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

[Alexander Graf <agraf@suse.de>]

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.


Alex