From dfea91d5a7c795fd6f4e1a97489a98e4e767463e Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Mon, 18 Jan 2010 12:10:48 -0800 Subject: [PATCH] x86, apic: use physical mode for IBM summit platforms 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 Tested-by: Ananth N Mavinakayanahalli Cc: Chris McDermott Cc: Yinghai Lu Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- arch/x86/kernel/apic/apic_flat_64.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c index eacbd2b31d27..e3c3d820c325 100644 --- 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(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;