MIUI 9, you are excited about.

Xiaomi revealed a few devices that would get the update first, starting tomorrow, but the company will be rolling the update even to devices that are almost 4-5 years old.
Here is the complete list of Xiaomi devices that will be updated to MIUI 9 in the coming days.
2017
Redmi Y1, Redmi Y1s, Mi Mix 2, Mi Note 3, Mi 6, Mi Max 2, Redmi Note 4, Redmi Note 4X, Redmi Note 5A, Redmi 4, Redmi 4X.
2016
Mi Mix, Mi Note 2, Mi 5, Mi 5s, Mi 5s Plus, Mi Max, Mi Max Prime, Redmi Note 3, Redmi 3, Redmi 3s, Redmi 4, Redmi 4A
2015
Mi Note, Mi 4i, Redmi 2, Redmi 2 Prime, Redmi Note 4G Prime, and Redmi Note 2
2014-2012
Mi 4, Redmi Note 4G, Mi 3, Mi 2

How to upgrade to MIUI 9?

Upgrading to MIUI 9 is going to be an easy process— the system will notify you when an update for your device is available, you will have to tap on it and confirm the download. Otherwise, you can go the Updater app and manually check for updates.
For those on a beta version or those who want to manually flash the MIUI 9 update when it’s available, check the MIUI forums for detailed guides on how to do so.

What’s new in MIUI 9?

MIUI 9 addresses some important issues that users have pointed out for a while now, including the notifications and app launch speeds. Making it an important part of today’s presentation, Xiaomi highlighted these features to show that it has addressed these issues after user feedback.