You could use a shared controller (Ember Guide) which saves the state of the private variable.
App.ApplicationController = Em.Controller.extend({
checkPrivate: null
});
Then, if you want to have accessible this value in a specific controller, you could import it with needs.
App. UserFeedPostsController = Em.ArrayController.extend({
needs: ['application']
});
App.ApplicationController = Em.Controller.extend({
needs: ['application']
});
If your case does not require to have accesible the data from the other controller, you can always access a specific controller from any route as:
this.controllerFor('application');