 
+        /* initialize rev and apic_phys_dest_mode for x86_64 genapic */
+        acpi_fadt.revision = fadt->revision;
+        acpi_fadt.force_apic_physical_destination_mode = fadt->force_apic_physical_destination_mode;
+
 #ifdef CONFIG_X86_PM_TIMER
         /* detect the location of the ACPI PM Timer */
         if (fadt->revision >= FADT2_REVISION_ID) {