Switch kernel to vmlinuz (from vmlinux) on ppc64el

[Mauricio Faria de Oliveira]

Hi,

May we discuss/implement switching the kernel image type/filename on ppc64el from vmlinu*x* to vmlinu*z* ?

Problem:
------------

In the current situation, some issues occur because of 1) or 2):

1) the presence of /boot/vmlinu*x* w/ no debug symbols (vmlinux conventionally contains debug symbols)
  - systemtap's search path includes it first, and assumes it has debug symbols, and thus fail on probes involving the "kernel" identifier
  - perf had a similar issue on trusty IIRC, which required specifying /proc/kallsyms by hand (it seems automatic on utopic)
2) the lack of /boot/vmlinu*z*
  - kdump-config (from makedumpfile): only tests for existence of /boot/vmlinu*z*

.. and potentially others.

I believe the limiting factors that kept us using vmlinu*x* was either
 1) yaboot, or
 2) lack of zImage support for 64el on kernel.

Neither should be a problem anymore: for 1) ppc64el uses grub only, and for 2) 3.16 contains the zImage-support patchset.

Solution Proposal:
-------------------------

I had success in building, booting and installing utopic w/ vmlinuz.

Attaching the (trivial) patches for the kernel (ubuntu-utopic.git, master branch) and debian-installer (src pkg).

The install w/ mini.iso finished successfully. Although it ended up installing vmlinux (it download linux-image from Canonical, I guess), it was just a matter of installing the patched linux-image package to get vmlinuz installed and booted successfully.

If there's no objection/more fixes to do, I'd submit the kernel patch on the kernel-team mailing list, and check what's needed to get this back on trusty (zImage support has 16 patches IIRC).

[Adam Conrad (adconrad)]

IIRC, there are a few other userspace spots this will "break" (due to silly assumptions) when we switch, but that's no excuse to not switch, so I'll make sure we hunt those down before release.

[Mauricio Faria de Oliveira (mfo)]

Thanks.

For the record, I'll file bugs upstream for the userpace tools failing (discussed on irc).

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "ppc64el-vmlinuz-kernel.patch" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Adam Conrad (adconrad)]

Argh. I assigned this to myself, specifically so I could do the investigation before someone went and applied the patch and broke the world. Unshockingly, various bits of the world are now broken. :P

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 3.16.0-11.16

---------------
linux (3.16.0-11.16) utopic; urgency=low

  [ Mauricio Faria de Oliveira ]

  * [Config] Switch kernel to vmlinuz (from vmlinux) on ppc64el
    - LP: #1358920

  [ Peter Zijlstra ]

  * SAUCE: (no-up) mmu_notifier: add call_srcu and sync function for listener to delay call and sync
    - LP: #1361300

  [ Tim Gardner ]

  * [Config] CONFIG_ZPOOL=y
    - LP: #1360428
  * Release Tracking Bug
    - LP: #1361308

  [ Upstream Kernel Changes ]

  * Revert "net/mlx4_en: Fix bad use of dev_id"
    - LP: #1347012
  * net/mlx4_en: Reduce memory consumption on kdump kernel
    - LP: #1347012
  * net/mlx4_en: Fix mac_hash database inconsistency
    - LP: #1347012
  * net/mlx4_en: Disable blueflame using ethtool private flags
    - LP: #1347012
  * net/mlx4_en: current_mac isn't updated in port up
    - LP: #1347012
  * net/mlx4_core: Use low memory profile on kdump kernel
    - LP: #1347012
  * Drivers: scsi: storvsc: Change the limits to reflect the values on the host
    - LP: #1347169
  * Drivers: scsi: storvsc: Set cmd_per_lun to reflect value supported by the Host
    - LP: #1347169
  * Drivers: scsi: storvsc: Filter commands based on the storage protocol version
    - LP: #1347169
  * Drivers: scsi: storvsc: Fix a bug in handling VMBUS protocol version
    - LP: #1347169
  * Drivers: scsi: storvsc: Implement a eh_timed_out handler
    - LP: #1347169
  * drivers: scsi: storvsc: Set srb_flags in all cases
    - LP: #1347169
  * drivers: scsi: storvsc: Correctly handle TEST_UNIT_READY failure
    - LP: #1347169
  * namespaces: Use task_lock and not rcu to protect nsproxy
    - LP: #1328088
  * net: xgene: Check negative return value of xgene_enet_get_ring_size()
  * mm/zbud: change zbud_alloc size type to size_t
    - LP: #1360428
  * mm/zpool: implement common zpool api to zbud/zsmalloc
    - LP: #1360428
  * mm/zpool: zbud/zsmalloc implement zpool
    - LP: #1360428
  * mm/zpool: update zswap to use zpool
    - LP: #1360428
  * ideapad-laptop: Change Lenovo Yoga 2 series rfkill handling
    - LP: #1341296
  * iommu/amd: Fix for pasid initialization
    - LP: #1361300
  * iommu/amd: Moving PPR fault flags macros definitions
    - LP: #1361300
  * iommu/amd: Drop oprofile dependency
    - LP: #1361300
  * iommu/amd: Fix typo in amd_iommu_v2 driver
    - LP: #1361300
  * iommu/amd: Don't call mmu_notifer_unregister in __unbind_pasid
    - LP: #1361300
  * iommu/amd: Don't free pasid_state in mn_release path
    - LP: #1361300
  * iommu/amd: Get rid of __unbind_pasid
    - LP: #1361300
  * iommu/amd: Drop pasid_state reference in ppr_notifer error path
    - LP: #1361300
  * iommu/amd: Add pasid_state->invalid flag
    - LP: #1361300
  * iommu/amd: Don't hold a reference to mm_struct
    - LP: #1361300
  * iommu/amd: Don't hold a reference to task_struct
    - LP: #1361300
  * iommu/amd: Don't call the inv_ctx_cb when pasid is not set up
    - LP: #1361300
  * iommu/amd: Don't set pasid_state->mm to NULL in unbind_pasid
    - LP: #1361300
  * iommu/amd: Remove change_pte mmu_notifier call-back
    - LP: #1361300
  * iommu/amd: Fix device_state reference counting
    - LP: #1361300...

[Launchpad Janitor (janitor)]

This bug was fixed in the package debian-installer - 20101020ubuntu338

---------------
debian-installer (20101020ubuntu338) utopic; urgency=medium

  * build/config/ppc64el.cfg: Switch kernel to vmlinuz (LP: #1358920)
 -- Mauricio Faria de Oliveira <email address hidden> Tue, 26 Aug 2014 14:16:21 -0600

[Mauricio Faria de Oliveira (mfo)]

Thanks for all the effort involved. :)

[Benjamin Herrenschmidt (benh-kernel)]

Except that OPAL/petitboot cannot boot a zImage ... FAIL !~

[Andy Whitcroft (apw)]

Reverted for linux until this is resolved.

[Mauricio Faria de Oliveira (mfo)]

> Except that OPAL/petitboot cannot boot a zImage ... FAIL !~

Epic fail.
Really sorry about that (and the effort involved).
Apologies, everyone.

[Adam Conrad (adconrad)]

In light of petitboot's inability to boot a zImage, I'm closing these both "Won't Fix" for now. We can revisit this in a later release if (a) petitboot is fixed and (b) people are willing to drop support for older firmware, but it's not worth entertaining right now.

Either way, we should fix all the userspace bits to deal with both image types and paths, and this has been ongoing elsewhere, no need to track it here.