Re: [PATCH] hw/ppc/Kconfig: NVDIMM is a hard requirement for the pseries machine

[Daniel Henrique Barboza <danielhb413@gmail.com>]

On 5/5/23 05:03, Thomas Huth wrote:
> On 04/05/2023 23.19, Daniel Henrique Barboza wrote:
>>
>>
>> On 5/4/23 15:05, Thomas Huth wrote:
>>> When building QEMU with "--without-default-devices", the pseries
>>> machine fails to start even when running with the --nodefaults option:
>>>
>>>   $ ./qemu-system-ppc64 --nodefaults -M pseries
>>>   Type 'spapr-nvdimm' is missing its parent 'nvdimm'
>>>   Aborted (core dumped)
>>>
>>> Looks like NVDIMM is a hard requirement for this machine nowadays.
>>
>> Ouch.
>>
>> I believe this has to do with this comment in hw/ppc/spapr.c, in
>> spapr_instance_init():
>>
>>      /*
>>       * NVDIMM support went live in 5.1 without considering that, in
>>       * other archs, the user needs to enable NVDIMM support with the
>>       * 'nvdimm' machine option and the default behavior is NVDIMM
>>       * support disabled. It is too late to roll back to the standard
>>       * behavior without breaking 5.1 guests.
>>       */
>>      if (mc->nvdimm_supported) {
>>          ms->nvdimms_state->is_enabled = true;
>>      }
>>
>> It seems like you found out another side effect of this nvdimm situation that Igor
>> documented 2 years ago in 55810e90 ("ppc/spapr: cleanup -machine pseries,nvdimm=X
>> handling").
>>
>>
>> Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
>>
>>
>> I'll send a PPC PR in the next few days. Let me know if you want me to queue it.
> 
> Yes, please add it to your queue!

Queued. Thanks,


Daniel

> 
>   Thanks,
>    Thomas
>