diff --git a/include/l4/api/capability.h b/include/l4/api/capability.h
index 72ecc80..4b58399 100644
--- a/include/l4/api/capability.h
+++ b/include/l4/api/capability.h
@@ -89,8 +89,8 @@ struct capability {
 	/* Use count of resource */
 	unsigned long used;
 
-	/* User-defined attributes on capability (like devtypes) */
-       	unsigned int uattr;
+	/* User attributes on capability such as device type, irqno */
+       	u32 uattr[2];
 };
 
 #endif /* __API_CAPABILITY_H__ */
diff --git a/include/l4/generic/cap-types.h b/include/l4/generic/cap-types.h
index 657cc58..118f9b3 100644
--- a/include/l4/generic/cap-types.h
+++ b/include/l4/generic/cap-types.h
@@ -52,16 +52,17 @@
 #define CAP_DEVNUM_MASK			0xFFFF0000
 #define CAP_DEVNUM_SHIFT		16
 
-#define cap_is_devmem(c)		(c)->uattr
+#define cap_is_devmem(c)		(c)->uattr[0]
 #define cap_set_devtype(c, devtype)			\
-	{(c)->uattr &= ~CAP_DEVTYPE_MASK;		\
-	 (c)->uattr |= CAP_DEVTYPE_MASK & devtype;}
+	{(c)->uattr[0] &= ~CAP_DEVTYPE_MASK;		\
+	 (c)->uattr[0] |= CAP_DEVTYPE_MASK & devtype;}
 #define cap_set_devnum(c, devnum)			\
-	{(c)->uattr &= ~CAP_DEVNUM_MASK;		\
-	 (c)->uattr |= CAP_DEVNUM_MASK & devnum;}
+	{(c)->uattr[0] &= ~CAP_DEVNUM_MASK;		\
+	 (c)->uattr[0] |= CAP_DEVNUM_MASK & devnum;}
 #define cap_devnum(c)					\
-	(((c)->uattr & CAP_DEVNUM_MASK) >> CAP_DEVNUM_SHIFT)
-#define cap_devtype(c)		((c)->uattr & CAP_DEVTYPE_MASK)
+	(((c)->uattr[0] & CAP_DEVNUM_MASK) >> CAP_DEVNUM_SHIFT)
+#define cap_devtype(c)		((c)->uattr[0] & CAP_DEVTYPE_MASK)
+#define cap_irqno(c)	((c)->uattr[1])
 
 /*
  * Access permissions
diff --git a/include/l4/generic/container.h b/include/l4/generic/container.h
index 09c59ad..08e837b 100644
--- a/include/l4/generic/container.h
+++ b/include/l4/generic/container.h
@@ -60,7 +60,7 @@ struct cap_info {
 	unsigned long start;
 	unsigned long end;
 	unsigned long size;
-	unsigned int uattr;	/* User-level attributes (like device types) */
+	unsigned int uattr[2];	/* User-level attributes (like device types) */
 };
 
 
diff --git a/include/l4/generic/tcb.h b/include/l4/generic/tcb.h
index 799ec77..b160d75 100644
--- a/include/l4/generic/tcb.h
+++ b/include/l4/generic/tcb.h
@@ -48,6 +48,7 @@ static inline l4id_t tid_to_cid(l4id_t tid)
 	return (tid & TASK_CID_MASK) >> TASK_CID_SHIFT;
 }
 
+/* Values that rather have special meaning instead of an id value */
 static inline int tid_special_value(l4id_t id)
 {
 	/* Special ids have top 2 nibbles all set */
diff --git a/src/generic/resource.c b/src/generic/resource.c
index 3992102..d65114d 100644
--- a/src/generic/resource.c
+++ b/src/generic/resource.c
@@ -336,7 +336,7 @@ int memcap_request_device(struct cap_list *cap_list,
 	list_foreach_removable_struct(cap, n, &cap_list->caps, list) {
 		if (cap->start == devcap->start &&
 		    cap->end == devcap->end &&
-		    cap->uattr == devcap->uattr) {
+		    cap_is_devmem(cap)) {
 			/* Unlink only. This is boot memory */
 			list_remove(&cap->list);
 			return 0;
@@ -347,7 +347,7 @@ int memcap_request_device(struct cap_list *cap_list,
 	       "capabilities start=0x%lx, end=0x%lx "
 	       "uattr=0x%x\n", __KERNELNAME__,
 	       __pfn_to_addr(devcap->start),
-	       __pfn_to_addr(devcap->end), devcap->uattr);
+	       __pfn_to_addr(devcap->end), devcap->uattr[0]);
 	BUG();
 }
 
@@ -849,7 +849,7 @@ int process_cap_info(struct cap_info *cap,
 			     &kres->virtmem_free,
 			     cap->start, cap->end);
 	} else if (cap_type(cap) == CAP_TYPE_MAP_PHYSMEM) {
-		if (!cap_is_devmem(cap))
+		if (cap_is_devmem(cap))
 			memcap_unmap(&kres->physmem_used,
 				     &kres->physmem_free,
 				     cap->start, cap->end);