Re: [Qemu-devel] [PATCH 5/5] s390x/ccs: add ccw-tester emulated device

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 7 Sep 2017 12:21:50 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> On 09/07/2017 10:08 AM, Cornelia Huck wrote:
> > On Thu, 7 Sep 2017 15:31:09 +0800
> > Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> wrote:

> >> I'm thinking of a method these days:
> >> Could passing through an fully emulated ccw device (e.g. 3270), or a
> >> virtio ccw device, in the level 1 kvm guest to a level 2 guest be a test
> >> method for this?
> >>
> >> All of the CCWs will be translated to IDAL CCWs by vfio-ccw in the level
> >> 1 guest (which is the level 2 kvm host) and issued to the level 1 kvm
> >> host. So, those IDALs will eventually be handled by the emulated device,
> >> or the virtio ccw device, on the level 1 kvm host...
> >>
> >> Some days ago, one of my colleague tried the emulated 3270 passing
> >> through. She stucked with the problem that the level 1 kvm host handling
> >> a senseid IDAL ccw as a Direct ccw.
> >>
> >> Maybe I could try to pass through a virtio ccw device. I don't think of
> >> any obvious problem that would lead to fail. Any comment?
> >>  
> > 
> > That actually looks like a good thing to try! Cool idea.
> >   
> 
> I'm afraid that it would not work without some extra work.
> AFAIR Connie we said that the 3270 does not use any IDA, so
> I did not touch the 3270 emulation code in QEMU. To make
> the scenario viable one should convert the 3270 emulation
> to ccw data stream (unless the original implementation
> already took care of IDA, which I doubt).

But the vfio-ccw code uses idals... no need to touch the 3270 emulation.