See slide 38 in the slide link at https://fosdem.org/2018/schedule/event/riscv/ https://fosdem.org/2018/schedule/event/riscv/ It mentions low speed peripherals

See slide 38 in the slide link at https://fosdem.org/2018/schedule/event/riscv/ https://fosdem.org/2018/schedule/event/riscv/ It mentions low speed peripherals like UART being open source, but high speed interfaces like DDR and ethernet are 3rd party licensed IP blocks.