On Tue, 11 Jun 2019 14:28:22 -0600 Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: > On Tue, 11 Jun 2019 21:45:08 +0200 > Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > > > On Fri, 7 Jun 2019 18:06:30 +0200 > > Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > > 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? > > > > If you have two drivers that match to the same device type, you'll > > always have the issue that the driver that is first matched with the > > device will bind to it and you have to do the unbind/rebind dance to > > get it bound to the correct device driver. (I guess that this was the > > basic motivation behind the ap bus default driver infrastructure, > > right?) I think that in our case the io_subchannel driver will be > > called first (alphabetical order and the fact that vfio-ccw will often > > be a module). I'm not sure if it is within the scope of mdevctl to > > ensure that the device is bound to the correct driver, or if it rather > > should work with devices already bound to the correct driver only. > > Maybe a separate udev-rules generator? > > Getting a device bound to a specific driver is exactly the domain of > driverctl. Implement the sysfs interfaces driverctl uses and see if it > works. Driverctl defaults to PCI and knows some extra things about > PCI, but appears to be written to be generally bus agnostic. Thanks, > > Alex Ok, looked at driverctl. Extending this one for non-PCI seems like a reasonable path. However, we would also need to extend any non-PCI device type we want to support with a driver_override attribute like you did for PCI in 782a985d7af26db39e86070d28f987cad2 -- so this is only for newer kernels. Adding that attribute for subchannels looks feasible at a glance, but I have not tried to actually do it :) Halil, do you think that would make sense? [This might also help with the lcs vs. ctc confusion on a certain 3088 cu model if this is added for ccw devices as well; but I'm not sure if these are still out in the wild at all. Probably not worth the effort for that.]
