Allow php sessions to carry over to subdomains

Question

I use php sessions (not cookies, except for session id cookie) for all user data, and when a user goes to their profile user.mydomain.com they are immediately \"logged out\"

Answer 1

        if(isset($_COOKIE['session_id']))
            session_id($_COOKIE['session_id']);
        Zend_Session::start(); //or session_start();
        if(!isset($_COOKIE['session_id']))
            setcookie('session_id', session_id(), 0, '/', '.yourdomain.com');

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