x86, apic: use physical mode for IBM summit platforms
authorSuresh Siddha <suresh.b.siddha@intel.com>
Mon, 18 Jan 2010 20:10:48 +0000 (12:10 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 18 Jan 2010 22:15:27 +0000 (14:15 -0800)
Chris McDermott from IBM confirmed that hurricane chipset in IBM summit
platforms doesn't support logical flat mode.  Irrespective of the other
things like apic_id's, total number of logical cpu's, Linux kernel
should default to physical mode for this system.

The 32-bit kernel does so using the OEM checks for the IBM summit
platform.  Add a similar OEM platform check for the 64bit kernel too.

Otherwise the linux kernel boot can hang on this platform under certain
bios/platform settings.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Tested-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Chris McDermott <lcm@linux.vnet.ibm.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/x86/kernel/apic/apic_flat_64.c

index eacbd2b31d27c0b947c3949c2ece59b549c9007a..e3c3d820c325b2cdacd136358efeb31d815b6dd4 100644 (file)
@@ -240,6 +240,11 @@ static int physflat_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
                printk(KERN_DEBUG "system APIC only can use physical flat");
                return 1;
        }
+
+       if (!strncmp(oem_id, "IBM", 3) && !strncmp(oem_table_id, "EXA", 3)) {
+               printk(KERN_DEBUG "IBM Summit detected, will use apic physical");
+               return 1;
+       }
 #endif
 
        return 0;