Question about hotplugging

[Michel Dänzer]

On 2018-08-28 5:55 p.m., Mark van Rossum wrote:
> On my laptop I use Xorg with the intel driver on Debian.
> 
> When I hotplug my 2560x1600 monitor, the desktop switches to that monitor.
> When I hotplug my 2560x1440 monitor, the desktop gets extended.
> 
> 
> Logs:
> Xorg (==) intel(0): Display hotplug detection enabled
> ....
> /usr/lib/gdm3/gdm-x-session: (II) intel(0): resizing framebuffer to
> 2560x1600
> /usr/lib/gdm3/gdm-x-session[2975]: (II) intel(0): switch to mode
> 2560x1600 at 59.9 on DP1 using pipe 0, position (0, 0), rotation normal,
> reflection none
> 
> However, when I plug in a 2560x1440:
> gdm-x-session[1788]: (II) intel(0): resizing framebuffer to 4480x1440
> gdm-x-session[1788]: (II) intel(0): switch to mode 2560x1440 at 60.0 on DP1
> using pipe 1, position (1920, 0), rotation normal, reflection none
> 
> This latter behaviour is not desired as it leads to occasional crashed.
> 
> 
> Question:
> - who does the mode-switching? (Xorg, driver, xinerama, gdm?)
> 
> - how can I change the behaviour, so that when I hotplug the 2560x1440
> monitor, the framebuffer becomes 2560x1440 and not 4480x1440

It's up to your desktop environment. Xorg merely sends hotplug events to
interested clients, it doesn't automatically change the configuration in
any way.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer