is there a way to get access to a cookie stored a root site in a session set at subdomain level

being at root level http://mydomain.com, I stored a cookie cookie[:login]

I can see the cookie in my browser

site: mydomain.cm

login

_myapp_session

upon redirection, to url => http://test.mydomain.com ,

I would like to access this cookie, cookie[;login], but as I maintain sessions at subdomain level, I have

site: test_domain.com

_myapp_session

how can I access the cookie[:login] ?

thanks for any clue …

I tried to use the :domain

cookies[:login] = { :value => 1, :domain =>“test.mydomain.com”, :expires => 1.hour.from_now }

but no way cookies is not set for test

should I rather use ?

cookies[:login] = { :value => 1, :domain =>".mydomain.com", :expires => 1.hour.from_now }