[IA64] SN: Add support for CPU disable

Add additional support for CPU disable on SN platforms.
Correctly setup the smp_affinity mask for I/O error IRQs.
Restrict the use of the feature to Altix 4000 and 450 systems
running with a CPU disable capable PROM, and do not allow disabling
of CPU 0.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 62209dcf06d3..308772f7cddc 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -58,6 +58,7 @@
 #include <asm/system.h>
 #include <asm/tlbflush.h>
 #include <asm/unistd.h>
+#include <asm/sn/arch.h>
 
 #define SMP_DEBUG 0
 
@@ -730,6 +731,11 @@ int __cpu_disable(void)
                 return (-EBUSY);
         }
 
+        if (ia64_platform_is("sn2")) {
+                if (!sn_cpu_disable_allowed(cpu))
+                        return -EBUSY;
+        }
+
         cpu_clear(cpu, cpu_online_map);
 
         if (migrate_platform_irqs(cpu)) {