Bug 507626

Summary: qemu-kvm VNC :: major display tearing garbage with windows guest and scrolling windows
Product: [Fedora] Fedora Reporter: Jonathan Underwood <jonathan.underwood>
Component: qemuAssignee: Glauber Costa <gcosta>
Status: CLOSED DUPLICATE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: 11CC: dwmw2, gcosta, itamar, jaswinder, markmc, virt-maint
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Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2009-07-20 04:43:13 EDT Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 480594    
Description Flags
Screenshot of Windows XP running in a guest none

Description Jonathan Underwood 2009-06-23 10:33:01 EDT
Created attachment 349096 [details]
Screenshot of Windows XP running in a guest

Description of problem:
When running a (Windows XP) guest under qemu-kvm viewed using a vnc viewer it seems that the display is not updated properly when scrolling windows resulting in unreadable tearing and garbage being displayed. Screenshot attached. This is a regression from the F-10 packages where this problem was absent. I see the problem with both the vinagre and virt-manager vnc client.

Version-Release number of selected component (if applicable):



How reproducible:
Every time

Steps to Reproduce:
1.Start a windows XP guest and connect via vnc
2.Scroll an application
Actual results:
Garbage on screen

Expected results:
No garbage on screen

Additional info:
Comment 1 Mark McLoughlin 2009-06-23 12:03:39 EDT
Thanks, I suspect this is a dup of bug #503156, but I'll leave it open until we can confirm that for sure
Comment 2 Jonathan Underwood 2009-07-13 07:15:13 EDT
Is there anything I can do to help debug this - this is a major problem, rendering guests pretty much useless for me.
Comment 3 Glauber Costa 2009-07-17 20:53:00 EDT
What I've found so far:

* It is qemu-kvm specific - does not happen with -no-kvm
* It is cirrus specific - does not happen with -vga std
* It worked until kvm-83 - stops working at kvm-84

I'll keep debugging this.
Comment 4 Mark McLoughlin 2009-07-20 04:43:13 EDT
Glauber posted a patch here:


Looks like it's confirmed as a dup of bug #503156, so marking it as such

*** This bug has been marked as a duplicate of bug 503156 ***