From: Jamie Lokier <jamie@shareable.org>
To: Richard Henderson <rth@twiddle.net>
Cc: Blue Swirl <blauwirbel@gmail.com>,
Nathan Froyd <froydnj@codesourcery.com>,
qemu-devel@nongnu.org, aurelien@aurel32.net
Subject: Re: [Qemu-devel] [PATCH 09/10] target-alpha: Implement load-locked/store-conditional properly.
Date: Fri, 26 Mar 2010 01:55:45 +0000 [thread overview]
Message-ID: <20100326015545.GH19308@shareable.org> (raw)
In-Reply-To: <4BABA93C.9010305@twiddle.net>
Richard Henderson wrote:
> On 03/25/2010 10:40 AM, Blue Swirl wrote:
> > Sparc V8 has two atomic instructions, ldstub and swap.
>
> I know -- but not the CAS operation being discussed here.
>
> As I think about this more and more, the Real Problem is
> not with the CAS, but with the memory ordering requirements
> of the guest vs the memory ordering of the host. It's easy
> to implement things on x86, because of the host's strict
> memory ordering. It would be much more difficult to properly
> emulate x86 on a relaxed memory ordering host. We'd need to
> insert barriers between pairs of qemu_{ld,st} operations.
>
> I may give this some proper thinking this weekend.
Some host architectures have a strongly ordered mode, which might
help, and be faster than putting barriers everywhere.
-- Jamie
next prev parent reply other threads:[~2010-03-26 1:55 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
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 [this message]
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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