On Thu, 22 Feb 2018 15:46:17 +0000
Peter Maydell <peter.mayd...@linaro.org> wrote:
> On 22 February 2018 at 15:37, Gerd Hoffmann <kra...@redhat.com> wrote:
> > On Mon, Feb 19, 2018 at 12:14:55PM +0100, Gerd Hoffmann wrote:
> >> vfio display support wants disable hotplug for certain devices, because
> >> qemu doesn't support hotplugging display devices and qemu consoles.
> >> Add a hotpluggable bool to DeviceState, initialize it from
> >> DeviceClass->hotpluggable, update device_get_hotpluggable accordingly.
> >> Devices can flip the new variable from true to false if needed.
> > Alex wants an ack for this one. Who maintains it these days?
> > MAINTAINERS doesn't list qdev. For QOM which is closest probably
> > Andreas Färber is listed. Havn't seen him on the list for a while
> > though.
> > Ok, lets try some usual suspects...
> > Markus? Eric? Paolo? Peter? Any comments on this one?
> What type of device is only sometimes hotpluggable ?
> The commit message says "display devices" and "consoles",
> but I would expect those to both be types of device which
> have a class which is never hotpluggable, so you can mark
> them non-hotpluggable with the existing class flag rather
> than needing a per-instance flag.
With this series, a vfio-pci device optionally supports a display. The
vfio-pci device is hotpluggable, but QEMU display support is not. So
the solution here is to make the vfio-pci device non-hotpluggable only
when it supports and enables a display.
Gerd, is there another solution that the display object is instantiated
separately from the vfio-pci object and the display support in the
vfio-pci device references the display object via an id. Possibly
vfio-pci could remain hotpluggable while the display class device is
not. Potentially one display could be switched between multiple
display capable devices, like an input control button on a monitor,
losing signal if none are connected. Possible? Clearly I have no idea
how display objects actually work in QEMU. Thanks,