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From: Richard Henderson <rth@twiddle.net>
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Date: Thu, 8 Sep 2016 09:26:13 -0700
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Subject: Re: [Qemu-devel] [PATCH v2 07/27] tcg: Add EXCP_ATOMIC
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To: =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>
Cc: qemu-devel@nongnu.org, cota@braap.org, pbonzini@redhat.com, peter.maydell@linaro.org, serge.fdrv@gmail.com

On 09/08/2016 01:38 AM, Alex Bennée wrote:
>> +            } else if (r == EXCP_ATOMIC) {
>> > +                /* ??? When we begin running cpus in parallel, we should
>> > +                   stop all cpus, clear parallel_cpus, and interpret a
>> > +                   single insn with cpu_exec_step.  In the meantime,
>> > +                   we should never get here.  */
>> > +                abort();
> Pranith has been hitting this abort in the latest merged tree with MTTCG
> but I'm a little unclear how it got here. So is the plan the MTTCG
> thread function should do a step_atomic a-la user mode but we'll never
> get here in the single threaded case?
> 

Yes, that's the plan.  I guess I could have filled in that blank, but I see
that I haven't even done that in the v3 patchset.


r~