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

[Cornelia Huck]

On Mon, 28 Aug 2017 10:28:53 -0400
Farhan Ali <address@hidden> wrote:

> 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.

Are you using different toolchains on the failing and the working
systems? Does it work when you copy the bios from a working system?

(Clutching at straws here...)