[PATCH] convert i386 Summit subarch to use SRAT info for apicid_to_node calls

Convert the i386 summit subarch apicid_to_node to use node information
provided by the SRAT.  It was discussed a little on LKML a few weeks ago
and was seen as an acceptable fix.  The current way of obtaining the nodeid

 static inline int apicid_to_node(int logical_apicid)
 {
   return logical_apicid >> 5;
 }

is just not correct for all summit systems/bios.  Assuming the apicid
matches the Linux node number require a leap of faith that the bios mapped
out the apicids a set way.  Modern summit HW (IBM x460) does not layout its
bios in the manner for various reasons and is unable to boot i386 numa.

The best way to get the correct apicid to node information is from the SRAT
table during boot.  It lays out what apicid belongs to what node.  I use
this information to create a table for use at run time.

Signed-off-by: Keith Mannthey <kmannth@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 020d873b7d21..82b26d5ce476 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -102,6 +102,8 @@ u8 x86_cpu_to_apicid[NR_CPUS] __read_mostly =
                         { [0 ... NR_CPUS-1] = 0xff };
 EXPORT_SYMBOL(x86_cpu_to_apicid);
 
+u8 apicid_2_node[MAX_APICID];
+
 /*
  * Trampoline 80x86 program as an array.
  */
@@ -645,7 +647,7 @@ static void map_cpu_to_logical_apicid(void)
 {
         int cpu = smp_processor_id();
         int apicid = logical_smp_processor_id();
-        int node = apicid_to_node(apicid);
+        int node = apicid_to_node(hard_smp_processor_id());
 
         if (!node_online(node))
                 node = first_online_node;
@@ -954,6 +956,7 @@ static int __devinit do_boot_cpu(int apicid, int cpu)
 
         irq_ctx_init(cpu);
 
+        x86_cpu_to_apicid[cpu] = apicid;
         /*
          * This grunge runs the startup process for
          * the targeted processor.