Re: [RFC v2 00/18] Refactor configuration of guest memory protection

[David Gibson]

On Fri, Jun 05, 2020 at 05:01:07PM -0300, Thiago Jung Bauermann wrote:
> 
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
> > On 05/06/20 01:30, Thiago Jung Bauermann wrote:
> >> Paolo Bonzini <pbonzini@redhat.com> writes:
> >>> On 04/06/20 23:54, Thiago Jung Bauermann wrote:
> >>>> QEMU could always create a PEF object, and if the command line defines
> >>>> one, it will correspond to it. And if the command line doesn't define 
> >>>> one,
> >>>> then it would also work because the PEF object is already there.
> >>>
> >>> How would you start a non-protected VM?
> >>> Currently it's the "-machine"
> >>> property that decides that, and the argument requires an id
> >>> corresponding to "-object".
> >>
> >> If there's only one object, there's no need to specify its id.
> >
> > This answers my question.  However, the property is defined for all
> > machines (it's in the "machine" class), so if it takes the id for one
> > machine it does so for all of them.
> 
> I don't understand much about QEMU internals, so perhaps it's not
> practical to implement but from an end-user perspective I think this
> logic can apply to all architectures (since my understanding is that all
> of them use only one object): make the id optional. If it's not
> specified, then there must be only one object, and the property will
> implicitly refer to it.
> 
> Then, if an architecture doesn't need to specify parameters at object
> creation time, it can be implicitly created and the user doesn't have to
> worry about this detail.

Seems overly complicated to me.  We could just have it always take an
ID, but for platforms with no extra configuration make the
pre-fabricated object available under a well-known name.

That's essentially the same as the way you can add a device to the
"pci.0" bus without having to instantiate and name that bus yourself.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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