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

[Daniel Henrique Barboza]

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