Re: [XENBUS PATCH v3 2/9] Merge all hardware IDs into one Models entry

[Owen Smith <owen.smith@xxxxxxxxx>]

On Wed, Aug 6, 2025 at 1:27 PM Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx> wrote:

On 06/08/2025 10:01, Owen Smith wrote:
> The XenVbd changes seem fine, but there is a problem if older xenvbd is
> loaded on this xenbus, where the devices do not cope with a change in
> the device_id or presence of the vendor device. To work around this, I
> had to set xenbus's PDOs DeviceID to exclude the PCI vendor ID (e.g.
> "XENBUS\VEN_XP&DEV_VBD")

Could you elaborate on the problem? Old xenvbd wouldn't have forced
unplug so I figured they wouldn't be affected. Maybe it has something to
do with the Active registry value, in which case something like this
would help?

Using old xenvbd, no force unplug value was set, but the standard unplug

key was set. When the VM was shut down, device_id changed, and restarted,

the unplug still occurred, but the xenvbd driver was not installed on

the new xenbus device_id and could not be installed from the driver store

during boot.

Using this scheme in xenvif would also be advantageous, as it would mean

xennet devices are not reinstalled when reparenting xenbus. If xennet doesnt

reinstall, then Windows does not create a new network connection, which

defaults to DHCP, improving user experience when a static IP or similar

settings have been applied.

 

>
>     Comma should be on the vendor device ID line, so if VENDOR_DEVICE_ID
>     is not defined, then the INF section is still valid, although it
>     'promotes' 0002 to HWID from CompatID

 From MS documentation, the INF Models section allows for a blank HWID.
So I did that to make sure that the platform IDs remain as compatible
IDs in the INF, since I'd prefer to avoid having identifier scores
change depending on the build configuration.

That makes sense.

Owen