ok I unplugged the link and kodi was installed correctly, but not retropie, I'll retry and keep this updated so this could be useful to others.

Yeah there is not great feedback information from the installation process for native apps. The big thing most people miss is that you need to completely unplug the device and plug it back in to get the installation to occur; the scripts that check the USB drive are only run on initial bootup of the device.

Some people were talking before of making an online "native app store" native app that could be installed, but it seems that fell through the cracks.

You are going to want to use the prebuilt cores by various people here on the forum with retroarch. It is easy enough to get retroarch built, but a lot of the cores don't build correctly with the SDK setup as is.

A separate Github should be started just for Retroarch for Steam Link really; that contains scripts and/or patches to actually compile the cores against the Steam Link SDK. ( or potentially just submit pull requests against the SDK itself; it seems that is how a number of things came to be in the SDK )

Originally posted by livxtrm:

You are going to want to use the prebuilt cores by various people here on the forum with retroarch. It is easy enough to get retroarch built, but a lot of the cores don't build correctly with the SDK setup as is.

I've managed to enable ssh and debug what was missing with gdb, I don't know what I'm doing wrong but I need to manually download assets in the retroarch dir in .config/retroarch/assets following this bug https://github.com/libretro/RetroArch/issues/3217 (notice the link to the assets is wrong but it shows the correct one).
The problem here is that I have a horrible skin, like this one http://vignette3.wikia.nocookie.net/emulation-general/images/8/8d/Rgui.png/revision/latest?cb=20131006191402 and I need to figure out how to reenable what retroarch was trying to load before me manually downloading that asset dir.

Now retroarch starts, to compilicate things a little I've cross compiled sshfs and mounted 30GB of roms from a network host, this is reeeeally cool.

OK, I needed to enable xmb under Settings ->Driver ->Menu Driver -> set XMB, update assets and now I have the beautiful blue skin!

I would recommend using EmulationStation to launch Retroarch to games directly instead of using the GUI of Retroarch directly. That is why I went through the effort to get it running on the Steam Link after all.

It is nice in that it has scraping for game art and description. Additionally you can select a custom core per ROM for ROMs that don't play nicely with the default core you typically use for a system.