regarding multi-site installation, subdomain need migrate the content from primary domain

hi, currently we have a single-domain site in production,
for the purpose to develop a mobile site, i plan to do the multi-site set up

so i add the extra folder under sites/m.myhostdomain.com, and have the setting file copy under the folder
the database table use prefix "m_"

when i go to the sub-domain url, eg: http://m.myhostdomain.com/install.php, it displays the install step-by-step, and i
am actually install a empty copy of drupal, the core modules tables are shared.

everything seems great, but however, it is an empty site, i have to actived all those contribute modules, check all the settings same as primary domain, and all of customize content type are gone too as well as contents.

my qustion is there a module or an easy way to actually copy the whole thing under primary domain to this sub-domain rather then install an empty copy ? cause i shouldn't create those content again if those are almost the same except just change to a mobile theme ...

thank you very much in advice

webon100