On Tue, 29 Aug 2017 08:39:27 -0400 Farhan Ali <al...@linux.vnet.ibm.com> wrote:
> On 08/29/2017 08:04 AM, Cornelia Huck wrote: > > On Mon, 28 Aug 2017 10:28:53 -0400 > > Farhan Ali <al...@linux.vnet.ibm.com> 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...) > > > > So yesterday we realized for the failing system, the bios wasn't being > built on that system rather it was being built on a different system and > being copied over to the failing system. :/ Oh dear... the system it was built on hopefully was missing the fix, right? (I'm getting a bit paranoid here.) > > Building the bios on the failing system with the fix, resolves the issue > and we did not see anymore failures. > So I think I can safely say this patch fixes the alignment problem. Out of interest, which toolchain are you using? My rebuild is on F26.
