Xiaomi MIUI 9 is still in development but it is believed the next-gen operating system would be based on Android 7.0 Nougat. A GFXBench result had appeared showing the Redmi Note 3 running Android 7.1.1, an indication that the latest Google OS would soon hit Xiaomi smartphones.
But before that would officially happen, an unofficial version of Android 7.1.1 for Xiaomi Mi Note, Mi 4 and Mi Note Pro has appeared. A screenshot of the Mi Note, Mi 4 and Mi Note Pro running Android 7.1 was shared recently on Weibo showing the security patch as having been updated on December 5, 2016.
According to the leak source, the ROM has been tested with no obvious bug and would become available for those interested in trying it out on their Mi Note. It is unofficial and only available on the three devices. Also, it may lack some of the features of the Android OS, so try it out at your own risk.