Setup i.MX

1. The release section contains a zip file with an Distro (e.g. fsl-imx-x11) Machine (e.g. imx6ulevkand) information and a date & time when the image was build. Download the zip file in the section.
2. Within the ZIP file which is currently (2019-05-01) about 200 MB large you’ll find the image file ending on rootfs.sdcard.bz2 (the date and distro will vary.) e.g.core-image-base-imx6ulevk-20190429085504.rootfs.sdcard.bz2
3. Once you downloaded the image you need to execute the following commands:

bunzip2 -dk -f <image_name>.sdcard.bz2
sudo dd if=<image name>.sdcard  of=/dev/sd<partition> bs=1M conv=fsync

From experience, the sd card device usually shows up as /dev/mmcblk0, at least in modern Ubuntu.