Nothing forces it to be in ROM. See for example https://github.com/carlosedp/riscv-bringup/blob/master/unleashed/Readme.md https://github.com/carlosedp/riscv-br

Nothing forces it to be in ROM. See for example https://github.com/carlosedp/riscv-bringup/blob/master/unleashed/Readme.md https://github.com/carlosedp/riscv-bringup/blob/master/unlea... where DRAM init seems to be in the FSBL part which is loaded from the SD card.