Modifications to Tizen are done by uploading code to be reviewed to https://review.tizen.org/gerrit/.
See more at Platform Development.
Overview of Gerrit
The detailed guideline for setting up a development environment, including gerrit, is available at following site.
- Setting up Development Environment
- Installing Development Tools
- Cloning Tizen Source
- Building Packages Locally
- Submitting and Reviewing on the Gerrit and OBS
- Creating Tizen Image
Code review guidelines