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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
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Date: Fri, 15 Jan 2016 14:51:31 +0000
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Subject: Re: [Qemu-devel] Status of my hacks on the MTTCG WIP branch
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To: alvise rigo <a.rigo@virtualopensystems.com>
Cc: MTTCG Devel <mttcg@listserver.greensocs.com>, Paolo Bonzini <pbonzini@redhat.com>, Pranith Kumar <bobby.prani@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>, KONRAD Frederic <fred.konrad@greensocs.com>


alvise rigo <a.rigo@virtualopensystems.com> writes:

> This problem could be related to a missing multi-threaded aware
> translation of the atomic instructions.
> I'm working on this missing piece, probably the next week I will
> publish something.

Maybe. We still have Fred's:

  Use atomic cmpxchg to atomically check the exclusive value in a STREX

Which I think papers over the cracks for both arm and aarch64 in MTTCG
while not being as correct as your work.

>
> Regards,
> alvise
>
> On Fri, Jan 15, 2016 at 3:24 PM, Pranith Kumar <bobby.prani@gmail.com> wrote:
>> Hi Alex,
>>
>> On Fri, Jan 15, 2016 at 8:53 AM, Alex Bennée <alex.bennee@linaro.org> wrote:
>>> Can you try this branch:
>>>
>>>
>>> https://github.com/stsquad/qemu/tree/mttcg/multi_tcg_v8_wip_ajb_fix_locks-r1
>>>
>>> I think I've caught all the things likely to screw up addressing.
>>>
>>
>> I tried this branch and the boot hangs like follows:
>>
>> [    2.001083] random: systemd-udevd urandom read with 1 bits of entropy
>> available
>> main-loop: WARNING: I/O thread spun for 1000 iterations
>> [   23.778970] INFO: rcu_sched detected stalls on CPUs/tasks: {} (detected
>> by 0, t=2102 jiffies, g=-165, c=-166, q=83)

This is just saying the kernel has been waiting for a while and nothing
has happened.

>> I will try to debug and see where it is hanging.

If we knew what the kernel was waiting for that would be useful to know.

>>
>> Thanks!
>> --
>> Pranith


--
Alex Bennée