After i was given bitbake meta-toolchain where it will be generated below images for boot from sdcard.
To boot a Linux image on i.MX 6 and i.MX 7, the following elements are needed:
• Bootloader (U-Boot)
• Linux kernel image (zImage)
• A device tree file (.dtb) for the board being used
• A root file system (rootfs) for the particular Linux image
• Arm Cortex-M4 Image for iMX 7ULP