To start a demo stored on SD / e-MMC from U-Boot:
setenv fdt_file <rpmsg enabled device tree>
setenv cm_image <demo>
run boot_cm_mmc
To demonstrate rpmsg and freertos a simple demo is included. When the demo
is started you can connect from running Linux to the rpmsg ping pong demo:
modprobe imx_rpmsg_pingpong
Note: This demo runs for a fixed number of cycles and terminates the RPMSG system. The kernel driver stack may generate a warning after the demo on Cortex M terminates.