A new software update is on its way to the OnePlus X, starting today. It's not Marshmallow, in case you were wondering. Your OnePlus X will still run Android 5.1.1 Lollipop even after applying this update.
But what Oxygen OS 2.1.3 does bring with it are several enhancements to the microSD card support on the device. You'll find UX improvements, along with exFAT SD card support, and the ability to move apps to and from the card. Thankfully, one nasty bug that made the handset reboot when you removed the SD card has been fixed.
According to OnePlus, some unnamed security patches are in too, as well as "general bug fixes and optimizations". The over-the-air rollout starts today, but the new bits will first only arrive on around 10% of devices out there, to ensure that everything about the update procedure is working fine. A wider release will then follow in a few days.
Source: GSM Arena