Add padding to ring headers for future expansion.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/include/public/io/ring.h b/xen/include/public/io/ring.h
index 6f1df572d3e388a3572798f6ac392b167818d445..d509181ae097159f422221e73d7a180e5d63986e 100644 (file)
--- a/xen/include/public/io/ring.h
+++ b/xen/include/public/io/ring.h
@@ -71,6 +71,7 @@ union __name##_sring_entry {                                            \
 struct __name##_sring {                                                 \
     RING_IDX req_prod, req_event;                                       \
     RING_IDX rsp_prod, rsp_event;                                       \
+    uint8_t  pad[48];                                                   \
     union __name##_sring_entry ring[1]; /* variable-length */           \
 };                                                                      \
                                                                         \
@@ -114,6 +115,7 @@ typedef struct __name##_back_ring __name##_back_ring_t
 #define SHARED_RING_INIT(_s) do {                                       \
     (_s)->req_prod  = (_s)->rsp_prod  = 0;                              \
     (_s)->req_event = (_s)->rsp_event = 1;                              \
+    memset((_s)->pad, 0, sizeof((_s)->pad));                            \
 } while(0)
 
 #define FRONT_RING_INIT(_r, _s, __size) do {                            \