I had built the RetroArch Packages for GameShell with the latest source from GitHub.
Here is the download location: https://mega.nz/#F!qX5nVaAZ!yiNdrcL3RHZ7jZA-fwnivw
Upload those RetroArch packages to GameShell.
Execute the following commands in the folder with uploaded packages:
sudo apt-get install fonts-mplus
sudo dpkg -i libretro-core-info_1.7.0-r201807280156-383f18f_all.deb
sudo dpkg -i retroarch-assets_1.7.0-r201806241613-69c6e99_all.deb
sudo dpkg -i retroarch_1.7.3-r201807301536-b5d5fb4_armhf.deb
To use RetroArch installed by packages (instead of the one original shipped), execute the follow command:
mv /usr/local/bin/retroarch /usr/local/bin/retroarch.cpi
You can always switch back to the original shipped version by using the following command:
mv /usr/local/bin/retroarch.cpi /usr/local/bin/retroarch
For details about RetroArch configuration and tweaking, please refer to fr500’s RetroArch Megathread. This RetroArch package is also built with configure parameters suggested by fr500.