Q:

create arbitrary values in php.ini

I would like to put some of my app config data in php.ini
I tried just to add new values there and then get them with ini_get
I get nothing displayed. 
Do I need to define new entries in an extension? 
I know I can create a config file/ini file and easily parse it with PHP, But I want to avoid that.  
I do that as I assume it is being loaded once per process. 
I do not give here the big big picture, as I want to keep it as much as possible only a technical question, sadly, this platform does not allow debates. 
I do need it inside the php.ini

A:

Have you looked at get_cfg_var( config_var )? 
http://www.php.net/manual/en/function.get-cfg-var.php
I believe this is for retrieving custom variables from e.g. the servers php.ini file

