[PATCH] x86-64: Use largest APIC number, not number of CPUs to decide on physflat mode

Handles case where BIOS gives CPUs very large APIC numbers correctly.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/x86_64/kernel/genapic.c b/arch/x86_64/kernel/genapic.c
index b1c144f73149..f3159a496e39 100644
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -45,7 +45,7 @@ void __init clustered_apic_check(void)
         u8 clusters, max_cluster;
         u8 id;
         u8 cluster_cnt[NUM_APIC_CLUSTERS];
-        int num_cpus = 0;
+        int max_apic = 0;
 
 #if defined(CONFIG_ACPI)
         /*
@@ -64,7 +64,8 @@ void __init clustered_apic_check(void)
                 id = bios_cpu_apicid[i];
                 if (id == BAD_APICID)
                         continue;
-                num_cpus++;
+                if (id > max_apic)
+                        max_apic = id;
                 cluster_cnt[APIC_CLUSTERID(id)]++;
         }
 
@@ -79,7 +80,7 @@ void __init clustered_apic_check(void)
                    we have ACPI platform support for CPU hotplug
                    we should detect hotplug capablity from ACPI tables and
                    only do this when really needed. -AK */
-                if (num_cpus <= 8)
+                if (max_apic <= 8)
                         genapic = &apic_flat;
 #endif
                 goto print;