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#1 2010-11-24 10:06:03

dharmabm
Member
From: Bangkok, Thailand
Registered: 2010-02-25
Posts: 10

Xorg/x11vnc crash (bug?)

Hi all,
I'm having a really annoying problem and I think it is probably a bug, but wanted to check here first. When I am using x11vnc (and ONLY when using x11vnc), either directly or through ssh tunnel I am getting a hard lockup in X. Actually, 95% of the time that happens, but a few times I have dropped back to a slim login. I have tried downgrading both packages, both individually and together, still happens. This problem is in both my minimal (openbox) build and my fullblown gnome (both on the same hardware on different partitions). I have an Acer Aspire 4810T laptop with the intel i915 chipset. I cannot reproduce this on my salix, ubuntu or antix installs (all also on the same hardware, but of course using older versions of both packages). Until today I thought the entire system was locked, as I could not switch to another console, and could only use the sysrq procedure to restart, but today I discovered i could still ssh into the machine. Unfortunately there do not seem to be any errors logged, unless I am missing something. Is there a way I can force verbose logging on the xserver to see if I can get a clue as to what is happening? Anyone have any thoughts or seen this before? I have been searching fruitlessly for over a week, but with no error log it's a bit difficult to find a solution. Also, now that I discovered that I can still ssh in, I cannot seem to kill X so I can resume the session without rebooting. The process shows as defunct, but nothing I do seems to terminate it. Any thoughts there?
thanks in advance for any ideas,
k

oh, I'm running 64bit, and everything is up to date.

<edit> I just discovered I can restart the slim daemon and get back in without rebooting, but the root problem is still there. At least that is some progress! ;>}

Last edited by dharmabm (2010-11-24 10:08:42)

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#2 2010-11-24 10:47:40

Gusar
Member
Registered: 2009-08-25
Posts: 3,472

Re: Xorg/x11vnc crash (bug?)

I don't have a solution for x11vnc, but I can suggest to try tigervnc. Get it here: https://aur.archlinux.org/packages.php?ID=29633
Then create an xorg.conf with this:

Section "Module"
    Load        "vnc"
EndSection

Section "Screen"
    Identifier    "Default Screen"
    Option        "PasswordFile"        "/home/username/.vnc/passwd"
EndSection

Now your regular X is a vnc server.

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#3 2010-11-26 02:55:18

dharmabm
Member
From: Bangkok, Thailand
Registered: 2010-02-25
Posts: 10

Re: Xorg/x11vnc crash (bug?)

Thanks for the suggestion Gusar, however I like to use x11vnc for 2 reasons, 1) it runs on display:0 and 2) I can spawn the server through ssh so it doesn't have to run all the time. I'm guessing tiger does #1, but can it do #2?
Anyway, it seems that this issue may be mouse related, as I can pretty consistently force it to happen by using the scrollwheel, although oddly the only time it crashes consistently is in geany, it never seems to happen when using the scrollwheel in a terminal or chromium. I was hoping for a fix in today's xorg update, but it is still happening. :>(
k

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#4 2010-11-26 03:21:48

dharmabm
Member
From: Bangkok, Thailand
Registered: 2010-02-25
Posts: 10

Re: Xorg/x11vnc crash (bug?)

Well, I'm not yet 100% sure, but it looks like I may have solved it myself. I appended -logfile to the x11vnc execution, and saw this:
26/11/2010 10:16:47 Scroll Detection: -scrollcopyrect mode is in effect to
26/11/2010 10:16:47   use RECORD extension to try to detect scrolling windows
26/11/2010 10:16:47   (induced by either user keystroke or mouse input).
26/11/2010 10:16:47   If this yields undesired behavior (poor response, painting
26/11/2010 10:16:47   errors, etc) it may be disabled via: '-noscr'
26/11/2010 10:16:47   Also see the -help entry for tuning parameters.
26/11/2010 10:16:47   You can press 3 Alt_L's (Left "Alt" key) in a row to
26/11/2010 10:16:47   repaint the screen, also see the -fixscreen option for
26/11/2010 10:16:47   periodic repaints.
26/11/2010 10:16:47   Note: '-scale' is on and this can cause more problems.

Since it seemed my problem was related to scrolling, I took a shot with -noscr and, voila! So far so good.

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#5 2010-11-26 09:37:03

ninian
Member
From: United Kingdom
Registered: 2008-02-24
Posts: 696
Website

Re: Xorg/x11vnc crash (bug?)

I'm on 32-bit Arch, fully updated, with Openbox as WM, and running the x11vnc server + remmina client combination on a few machines. Over the past couple of weeks I've encountered hard lockups on the x11vnc servers too. I'll watch out for the scrolling problem as you suggest. Thanks for the tip.

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#6 2010-11-26 10:09:36

Gusar
Member
Registered: 2009-08-25
Posts: 3,472

Re: Xorg/x11vnc crash (bug?)

dharmabm wrote:

Thanks for the suggestion Gusar, however I like to use x11vnc for 2 reasons, 1) it runs on display:0 and 2) I can spawn the server through ssh so it doesn't have to run all the time. I'm guessing tiger does #1, but can it do #2?

It's true that with tigervnc, the server will always be running. But simply don't open port 5900 in your firewall, so a ssh tunnel will be the only way to reach it. Also, tigervnc has an advantage over x11vnc - speed.

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#7 2010-11-26 15:53:04

krunge
Member
Registered: 2009-12-05
Posts: 10

Re: Xorg/x11vnc crash (bug?)

dharmabm wrote:

Hi all,
I'm having a really annoying problem and I think it is probably a bug, but wanted to check here first. When I am using x11vnc (and ONLY when using x11vnc), either directly or through ssh tunnel I am getting a hard lockup in X. Actually, 95% of the time that happens, but a few times I have dropped back to a slim login. I have tried downgrading both packages, both individually and together, still happens.

There is a recent bug in Xorg that gives something that looks like a lock-up.

https://bugs.freedesktop.org/show_bug.cgi?id=30032

The workaround is to apply the "-noxrecord" option to x11vnc.  Search for "x11vnc noxrecord" at ubuntuforums.org for more info on the problem.

There is an older bug in the Xorg X server where it is also crashed.  The workaround there is to supply "-noxfixes" x11vnc option to disable cursor fetching.  Try that too if "-noxrecord" doesn't work.

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