Hi!
Rsync isn't mentioned here: http://git.denx.de/u-boot.git/ , this fact makes me think that rsync support isn't present.
2.
"git clone http://git.denx.de/u-boot.git" just hangs with: Cloning into 'u-boot'...
U-Boot repo is very large, so it takes a lot of time and traffic to clone it. Are you sure that git clone hangs? It you enable enough verbosity, you'll see that git is doing something: $ git clone -vvvvvv http://git.denx.de/u-boot.git Cloning into 'u-boot'... Getting alternates list for http://git.denx.de/u-boot.git Getting pack list for http://git.denx.de/u-boot.git Getting index for pack 09e0accc51ea3a5c8d84fdf7fe7193bf7c7b51ff ... You can also use some network activity monitor to see that git is silently downloading a lot of information.
Btw, git:// protocol works fine, do you have any reasons to avoid using it?