[RFC] mark Netlogic XLR chip as SMT capable

[Hillf Danton <dhillf@gmail.com>]

Netlogic XLR chip has multiple cores. Each core includes four integrated
hardware threads, and they share L1 data and instruction caches.

If XLR chip is marked to be SMT capable, linux scheduler then could do more,
say idle load balancing.

Any comment is welcom, thanks.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
---

--- a/arch/mips/netlogic/xlr/smp.c      Sun Oct  2 14:15:28 2011
+++ b/arch/mips/netlogic/xlr/smp.c      Sun Oct  2 14:15:58 2011
@@ -176,6 +176,7 @@ void __init nlm_smp_setup(void)

 void nlm_prepare_cpus(unsigned int max_cpus)
 {
+       smp_num_siblings = 4;
 }

 struct plat_smp_ops nlm_smp_ops = {
--- a/arch/mips/kernel/smp.c    Sun Oct  2 14:12:09 2011
+++ b/arch/mips/kernel/smp.c    Sun Oct  2 14:14:58 2011
@@ -73,7 +73,12 @@ static inline void set_cpu_sibling_map(i

        if (smp_num_siblings > 1) {
                for_each_cpu_mask(i, cpu_sibling_setup_map) {
-                       if (cpu_data[cpu].core == cpu_data[i].core) {
+                       if (current_cpu_type() == CPU_XLR) {
+                               if (((i>>2) & 0x7) == ((cpu>>2) & 0x7))
+                                       goto set;
+                       }
+                       else if (cpu_data[cpu].core == cpu_data[i].core) {
+set:
                                cpu_set(i, cpu_sibling_map[cpu]);
                                cpu_set(cpu, cpu_sibling_map[i]);
                        }