Re: [Qemu-devel] [RFC PATCH] target-arm: protect cpu_exclusive_*.

[Mark Burton]

> On 17 Dec 2014, at 11:28, Alexander Graf <address@hidden> wrote:
> 
> 
> 
> On 17.12.14 11:27, Frederic Konrad wrote:
>> On 16/12/2014 17:37, Peter Maydell wrote:
>>> On 16 December 2014 at 09:13,  <address@hidden> wrote:
>>>> From: KONRAD Frederic <address@hidden>
>>>> 
>>>> This adds a lock to avoid multiple exclusive access at the same time
>>>> in case of
>>>> TCG multithread.
>> Hi Peter,
>> 
>>> This feels to me like it's not really possible to review on
>>> its own, since you can't see how it fits into the design of
>>> the rest of the multithreading support.
>> true the only thing we observe is that it didn't change anything right now.
>> 
>>> The other approach here rather than having a pile of mutexes
>>> in the target-* code would be to have TCG IR support for
>>> "begin critical section"/"end critical section". Then you
>>> could have the main loop ensure that no other CPU is running
>>> at the same time as the critical-section code. (linux-user
>>> already has an ad-hoc implementation of this for the
>>> exclusives.)
>>> 
>>> -- PMM
>>> 
>> What do you mean by TCG IR?
> 
> TCP ops. The nice thing is that TCG could translate those into
> transactions if the host supports them as well.
> 

Hows that different in reality from what we have now?
Cheers
Mark.

> 
> Alex


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        mark.burton