diff -r cb51609ddbe8 -r 56eeaad266cf src/proto/packet.proto
--- a/src/proto/packet.proto	Thu Mar 14 14:05:48 2013 +0000
+++ b/src/proto/packet.proto	Thu Mar 14 14:06:21 2013 +0000
@@ -52,11 +52,14 @@
 // the address, and the size in bytes. The optional flags are used to
 // capture the request flags that convey information about
 // cacheability, if the packet is an instruction fetch or prefetch or
-// not, etc.
+// not, etc. An optional id field is added for generic use to identify
+// the packet or the "owner" of the packet. An example of the latter
+// is the sequential id of an instruction, or the master id etc.
 message Packet {
   required uint64 tick = 1;
   required uint32 cmd = 2;
   required uint64 addr = 3;
   required uint32 size = 4;
   optional uint32 flags = 5;
+  optional uint64 id = 6;
 }