I have been trying to get the lwip demo from processors.wiki.ti.com/.../HALCoGen_Ethernet_Driver_and_lwIP_Integration_Demonstration working on the RM46, but it would crash after getting a DHCP lease or when receiving pings.
I have finally worked out that the problem was a stack overflow. The code runs in supervisor mode and the supervisor stack is only set to 256 bytes. Increasing the size of the stack fixes the problem.
To change the stack size go to the "RAM" sub-tab of the main processor tab in HalCoGen and re-generate the code.