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Date: Wed, 22 Jul 2015 15:44:12 +0200
From: Andrew Jones <drjones@redhat.com>
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Subject: Re: [Qemu-devel] Self-modifying test case for mttcg
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: mttcg@greensocs.com, Mark Burton <mark.burton@greensocs.com>, Alexander Spyridakis <a.spyridakis@virtualopensystems.com>, Claudio Fontana <Claudio.Fontana@huawei.com>, QEMU Developers <qemu-devel@nongnu.org>, Alvise Rigo <a.rigo@virtualopensystems.com>, Jani Kokkonen <Jani.Kokkonen@huawei.com>, Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>, KONRAD =?iso-8859-1?Q?Fr=E9d=E9ric?= <fred.konrad@greensocs.com>

On Wed, Jul 22, 2015 at 03:06:03PM +0200, Paolo Bonzini wrote:
> 
> 
> On 22/07/2015 14:38, Andrew Jones wrote:
> > I took a quick look at this and see issues with the test code. First,
> > you're spinning on a stack variable with this,
> > 
> >     /* Wait for our turn */
> >     while(next_cpu != cpu);
> > 
> > next_cpu needs to be global, and incremented atomically. I haven't gotten
> > around to adding atomic_add/inc yet, but it would easy, and I'm happy to
> > do it, even yet this week.
> 
> You can just use __sync_fetch_and_add(&next_cpu, 1) too, so we don't end
> up with too much arch-specific code.

Ah yes, I should take more advantage of gcc-builtins in general.

drew