Re: [RFC PATCH 00/10] hw/misc/vmcoreinfo: Convert from QDev to plain Object

[Daniel P . Berrangé]

On Thu, Dec 19, 2024 at 04:38:47PM +0100, Philippe Mathieu-Daudé wrote:
> No reason for vmcoreinfo to be based on QDev, since it
> doesn't use any QDev API. Demote to plain Object.

I'm not especially convinced by that rationale, at least in the short
term[1].

As a user of QEMU, I would tend to view -device  as being the way to
create devices that are visible to the guest, and -object as being
for dealing with host backends.

vmcoreinfo is quite an unusal device, in that if only exists as a
fwcfg field, but that's an internal impl detail from a user's POV,
and it is still a guest visible device type.

So while it may not leverage QDev API, I still feel it is more of
a fit for -device, than -object.  Is there any functional benefit
to moving it to -object, that outweighs the disruption ?


With regards,
Daniel

[1] I say "short term", because overall I'm of the opinion that
-device, -machine, -cpu, -chardev, etc should not exist, and
-object ought to be made capable of instantiating any type of
object whatever subclass it might be. I doubt that will change
any time in the forseeable future though, so it is more of a
hypothetical point.

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