Re: [Qemu-devel] [PATCH v4 4/7] qdev: add hotpluggable to DeviceState

[Peter Maydell]

On 22 February 2018 at 16:59, Alex Williamson
<address@hidden> wrote:
> On Thu, 22 Feb 2018 15:46:17 +0000
> Peter Maydell <address@hidden> wrote:
>> 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.

Ah, I see. I don't have a good suggestion offhand, but I suspect
the patch as it stands is insufficient if we want to take the
approach it uses. For instance qdev_unplug() in qdev-monitor.c
looks directly at dc->hotpluggable to decide whether it should
refuse a user request to hot-unplug a device.

thanks
-- PMM