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x86, apic: use physical mode for IBM summit platforms

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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>
This commit is contained in:
Suresh Siddha 2010-01-18 12:10:48 -08:00 committed by Linus Torvalds
parent 54ef91dcf0
commit dfea91d5a7
1 changed files with 5 additions and 0 deletions
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arch/x86/kernel/apic/apic_flat_64.c
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@ -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;