CVS difference for ais/ai-00333.txt

Differences between 1.3 and version 1.4
Log of other versions for file ais/ai-00333.txt

--- ais/ai-00333.txt	2004/07/29 06:42:19	1.3
+++ ais/ai-00333.txt	2004/07/31 00:00:50	1.4
@@ -156,9 +156,67 @@
   a Locking_Policy (see D.3) also shall be specified for the partition.
 which is cleaner and has no magic semantics. However, that is option (3) and
-that got  less support at the meeting.
+that got less support at the meeting.
+From: Alan Burns
+Sent: Friday, July 30, 2004  3:07 AM
+Yes option 2 was a compromise. Wishing to keep the close association between
+FIFO and Ceiling Locking but not always requiring both. I agree that using a
+default does not fit well with Ada style, but the second suggestion you have
+was not supported by the straw votes. Does not seem to be a solution to this;
+but here is another possibility:
+  If the FIFO_Within_Priorities policy is specified for a partition, then
+  the Locking_Policy (see D.3) is Ceiling_Locking unless a different
+  Locking_Policy is defined for the partition.
+not sure this is any better!
+From: Tucker Taft
+Sent: Friday, July 30, 2004  4:47 AM
+Rather than "... unless a different Locking_Policy is defined..."
+perhaps something like "unless overridden by the explicit
+specification of some other Locking_Policy".
+I don't understand Randy's concern about knowing the locking policy
+in advance, since that is an existing problem.  If you must know
+the locking policy when generating code, then the implementation
+can require that it be specified prior to compiling any code
+in the environment, per 10.1.5(9).   In any case, all implementations have
+a default locking policy.  I don't see how we could possibly be sacrificing
+safety by specifying what this default is under certain
+circumstances.  Users can still specify Ceiling_Locking
+explicitly.  But now, if they *don't* specify the Locking_Policy
+but they do specify the dispatching policy, they get
+additional implementation uniformity.  That seems consistent
+with other attempts to achieve uniformity in the real-time annex.
+And my suspicion is that almost all implementations have
+Ceiling_Locking as the default, and almost no implementations
+currently enforce D.2.2(5).
+From: Tullio Vardanega
+Sent: Friday, July 30, 2004  11:06 AM
+I missed that part of the Palma meeting.
+If I were present I would have voted for option 3),
+which did not fly :-(
+To me, Alan's text as modified by Tucker has a better taste
+than Randy's initial cut at it, because it does not reason on
+the absence of, but on the presence of possibly overring
+locking_policy configuration.

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