[Bug 1941889] Re: [FFE] Enhancing 'autoinstall-user-data' with s390x specific device enablement

[Frank Heimes]

** Changed in: ubuntu-z-systems
       Status: Fix Committed => Fix Released

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Title:
  [FFE] Enhancing 'autoinstall-user-data' with s390x specific device
  enablement

Status in subiquity:
  Fix Committed
Status in Ubuntu on IBM z Systems:
  Fix Released
Status in subiquity package in Ubuntu:
  Fix Released
Status in subiquity source package in Plucky:
  Fix Released

Bug description:
  Request
  -------
  We want Subiquity to have built-in support for enabling (or disabling) s390-specifc devices, when running an automated install.

  We are past FF for plucky, so I would like to request an exception.

  Why Needed
  ----------
  On s390x, CCW devices need to be enabled (using chzdev from s390-tools) before they can be used. For manual installations of Ubuntu Server, we already have a TUI screen allowing people to enable or disable specific devices. However, we didn't have support for doing such actions in automated installs. Although it is true that early-commands can be used as an alternative, proper autoinstall support provides a cleaner approach, and makes it possible to use the generated autoinstall-user-data (from a manual installation) as a template for automated installs.

  This feature is a request from the partner engineering team.

  What changed
  ------------
  * Subiquity can now read from a "zdevs" autoinstall section, allowing users to specify which devices should be enabled or disabled.
  * On startup, devices that have been declared as "enabled": true are automatically enabled using a call to chzdev --enable "$device".
  * On startup, devices that have been declared as "enabled": false are automatically disabled using a call to chzdev --disable "$device".

  Code to be merged
  -----------------
  https://github.com/canonical/subiquity/pull/2167

  Original description
  --------------------

  On s390x systems (IBM Z and LinuxONE) the s390x specific devices (or better ccw-devices) need to be enabled prior to their usage.
  (This does _not_ apply to PCIe devices that the platform supports as well.)

  Today this aspect of the special ccw-device enablement is not
  addressed in the 'autoinstall-user-data' file, which is created while
  doing a manual installation, but could be easily.

  At the end of an interactive installation on a s390x system (or actually already right after the 'zDev' activation screen of subiquity) all s390x specific devices are known and can be obtained by:
  $ lszdev --online
  TYPE       ID                                              ON   PERS  NAMES
  zfcp-host  0.0.e000                                        yes  yes
  zfcp-host  0.0.e100                                        yes  yes
  zfcp-lun   0.0.e000:0x50050763060b16b6:0x4026400300000000  yes  yes   sda sg0
  zfcp-lun   0.0.e000:0x50050763061b16b6:0x4026400300000000  yes  yes   sdb sg1
  zfcp-lun   0.0.e100:0x50050763060b16b6:0x4026400300000000  yes  yes   sdd sg3
  zfcp-lun   0.0.e100:0x50050763061b16b6:0x4026400300000000  yes  yes   sdc sg2
  qeth       0.0.c000:0.0.c001:0.0.c002                      yes  yes   encc000
  But this output can also be nicely filtered to just print the relevant device information like this:
  $ lszdev --online --column ID --no-headings
  0.0.e000
  0.0.e100
  0.0.e000:0x50050763060b16b6:0x4026400300000000
  0.0.e000:0x50050763061b16b6:0x4026400300000000
  0.0.e100:0x50050763060b16b6:0x4026400300000000
  0.0.e100:0x50050763061b16b6:0x4026400300000000
  0.0.c000:0.0.c001:0.0.c002

  This is already the base for the device activation.
  Enriching this information with the command that triggers the enablement ('chzdev --enable'):
  $ for i in $(lszdev --online --column ID --no-headings); do echo chzdev -e $i; done
  chzdev -e 0.0.e000
  chzdev -e 0.0.e100
  chzdev -e 0.0.e000:0x50050763060b16b6:0x4026400300000000
  chzdev -e 0.0.e000:0x50050763061b16b6:0x4026400300000000
  chzdev -e 0.0.e100:0x50050763060b16b6:0x4026400300000000
  chzdev -e 0.0.e100:0x50050763061b16b6:0x4026400300000000
  chzdev -e 0.0.c000:0.0.c001:0.0.c002
  produces the list of commands that can be _directly_ added to the 'early-commands' section of the 'autoinstall-user-data' file.

  Even if some devices get enabled using a different approach (for example using the boot kernels parm file or using the auto-conf option of a DPM machine), this doesn't hurt since it will be noticed and tolerated by the chzdev command:
  $ for i in $(lszdev --online --column ID --no-headings); do chzdev -e $i; done
  FCP device 0.0.e000 already configured
  FCP device 0.0.e100 already configured
  zFCP LUN 0.0.e000:0x50050763060b16b6:0x4026400300000000 already configured
  zFCP LUN 0.0.e000:0x50050763061b16b6:0x4026400300000000 already configured
  zFCP LUN 0.0.e100:0x50050763060b16b6:0x4026400300000000 already configured
  zFCP LUN 0.0.e100:0x50050763061b16b6:0x4026400300000000 already configured
  QETH device 0.0.c000:0.0.c001:0.0.c002 already configured
  $ echo $?
  0

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