Re: [PATCH V2] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses

[Ani Sinha]

> On Apr 29, 2020, at 10:58 AM, Michael S. Tsirkin <address@hidden> wrote:
> 
> o if there's a need to disable
> just one of these, commit log needs to do a better job documenting the
> usecase.

The use case is simple. With this feature admins will be able to do what they 
were forced to do from Windows driver level but now at the bus level. Hence, 
(a) They need not have access to the guest VM to change or update windows 
driver registry settings. They can enable the same setting from admin 
management console without any access to VM.
(b) It is more robust. No need to mess with driver settings. Incorrect settings 
can brick guest OS. Also no guest specific knowhow required.
(c) It is more scalable since a single cluster wide setting can be used for all 
VM power ons and the management plane can take care of the rest automatically. 
No need to access individual VMs to enforce this.
(d) I am told that the driver level solution does not persist across a reboot. 

Ani