SiFive Unleashed U5 hardware support

[Logicwax]

I'm trying to get some baremetal code running on the SiFive Unleashed board, enough to provide some two-way communication over the virtual comm serial port (sifive UART) with printf/getchar function calls.

I have been trying to compare the differences between the hardware E2 core and the qemu E2 core folders to try and see if I can adopt the qemu U5 core to work on the actual unleashed board U5 hardware, but I just can't see to get it working. Looking in the memory layout of the E2 hardware default.lds I see,

flash (rxai!w) : ORIGIN = 0x40400000, LENGTH = 128M
ram   (wxa!ri) : ORIGIN = 0x80000000, LENGTH = 64K

I have tried changing it to:

ram   (wxa!ri) : ORIGIN = 0x80000000, LENGTH = 128M
flash (rxai!w) : ORIGIN = 0x10000, LENGTH = 64M

but no luck. any idea on how I could get my code which is working on the qemu simulation of U5 to work on actual hardware? There already is E2 qemu to hardware parity, so I must be missing something very small.