[Bug 1893775] Re: [UBUNTU 20.04.1] Failure to install Ubuntu 20.04.1 as KVM guest on DASD

[Dimitri John Ledkov]

Request to always force ms-dos partition table in KVM was requested
before.

However, surely it is virtualization/layering violation, when a physical
host device which is not virtio-scsi compatible is passed through to
qemu which emulates it as scsi, despite the underlying device on the
host not able to create GPT, extended partitions, etc.

Can we please prohibit passing through /dev/dasda to qemu as virtio-scsi
provider on qemu and/or virtio layer?

If one passes /dev/dasda to qemu, it must show up as /dev/dasd* inside
the guest too. As there is no way for the guest to know or figure out
that the passthrough device is actually masquerading a dasd drive.

Can you please explain again, why is it correct and desired to provide
/dev/vda in the guest with /dev/dasda on the host, when the two types
are incompatible with each other?

** Changed in: subiquity (Ubuntu Groovy)
       Status: New => Incomplete

** Changed in: subiquity (Ubuntu Focal)
       Status: New => Incomplete

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Title:
  [UBUNTU 20.04.1] Failure to install Ubuntu 20.04.1 as KVM guest on
  DASD

Status in Ubuntu on IBM z Systems:
  Triaged
Status in subiquity package in Ubuntu:
  Incomplete
Status in subiquity source package in Focal:
  Incomplete
Status in subiquity source package in Groovy:
  Incomplete

Bug description:
  ---Problem Description---
  Failure to install Ubuntu 20.04.1 as KVM guest on DASD
    
  ---uname output---
  Linux version 5.4.0-42-generic (buildd at bos02-s390x-003) (gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)) #46-Ubuntu SMP Fri Jul 10 00:21:32 UTC 2020 (Ubuntu 5.4.0-42.46-generic 5.4.44)
   
  Machine Type = 3096-703 
   
  ---boot type---
  CDROM / ISO image
   
  ---Install repository type---
  Internet repository
   
  ---Install repository Location---
  ports.ubunut.com
   
  ---Point of failure---
  Other failure during installation (stage 1)

  I tried to install an Ubuntu 20.04.1 guest from ISO which failed.
  Steps to reproduce.
  1. Boot from ISO to start installer, in my case I used virt-install, but a manually defined libvirt domain has the same issue:
  $ virt-install --name focal.1 --memory 2048 --disk path=/dev/disk/by-path/ccw-0.0.a03f --cdrom ubuntu-20.04.1-live-server-s390x.iso

  2. On the installer screen, stay in simple mode and accept all
  defaults

  3. Shortly after a error pop-up appears, saying the installation has failed. Opening the log I see:
  ...
   storage:
     config:
     - {ptable: gpt, path: /dev/vda, wipe: superblock-recursive, preserve: false, name: '',
       grub_device: false, type: disk, id: disk-vda}
     - {device: disk-vda, size: 22153265152, wipe: superblock, flag: '', number: 1, preserve: false,
       type: partition, id: partition-0}
     - {fstype: ext4, volume: partition-0, preserve: false, type: format, id: format-0}
     - {device: format-0, path: /, type: mount, id: mount-0}
     version: 1
  ...
  An error occured handling 'format-0': OSError - could not get path to dev from kname: vda1
   finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: configuring format: format-0
   TIMED BLOCK_META: 1.942
   finish: cmd-install/stage-partitioning/builtin/cmd-block-meta: FAIL: curtin command block-meta

  
  It seems that the new installation procedure isn't correctly detecting virtio-attached DASDs and tries to handle them like SCSI disks (gpt label, ...). This is a regression compared to the debian-installer and prevents the installation of Ubuntu 20.04 KVM guests on DASD.

  I cross-checked by running the installation on a QCOW2 image, which
  succeeded without problems.

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