Session cookie name for Symfony2 and subdomains

config.yml

framework:
    esi:             { enabled: true }
    translator:      { fallback: %locale% }
    secret:          %secret%
    router:
        resource: "%kernel.root_dir%/config/routing.yml"
        strict_requirements: %kernel.debug%
    form:            ~
    csrf_protection: ~
    validation:      { enable_annotations: true }
    templating:
        engines: ['twig']
        #assets_version: SomeVersionScheme
    default_locale:  "%locale%"
    trusted_proxies: ~
    session:
        cookie_lifetime: 0
        save_path: %kernel.root_dir%/var/sessions
        cookie_domain: .my-domain.com
        name: SFSESSID
    fragments:       ~