Re: [Qemu-devel] [RFC PATCH] target-ppc: Add compatibility between P7/P7+ and P8E/P8

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 06/28/2014 02:14 AM, Alexander Graf wrote:
> 
> On 27.06.14 17:54, Alexey Kardashevskiy wrote:
>> At the moment POWER7+ and POWER7 CPUs are different incompatible
>> families in QOM. The same is valid for POWER8E and POWER8 CPUs.
>> However, these couples are architecturally equal and there is no
>> good reason, for example, not to let run -cpu POWER7 on the real
>> POWER7+ CPU machine.
>>
>> This introduces one more level in hierarchy of POWERPC CPU classes.
>> New macro POWERPC_FAMILY_2 takes a family class and the parent family
>> class and, for example, for POWER7+ the hierarchy looks like:
>> TYPE_CPU
>> TYPE_POWERPC_CPU
>> POWER7-powerpc64-cpu
>> POWER7+-powerpc64-cpu
>>
>> This registers new dynamic POWERPC CPU classes for all classes between
>> the lowest one which matches the real PVR and TYPE_POWERPC_CPU.
>> So for POWER7, it is still going to be just a single dynamic "POWER7"
>> class but for POWER7+ inherited from POWER7 there are going to be
>> 2 dynamic classes  - "POWER7+" and "POWER7" so management software
>> can use both to ensure successful migration.
>>
>> Since POWER7+ inherits from POWER7 and POWER8E from POWER8, this
>> removes recurring pieces of code. CPUs with shorter names were chosen
>> as parents.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>>
>> This is rather RFC patch and there is no hurry in reviewing this,
>> and this is not 2.1 material and everyhting, just tried to solve
>> a QOM puzzle here :)
> 
> I'm not sure - I'd rather make sure we have this sorted out for 2.1 so we
> can keep the -cpu list stable.
> 
> Could we make the PVR matching a function callback rather than value+mask?
> Then we could have p7 and p8 just match on 2 different PVR ranges.

POWER8:
>>> bin(0x4d)
'0b1001101'
>>> bin(0x4b)
'0b1001011'
>>> bin(0x4c)
'0b1001100'

4D == POWER8, 4B == POWER8E, 4C - does not exist and when it will, I do not
know what it is going to be.

POWER7:
>>> bin(0x3f)
'0b111111'
>>> bin(0x4a)
'0b1001010'
>>>


What should mask look like for P7 and P8?


-- 
Alexey