From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
mingo@kernel.org
Cc: stern@rowland.harvard.edu, parri.andrea@gmail.com,
will.deacon@arm.com, peterz@infradead.org, boqun.feng@gmail.com,
npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
luc.maranget@inria.fr, willy@infradead.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Arnd Bergmann <arnd@arndb.de>,
David Laight <David.Laight@ACULAB.COM>,
linux-doc@vger.kernel.org,
"Paul E . McKenney" <paulmck@linux.ibm.com>
Subject: [PATCH RFC LKMM 5/7] docs/memory-barriers.txt: Enforce heavy ordering for port I/O accesses
Date: Wed, 9 Jan 2019 13:07:46 -0800 [thread overview]
Message-ID: <20190109210748.29074-5-paulmck@linux.ibm.com> (raw)
In-Reply-To: <20190109210706.GA27268@linux.ibm.com>
From: Will Deacon <will.deacon@arm.com>
David Laight explains:
| A long time ago there was a document from Intel that said that
| inb/outb weren't necessarily synchronised wrt memory accesses.
| (Might be P-pro era). However no processors actually behaved that
| way and more recent docs say that inb/outb are fully ordered.
This also reflects the situation on other architectures, the the port
accessor macros tend to be implemented in terms of readX/writeX.
Update Documentation/memory-barriers.txt to reflect reality.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <linux-arch@vger.kernel.org>
Cc: <linux-doc@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
Documentation/memory-barriers.txt | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 1c22b21ae922..a70104e2a087 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -2619,10 +2619,8 @@ functions:
intermediary bridges (such as the PCI host bridge) may not fully honour
that.
- They are guaranteed to be fully ordered with respect to each other.
-
- They are not guaranteed to be fully ordered with respect to other types of
- memory and I/O operation.
+ They are guaranteed to be fully ordered with respect to each other and
+ also with respect to other types of memory and I/O operation.
(*) readX(), writeX():
--
2.17.1
next prev parent reply other threads:[~2019-01-09 21:08 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 21:07 [PATCH RFC memory-model 0/6] LKMM updates Paul E. McKenney
2019-01-09 21:07 ` [PATCH RFC LKMM 1/7] tools/memory-model: Rename some RCU relations Paul E. McKenney
2019-01-09 21:07 ` [PATCH RFC LKMM 2/7] tools/memory-model: Refactor " Paul E. McKenney
2019-01-09 21:07 ` [PATCH RFC LKMM 3/7] tools/memory-model: Add SRCU support Paul E. McKenney
2019-01-09 21:07 ` [PATCH RFC LKMM 4/7] tools/memory-model: Update README for addition of SRCU Paul E. McKenney
2019-01-09 21:07 ` Paul E. McKenney [this message]
2019-01-11 9:53 ` [PATCH RFC LKMM 5/7] docs/memory-barriers.txt: Enforce heavy ordering for port I/O accesses Peter Zijlstra
2019-02-11 15:30 ` Will Deacon
2019-02-11 17:11 ` Arnd Bergmann
2019-02-11 17:32 ` Will Deacon
2019-01-09 21:07 ` [PATCH RFC LKMM 6/7] tools/memory-model: Update Documentation/explanation.txt to include SRCU support Paul E. McKenney
2019-01-09 21:07 ` [PATCH RFC LKMM 7/7] tools/memory-model: Dynamically check SRCU lock-to-unlock matching Paul E. McKenney
2019-01-10 9:41 ` Andrea Parri
2019-01-10 14:40 ` Paul E. McKenney
2019-01-10 23:20 ` Andrea Parri
2019-01-11 21:44 ` Paul E. McKenney
2019-01-11 21:57 ` Alan Stern
2019-01-09 23:18 ` [PATCH RFC memory-model 0/6] LKMM updates Andrea Parri
2019-01-09 23:40 ` Paul E. McKenney
2019-01-10 0:39 ` Andrea Parri
2019-01-10 4:20 ` Paul E. McKenney
2019-01-10 8:40 ` Andrea Parri
2019-01-10 14:31 ` Paul E. McKenney
2019-01-10 15:41 ` Alan Stern
2019-01-10 16:31 ` Paul E. McKenney
2019-01-10 22:46 ` Andrea Parri
2019-01-10 15:47 ` Alan Stern
2019-01-10 19:03 ` Paul E. McKenney
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