Fix a problem with tag->boundary inheritence that has existed since day one

and was propagated to nearly every platform.  The boundary of the child needs
to consider the boundary of the parent and pick the minimum of the two, not
the maximum.  However, if either is 0 then pick the appropriate one.
This bug was exposed by a recent change to ATA, which should now be fixed by
this change.  The alignment and maxsegsz tag attributes likely also need
a similar review in the near future.

This is a MT5 candidate.

Reviewed by: marcel
Submitted by: sos (in part)

1 files changed, 5 insertions, 6 deletions

diff --git a/sys/sparc64/sparc64/bus_machdep.c b/sys/sparc64/sparc64/bus_machdep.c
index d1cdac8..47f4183 100644
--- a/sys/sparc64/sparc64/bus_machdep.c
+++ b/sys/sparc64/sparc64/bus_machdep.c
@@ -255,12 +255,11 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 		    newtag->dt_lowaddr);
 		newtag->dt_highaddr = ulmax(parent->dt_highaddr,
 		    newtag->dt_highaddr);
-		/*
-		 * XXX Not really correct??? Probably need to honor boundary
-		 *     all the way up the inheritence chain.
-		 */
-		newtag->dt_boundary = ulmin(parent->dt_boundary,
-		    newtag->dt_boundary);
+                if (newtag->dt_boundary == 0)
+                        newtag->dt_boundary = parent->dt_boundary;
+                else if (parent->dt_boundary != 0)            
+			newtag->dt_boundary = ulmin(parent->dt_boundary,
+			    newtag->dt_boundary);
 		atomic_add_int(&parent->dt_ref_count, 1);
 	}