If your Mi A1 is enrolled to Xiaomi's Beta program you should have received the over-the-air update notification for the Android 8.0 Oreo Beta update.
The Oreo Beta with December 2017 patch for the Mi A1 weighs in at around 1104.1MB. Android 8.0 Oreo brings along brand new System Interface, Autofill, Picture In Picture, Better Battery Life, Fast Boot, and more.
If you haven't got the notification of this new software update yet, Just go to Settings - About Phone - Software updates, and It will automatically start downloading the latest update. The update will take around 10-15 minutes to get Installed on your device. Stay tuned to our Facebook and Twitter page to get the first News.