1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index 62c2e747af58..4c161c208d5b 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -60,6 +60,7 @@
 #include <asm/irq.h>
 #include <asm/hw_irq.h>
 #include <asm/numa.h>
+#include <asm/genapic.h>
 
 /* Number of siblings per CPU package */
 int smp_num_siblings = 1;
@@ -1167,6 +1168,13 @@ int __cpuinit __cpu_up(unsigned int cpu)
 
         while (!cpu_isset(cpu, cpu_online_map))
                 cpu_relax();
+
+        if (num_online_cpus() > 8 && genapic == &apic_flat) {
+                printk(KERN_WARNING
+                       "flat APIC routing can't be used with > 8 cpus\n");
+                BUG();
+        }
+
         err = 0;
 
         return err;