Re: [Qemu-devel] [PATCH 1/2] s390x/ccs: add ccw-tester emulated device

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 18 Sep 2017 10:30:32 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 09/15/2017 09:27 AM, Cornelia Huck wrote:
> > On Thu, 14 Sep 2017 18:50:29 +0200
> > Halil Pasic <pasic@linux.vnet.ibm.com> wrote:
> >   
> >> On 09/14/2017 04:26 PM, Cornelia Huck wrote:  
> >>> On Wed, 13 Sep 2017 15:27:51 +0200
> >>> Halil Pasic <pasic@linux.vnet.ibm.com> wrote:  
> >   
> >>>> +static Property ccw_tester_properties[] = {
> >>>> +    DEFINE_PROP_UINT16("cu_type", CcwTesterDevice, cu_type,
> >>>> +                        0x3831),    
> >>>
> >>> 0x4711 would be nice :)    
> >>
> >> I don't understand the joke/pun/whatever if there is one,
> >> but I'm fine with changing this too.  
> > 
> > https://en.wikipedia.org/wiki/4711
> > 
> > That's my default if I need a four-digit number :)
> >   
> >>  
> >>>
> >>> If we want to follow up on that testdev idea (and I think we should),
> >>> it might make sense to have a proper type reserve to prevent accidental
> >>> clashes.    
> >>
> >> I agree. Although I would still keep the cu_type configurable,
> >> because it might make sense to test a particular 'real' driver
> >> (and not a test driver like here). I haven't really thought
> >> this through, but it was an idea I had while agonizing over
> >> not having a proper type reserved.
> >>
> >> I suppose you did something like that for virtio, or? I'm in dark
> >> when it comes to the question what process do we/I have to go to
> >> get a type,for example 0x4711, reserved.  
> > 
> > 4711 is more a joke :) It might be worth trying the same channels as
> > for virtio-ccw.
> > 
> > Christian should know more about that.  
> 
> Getting a new number was very easy (because it is attached to a machine type
> number). I I remember correctly, only numerical values are uses, so maybe
> we can use ffff as there will never be such a real value?
> 

Yes, that sounds like the easiest way to do that.