On Mon, 21 Dec 2020 16:46:34 +0100 Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > On Sat, 19 Dec 2020 07:33:16 +0100 > Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > > I finally came around to test this. In my experience driverctl works for > > subchannels and vfio_ccw without this patch, and continues to work with > > it. I found the code in driverctl that does the unbind and the implicit > > bind (via drivers_probe after after driver_override was set). > > > > So now I have to ask, how exactly was the original problem diagnosed? > > > > In https://marc.info/?l=linux-s390&m=158591045732735&w=2 there is a > > paragraph like: > > > > """ > > So while there's definitely a good reason for wanting to delay uevents, > > it is also introducing problems. One is udev rules for subchannels that > > are supposed to do something before a driver binds (e.g. setting > > driver_override to bind an I/O subchannel to vfio_ccw instead of > > io_subchannel) are not effective, as the ADD uevent will only be > > generated when the io_subchannel driver is already done with doing all > > setup. Another one is that only the ADD uevent is generated after > > uevent suppression is lifted; any other uevents that might have been > > generated are lost. > > """ > > > > This is not how driverclt works! I.e. it deals with the situation that > > the I/O subchannel was already bound to the io_subchannel driver at > > the time the udev rule installed by driverctl activates (via the > > mechanism I described above). > > That's... weird. It definitely did not work on the LPAR I initially > tried it out on! > I think Boris told me some weeks ago that it didn't work for him either. I will check with him after the winter sleep. > However, I think removing the suppression still looks like a good idea: > we still have the "any uevent other than ADD will have been lost" > problem. > I agree. I didn't look into the details, in general I think removing quirks specific to 390 (when possible) is a good thing. Regards, Halil
