What is the correct format of an EGLFS configuration file?

HolgerS

Hi,

I am trying using a EGLFS configuration file along the lines of:

https://doc.qt.io/qt-5/embedded-linux.html

My configuration file looks like this:

{
  "device": "/dev/dri/card0",
  "outputs": [
      { "name": "HDMI-A-1", "mode": "1920x1080" },
      { "name": "DP-1", "mode": "1920x1080", "clones": "HDMI-A-1" },
      { "name": "DP-2", "mode": "1920x1080", "clones": "HDMI-A-1" },
  ]
}

I store this configuration in the file /etc/eglfs.conf.

When I try to load it using the variable QT_QPA_EGLFS_KMS_CONFIG I get the error:

qt.qpa.eglfs.kms: Invalid config file "/etc/eglfs.conf"  -- no top-level JSON object

Apparently, my configuration is incomplete.

What is missing?

Best,
Holger

SGaist

Hi,

Your JSON is invalid (meaning the file format). Remove the coma after the last outputs entry.

JonB

@SGaist
Yes, and isn't this an absolutely infuriating aspect of JSON...?!

SGaist

I wouldn't go as far as that. The format being strict avoids the need to write parser that must support that kind of cases which may or may not indicate that an entry might be missing.

HolgerS

@SGaist Thanks! Didn't see that one. I was too distracted by the error message "no top-level JSON object", thinking there was something fundamentally wrong with the structure of my JSON.