From: David Laight <David.Laight@ACULAB.COM>
To: "'paulmck@linux.ibm.com'" <paulmck@linux.ibm.com>,
Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
Peter Zijlstra <peterz@infradead.org>,
Will Deacon <Will.Deacon@arm.com>,
arcml <linux-snps-arc@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: RE: single copy atomicity for double load/stores on 32-bit systems
Date: Thu, 6 Jun 2019 16:34:52 +0000 [thread overview]
Message-ID: <8d1666df180d4d01aaebb5d41370b338@AcuMS.aculab.com> (raw)
In-Reply-To: <20190606094340.GD28207@linux.ibm.com>
From: Paul E. McKenney
> Sent: 06 June 2019 10:44
...
> But m68k is !SMP-only, correct? If so, the only issues would be
> interactions with interrupt handlers and the like, and doesn't current
> m68k hardware use exact interrupts? Or is it still possible to interrupt
> an m68k in the middle of an instruction like it was in the bad old days?
Hardware interrupts were always on instruction boundaries, the
mid-instruction interrupts would only happen for page faults (etc).
There were SMP m68k systems (but I can't remember one).
It was important to continue from a mid-instruction trap on the
same cpu - unless you could guarantee that all the cpus had
exactly the same version of the microcode.
In any case you could probably use the 'cmp2' instruction
for an atomic 64bit write.
OTOH setting that up was such a PITA it was always easier
to disable interrupts.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-06-06 16:34 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 18:22 single copy atomicity for double load/stores on 32-bit systems Vineet Gupta
2019-05-30 18:22 ` Vineet Gupta
2019-05-30 18:53 ` Paul E. McKenney
2019-05-30 18:53 ` Paul E. McKenney
2019-05-30 19:16 ` Vineet Gupta
2019-05-30 19:16 ` Vineet Gupta
2019-05-31 8:23 ` Peter Zijlstra
2019-05-31 8:23 ` Peter Zijlstra
2019-05-31 8:25 ` Peter Zijlstra
2019-05-31 8:25 ` Peter Zijlstra
2019-05-31 8:21 ` Peter Zijlstra
2019-05-31 8:21 ` Peter Zijlstra
2019-06-03 18:08 ` Vineet Gupta
2019-06-03 18:08 ` Vineet Gupta
2019-06-03 20:13 ` Paul E. McKenney
2019-06-03 20:13 ` Paul E. McKenney
2019-06-03 21:59 ` Vineet Gupta
2019-06-03 21:59 ` Vineet Gupta
2019-06-04 7:41 ` Geert Uytterhoeven
2019-06-04 7:41 ` Geert Uytterhoeven
2019-06-06 9:43 ` Paul E. McKenney
2019-06-06 9:43 ` Paul E. McKenney
2019-06-06 9:53 ` Geert Uytterhoeven
2019-06-06 9:53 ` Geert Uytterhoeven
2019-06-06 16:34 ` David Laight [this message]
2019-06-06 16:34 ` David Laight
2019-06-06 21:17 ` Paul E. McKenney
2019-06-06 21:17 ` Paul E. McKenney
2019-06-03 18:43 ` Vineet Gupta
2019-06-03 18:43 ` Vineet Gupta
2019-07-01 20:05 ` Vineet Gupta
2019-07-01 20:05 ` Vineet Gupta
2019-07-02 10:46 ` Will Deacon
2019-07-02 10:46 ` Will Deacon
2019-05-31 9:41 ` David Laight
2019-05-31 9:41 ` David Laight
2019-05-31 11:44 ` Paul E. McKenney
2019-05-31 11:44 ` Paul E. McKenney
2019-06-03 18:44 ` Vineet Gupta
2019-06-03 18:44 ` Vineet Gupta
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