Index: sys/arm64/acpica/acpi_iort.c
===================================================================
--- sys/arm64/acpica/acpi_iort.c
+++ sys/arm64/acpica/acpi_iort.c
@@ -154,7 +154,7 @@
 	for (i = 0; i < node->nentries; i++, entry++) {
 		if (i == id_map)
 			continue;
-		if (entry->base <= id && id <= entry->end)
+		if (entry->base <= id && id < entry->end)
 			break;
 	}
 	if (i == node->nentries)
@@ -234,7 +234,8 @@
 	node->entries.mappings = mapping;
 	for (i = 0; i < node->nentries; i++, mapping++, map_entry++) {
 		mapping->base = map_entry->InputBase;
-		mapping->end = map_entry->InputBase + map_entry->IdCount - 1;
+		/* ARM DEN 0049D: "The number of IDs in the range minus one" */
+		mapping->end = map_entry->InputBase + map_entry->IdCount + 1;
 		mapping->outbase = map_entry->OutputBase;
 		mapping->out_node_offset = map_entry->OutputReference;
 		mapping->flags = map_entry->Flags;