[PATCH] Make Intel 8-way Xeons boot again

From: Ananth N Mavinakayanahalli
Date: Sat Jan 09 2010 - 05:11:49 EST


On an 8-way system with Intel Xeon X7350 CPUs, booting 2.6.32 or newer
kernels fails at:

...
CPU0: Intel(R) Xeon(R) CPU X7350 @ 2.93GHz stepping 0b
Booting Node 0, Processors #1 #2 #3 #4 #5 #6 #7 Ok.
Brought up 8 CPUs
Total of 8 processors activated (46906.05 BogoMIPS).

Git bisect showed 2fbd07a5f as the offending commit.

With the patch below, I am able to boot the latest Linus' git tree on
the machine. If this patch is correct, it needs to get into the stable
tree too.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
---
Index: linux-2.6/arch/x86/kernel/apic/probe_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/probe_64.c 2010-01-09 14:54:29.000000000 +0530
+++ linux-2.6/arch/x86/kernel/apic/probe_64.c 2010-01-09 14:57:53.000000000 +0530
@@ -70,7 +70,7 @@
if (apic == &apic_flat) {
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_INTEL:
- if (num_processors > 8)
+ if (num_processors >= 8)
apic = &apic_physflat;
break;
case X86_VENDOR_AMD:
--
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