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

[Thomas Huth]

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!

 Thanks,
  Thomas