Is it possible to force a monitor to stay in the server layout?

[Alex Deucher]

On Fri, Dec 21, 2012 at 10:52 AM, Aaron Plattner <aplattner at nvidia.com> wrote:
> On 12/21/12 06:29, Sven Berkvens-Matthijsse wrote:
>>
>> Hello,
>>
>> I can't seem to find an answer to my question anywhere on the web.
>> Either my use case is weird, or I'm not searching correctly :-)
>>
>> I have X.org server 1.11.3 running on Ubuntu. I'm using the radeon
>> driver with a Radeon HD6450. I have three monitors connected to the card
>> (all three monitors have a DVI input), and I've set up the server to
>> have all three monitors in one large desktop. This works brilliantly!
>>
>> Sometimes, I need to connect one of the monitors to another PC or other
>> equipment with a HDMI or DVI output. My problem is that if I pull out
>> one of the cables that is connected to the HD6450, that the card (and
>> the X server) will detect that the monitor has been disconnected from
>> the card. Consequently, the desktop size is modified and all my Gnome
>> panels will be jumbled. If I reconnect the monitor, it comes back
>> online, but the positioning of the windows and panels is not restored to
>> what it used to be.
>
>
> It's the X clients' job to effect that sort of policy.  In your case, it's
> probably gnome-settings-daemon.  You could try killing it as an experiment
> to see if the behavior goes away, or logging into a simpler desktop
> environment like Fluxbox that doesn't have a monitor policy daemon.
>
> I don't know offhand if gnome-settings-daemon has an option to turn off
> automatic reconfiguration of the screens.
>
>
>> What I would like is to be able to tell the X server that I don't care
>> whether monitors are disconnected or not, and that it should keep the
>> desktop size fixed, no matter which monitors are connected. My X
>> configuration file includes a full server layout section, and also
>> contains the resolutions of the monitors. Therefor, it should be
>> possible, I guess, I just don't know how. Perhaps the current software
>> is not able to handle this specific situation. I can live with it if the
>> monitors need to be connected at the time that the X server starts. As
>> long as I can disconnect them later on without the server layout and
>> desktop size changing.
>
>
> The nvidia driver has a "UseHotplugEvents" option you can use to suppress
> the RandR events that clients like gnome-settings-daemon listen for, to work
> around this sort of problem.  Maybe the radeon driver has something similar?

There's no runtime option, but you can disable udev support in the
build with the --disable-udev configure option for xf86-video-ati.  As
Aaron said, it's preferable to disable that behavior in your desktop
environment however.

Alex