Software information: Raspberry Pi: Firmware (changes)

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Raspberry Pi models supported

The instructions given below are suitable for models of Raspberry Pi up to and including the Pi 4B and Pi 400.
The Raspberry Pi 5 is not supported.

Accessing the bootloader partition

The Raspberry Pi bootloader files live in the FAT16 partition of the boot SD. On a standardDOS partition of the boot SD. On a standard RISC OS build using a Dual-format SD card, this can be reached by double-clicking on !Boot.Loader (i.e. shift-doubleclick on !Boot and then double-click on the file called “Loader”).

Pi bootloader files

The Pi Zero, Pi 1, Pi 2 and Pi 3 use the following files:

• bootcode.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.

• cmdline.txt – (Optional) Additional parameters to be passed to the kernel (i.e. RISC OS). See below for possible contents.

On the Pi 4 (and Pi 400) the following two files take the place of bootcode.bin, start.elf and fixup.dat:

• start4.elf – The Pi 4 GPU firmware. Forms a matched pair with fixup4.dat

• fixup4.dat – Additional code for the Pi 4 GPU. Forms a matched pair with start4.elf

Note If that you the are installing recent firmware on a Pi 4 4B has or its Pi boot 400, code you in may need to update theonboard EEPROMEEPROM so as it well. does See not the need bootcode.bin.Pi 4 EEPROM section below.

Obtaining Pi firmware

If you are running a recent build of RISC OS 5.31 beta – and only if you are running RISC OS 5.31 – there is a good chance that the latest Raspberry Pi firmware will work. Use these direct links to download the latest firmware:

• bootcode.bin
• fixup.dat
• fixup4.dat
• start.elf
• start4.elf

In all other cases – and particularly if you experience problems with the latest firmware – you should try an older firmware build, available from the following index pages¹:

• RISC OS 5.24 and 5.26: Use January 2019 firmware
• RISC OS 5.28: Use April 2023 firmware
• RISC OS 5.29: Use firmware with a build date² of 29 February 2024
• RISC OS 5.30: Use firmware with a build date² of 29 February 2024
• RISC OS 5.31: Use firmware with a build date² of 29 February 2024

For the Pi Zero, Pi 1, Pi 2 and Pi 3, the procedure to follow is:

• Go to the appropriate firmware page on GitHub (see above).
• Click on “boot”
• Click on “bootcode.bin”
• Click on the Download button (at the extreme right of the window) ³
• Click on your browser’s BACK button
• Click on “fixup.dat”
• Click on the Download button
• Click on your browser’s BACK button
• Click on “start.elf”
• Click on the Download button

For the Pi 4B and Pi 400, the procedure to follow is:

• Go to the appropriate firmware page on GitHub (see above).
• Click on “boot”
• Click on “fixup4.dat”
• Click on the Download button (at the extreme right of the window) ³
• Click on your browser’s BACK button
• Click on “start4.elf”
• Click on the Download button

¹ These index pages may not work if you are using NetSurf. Please use another browser to retrieve the firmware files.

² This is the date as reported by “vcgencmd version”. The website will mention the commit date, which can be later than the build date.

³ The download button contains a downward-pointing arrow – when you hover the mouse pointer over the button you should see a tooltip of “Download raw file”.

Installing the new firmware

From RISC OS:

• Click on the SD card icon to open a Filer window.
• Shift-doubleclick on !Boot.
• Doubleclick Double-click on Loader.
• For a Pi 4B or Pi 400, delete the files “fixup4/dat” and “start4/elf”, replacing them with the new versions you downloaded above.
• For a Pi Zero, Pi 1, Pi 2 or Pi 3, delete the files “bootcode/bin”, “fixup/dat” and “start/elf”, replacing them with the new versions you downloaded above.
• Close all Filer windows.
• Wait 15 seconds, then reboot.

From Windows/macOS/Linux:

• Insert the RISC OS SD card into a SD card reader connected to a Windows/macOS/Linux machine.
• Open a window on the first (or only) partition on the card. This is usually labelled “Boot” and will contain files with names such as config.txt, fixup.dat, fixup4.dat, riscos.img, start.elf and start4.elf.
• For a Pi 4B or Pi 400, delete the files “fixup4.dat” and “start4.elf”, replacing them with the new versions you downloaded above.
• For a Pi Zero, Pi 1, Pi 2 or Pi 3, delete the files “bootcode.bin”, “fixup.dat” and “start.elf”, replacing them with the new versions you downloaded above.
• Dismount the card (on macOS this option is labelled “Eject”) and wait for its icon to disappear. You may instead get a message of the form “It is now safe to disconnect the device”.
• Unplug the SD card from the card reader and reinsert the SD card into the Pi.

Configuration files

config.txt

This is a plain text file. The following example should be suitable for all models of Raspberry Pi supported by RISC OS:

[pi4]
enable_gic=1
[all]
arm_64bit=0
fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
init_emmc_clock=100000000
kernel=RISCOS.IMG
ramfsfile=CMOS
ramfsaddr=0x508000

If you have a Pi 4B or Pi 400, config.txt must have a [pi4] section containing the line
enable_gic=1

Parameters applicable to all models of Raspberry Pi appear in the [all] section.

These parameters – and several others that may be of interest to RISC OS users – are discussed in more detail at config.txt (Raspberry Pi).

cmdline.txt

This file is optional: RISC OS will still boot if it is not present.

If you are running a development version of RISC OS (5.27, 5.29 or 5.31) you may need to specify the following parameter to avoid a blank screen issue.

disable_gamma

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).