Re: [Qemu-devel] [PATCH v2 1/8] kvm: Set cpu_single_env only once

[Andreas Färber]

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Am 11.02.2012 15:24, schrieb Jan Kiszka:
> On 2012-02-11 15:12, Andreas Färber wrote:
>> Am 11.02.2012 15:02, schrieb Jan Kiszka:
>>> On 2012-02-11 14:59, Andreas Färber wrote:
>>>> Am 11.02.2012 14:35, schrieb Jan Kiszka:
>>>>> On 2012-02-11 14:21, Andreas Färber wrote:
>>>>>> CPU base class v3:
>>>>>> http://patchwork.ozlabs.org/patch/139284/ (v4 coming up)
>>>>>> 
>>>>>> That doesn't prevent target-specific devices. Although
>>>>>> Paolo does want that to change wrt properties.
>>>> 
>>>>> This patch doesn't explain yet what shall happen to 
>>>>> cpu_single_env and CPUState accesses from target-specific 
>>>>> devices.
>>>> 
>>>> True. We can't change them before all targets are converted.
>>>> So far I have 3/14 and still some review comments to work
>>>> in.
>>>> 
>>>> Another patch in that series uses a macro 
>>>> s/ENV_GET_OBJECT/ENV_GET_CPU/ to go from CPUState -> CPU
>>>> while we convert targets.
>>>> 
>>>> Depending on our taste, cpu_single_env might become 
>>>> cpu_single_cpu, single_cpu or cpu_single.
>>>> 
>>>>> Do you plan accessors for registers?
>>>> 
>>>> No, registers are in target-specific ARMCPU, S390CPU,
>>>> MIPSCPU, etc. and their CPU*State. It would be possible to
>>>> have static inline accessors but so far I've seen no need.
>> 
>>> Then the devices need to have access to a CPUState pointer,
>>> just as so far.
>> 
>> Yes and no. They can have any target-specific pointer they want,
>> just as before. But no global first_cpu / cpu_single_env pointer
>> - that's
> 
> If you want to drop first_cpu, you need to provide a for_each_cpu 
> iterating service instead. And cpu_single_env can only be obsoleted
> if I/O access handlers can otherwise query the triggering CPU.

I already answered that above. Please join #qemu if you further want
to discuss that, for this thread seems to lead nowhere.

Andreas

> 
>> replaced by CPU pointers, through which members of derived
>> classes can be accessed (which did not work for CPUState due to
>> CPU_COMMON members being at target-specific offset in the
>> middle).
>> 
>> There's nothing wrong with your patch per se, just that it may
>> need to get refactored some time soonish. We need to be aware of
>> it so that we don't create merge conflicts for Anthony.
> 
> There can't be logical merge conflicts as the no fundamentally new 
> requirements are introduced with this series. And we have no code 
> proposal seen yet to address them already for the existing use
> cases.
> 
> Jan
> 


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