Software information: Raspberry Pi: Firmware (Rev #3)

Raspberry Pi models supported

The instructions given below are suitable for earlier versions of the Raspberry Pi up to and including the Raspberry Pi 3 (all models, including Compute Module 3+).

The Raspberry Pi 4 is not supported, although work is underway to add support. See Raspberry Pi 4 port status? for more information.

Pi bootloader files

Files which must be present

bootloader.bin – The boot loader for the CPU.

start.elf – The GPU firmware. Forms a matched pair with fixup.dat

fixup.dat – Additional code for the GPU. Forms a matched pair with start.elf

riscos.img – The RISC OS ROM

config.txt – Configuration parameters for the boot loader. See below for suggested contents.

Optional files

cmdline.txt – Additional parameters to be passed to the kernel (i.e. RISC OS). For details of the parameters available, see cmdline.txt (Raspberry Pi).

Obtaining Pi firmware

RISC OS 5.24 and RISC OS 5.26 should use the firmware supplied with the distribution: there is no point in using later firmware.

A code change in January 2019 means that RISC OS 5.27 cannot use the firmware supplied with earlier distributions, but there is a risk in using the absolute latest firmware as recent changes in the firmware could have had a detrimental effect on RISC OS operation.

The current recommendation is to use January 2019 firmware obtained from the download site

The files you need are: bootcode.bin, fixup.dat, start.elf.

• To obtain firmware for a given date, choose each component in turn and click on the History button.
• start.elf and fixup.dat are a matched pair, so you should use files released on the SAME date.
• bootcode.bin is not as heavily constrained, but for maximum peace of mind you should use the release closest in date to the chosen version of start.elf/fixup.dat.

Configuration files

config.txt

The contents of config.txt does not change much between RISC OS releases. The following parameters should be suitable for RISC OS 5.24, 5.26 and 5.27:

fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
init_emmc_clock=100000000
ramfsfile=CMOS
ramfsaddr=0x508000
kernel=RISCOS.IMG

These parameters are discussed in more detail at config.txt (Raspberry Pi).

Welcome to RISC OS Pi contains details of several other parameters (disable_overscan, hdmi_pixel_freq_limit etc.) that may be of interest to RISC OS users.

For a full list of boot options, see the documentation pages on the Raspberry Pi website and/or elinux.org

cmdline.txt

This file is optional: the system will still boot if it is not present.

Parameters must be space separated on the first line of the file, so if you wanted to specify two parameters you would do it like this:

disable_mode_changes disable_gamma

For details of the parameters available, see cmdline.txt (Raspberry Pi).