linux-kvm: please support kexec

Bug #1799791 reported by Steve Langasek on 2018-10-24
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux-kvm (Ubuntu)
Medium
Connor Kuehl
Xenial
Undecided
Connor Kuehl
Bionic
Undecided
Connor Kuehl
Cosmic
Medium
Connor Kuehl
Disco
Undecided
Connor Kuehl

Bug Description

linux-kvm doesn't support kexec.

Adding support for kexec would enable other interesting uses of linux-kvm, such as for a linuxboot embedded kernel in kvm.

Please enable CONFIG_KEXEC=y, CONFIG_KEXEC_FILE=y in linux-kvm.

Changed in linux-kvm (Ubuntu):
importance: Undecided → Medium
status: New → Triaged
Changed in linux-kvm (Ubuntu Bionic):
status: New → Triaged
importance: Undecided → Medium
Changed in linux-kvm (Ubuntu Cosmic):
assignee: nobody → Joseph Salisbury (jsalisbury)
Changed in linux-kvm (Ubuntu Bionic):
assignee: nobody → Joseph Salisbury (jsalisbury)
Changed in linux-kvm (Ubuntu Cosmic):
status: Triaged → In Progress
Changed in linux-kvm (Ubuntu Bionic):
status: Triaged → In Progress
no longer affects: linux-kvm (Ubuntu Bionic)
Joseph Salisbury (jsalisbury) wrote :

I built a test kernel from the linux-kvm repo. This repo already has those two options enabled:

https://paste.ubuntu.com/p/b89KnWhdqq/

The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1799791

Ryan Harper (raharper) wrote :

The virtio configuration in this new kernel build changed, can it get reverted to what the -kvm kernel currently has?

% grep VIRTIO /boot/config-*kvm
CONFIG_BLK_MQ_VIRTIO=y
CONFIG_HW_RANDOM_VIRTIO=y
CONFIG_NET_9P_VIRTIO=y
# CONFIG_RPMSG_VIRTIO is not set
CONFIG_SCSI_VIRTIO=y
CONFIG_VIRTIO=y
CONFIG_VIRTIO_BALLOON=y
CONFIG_VIRTIO_BLK=y
# CONFIG_VIRTIO_BLK_SCSI is not set
CONFIG_VIRTIO_CONSOLE=y
# CONFIG_VIRTIO_INPUT is not set
CONFIG_VIRTIO_MMIO=y
CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
CONFIG_VIRTIO_NET=y
CONFIG_VIRTIO_PCI=y
CONFIG_VIRTIO_PCI_LEGACY=y

Joseph Salisbury (jsalisbury) wrote :

Sure, I'll take a look and build a new kernel.

Joseph Salisbury (jsalisbury) wrote :

I posted another test kernel built using the linux-kvm tree, with no changes made.

The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1799791

This is the output from the default config files in this repo:

https://paste.ubuntu.com/p/79TsTgpXWt/

Ryan Harper (raharper) wrote :

Could you re-apply the KEXEC config changes to the linux-kvm tree build?

Joseph Salisbury (jsalisbury) wrote :

The CONFIG_KEXEC and CONFIG_KEXEC_FILE config options are already enabled for the linux-kvm repo. Here is a grep of the config directory:

https://paste.ubuntu.com/p/w84BrTZKVc/

This tree was cloned from:
lp:~canonical-kernel/ubuntu/+source/linux-kvm/+git/cosmic

Do you see these options enabled on your test environment after installing that kernel?

Changed in linux-kvm (Ubuntu Cosmic):
status: In Progress → Confirmed
Changed in linux-kvm (Ubuntu):
status: In Progress → Confirmed
assignee: Joseph Salisbury (jsalisbury) → nobody
Changed in linux-kvm (Ubuntu Cosmic):
assignee: Joseph Salisbury (jsalisbury) → nobody
Connor Kuehl (connork) on 2019-04-22
Changed in linux-kvm (Ubuntu):
assignee: nobody → Connor Kuehl (connork)
Changed in linux-kvm (Ubuntu Cosmic):
assignee: nobody → Connor Kuehl (connork)
Connor Kuehl (connork) wrote :

At first glance it looked like these options were enabled for linux-kvm because they showed up as being set to "yes" under the "debian.master/config/config.common.ubuntu" file. However, my grepping was too narrow because grepping for "CONFIG_KEXEC=" didn't show the following lines:

debian.kvm/config/config.common.ubuntu:# CONFIG_KEXEC is not set
debian.kvm/config/config.common.ubuntu:# CONFIG_KEXEC_FILE is not set

For derivative kernels like linux-kvm, if it's set in the debian.master but unset in debian.kvm, then it's unset for the package.

Sent a patch to the ML to enable it for linux-kvm: https://lists.ubuntu.com/archives/kernel-team/2019-April/100350.html

Changed in linux-kvm (Ubuntu Xenial):
status: New → In Progress
Changed in linux-kvm (Ubuntu Bionic):
status: New → In Progress
Changed in linux-kvm (Ubuntu Cosmic):
status: Confirmed → In Progress
Changed in linux-kvm (Ubuntu Disco):
status: New → In Progress
Connor Kuehl (connork) on 2019-05-08
Changed in linux-kvm (Ubuntu Xenial):
assignee: nobody → Connor Kuehl (connork)
Changed in linux-kvm (Ubuntu Bionic):
assignee: nobody → Connor Kuehl (connork)
Changed in linux-kvm (Ubuntu Disco):
assignee: nobody → Connor Kuehl (connork)

We are applying these changes on linux-kvm only for Cosmic and Disco for now. If they don't cause any problems (e.g. boot speed increase) we will apply later also for the older series.

Changed in linux-kvm (Ubuntu Cosmic):
status: In Progress → Fix Committed
Changed in linux-kvm (Ubuntu Disco):
status: In Progress → Fix Committed
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