TX1 disable Ubuntu Unity and Start Qt App on startup

I am using R23.2 on TX1.
I want to start my QT app after TX1 boot without showing any linux boot messages and login prompt.

I have disable linux boot message and enable autologin. And added desktop entry in /etc/xdg/autostart. Now my app automatically start after boot with no boot messages.

But Below is my problems,

  1. When my application starts its shows Unity desktop for fraction of seconds.
  2. Unity desktop is running in background so if someone presses Alt+TAB or some other key combination it will minimise my qt app and switched to Ubuntu Unity.

So is there any way i can start my Qt app just after x11 or lightdm start and before unity appears. or just disable unity and only init x11.

I have asked same questions some months ago in the following thread.
https://devtalk.nvidia.com/default/topic/970098/tx1-l23-2-run-qt-qml-gui-app-on-startup
linuxdev suggested solution using startx. But i think i didn’t able to completely understand his suggestion. And as i had some other imp task i dropped the issue at that time.

So anyone suggest some code snippet, how to achieve this?

Here is a similar reply to a recent question:
https://devtalk.nvidia.com/default/topic/988135/jetson-tx1/customize-start-sequence/post/5057956/#5057956

Basic flow of boot is:

  1. kernel load -> starts init
  2. [u]At multi-user stage:
    1. [/u] init -> starts getty/agetty
  3. getty/agetty -> starts console logins
  • At graphical stage: getty/agetty -> replaces one console login with X11 using login manager arguments
  • At graphical login: login manager -> replaces existing X+login with X+window manager run sudo user
  • Changing the arguments passed to X at start changes what X runs with it; default is either a login manager or a window manager. You have to edit that (I have no example of a specific edit).

    One option is to edit the startup of the standard X init file location in “/etc/X11” and let the normal X startup use that. The other option is to start X independently with your own configuration directly naming what you want started with it (this would mean having getty/agetty start X with your arguments instead of those of “/etc/X11”). The decision on which to choose would be related to whether you want just this application to run, or if you want your application to run within a windowing environment (see that URL listed above).

    Startx is somewhat of a hybrid. systemd or init scripts normally tell getty to replace a console session with an X graphical session based on “/etc/X11” files. Startx is intended for manual start and offers some command line customization, but I think it still uses some of “/etc/X11” unless your options override (one part which startx does not do from “/etc/X11” is run a login manager…startx directly starts as the user running startx). Note that startx is a human-readable script…you can walk through this to see how it is done and then manually create your own startx style script.

    To emphasize, X is just a program which starts with arguments like any other program. The init process is configured to start with a login manager argument unless autologin occurs, in which case X starts instead with a window manager argument (and sudo some user). Manual login at the login manager replaces an existing X session running a login manager with an X session using a window manager (sudo user). If at any point you change the arguments to X then you change what it spawns with…the trick is deciding where you want to intercept it.

    To know what occurs automatically you’d need to study how getty/agetty is started and configured.

    Hi Linuxdev,

    Thanks for your detail explanation.
    I got one simple solution.

    Add following line in /etc/lightdm/lightdm.conf

    session-setup-script="QT App Path"
    

    Now my Qt App start after boot without Unity to be load…