Bug 538727

Summary: Dual-head with a resolution sum greater than 2048 wide or tall breaks things
Product: [Fedora] Fedora Reporter: Richard Schwarting <aquarichy>
Component: xorg-x11-drv-intelAssignee: Adam Jackson <ajax>
Status: CLOSED CANTFIX QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: low    
Version: 12CC: ajax, mcepl, sitsofe, xgl-maint
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OS: Linux   
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Last Closed: 2010-08-30 20:36:35 UTC Type: ---
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Screenshot of warning given when preventing resizing beyond max XvImage size none

Description Richard Schwarting 2009-11-19 08:32:15 UTC 
Description of problem:
I have an IBM Thinkpad x41t with an Intel 915GM and a primary display of 1024x768.

Normally, compiz, gstreamer, xv, etc run well.  If I attach a second monitor, and keep the total horizontal screen width below 2048 pixels, things are still fine.  

If I set the second monitor to 1024x768 or higher (resulting in a screen width of 2048 or greater), I run into ugly issues.  

* Compiz distorts the desktop, replaces it with white (and a functioning cursor) and sooner or later freezes X.  Bug 530803.
* Also, Gstreamer is stuck using "X Window System (no xv)" (as reported in gnome-media-apps' gstreamer-properties) and, consequently, the following stop working:
** Cheese's view finder (shows black) (bug 538669) 
** Rhythmbox and Totems visualisations don't display (black space that don't repaint)
** mplayer can't use Xv

I think it might have something to do with kms and overlays: 
https://bugs.freedesktop.org/show_bug.cgi?id=20901

xvinfo reports the following:
"maximum XvImage size: 2048 x 2048"

I suppose if support for large spanning resolutions can't be added (i.e. due to vram size or something), would it be possible to get a warning with gnome-display-properties to alert users that having so large a screen will disable functionality?


Version-Release number of selected component (if applicable):
xorg-x11-drv-intel-2.9.1-1.fc12

How reproducible:
Always

Steps to Reproduce:
1. attach a second monitor
2. set its resolution such that the total width of the two screens together is at least 2048 or higher
3. try to start compiz (it leads to a freeze), Cheese (shouldn't get a viewfinder), or a visualisation, etc.
  
Actual results:
A freeze or blackness

Expected results:
Desktop effects! Or a viewfinder!  Or a visualisation!

Additional info:
Comment 1 Richard Schwarting 2009-11-26 06:56:35 UTC 
Playing around, I changed the bitdepth to 16 bit from 24.  Now I have a region from the left edge of my screen extending 600 pixels wide out where Xv video will display.  I can move, say, Totem so that the centre of the video is at the 600th pixel out, and the left half will still be rendered, while the right half will no longer be updated.  

Any ideas?
Comment 2 Richard Schwarting 2009-11-26 07:31:53 UTC 
Created attachment 373931 [details]
Screenshot of warning given when preventing resizing beyond max XvImage size

So I tried disabling Kernel Mode Setting (used nomodeset at grub) and was actually prevented from exceeding 2048x2048 when trying to set the size of my second monitor.

I suppose KMS somehow allows someone to use larger screens, but sacrifices full Xv support in the process?  (I say full, since when I lower bitdepth from 24 to 16, I get to play videos using Xv and use Cheese in part of the screen as described above)
Comment 3 Sitsofe Wheeler 2010-03-06 18:31:24 UTC 
This might be a dup of bug #513736 ...
Comment 4 Matěj Cepl 2010-03-11 23:20:18 UTC 
Thanks for the bug report.  We have reviewed the information you have provided above, and there is some additional information we require that will be helpful in our diagnosis of this issue.

Please attach your X server config file (/etc/X11/xorg.conf, if available), output of the dmesg command, system log (/var/log/messages), and X server log file (/var/log/Xorg.*.log) to the bug report as individual uncompressed file attachments using the bugzilla file attachment link above.

Actually, you might be lucky and having Xv together with KMS. Not sure about it, but certainly worth a try.

We will review this issue again once you've had a chance to attach this information.

Thanks in advance.
Comment 5 Matěj Cepl 2010-03-12 00:12:17 UTC 
(In reply to comment #3)
> This might be a dup of bug #513736 ...    

Most likely not, there is no crash here ... or is there?
Comment 6 Richard Schwarting 2010-03-14 05:03:27 UTC 
It will be a couple weeks until I have access to that computer again. Will  update when I do.
Comment 7 Adam Jackson 2010-08-30 20:36:35 UTC 
The 3D engine in Intel gen3 chipsets is limited to 2048 pixels wide.  Xv is implemented with the 3d engine.  So yeah, things break.  We allow resolutions up to 4096 wide because the 2d engine works fine at that size and people generally want multihead more than they want 3d.
Comment 8 Richard Schwarting 2010-08-30 22:35:24 UTC 
Couldn't a fix for this include some feedback for the user to let them know their hardware isn't capable?