Delete me: Raspberry Pi 4 port status (Rev #38, changes)
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Overview
The Raspberry Pi 4 was launched in June 2019, and work on porting RISC OS to the Raspberry Pi 4 is still ongoing.
Some features are not working, so as this a build result is there not are yet no suitable prebuilt for new users.ROM images available for the Pi 4. If you wish to work on the port of RISC OS to the Pi 4, you will have to compile the ROM from source (see Further information below).
RISCA development OS builds for all previous versions of the Raspberry Pi (Pi 1, Pi 2, Pi 3, Pi Zero etc.) are still available from the ROM image is available from the Downloads page. page – be sure to choose the one marked “Beta RPiROM”.
Current status
Components that work
| Date | Details |
|---|---|
| 03 Sep 2019 | UART0 fixed: access to the command line via the serial port now works. |
| 13 Sep 2019 | Add GICv2 interrupt controller support. |
| 16 Feb 2020 | Audio output now works. |
| 18 Feb 2020 | USB devices now visible via USB-C (power input) port. |
The non-availability of the USB ports is a limiting factor:
- The Pi4 can optionally be powered via the GPIO pins, freeing up the USB-C (power input) port for a conventional hub.
- If you have the WiFi HAT for the Raspberry Pi, input is possible via VNC.
Major components needing attention
| Item | Comments |
|---|---|
| Ethernet port | Ethernet is now “direct-attach” rather than “via USB” so a new driver needs to be written. |
| USB ports | The Pi 4 has a USB3 controller, which RISC OS does not yet support. |
| Memory addressing | Ethernet and USB now live above the 4GiB boundary in the memory map: RISC OS will have to add “address extension” code to be able to access them. |
How to get RISC OS running on the Pi 4
The non-availability of the USB ports is a limiting factor. To use RISC OS on the Raspberry Pi 4, you have three options:
- Use a USB-C hub with Power Delivery and an external power supply capable of delivering 3 amps. This allows USB devices to be connected to the hub plugged into the USB-C (power input) port.
- Supply power to the GPIO pins, freeing up the USB-C (power input) port for a conventional USB hub.
- If you have the WiFi HAT for the Raspberry Pi, input is possible via VNC – as no USB devices are needed, a standard power supply can be connected to the USB-C port.
See Software information: Raspberry Pi: Firmware for the firmware required for the Raspberry Pi 4, along with details of the changes needed to config.txt.
Further information
- ROOL announcement (02 July 2019)
- Discussion thread in the General forum
- Discussion thread in the Porting RISC OS forum
- Ben Avison’s Work In Progress page on GitLab gives a run-down on how to get RISC OS loaded on the Pi 4 (it involves compiling the ROM from source, so You Really Need To Know What You Are Doing).
For more general information, see Using RISC OS on the Raspberry Pi.
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