Load and step through LPC43xx's M0 core?

I’ve been struggling with getting FreeRTOS up and running on the M0APP core of the LPC4350, and I could really use GDB, but I haven’t found any examples of how to do so.

How would I go about connecting GDB to the M0 instead of the primary M4, load an image, and actually start running the core? I would like to do this entirely from GDB if possible (which would of couse include setting the M0APPMEMMAP register and manipulating the RTU_RESET_CTRL bits to start the core) in addition to being able to connect to a running image, primarily because I suspect something to be wrong with how I’m loading the M0 image into RAM (objcopy -O binary, verbatim copy that into memory and set MEMMAP).

Thanks!