Functional Accesses: Update states to support Broadcast/Snooping protocols.

In the current implementation of Functional Accesses, it's very hard to
implement broadcast or snooping protocols where the memory has no idea if it
has exclusive access to a cache block or not. Without this knowledge, making
sure the RW vs. RO permissions are right are next to impossible. So we add a
new state called Backing_Store to enable the conveyance that this is the backup
storage for a block, so that it can be written if it is the only possibly RW
block in the system, or written even if there is another RW block in the
system, without causing problems.

Also, a small change to actually set the m_name field for each Controller so
that debugging can be easier. Now you can access a controller's name just by
controller->getName().

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mem/protocol/RubySlicc_Exports.sm b/src/mem/protocol/RubySlicc_Exports.sm
index e8616521a..ca80047f7 100644
--- a/src/mem/protocol/RubySlicc_Exports.sm
+++ b/src/mem/protocol/RubySlicc_Exports.sm
@@ -63,6 +63,14 @@ enumeration(AccessPermission, desc="...", default="AccessPermission_NotPresent")
   // writes should update the block because a dataless PUT request may
   // revalidate the block's data.
   Maybe_Stale, desc="block can be stale or revalidated by a dataless PUT";
+  // In Broadcast/Snoop protocols, memory has no idea if it is exclusive owner
+  // or not of a block, making it hard to make the logic of having only one
+  // read_write block in the system impossible. This is to allow the memory to
+  // say, "I have the block" and for the RubyPort logic to know that this is a
+  // last-resort block if there are no writable copies in the caching hierarchy.
+  // This is not supposed to be used in directory or token protocols where
+  // memory/NB has an idea of what is going on in the whole system.
+  Backing_Store, desc="for memory in Broadcast/Snoop protocols";
 
   // Invalid data
   Invalid,    desc="block is in an Invalid base state";