Hello Arunkumar V,
My recommendation is downloading the Linux Document Bundle for the Kernel BSP in which you are interested.
https://www.nxp.com/support/developer-resources/run-time-software/linux-software-and-development-too...
For example, for the 4.1.15_2.0.0 Linux BSP Release it would be the following link (you may need to login to download this documentation bundle).
https://www.nxp.com/webapp/Download?colCode=L4.1.15_2.0.0-LINUX-DOCS
Inside you will find the i.MX Yocto Project User’s Guide. Please follow this document for instructions on how to build a Linux image for the i.MX6 NXP’s Boards. The i.MX BSPs use Yocto as a means of distribution and customization.
If you are using a third-party board some are supported by the Community BSP (link below).
http://freescale.github.io/
I hope this information helps!
Regards,