On 12/21/20 5:51 PM, Halil Pasic wrote:
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.
Yesterday I used driverctl successfully for a subchannel on F33.
Not sure what went wrong a couple of months ago but I cannot reproduce
driverctl not working now.
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 totally agree with this.
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
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