Bug 1534998 - The default display resolutions of guests running on qemu-kvm do not match the host's default ones
Summary: The default display resolutions of guests running on qemu-kvm do not match th...
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Fedora
Classification: Fedora
Component: libvirt
Version: 30
Hardware: x86_64
OS: Linux
unspecified
low
Target Milestone: ---
Assignee: Libvirt Maintainers
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2018-01-16 12:35 UTC by ricky.tigg
Modified: 2019-05-29 15:55 UTC (History)
9 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2019-05-29 15:55:25 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)
virsh – dumpxml – sample (4.09 KB, text/plain)
2018-09-12 15:00 UTC, ricky.tigg
no flags Details

Description ricky.tigg 2018-01-16 12:35:26 UTC
Description of problem: The default screen display resolutions of guests created and running on QEMU-KVM do not match the host's default ones.

Version-Release number of selected component: 3.7.0-3.fc27.x86_64

Steps to Reproduce: On both host and guest with GUI and still with default screen resolutions, in terminal, execute 'xrandr|grep +'.

Actual results: Default display resolutions differ from each other.

Expected results: Emulator QEMU-KVM to interpret correctly host's default display resolutions.

Additional info: Assumed that host, a 13,3''-screen laptop whose default resolution 1280 x 800 pix (16:10) is used. Then each virtual machine with GUI display default resolution is 1024 x 768 (4:3), regardless the GUI environment.

Comment 1 ricky.tigg 2018-04-06 09:05:28 UTC
Issue alive since v. 27 to v. 28 beta.

Comment 2 Pavel Hrdina 2018-09-06 12:54:11 UTC
Hi, thanks for the report.  Can you please provide XML of that guest?  What are you using to view the screen of guest, virt-manager/virt-viewer or some other vnc/spice client?

Some notes, I don't thing that this is an issue for several reasons.

The resolution is usually detected from monitor connected to the graphic card, in case of virtualization the guest as an virtual graphic card and monitor is replaced usually by VNC or Spice server.

With spice you can have "autoresize" feature which will report back to the guest what is the resolution of the client application.

Comment 3 ricky.tigg 2018-09-12 15:00:48 UTC
Created attachment 1482710 [details]
virsh – dumpxml – sample

Tested on virt-manager. In Virsh, output resulting from 'dumpxml [domain]' (see attachment).

Comment 4 Ben Cotton 2019-05-02 20:56:43 UTC
This message is a reminder that Fedora 28 is nearing its end of life.
On 2019-May-28 Fedora will stop maintaining and issuing updates for
Fedora 28. It is Fedora's policy to close all bug reports from releases
that are no longer maintained. At that time this bug will be closed as
EOL if it remains open with a Fedora 'version' of '28'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 28 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 5 Ben Cotton 2019-05-28 22:24:26 UTC
Fedora 28 changed to end-of-life (EOL) status on 2019-05-28. Fedora 28 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
are unable to reopen this bug, please file a new report against the
current release. If you experience problems, please add a comment to this
bug.

Thank you for reporting this bug and we are sorry it could not be fixed.

Comment 6 Laine Stump 2019-05-29 15:55:25 UTC
What is your reasoning for thinking that the guest should have the same resolution as the host? As Pavel pointed out back in Comment 2, the guest OS detects the resolution from the "monitor" that the emulated graphics device is connected to. At boot time (and often for a long time afterwards) there is no "monitor" (connection to a VNC client). Beyond that, it's not valid to assume that the most common usage will be to run the VNC client in full screen mode (even if it is run on the same host that contains the guest, which is very often not true - very often the virtualization host has no display at all.)

So even if there was a way to report the host display resolution to the guest display driver, it would be incorrect most of the time.

As Pavel said, the solution to this is to use spice rather than VNC - the spice client will report the client resolution to the spice server inside qemu, which will update the driver in the guest. This way no matter what size of display client you open, the guest will always automatically reconfigure its video driver accordingly.


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