Recompilling the NEORV32 Bootloader

The NEORV32 default bootloader has various configuration options. Here’s how to modify and recompile it.

If you want to modify the bootloader, edit the bootloader.c file first. Then recompile the bootloader into a .vhd file representing the ROM:

cd lib/neorv32/sw/bootloader
make clean_all
make make bl_image

Memory utilization:
   text    data     bss     dec     hex filename
   4092       0       8    4100    1004 main.elf
Compiling image generator...
Generating neorv32_bootloader_image.vhd

Finally, install this file somewhere along our modified NEORV32 sources:

mv neorv32_bootloader_image.vhd ../../../../src/hdl/neorv32/neorv32_bootloader_image.vhd

In our top-level Makefile, make sure you use this file instead of the original neorv32_bootloader_image.vhd. Then simply re-synthesize and re-flash the FPGA firmware.

If you’re making modifications and just want to test the bootloader, you can use make exe instead of make bl_image and run the bootloader like a normal application.