NixOS on the HoneyComb / ClearFog LX2k

Overview

This is the minimal viable configuration: vendor bootloader and NixOS image with vendor kernel but buildable with Nix.

Usage

To boot this configuration, you require a microSD card for uboot, and USB (or similar) storage for NixOS. This is required due to the write-enable line floating on the hardware which prevents writing to the microSD slot, and NixOS’s sdImage assuming the device it boots from is writeable.

Build and write the sdImage to USB

# Build the sdImage
nix-build release.nix -A sdImage -o sdImage

# Write to storage
cat sdImage/sd-image/*.img > /dev/$usb

Build and write the bootloader to microSD

# Build the uboot image
nix-build release.nix -A ubootImage -o ubootImage

# Write to microSD storage
cat ubootImage/*.img > /dev/$microSD

The default memory speed is 3200mhz. If your memory is slower, you will need to specify a compatible speed with:

# Build the uboot image
nix-build release.nix -A ubootImage -o ubootImage --arg ddrSpeed 2600

Insert both images and boot

Note that uboot from upstream has some issues and incompatibilities. These have been patched into the uboot configuration, so everything should work with no additional effort.

ramdisk_addr_r unset

This causes ramdisk loading to fail. Set this explicitly via setenv

setenv ramdisk_addr_r 83900000

fdtfile unset

This allows the usage of FDTDIR in extlinux.conf, and should be set via

setenv fdtfile freescale/fsl-lx2160a-cex7.dtb

scriptaddr leaves 4k for extlinux.conf

This is very easy to overrun in NixOS, and results in the ethernet firmware failing to load. The vendor uboot configuration allows 4K, while the recomended value for this is 1MB.

setenv scriptaddr 0x83800000

bonus: boot_targets

This can be set to only scan the device you want to boot.

setenv boot_targets nvme0

Full example of booting from the nvme storage

setenv scriptaddr 0x83800000
setenv ramdisk_addr_r 83900000
setenv fdtfile freescale/fsl-lx2160a-cex7.dtb
setenv boot_targets nvme0

Good luck!

Notes

make menuconfig

Requires some dependencies:

nix-shell -E 'with (import <nixpkgs> {}); stdenv.mkDerivation { name = "fake"; nativeBuildInputs = [ ncurses pkgconfig bison flex ]; }'

export NIX_CFLAGS_LINK=$(pkg-config --libs ncurses)

Future work

Make a squashfs image

Distributing disk images is strange, especialy when devices have onboard emmc, sata, usb and nvme. A squashfs image would boot from read-only media and allow nixos-install onto their desired target.

It’s also much smaller.

uefi support

The source repo has uefi build scripts, which were completely ignored.

Improve self-hosting

Determine which of boot.kernelParams are important and move them to a module that can be included by installed systems.

Why is 2gb of memory allocated to huge pages?

LICENSE

This repo is a port of Solidrun/lx2160a_build, and has a copy of the patches from that repository, it is subject to the same conditions. Anything original to this repository is available under the same conditions as nixpkgs for ease of upstreaming.