Re: Hotplugged devices in Xen 4.5 and domain reboot

["Roger Pau Monné" <roger.pau@citrix.com>]

Hello,

El 01/12/15 a les 15.58, Iurii Mykhalskyi ha escrit:
> Our real usb mass-storage device are located at driver domain (DomD). So we
> setup second block-device backend there.
> 
> To hotplug usb mass-storage from DomD we use follow command:
> 
> xl block-attach domU_id phy:/bla-bla,xvda10,w,backend="DomD"

This is not possible by design, you should only be able to execute `xl 
block-attach ...` from the control domain (Dom0). This is due to the 
fact that attaching a new device to a guest requires write permissions 
in the guest xenstore paths, which the driver domain should not have.

> 
> There was no support of attaching block-device in runtime from domain other
> to Domain-0, so we have made some hacks to allow call block-attach command
> from non-dom0 privileged domain.

Do you have either the `xl devd` command running or udev rules 
correctly setup inside of the driver domain?

Does something like the following work? If not, could you paste the 
error when running it with -vvv.

xl block-attach DomU format=raw,vdev=hdc,access=rw,backend=DomD,target=/path/to/dev

Roger.