Unable to set resolution for web client above 1920x1080 (ubuntu) in Nice DCV web client

Question

Hi team

I used to be able to override the default 1920x1080 display by running a command such as `sudo dcv set-display-layout --session session1 2560x1440+0+0` but that no longer seems to work.

I can see there are config settings that allow you to change the maximum resolution allowed but I haven't successfully managed to do so (I'm aware of the native client but I can't use it in this case)

As per [this page](https://docs.aws.amazon.com/dcv/latest/adminguide/config-param-ref.html), web-client-max-head-resolution config var doesn't seem to do anything?

Any help is appreciated

Cheers

MikeLim · Accepted Answer

I am able to get this working with web browser client connecting to Ubuntu 22.04 NICE DCV *virtual session* after editing /etc/dcv/dcv.conf and rebooting.

EC2 with NICE DCV created using [CloudFormation](https://github.com/aws-samples/amazon-ec2-nice-dcv-samples) template. 
Test with Intel (m6i.large) and Graviton(m4g.medium) instance types.

```
ubuntu@ip-172-31-30-156:~$ sudo cat /etc/dcv/dcv.conf | grep -B1 web-client-max-head-resolution
[display]
web-client-max-head-resolution=(3840,2160)
```

Web client was able to auto adjust resolution on my 4K display

In any case, I can manually set it as well
```
ubuntu@ip-172-31-30-156:~$ dcv list-sessions
Session: 'ubuntu' (owner:ubuntu type:virtual)
ubuntu@ip-172-31-30-156:~$ sudo dcv set-display-layout --session ubuntu 2560x1440+0+0
```

Edit:

Thanks for clarification; the above is for virtual session. You are using *console* (and not virtual) session on non-GPU instance.

As per [Install XDummy driver for non-GPU instances](https://docs.aws.amazon.com/dcv/latest/adminguide/setting-up-installing-linux-prereq.html#linux-prereq-nongpu), xorg.conf seems to limit resolution to 1920x1080 (`virtual 1920 1080` ? ). Try changing the configuration.

```
Section "Monitor"
..
    Identifier "DummyMonitor"
    HorizSync   5.0 - 1000.0
    VertRefresh 5.0 - 200.0
    Modeline "1920x1080" 23.53 1920 1952 2040 2072 1080 1106 1108 1135
    Modeline "1600x900" 33.92 1600 1632 1760 1792 900 921 924 946
...
EndSection
Section "Screen"
    Identifier "DummyScreen"
    Device "DummyDevice"
    Monitor "DummyMonitor"
    DefaultDepth 24
    SubSection "Display"
        Viewport 0 0
        Depth 24
        Modes "1920x1080" "1600x900" "1440x900" "1366x768" "1280x800" "1024x768"
        virtual 1920 1080
    EndSubSection

```
I am not familiar with the xorg.conf syntax. You will need to test out your changes. 
Alternatively,  consider using virtual session. The  [Ubuntu CloudFormation template](https://github.com/aws-samples/amazon-ec2-nice-dcv-samples/blob/main/cfn/Ubuntu-NICE-DCV.yaml)  from [github](https://github.com/aws-samples/amazon-ec2-nice-dcv-samples) may help

louis · Answer

even on a GPU instance (g5.4xlarge) the maximum resolution with NICE DCV is 1920.1080. 4K is advertised in the description and mandatory for my workstation use case. 
Could you share any pointer? much appreciated

EDIT: 
The default session created is CONSOLE session (strange on a gpu machine?)
if I disable auto creating sessions on startup. in the dcv.conf: create-session = false
then i can manually create a virtual session:
dcv create-session 1 --type virtual --owner ubuntu
in that case the resolution auto-adjusts to my 4k screen. great!

new question: how can I automatically create a VIRTUAL session? 
i couldnt find any parameter in the doc: https://docs.aws.amazon.com/dcv/latest/adminguide/config-param-ref.html#session_management_automatic_console_session
thank you very much for any pointer! @Mike_L

Unable to set resolution for web client above 1920x1080 (ubuntu) in Nice DCV web client

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