[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Sebastian Kügler]

https://bugs.kde.org/show_bug.cgi?id=370494

Sebastian Kügler  changed:

   What|Removed |Added

 Status|CONFIRMED   |RESOLVED
 Resolution|--- |DUPLICATE

--- Comment #17 from Sebastian Kügler  ---
So, good news.

This bug is a duplicate of another of bug:356864. 

Here's a bit of context, before I redirect this bug's traffic to the other one,
which has tracked the related changes.

libkscreen's list of modes for each output were never assumed to change at
runtime, so a whole lot of components assumed it would never change and not
react to changes, the list of modes was constant, as reasonable assumption
given hardware. Less reasonable in vms, as we know. So the vm presents us with
changing modes for outputs, but these were never re-read (in our xrandr
backend), and changes never propagated through libkscreen's API to the kded
module (which handles all the policy bits and initiates the actual changes at
runtime). A few patches down the road, and I've now successfully (with git
master) resizing Plasma inside the VM window.

In my setup (qemu with neon git unstable inside, host is a debian unstable
thinkpad with intel graphics), I'm running into a bug, however. When at least
one axis of the vm window shrinks, I reliably get a black screen, when I grow
any or both axes, and kscreen's kded sets the new mode, it works again. I can
reproduce this behavior also with using bare xrandr, so I assume that this is
not a problem in kscreen. More info on that welcome, of course.

So git master has all the patches in place, and I'll look into backporting
these bits to Plasma 5.8.4.

*** This bug has been marked as a duplicate of bug 356864 ***

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Sebastian Kügler via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #16 from Sebastian Kügler  ---
Interesting. So it seems we do get an update event, but since we don't reparse
the mode list, it stays static, and nothing actually changes.

Thanks a lot for the info, I'll look into coming up with a fix.

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #15 from Pavel Grunt  ---
Created attachment 101634
  --> https://bugs.kde.org/attachment.cgi?id=101634=edit
kded5 debug with timestamp

can the bug be related to this:
[20::00:58.168] unknown: Unable to get EDID for output "Virtual-1"
[20::00:58.205] unknown: Failed to register device: "device id
'xrandr-Virtual-1' already exists"
[20::00:58.207] unknown: Failed to create ICC profile on cmsCreateRGBProfile
[20::00:59.150] unknown: Config does not have at least one screen enabled, WILL
NOT save this config, this is not what user wants.

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #14 from Pavel Grunt  ---
(In reply to Sebastian Kügler from comment #8)
> Thanks! Could you also post the output of:
> 
> * kscreen-console (should show the same mode info as xrandr -q, but does it
> really?)
> * and the remaining files in ~/.local/share/kscreen/
> 
> Also, if you look "tail -f ~/.local/share/kscreen/", are there any new
> events in kscreen.log when you resize the window?

yes, there is a notify but not matching newly requested size
> 
> If you kill kscreen_backend_launcher (it will be automatically restarted
> when needed), does kscreen-console show the information matching with xrandr
> -q?
yes, both provide the same info - the correct preferred size
> 
> I've looked into the hotplug flag that was added in GNOME to make this case
> work, but this is not available through XCB (I couldn't find it), but should
> work automatically -- that is we do monitor the relevant events for the
> output, this is done in libkscreen/backends/xcblistener.cpp

mutter uses drmModeGetProperty to get info about "hotplug_mode_update" (it is
drm kms property - I googled for some info and found
https://01.org/linuxgraphics/gfx-docs/drm/drm-kms-properties.html )

Also in mutter it is not about the value of the property, but about its
presence. This comment may be useful:
https://git.gnome.org/browse/mutter/tree/src/backends/meta-monitor-config.c#n1478

> 
> xcb_randr_select_input(c, m_window,
> XCB_RANDR_NOTIFY_MASK_SCREEN_CHANGE |
> XCB_RANDR_NOTIFY_MASK_OUTPUT_CHANGE |
> XCB_RANDR_NOTIFY_MASK_CRTC_CHANGE |
> XCB_RANDR_NOTIFY_MASK_OUTPUT_PROPERTY
> );

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #13 from Pavel Grunt  ---
Created attachment 101632
  --> https://bugs.kde.org/attachment.cgi?id=101632=edit
tail -f ~/.local/share/kscreen/

Resized to something bigger than 1024x768

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #12 from Pavel Grunt  ---
Created attachment 101631
  --> https://bugs.kde.org/attachment.cgi?id=101631=edit
another file under kscreen

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

Pavel Grunt  changed:

   What|Removed |Added

 Attachment #101622|0   |1
is obsolete||

--- Comment #11 from Pavel Grunt  ---
Created attachment 101630
  --> https://bugs.kde.org/attachment.cgi?id=101630=edit
~/.local/share/kscreen/kscreen.log

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #10 from Pavel Grunt  ---
Created attachment 101629
  --> https://bugs.kde.org/attachment.cgi?id=101629=edit
kscreen-console

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

Pavel Grunt  changed:

   What|Removed |Added

 Attachment #101623|0   |1
is obsolete||

--- Comment #9 from Pavel Grunt  ---
Created attachment 101628
  --> https://bugs.kde.org/attachment.cgi?id=101628=edit
xrandr -q

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Sebastian Kügler via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

Sebastian Kügler  changed:

   What|Removed |Added

 Status|UNCONFIRMED |CONFIRMED
 Ever confirmed|0   |1

--- Comment #8 from Sebastian Kügler  ---
Thanks! Could you also post the output of:

* kscreen-console (should show the same mode info as xrandr -q, but does it
really?)
* and the remaining files in ~/.local/share/kscreen/

Also, if you look "tail -f ~/.local/share/kscreen/", are there any new events
in kscreen.log when you resize the window?

If you kill kscreen_backend_launcher (it will be automatically restarted when
needed), does kscreen-console show the information matching with xrandr -q?

I've looked into the hotplug flag that was added in GNOME to make this case
work, but this is not available through XCB (I couldn't find it), but should
work automatically -- that is we do monitor the relevant events for the output,
this is done in libkscreen/backends/xcblistener.cpp

xcb_randr_select_input(c, m_window,
XCB_RANDR_NOTIFY_MASK_SCREEN_CHANGE |
XCB_RANDR_NOTIFY_MASK_OUTPUT_CHANGE |
XCB_RANDR_NOTIFY_MASK_CRTC_CHANGE |
XCB_RANDR_NOTIFY_MASK_OUTPUT_PROPERTY
);

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #7 from Pavel Grunt  ---
Created attachment 101623
  --> https://bugs.kde.org/attachment.cgi?id=101623=edit
xrandr -q

Preferred changed to:
1920x1080 59.96 +  60.00
but the current didn't adjust

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #6 from Pavel Grunt  ---
Created attachment 101622
  --> https://bugs.kde.org/attachment.cgi?id=101622=edit
~/.local/share/kscreen/kscreen.log

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Pavel Grunt via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

Pavel Grunt  changed:

   What|Removed |Added

 CC||pavlik.gr...@seznam.cz

--- Comment #5 from Pavel Grunt  ---
Hi, it is not fixed in
plasma-desktop-5.8.1-1.fc25.x86_64

Respectively it resizes once, just after the login, after that it doesn't react
on changes of window size

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Sebastian Kügler via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #4 from Sebastian Kügler  ---
The thing is, I need to know if it works with 5.8, I won't spend time on it
without knowing that it's still broken as I can't fix it twice. So if you ask
me to prioritize this problem, that's useless unless I get the information I
need to actually work on this.

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #3 from adrela...@riseup.net ---
Unfortunately I run Debian Stable and it will be a while before 5.8 lands in
the repo. I understand there is a lot going on that you have to handle but
please try to prioritize this before the Debian Stretch freeze.

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Sebastian Kügler via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

--- Comment #2 from Sebastian Kügler  ---
This could be two things:

(1) libkscreen failing to mode-set for some reason, we had a number of bugs
that could lead to that and fixed them for 5.8.

(2) https://bugs.kde.org/show_bug.cgi?id=356864 which means that xrandr changes
the list of modes on the fly, which libkscreen doesn't handle gracefully enough
(yet). In that case, killing kscreen_backend_launcher and kded5, then
restarting kded5 should allow to set the correct mode (not an acceptable
workaround, of course, just a quick test to confirm this hunch).

To judge, we'd need
* confirmation if this is fixed in Plasma 5.8, or not
* xrandr -q, ~/.local/share/kscreen/kscreen.log, etc., as explained on
https://community.kde.org/Solid/Projects/ScreenManagement#Debugging_Information

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[KScreen] [Bug 370494] Automatic VM display resolution broken under KDE hosts

[Martin Gräßlin via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=370494

Martin Gräßlin  changed:

   What|Removed |Added

Version|unspecified |5.8.0
   Assignee|kwin-bugs-n...@kde.org  |se...@kde.org
Product|kwin|KScreen
  Component|general |common

--- Comment #1 from Martin Gräßlin  ---
This is nothing the window manager should do. Reassigning to kscreen which
might be the best fitting area.

Personally I think that's a problem of virt-viewer. This used to work in the
past and got broken. There is no reason why every desktop environment has to
reimplement the same code instead of having one generic solution.

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