On Fri, 24 May 2019 12:11:06 +0200 Cornelia Huck <cohuck@redhat.com> wrote:
On Thu, 23 May 2019 17:20:01 -0600 Alex Williamson <alex.williamson@redhat.com> wrote:
Hi,
[..]
It would be really useful if s390 folks could help me understand whether it's possible to glean all the information necessary to recreate a ccw or ap mdev device from sysfs. I expect the file where we currently only store the mdev_type to evolve into something that includes more information to facilitate more complicated devices. For now I make no claims to maintaining compatibility of recorded mdev devices, it will absolutely change, but I didn't want to get bogged down in making sure I don't accidentally source a root kit hidden in an mdev config file.
I played a bit with it on my LPAR, and it is at least not obviously broken with vfio-ccw :) I don't have any ap devices to play with, though.
Sorry for being late... I guess for vfio-ccw one needs to make sure that the ccw device is bound to the vfio-ccw driver first, and only after that can one use create-mdev to create the mdev on top of the subchannel. So to make this work persistently (survive a reboot) one would need to take care of the subchannel getting bound to the right vfio_ccw driver before mdevctl is called. Right? BTW how does this concurrence situation between the drivers io_subchannel and vfio_ccw work? Especially if both are build in?
I'm also curious how or if libvirt or openstack might use this. If nothing else, it makes libvirt hook scripts easier to write, especially if we add an option not to autostart mdevs, or if users don't mind persistent mdevs, maybe there's nothing more to do.
+1 @Alex: I'm curious what is the big management picture for non-auto looks like. Regards, Halil [..]