changeset 047bd5f02c6e in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=047bd5f02c6e
description:
Packet: Updated comments for src and dest fields
This patch updates the comments for the src and dest fields to reflect
their actual use. Due to a number of patches (e.g. removing the
Broadcast flag), the old comments are no longer indicative of the
current usage.
diffstat:
src/mem/packet.hh | 35 +++++++++++++++++++++--------------
1 files changed, 21 insertions(+), 14 deletions(-)
diffs (63 lines):
diff -r 120ba616606e -r 047bd5f02c6e src/mem/packet.hh
--- a/src/mem/packet.hh Wed May 30 05:28:06 2012 -0400
+++ b/src/mem/packet.hh Wed May 30 05:29:07 2012 -0400
@@ -295,19 +295,26 @@
unsigned size;
/**
- * Device address (e.g., bus ID) of the source of the
- * transaction. The source is not responsible for setting this
- * field; it is set implicitly by the interconnect when the packet
- * is first sent.
+ * Source port identifier set on a request packet to enable
+ * appropriate routing of the responses. The source port
+ * identifier is set by any multiplexing component, e.g. a bus, as
+ * the timing responses need this information to be routed back to
+ * the appropriate port at a later point in time. The field can be
+ * updated (over-written) as the request packet passes through
+ * additional multiplexing components, and it is their
+ * responsibility to remember the original source port identifier,
+ * for example by using an appropriate sender state. The latter is
+ * done in the cache and bridge.
*/
NodeID src;
/**
- * Device address (e.g., bus ID) of the destination of the
- * transaction. The special value Broadcast indicates that the
- * packet should be routed based on its address. This field is
- * initialized in the constructor and is thus always valid (unlike
- * addr, size, and src).
+ * Destination port identifier that is present on all response
+ * packets that passed through a multiplexing component as a
+ * request packet. The source port identifier is turned into a
+ * destination port identifier when the packet is turned into a
+ * response, and the destination is used, e.g. by the bus, to
+ * select the appropriate path through the interconnect.
*/
NodeID dest;
@@ -527,8 +534,7 @@
/**
* Constructor. Note that a Request object must be constructed
* first, but the Requests's physical address and size fields need
- * not be valid. The command and destination addresses must be
- * supplied.
+ * not be valid. The command must be supplied.
*/
Packet(Request *_req, MemCmd _cmd)
: cmd(_cmd), req(_req), data(NULL),
@@ -620,9 +626,10 @@
/**
* Take a request packet and modify it in place to be suitable for
- * returning as a response to that request. The source and
- * destination fields are *not* modified, as is appropriate for
- * atomic accesses.
+ * returning as a response to that request. The source field is
+ * turned into the destination, and subsequently cleared. Note
+ * that the latter is not necessary for atomic requests, but
+ * causes no harm as neither field is valid.
*/
void
makeResponse()
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