[vfio-users] 'dnf update' killed working VM

[Laszlo Ersek]

On 08/09/17 23:37, Alex Williamson wrote:
> On Wed, 09 Aug 2017 21:55:00 +0100
> "Patrick O'Callaghan" <poc at usb.ve> wrote:
>
>> On Wed, 2017-08-09 at 13:24 -0500, David wrote:
>>> Anyone else having trouble with a recent version of KVM / QEMU?
>>> Also I am still a Linux newbie, how should I troubleshoot this?
>>
>> For one thing, you could start by looking in the QEMU log file and/or
>> the system journal. You don't give any information about the VM (e.g.
>> I assume you're using GPU passthrough but you don't say anything
>> about it) so it's going to be hard for anyone else to guess what the
>> problem is. Perhaps if you post the XML file it might give someone a
>> clue.
>>
>> Also, note that Fedora 24 was EOL-ed today. You should update your
>> system to at least F25 as soon as possible. I'm on F26 and having no
>> problems.
>
> Yep, really hard to act on the limited information here.  Is it by
> chance a GPU assigned VM running OVMF and does that OVMF come from the
> kraxel repo rather than the base fedora repo?  Thanks,

Yes, someone who can reproduce the problem -- from the reports, there
are several users -- will have to bite the bullet, and bisect OVMF,
and/or bisect the host kernel.

(As a word of encouragement, I'll mention that last weekend a QEMU user
reported *and bisected* an OVMF regression (a corner case), and I wrote
the patch for him on Sunday.

  http://mid.mail-archive.com/b0a52980-bb3a-e1f2-c6d8-9832cd2df9da@redhat.com
  http://mid.mail-archive.com/20170806121622.30494-1-lersek@redhat.com

Not promising this as a general rule (especially not if the regression
turns out to be in the kernel, or in an edk2 module outside of
OvmfPkg/), but you should still be aware that bisection works wonders.
Learn it, and do it, please. Thanks.)

Especially in David's case, when there is a know version change for the
host kernel, and a (likely) known version change for OVMF -- see your
dnf history --, it should be trivial to isolate the regression to one
component. Then bisect that component while keeping the other component
constant.

Good luck everyone, and thank you for your cooperation.
Laszlo