NixOS on the Marvell ESPRESSObin

http://espressobin.net/

Bootloader

Different versions of the ESPRESSObin board have different memory layouts, which require different builds of the bootloader.

Note which one of these applies to your board, and replace <configuration> in the instructions below with the appropriate one.

• 512MB
• V5_1GB_2CS
• V5_1GB_1CS
• V7_1GB
• V7_2GB
• V5_2GB

Cross-compiling via default.nix

Clone the repository and run nix-build -A pkgsCross.aarch64-multiplatform.ubootEspressobinImages_<configuration>

Note that this uses your system nixpkgs, which may not be compatible. The flake build guarantees using a known working revision of nixpkgs.

eg. To build for the V7 1GB board, run nix-build -A pkgsCross.aarch64-multiplatform.ubootEspressobinImages_V7_1GB

Building via the flake

NOTE: Flake builds don't support cross-compilation. I build it on my x86_64-linux NixOS machines by enabling AArch64 binfmt emulation, but that is very slow compared to cross-compilation. See https://wiki.nixos.org/wiki/NixOS_on_ARM/Building_Images#Compiling_through_binfmt_QEMU

Build the bootloader without needing to clone the repository with nix build --experimental-features 'nix-command flakes' github:mirrexagon/espressobin-nix#packages.aarch64-linux.ubootEspressobinImages_<configuration>

eg. To build for the V7 1GB board, run nix build --experimental-features 'nix-command flakes' github:mirrexagon/espressobin-nix#packages.aarch64-linux.ubootEspressobinImages_V7_1GB

Flashing from U-Boot (original or from this repo)

Adapted from the USB stick instructions from http://wiki.espressobin.net/tiki-index.php?page=Update+the+Bootloader

1. Copy result/flash-image.bin to a USB stick.
2. Connect a USB cable to the serial port on the ESPRESSObin and boot it with the current bootloader.
3. Press enter to stop autoboot and get to the shell.
4. Run bubt flash-image.bin spi usb
5. Run reset to reset the board and boot into the new bootloader.

Extra steps after flashing

Stop autoboot, load the default U-Boot environment with env default -a, save it with env save, then reset.

The main goal is to get the fdtfile U-Boot variable to be automatically set correctly. To see the current value, run echo $fdtfile.

• On an ESPRESSObin V5, the correct value is marvell/armada-3720-espressobin.dtb.
• On an ESPRESSObin V7, the correct value is marvell/armada-3720-espressobin-v7.dtb.

Recovering from a bad flash

• Make sure you have built the appropriate U-Boot images for your board - the result symlink in the repo top level should point to them.
• Set the boot jumpers on the board to boot into UART mode: http://wiki.espressobin.net/tiki-index.php?page=Ports+and+Interfaces#Boot_selection
• Connect the USB serial port, ensure it comes up as /dev/ttyUSB0, then run ./uart-recover.sh, where <configuration> is as in the U-Boot section.
• Set the boot jumpers back to booting from the SPI NOR flash and reset the board (press the reset button or unplug and plug in the power).

SD image

The default AArch64 NixOS image will boot unmodified on the ESPRESSObin.

This should already work as it is set in the device tree, but if you don't get serial output over USB in Linux, console=ttyMV0,115200n8 needs to be added to the kernel command line.

NixOS configuration

MAC addresses

If not set in the U-Boot environment, MAC addresses are randomized on boot. To set these up so that U-Boot sets them and passes them to Linux, boot to the U-Boot console and set these variables in the environment (using the MAC addresses printed on my device as an example, adjust them to what yours has if you can):

• env set ethaddr f0:ad:4e:09:08:a0 for the switch-SoC connection end0
• env set eth1addr f0:ad:4e:09:08:a1 for wan
• env set eth2addr f0:ad:4e:09:08:a2 for lan0
• env set eth3addr f0:ad:4e:09:08:a3 for lan1
• env save

A secondary option is setting in NixOS configuration instead. This is slightly less desirable as the MAC addresses in the U-Boot environment (eg. for network boot) will still be randomized.

networking.interfaces.end0.macAddress = "f0:ad:4e:09:08:a0";
networking.interfaces.wan.macAddress = "f0:ad:4e:09:08:a1";
networking.interfaces.lan0.macAddress = "f0:ad:4e:09:08:a2";
networking.interfaces.lan1.macAddress = "f0:ad:4e:09:08:a3";

DHCP and eth0/end0

On at least Linux 6.6.60, networking should work correctly with a default setup.

See these links for more information and discussion on potential configuration issues with the ESPRESSObin ethernet hardware:

• #2
• systemd/systemd#7478

Hardware notes

• The V7 schematics (page 9) imply you can boot U-Boot from SD card by setting the three mode jumpers to 1. The wiki page table seems to be wrong, all modes except SPI NOR flash are the same.