Commit-ID: 8d4840e84871847ee1bae56a776907d08a9265f7 Gitweb: http://git.kernel.org/tip/8d4840e84871847ee1bae56a776907d08a9265f7 Author: David Howells <[email protected]> AuthorDate: Tue, 26 Apr 2016 10:22:06 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 28 Apr 2016 10:57:51 +0200
locking/Documentation: State purpose of memory-barriers.txt There has been some confusion about the purpose of memory-barriers.txt, so this commit adds a statement of purpose. Signed-off-by: David Howells <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- Documentation/memory-barriers.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index fb2dd35..8b11e54 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -19,6 +19,22 @@ in case of any doubt (and there are many) please ask. To repeat, this document is not a specification of what Linux expects from hardware. +The purpose of this document is twofold: + + (1) to specify the minimum functionality that one can rely on for any + particular barrier, and + + (2) to provide a guide as to how to use the barriers that are available. + +Note that an architecture can provide more than the minimum requirement +for any particular barrier, but if the architecure provides less than +that, that architecture is incorrect. + +Note also that it is possible that a barrier may be a no-op for an +architecture because the way that arch works renders an explicit barrier +unnecessary in that case. + + ======== CONTENTS ========
