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authorAndrea Parri <andrea.parri@amarulasolutions.com>2019-06-29 23:10:44 +0200
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-08-09 10:28:57 -0700
commit6738ff85c3ee8073d5b030cb26241d0009d4ce29 (patch)
tree925debdeae5d0d6ff762c0fbfa881823db134723 /tools/memory-model/README
parent6240973e5661a83df24e35a9a9c2013496931e2b (diff)
tools/memory-model: Update the informal documentation
The formal memory consistency model has added support for plain accesses (and data races). While updating the informal documentation to describe this addition to the model is highly desirable and important future work, update the informal documentation to at least acknowledge such addition. Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: Jade Alglave <j.alglave@ucl.ac.uk> Cc: Luc Maranget <luc.maranget@inria.fr> Cc: "Paul E. McKenney" <paulmck@linux.ibm.com> Cc: Akira Yokosawa <akiyks@gmail.com> Cc: Daniel Lustig <dlustig@nvidia.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Acked-by: Alan Stern <stern@rowland.harvard.edu>
Diffstat (limited to 'tools/memory-model/README')
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1 files changed, 9 insertions, 9 deletions
diff --git a/tools/memory-model/README b/tools/memory-model/README
index 2b87f3971548..fc07b52f2028 100644
--- a/tools/memory-model/README
+++ b/tools/memory-model/README
@@ -167,15 +167,15 @@ scripts Various scripts, see scripts/README.
LIMITATIONS
===========
-The Linux-kernel memory model has the following limitations:
-
-1. Compiler optimizations are not modeled. Of course, the use
- of READ_ONCE() and WRITE_ONCE() limits the compiler's ability
- to optimize, but there is Linux-kernel code that uses bare C
- memory accesses. Handling this code is on the to-do list.
- For more information, see Documentation/explanation.txt (in
- particular, the "THE PROGRAM ORDER RELATION: po AND po-loc"
- and "A WARNING" sections).
+The Linux-kernel memory model (LKMM) has the following limitations:
+
+1. Compiler optimizations are not accurately modeled. Of course,
+ the use of READ_ONCE() and WRITE_ONCE() limits the compiler's
+ ability to optimize, but under some circumstances it is possible
+ for the compiler to undermine the memory model. For more
+ information, see Documentation/explanation.txt (in particular,
+ the "THE PROGRAM ORDER RELATION: po AND po-loc" and "A WARNING"
+ sections).
Note that this limitation in turn limits LKMM's ability to
accurately model address, control, and data dependencies.