From: Will Deacon <will.deacon@arm.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [RFC][PATCH v3]: documentation,atomic: Add new documents
Date: Wed, 2 Aug 2017 09:46:54 +0100 [thread overview]
Message-ID: <20170802084653.GD15219@arm.com> (raw)
In-Reply-To: <20170801221818.GN3730@linux.vnet.ibm.com>
On Tue, Aug 01, 2017 at 03:18:18PM -0700, Paul E. McKenney wrote:
> On Tue, Aug 01, 2017 at 06:42:00PM +0200, Peter Zijlstra wrote:
> > On Tue, Aug 01, 2017 at 09:14:12AM -0700, Paul E. McKenney wrote:
> > > So if ARM really needs the litmus test with smp_rmb() to be allowed,
> > > we need to adjust the Linux-kernel memory model appropriately. Which
> > > means that one of us needs to reach out to the usual suspects. Would
> > > you like to do that, or would you like me to?
> >
> > I'm really sad ARM8.1 LSE breaks this stuff.. It is rather counter
> > intuitive (then again, we _are_ talking barriers).
>
> No argument.
>
> Then again, when we said that the Linux kernel memory model would
> have a non-trivial rate of change, we weren't joking.
>
> Will, is this the official description?
>
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0557a.b/index.html
>
> If so, is B6.1 what we should be looking at?
Sorry it's so tricky to find. The architecture document is here:
https://static.docs.arm.com/ddi0487/b/DDI0487B_a_armv8_arm.pdf
and in section C3.2.13 ("Atomic memory operations") it states:
| The ST<OP> instructions are not regarded as doing a read for the purpose
| of a DMB LD barrier.
Will
next prev parent reply other threads:[~2017-08-02 8:46 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-09 9:24 [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Peter Zijlstra
2017-06-09 11:05 ` [RFC][PATCH] atomic: Fix atomic_set_release() for 'funny' architectures Peter Zijlstra
2017-06-09 11:13 ` Peter Zijlstra
2017-06-09 17:28 ` Vineet Gupta
2017-06-09 17:28 ` Vineet Gupta
2017-06-09 18:49 ` Peter Zijlstra
2017-06-09 18:49 ` Peter Zijlstra
2017-06-09 18:58 ` James Bottomley
2017-06-09 14:03 ` Chris Metcalf
2017-08-10 12:10 ` [tip:locking/core] locking/atomic: " tip-bot for Peter Zijlstra
2017-06-09 15:44 ` [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Will Deacon
2017-06-09 19:36 ` Peter Zijlstra
2017-06-11 13:56 ` Boqun Feng
2017-06-12 14:49 ` Peter Zijlstra
2017-06-13 6:39 ` Boqun Feng
2017-06-14 12:33 ` Will Deacon
2017-07-12 12:53 ` Boqun Feng
2017-07-12 13:08 ` Peter Zijlstra
2017-07-12 19:13 ` Paul E. McKenney
2017-07-26 11:53 ` [RFC][PATCH v3]: documentation,atomic: Add new documents Peter Zijlstra
2017-07-26 12:47 ` Boqun Feng
2017-07-31 9:05 ` Peter Zijlstra
2017-07-31 11:04 ` Boqun Feng
2017-07-31 17:43 ` Paul E. McKenney
2017-08-01 2:14 ` Boqun Feng
2017-08-01 9:01 ` Peter Zijlstra
2017-08-01 10:19 ` Will Deacon
2017-08-01 11:47 ` Peter Zijlstra
2017-08-01 12:17 ` Will Deacon
2017-08-01 12:52 ` Peter Zijlstra
2017-08-01 16:14 ` Paul E. McKenney
2017-08-01 16:42 ` Peter Zijlstra
2017-08-01 16:53 ` Will Deacon
2017-08-01 22:18 ` Paul E. McKenney
2017-08-02 8:46 ` Will Deacon [this message]
2017-08-01 18:37 ` Paul E. McKenney
2017-08-02 9:45 ` Will Deacon
2017-08-02 16:17 ` Paul E. McKenney
2017-08-03 14:05 ` Boqun Feng
2017-08-03 14:55 ` Paul E. McKenney
2017-08-03 16:12 ` Will Deacon
2017-08-03 16:58 ` Paul E. McKenney
2017-08-01 13:35 ` Paul E. McKenney
2017-07-26 16:28 ` Randy Dunlap
2017-06-09 18:15 ` [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Randy Dunlap
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