I find some links for you, hope helpful for you
"https://community.nxp.com/t5/i-MX-Processors/RTOS-supported-for-i-mx6/td-p/418876"
"https://www.freertos.org/Using-FreeRTOS-on-Cortex-A-Embedded-Processors.html"
"https://www.freertos.org/Using-FreeRTOS-on-Cortex-A-proprietary-interrupt-controller.html"