[virt-tools-list] virt-manager vnc blank console

[Fabio Coatti]

In data domenica 9 agosto 2015 13:29:44, Cole Robinson ha scritto:
> On 07/30/2015 08:13 AM, Fabio Coatti wrote:
> > Hi all,
> > 
> > I'm facing a long-standing issue that I wasn't able to debug, whatever
> > forum or log I tried to read, so I'm asking here for some help.
> > 
> > 
> > 
> > Short description:
> > 
> > when I use virt-manager to connect to a remote kvm host (qemu+ssh), all
> > works just fine except the console screen of a vm, that is always black.
> > This happens with different versions of libvirt/kvm/virt-manager.
> > 
> > 
> > 
> > More symptoms:
> > 
> > - the vnc screen when it opens up, shows for few seconds scrolling
> > controls, but then only a black window
> > 
> > - using different clients the behavior is quite different. Basically,
> > connecting with standard ubuntu/debian/rh client (from 0.9 to 1.2) works
> > 
> > - on faulty client, same client version(s), so from 0.9 to 1.2) the vnc
> > screen is blank.
> > 
> > - not working clients are compiled from source (gentoo based)
> > 
> > - vnc by itself otherwise works (creating a tunnel and connecting to
> > virtual machine vnc port)
> > 
> > 
> > 
> > Basically what it would be useful for me is some hint about how to debug
> > this issue. I don't know if this can be related to some lib used by
> > virt-manager, tunnel issue or whatever. Of course, if someone has already
> > seen this issue and solved it it would be great, but I will be more than
> > happy with suggestions on how to debug this issue.
> > 
> > 
> > 
> > 
> > 
> > Of course I can provide more information.
> > 
> > 
> > 
> > Many thanks in advance.
> 
> Hi, thanks for the report. Please provide the full virt-manager --debug
> output when reproducing the issue and we can go from there


Thanks for the reply; in the meantime I made some research and i turned out that the 
problem was in cairo libs, or better in a specific compilation option.
Basically, enabling xlib-xcb configure flag in cairo causes virt-manager to show the 
reported bug (and breaks libreoffice impress too, btw). I can't recall why I turned on this 
flag (with gentoo is quite easy to change things like this one :) ), but turning it off and 
recompiling cairo fixed virtmanager behaviour.
Now, I can't say if the problem is only on cairo side or it is something in virtmanager that 
triggers the bug, however at least virtmanager now works as expected, maybe it is worth 
investigating.

Many thanks for your answer!


-- 
Fabio
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