Messages in this thread Patch in this message | | | Date | Wed, 20 Jan 2010 20:15:31 -0800 | From | Greg KH <> | Subject | [10/30] x86, apic: use physical mode for IBM summit platforms |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Suresh Siddha <suresh.b.siddha@intel.com>
commit dfea91d5a7c795fd6f4e1a97489a98e4e767463e upstream.
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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/kernel/apic/apic_flat_64.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/arch/x86/kernel/apic/apic_flat_64.c +++ b/arch/x86/kernel/apic/apic_flat_64.c @@ -240,6 +240,11 @@ static int physflat_acpi_madt_oem_check( 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;
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