Bug 69730

Summary:	Intel driver SNA causes x11vnc to display black screen when running xbmc
Product:	xorg	Reporter:	John <da_audiophile>
Component:	Driver/intel	Assignee:	Chris Wilson <chris>
Status:	RESOLVED FIXED	QA Contact:	Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity:	normal
Priority:	medium	CC:	da_audiophile
Version:	unspecified	Keywords:	regression
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description John 2013-09-23 19:29:05 UTC

Connecting to a vncserver (x11vnc) running on a machine that uses the intel drivers with onboard video using SNA acceleration (default these days) causes a black screen to be displayed on the vncclient but only when xbmc is active.  Exiting xbmc restores the expected vnc behavior.  Disabling sna in /etc/X11/xorg.conf.d/20-intel.conf fixes the problem but causes poor video performance.  Note that I see nothing relevant in my Xorg logs to indicate there is a problem.

Note that I can connect to other machines that do not use the intel drivers (nvidia) and I get the expected results.

Linux distro: Arch linux x86_64

Example video hardware: Intel GMA X4500HD

Xorg version: 1.14.3

Drivers packages in use (official ARCH packages):
* intel-dri 9.2.0-2
* libva-intel-driver 1.2.0-1
* xf86-video-intel 2.21.15-1

Command used to start x11vnc on the target box:
/usr/bin/x11vnc -nap -wait 50 -passwd xxx -display :0 -forever -o /var/log/x11vnc.log -bg

It does not matter if I use the -noxdamage switch; the result is the same.

Comment 1 John 2013-09-23 19:37:06 UTC

I just built the xf86-video-intel-git package from the AUR[1].  No change following a reboot (I added --enable-sna to the ./autogen.sh step).  Git version: 2.99.902.45.g8f54e9d

1. https://aur.archlinux.org/packages/xf86-video-intel-git/

Comment 2 Chris Wilson 2013-09-23 19:59:17 UTC

That makes it onto my weird list. Other DRI clients area captured correctly, I wonder what games xbmc is playing.

Comment 3 Chris Wilson 2013-09-23 20:12:51 UTC

commit 3fd116782bb1c05a140f4783e92a8ee6a57143cd
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Sep 23 21:03:07 2013 +0100

    sna/dri: Clear the clear hint upon applying DRI damage
    
    Otherwise a later call to GetImage will not notice the DRI update if it
    was already clear - and so return a blank image. One example is the use
    of x11vnc replaying xbmc.
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=69730
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Comment 4 John 2013-09-24 22:22:13 UTC

Thank you, Chris.  This commit fixed the problem and was amazingly fast!

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