Rewriting a CI url
This could be too simple of a solution but why not in your routing config do something simple like
in your config do something like
if ($_SERVER['SERVER_NAME'] == 'm.myhost.tld') $route['default_controller'] = "mobile";
This would make the default controller mobil so you wouldn't have to have /mobile...
As i said maybe too simple
EDIT: Doesn't work, but maybe someone can turn it into something that does
Try this:
RewriteCond $1!^mobile/RewriteCond %{HTTP_HOST} ^m\.myhost\.tldRewriteRule (.*) /mobile/$1 [L]