From: Richard Henderson <rth@twiddle.net>
To: Nathan Froyd <froydnj@codesourcery.com>
Cc: qemu-devel@nongnu.org, aurelien@aurel32.net
Subject: Re: [Qemu-devel] [PATCH 09/10] target-alpha: Implement load-locked/store-conditional properly.
Date: Thu, 25 Mar 2010 08:46:06 -0700 [thread overview]
Message-ID: <4BAB853E.1070303@twiddle.net> (raw)
In-Reply-To: <20100325133920.GS16726@codesourcery.com>
On 03/25/2010 06:39 AM, Nathan Froyd wrote:
> On Wed, Mar 24, 2010 at 05:11:43PM -0700, Richard Henderson wrote:
>> Use __sync_bool_compare_and_swap to yield correctly atomic results.
>> As yet, this assumes running on an strict-memory-ordering host (i.e. x86),
>> since we're still "implementing" the memory-barrier instructions as nops.
>
> Did the approach taken by other targets (arm/mips/ppc) not work on
> Alpha?
Mips doesn't even pretend to be atomic.
Powerpc and Arm -- if I've got this straight -- use some sort of stop-the-world
mutex+condition and then perform the compare-and-exchange by hand. I can't
see how that's better than using an actual compare-and-exchange provided by
the host cpu. In fact, I'm mildly horrified by the prospect.
Honestly. Even ARM and HPPA which doesn't (always) natively have cmpxchg, have
an easy to use kernel trap to perform the operation. I suppose real 80386 and
sparc-pre-v9 don't have anything particularly useful, but frankly it wouldn't
bother me to deprecate them as hosts since the modern editions all do work.
r~
next prev parent reply other threads:[~2010-03-25 15:46 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-25 0:24 [Qemu-devel] [PATCH 00/10, v3] target-alpha improvements Richard Henderson
2010-03-12 18:31 ` [Qemu-devel] [PATCH 01/10] target-alpha: Add flags markups to helpers.h Richard Henderson
2010-03-12 19:22 ` [Qemu-devel] [PATCH 02/10] target-alpha: Implement cpys{, n, e} inline Richard Henderson
2010-03-15 14:49 ` [Qemu-devel] [PATCH 03/10] target-alpha: Implement rs/rc properly Richard Henderson
2010-03-15 15:38 ` [Qemu-devel] [PATCH 05/10] target-alpha: Implement cvtlq inline Richard Henderson
2010-03-16 20:04 ` [Qemu-devel] [PATCH 06/10] target-alpha: Use setcond for int comparisons Richard Henderson
2010-03-16 21:44 ` [Qemu-devel] [PATCH 07/10] target-alpha: Use non-inverted arguments to gen_{f}cmov Richard Henderson
2010-03-16 22:10 ` [Qemu-devel] [PATCH 08/10] target-alpha: Emit goto_tb opcodes Richard Henderson
2010-03-19 22:55 ` [Qemu-devel] [PATCH 04/10] target-alpha: Implement cvtql inline Richard Henderson
2010-03-25 0:11 ` [Qemu-devel] [PATCH 09/10] target-alpha: Implement load-locked/store-conditional properly Richard Henderson
2010-03-25 13:39 ` Nathan Froyd
2010-03-25 15:46 ` Richard Henderson [this message]
2010-03-25 16:06 ` Nathan Froyd
2010-03-25 16:29 ` Richard Henderson
2010-03-25 16:42 ` Nathan Froyd
2010-03-25 16:50 ` Richard Henderson
2010-03-25 17:40 ` Blue Swirl
2010-03-25 18:19 ` Richard Henderson
2010-03-26 1:55 ` Jamie Lokier
2010-03-26 2:01 ` Jamie Lokier
2010-03-25 0:13 ` [Qemu-devel] [PATCH 10/10] target-alpha: Enable NPTL Richard Henderson
2010-03-26 1:52 ` [Qemu-devel] [PATCH 00/10, v3] target-alpha improvements Jamie Lokier
2010-03-26 13:37 ` Richard Henderson
2010-04-01 13:44 ` Paul Brook
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