dispwin: ../../src/xcb_io.c:542: _XRead: Assertion `dpy->xcb->reply_data != ((void *)0)' failed.

Bug #481556 reported by Torsten Hilbrich on 2009-11-12
This bug affects 1 person
Affects Status Importance Assigned to Milestone
argyll (Ubuntu)

Bug Description

Binary package hint: argyll

Version: 1.0.3+dfsg1-3

Here is a description of the bug I sent to the argyll mailing list in may 2009:

On my system argyll crashed with the following output:

$ dispwin
dispwin: ../../src/xcb_io.c:542: _XRead: Assertion `dpy->xcb->reply_data
!= 0' failed.

I was able to track it down to the call of XRRGetCrtcGamma in the
function get_displays (source dispwin.c). The function assumes that a
output in connected state has always a valid crtc entry which is not
true with my hardware.

I added a test for outi->crtc != 0 (see attached patch against argyll
1.0.3) and everything works fine. I took the idea for checking crtc from

I will attach the following information:
- output of xrandr
- Xorg server log
- patch that fixes the problem, based on ubuntu package

Other packages:
ii libxrandr2 2:1.3.0-2
ii xserver-xorg-video-ati 1:6.12.99+git20090929.7968e1fb-0ubuntu1
ii xserver-xorg 1:7.4+3ubuntu10

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