[Patch] XPC fails to discover partitions with all nasids above 128.

[Holt <holt]

UV hardware defines 256 memory protection regions versus the baseline
64 with increasing size for the SN2 ia64.  This was overlooked when XPC
was modified to accomodate both UV and SN2.

Without this patch, a user could reconfigure their existing system and
suddenly disable cross-partition communications with no indication of
what has gone wrong.  It also prevents larger configurations from using
cross-partition communication.

Signed-off-by: Robin Holt <holt@xxxxxxx>
Cc: stable@xxxxxxxxxx
To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx

---

 drivers/misc/sgi-xp/xpc_partition.c |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

Index: pv1012187/drivers/misc/sgi-xp/xpc_partition.c
===================================================================
--- pv1012187.orig/drivers/misc/sgi-xp/xpc_partition.c	2010-11-11 15:01:51.963024726 -0600
+++ pv1012187/drivers/misc/sgi-xp/xpc_partition.c	2010-11-11 15:02:26.471574791 -0600
@@ -439,18 +439,23 @@ xpc_discovery(void)
 	 * nodes that can comprise an access protection grouping. The access
 	 * protection is in regards to memory, IOI and IPI.
 	 */
-	max_regions = 64;
 	region_size = xp_region_size;
 
-	switch (region_size) {
-	case 128:
-		max_regions *= 2;
-	case 64:
-		max_regions *= 2;
-	case 32:
-		max_regions *= 2;
-		region_size = 16;
-		DBUG_ON(!is_shub2());
+	if (is_uv())
+		max_regions = 256;
+	else {
+		max_regions = 64;
+
+		switch (region_size) {
+		case 128:
+			max_regions *= 2;
+		case 64:
+			max_regions *= 2;
+		case 32:
+			max_regions *= 2;
+			region_size = 16;
+			DBUG_ON(!is_shub2());
+		}
 	}
 
 	for (region = 0; region < max_regions; region++) {

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