What is bootaux command?

Question

I'm trying to load FreeRTOS on Cortex-M4 of i.MX8MQ SoC and found that it is a heterogeneous multi-core architecture, where the Cortex-A53 processor acts as master and loads the Cortex-M4 controller by using the bootaux command. When tried to get information on bootaux I was unable to find any except the references to TCM & DDR. I tried looking into the U-boot reference manual and no luck.

So, my questions are What exactly does the bootaux command do? How it loads the binary to Cortex-M4 controller? And kick-off execution of that binary? What is the physical medium over which U-boot of Cortex-A53 loads binary to Cortex-M4? Are these kind of processor architectures physically connected inside the SoC? I think bootaux is custom command implemented by the NXP customization to U-boot, where can I find the code for the same?

I'm new to U-boot, any corrections to my understanding, references and additional info is appreciated.

Quoted from below link (tried it and it works):

You can then start your first Hello World application on the Cortex-M4 manually (after copying one of the binary above to your storage):

=> load mmc 0 $m4loadaddr hello_world.bin
=> dcache flush
=> bootaux $m4loadaddr

https://boundarydevices.com/freertos-sdk-v2-3-for-i-mx8mq/