Ubuntu 20.4.6 LTS Nvidia legacy 340 driver and external monitor

[Richmond]

Sorin Srbu via ubuntu-users wrote:
> On Mon, 2024-08-26 at 12:58 +0100, Richmond via ubuntu-users wrote:
>> Sorin Srbu via ubuntu-users wrote:
>>> On Sun, 2024-08-25 at 00:07 +0100, Richmond via ubuntu-users wrote:
>>>> Liam Proven wrote:
>>>>> On Sat, 24 Aug 2024 at 20:21, Richmond via ubuntu-users
>>>>> <ubuntu-users at lists.ubuntu.com> wrote:
>>>>>> when gdm3 starts up the graphics card is reset to its default
>>>>>> settings, which are not quite right. I tried to change these
>>>>>> settings in the gnome preferences - displays, but it doesn't
>>>>>> quite work the same and sets the virtual screen bigger than
>>>>>> the screen.
>>>>> Are you using GNOME on Wayland or on X.org?
>>>>>
>>>>> Settings in `/etc/X11/xorg.conf` won't affect Wayland.
>>>>>
>>>>>
>>>> I would ask how to tell, but if xorg.conf doesn't affect Wayland,
>>>> then I must be using xorg, because it clearly works until gdm or
>>>> gnome resets the card.
>>>>
>>>> I think on Debian there was an option on the login screen to
>>>> choose between Wayland and Xorg, but I don't see that with Ubuntu.
>>>>
>>>>
>>> Hello!
>>>
>>> What's the output from the below command in a terminal?
>>>
>>> echo $XDG_SESSION_TYPE
>>>
>>>
>>> Just making sure we're on the same track. :-)
>> Hi,
>>
>> The output is:
>>
>> x11
>>
>> According to the ever dependable chatgpt, this variable is set by the
>> display manager. So x11 is what I would expect as I currently have the
>> display manager set to xdm. Then, depending on which user I log in as,
>> either the window manager ctwm is called from .xsession, or the
>> default
>> gnome desktop is started if there is no .xsession file.
>>
>> So the case I am considering is the latter where no .xsession file
>> exists and I am using the default desktop environment, gnome.
>>
>> This gave me an idea to check /etc/gdm3/config and set
>> WaylandEnable=false the dpkg-reconfigure gdm3 but the display was
>> still
>> not set correctly so I changed the display manager back to xdm.
> Ok, thanks.
>
> But isn't gdm3 the default with Gnome?
> Why is xdm being used, or is this a recent change with Ubuntu?
I changed it to xdm because gdm3 resets the graphics card losing the
changes from xorg.conf.
> Anyway, when I've had weirdish graphic problems I've used xrandr to
> hard-set resolutions, screen setups etc. Those setting are remembered
> between reboots and logoffs in my experience.
>
> Would that maybe be of help for you too?
Thanks, I managed to improve it a bit with that. But there is still some
strange thing happening with the virtual screen/physical screen not
being the same. I admit defeat with nvidia-settings as it does not even
accept its own output configuration file as valid.