Integrate existing Git Repository with Perforce (P4)

I have browsed through the web, but I cannot find an answer.
What I am trying to do is the following:

  1. I have a git repository which has been used for over 1 year with lots of commits
  2. Due to productization, the code has to be moved into a P4 rep.
  3. However, the codebase (after transport) may change in git as well as P4

Now lets assume that reference branch in git is master

What I did is the following:

  1. Copy the latest code from git into P4 and submit it there
  2. Use git-p4 sync –branch=refs/remotes/p4/masterp4 //../ in order to create a new branch in my existing repository
  3. git merge master into masterp4
  4. does not work since a common commit is missing
  5. git-p4 submit, moreover, is not able to work with merge commits anyway

Another option was rebasing

  1. Start with an empty repository in P4
  2. Use git-p4 sync to create an empty masterp4 branch in git
  3. Rebase master onto masterp4
  4. Rebase masterp4 onto remote/p4/master
  5. Leads to thousands of p4 changelists.

The main problem is the broken link between the master branch and this masterp4 branch.
I wondered if there is not an easier solution anyway. Unfortunately, I am a git n00b.

Thanks for any ideas,

Philipp

Git Baby is a git and github fan, let's start git clone.