Re: [PATCH v1 2/9] s390x: toplogy: adding drawers and books to smp parsing

[Cornelia Huck]

On Tue, Jul 20 2021, Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 7/20/21 10:20 AM, Cornelia Huck wrote:
>> On Tue, Jul 20 2021, Pierre Morel <pmorel@linux.ibm.com> wrote:
>> 
>>> On 7/19/21 5:50 PM, Cornelia Huck wrote:
>>>> On Fri, Jul 16 2021, Daniel P. Berrangé <berrange@redhat.com> wrote:
>>>>> Is the book/drawer thing architecture specific, or is it machine
>>>>> type / CPU specific. ie do /all/ the s390x machine types / CPUS
>>>>> QEMU support the book/drawer concept, or only a subset.
>>>>
>>>> Should not be by machine type, but might be by cpu model (e.g. older
>>>> hardware lacking the needed support for exposing this to the guest.) IBM
>>>> folks, please correct me if I'm wrong.
>>>
>>>
>>> Looks correct to me this is an information indicated by a facility
>>> introduced with Z10 if I do not make an error.
>> 
>> Hm. Would that become a problem if we made availability of parameters
>> dependent upon a value in the machine (see the other thread I cc:ed you
>> on?)
>> 
>
> Why?
> The parameter can always be there, it is just that with older cpu model 
> we will not report the topology information to the guest.

If we are fine with a configuration like that, sure.

>
> The discussion on dies and on smp_dies_supported in this thread will be 
> interesting to follow because in my opinion dies for X or books/drawers 
> for Z are to be treated equally.

Agreed. There was also talk of "clusters" in that thread, which I assume
are yet anothor machine specific parameter.