1 files changed, 26 insertions, 0 deletions

diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c
index 033c8a9f000..f3c69329e14 100644
--- a/arch/ia64/sn/kernel/sn2/sn2_smp.c
+++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c
@@ -40,6 +40,7 @@
 #include <asm/sn/shub_mmr.h>
 #include <asm/sn/nodepda.h>
 #include <asm/sn/rw_mmr.h>
+#include <asm/sn/sn_feature_sets.h>
 
 DEFINE_PER_CPU(struct ptc_stats, ptcstats);
 DECLARE_PER_CPU(struct ptc_stats, ptcstats);
@@ -429,6 +430,31 @@ void sn2_send_IPI(int cpuid, int vector, int delivery_mode, int redirect)
         sn_send_IPI_phys(nasid, physid, vector, delivery_mode);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/**
+ * sn_cpu_disable_allowed - Determine if a CPU can be disabled.
+ * @cpu - CPU that is requested to be disabled.
+ *
+ * CPU disable is only allowed on SHub2 systems running with a PROM
+ * that supports CPU disable. It is not permitted to disable the boot processor.
+ */
+bool sn_cpu_disable_allowed(int cpu)
+{
+        if (is_shub2() && sn_prom_feature_available(PRF_CPU_DISABLE_SUPPORT)) {
+                if (cpu != 0)
+                        return true;
+                else
+                        printk(KERN_WARNING
+                              "Disabling the boot processor is not allowed.\n");
+
+        } else
+                printk(KERN_WARNING
+                       "CPU disable is not supported on this system.\n");
+
+        return false;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 #ifdef CONFIG_PROC_FS
 
 #define PTC_BASENAME    "sgi_sn/ptc_statistics"