Re: [Qemu-devel] [PATCH] s390-ccw: Fix alignment for CCW1

[Farhan Ali]

On 08/28/2017 10:19 AM, Halil Pasic wrote:
> On 08/28/2017 04:15 PM, Farhan Ali wrote:
> > On 08/28/2017 10:05 AM, Cornelia Huck wrote:
> > > > > > It's the alignment of the CCW which causes the problem.
> > > > > >
> > > > > > The exact error message when starting the guest was:
> > > > > >
> > > > > > ! No virtio device found !
> > > > > >
> > > > > > Since it worked for SCSI and CDL, and failed for LDL disks on that particular 
> > > > > > system, we are not really sure what caused the failure.
> > > > > > Debugging it further showed the CCW for LDL disks were not aligned at double 
> > > > > > word boundary.
> > > This is really, really odd, as the low-level ccw code is the same for
> > > any disk type...
> > Exactly!
> >
> > > > > > Trying the test on a different system with LDL disks worked fine, with the 
> > > > > > aligned(8) fix.
> > > > > Do you happen to have an old s390-ccw.img laying around in the test folder? 
> > > > > QEMU might pick up
> > > > > this one (e.g. when calling it without libvirt from the command line).
> > > > I explicitly mention the bios to use with '-bios' option and pick up the
> > > > latest bios. Without the aligned fix I see the error and with the fix it
> > > > works fine.
> > > Wait, so the fix fixes it? Or am I confused now?
> >
> > It fixes in my system and one other system we tried on. But fails on a system 
> > where this issue was first noticed.
>
> This is very confusing. So you have tried -bios on the system
> where the issue was first noticed and the issue still persists
> despite of the fixed bios is specified?
Yes.

The system where the issue was first noticed, applying the fix for the 
bios, fixes for:

1) CDL disks
2) SCSI disks

But fails for LDL disk.

On my system and one other system, the fix works for all the disk types, 
CDL, SCSI and LDL and fixes the issue.