Re: [PATCH v1] s390x: kvm-unit-tests: a PONG device for Sub Channels tests

[Halil Pasic <pasic@linux.ibm.com>]

On Thu, 14 Nov 2019 14:19:15 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> On Thu, 14 Nov 2019 14:02:35 +0100
> Halil Pasic <pasic@linux.ibm.com> wrote:
> 
> > On Thu, 14 Nov 2019 11:38:23 +0100
> > Cornelia Huck <cohuck@redhat.com> wrote:
> > 
> > > On Wed, 13 Nov 2019 20:02:33 +0100
> > > Pierre Morel <pmorel@linux.ibm.com> wrote:
> > > 
> > > Minor nit for $SUBJECT: this isn't a kvm-unit-tests patch, that's just
> > > one consumer :)  
> > 
> > And subchannel is one word in s390-speak.
> > 
> > >   
> > 
> > [..]
> > 
> > > Some questions regarding this device and its intended usage:
> > > 
> > > - What are you trying to test? Basic ccw processing, or something more
> > >   specific? Is there any way you can use the kvm-unit-test
> > >   infrastructure to test basic processing with an existing device?  
> > 
> > I'm also curious about the big picture (what is in scope and what out
> > of scope). Your design should be evaluated in the light of intended
> > usage.
> > 
> > BTW have you had a look at this abandoned patch-set of mine:
> > 
> > https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg04220.html
> 
> Do you recall why it was abandoned? Or did we just forget to follow up
> on it?
> 

I think I do remember. Priorities. Some colleagues were supposed to take
over the job of making proper tests for this device -- the part that is
now intended to be played by kvm-uni-tests. But they never got to
actually start working on it. And my tests for IDA are just a kernel
module -- i.e. nothing sustainable. So without proper exploitation, and
with no time to do a proper test suite myself, I decided to not invest
any more for the time beeing. 

> > 
> > We made some different design decisions, while aiming essentially for the
> > same. Maybe it's due to different scope, maybe not. For instance one
> > can't test IDA with PONG, I guess.
> 
> Now that I saw this again, I also recall the discussion of comparing it
> with the "testdev" for pci/isa. Anybody knows if these are used by
> kvm-unit-tests?
> 

I don't.

Regards,
Halil

> > 
> > Regards,
> > Halil
> > 
> > > - Who is instantiating this device? Only the kvm-unit-test?
> > > - Can you instantiate multiple instances? Does that make sense? If yes,
> > >   it should probably not request a new chpid every time :)
> > > - What happens if someone instantiates this by hand? The only drawback
> > >   is that it uses up a subchannel and a chpid, right?
> > > - Do you plan to make this hotpluggable later?
> > > 
> > >   
> > 
> 
>