Nix cross-compilation to the reMarkable tablet

Note: The reMarkable 1 and 2 have been added as cross-compile targets to Nixpkgs. As such, if you want to build things from source and not trust the company's toolchain, follow these instructions

Cross-compiling using Nixpkgs infrastructure

1. Ensure that your nixpkgs channel is up to date (or equivalent with niv and flakes). You can check if it can cross-compile to reMarkable 1 by running the following, replace with remarkable2 to check the same for reMarkable 2.

$ nix eval -f '<nixpkgs>' 'lib.systems.examples.remarkable1'

2. Create a non-root user on the tablet, e.g. useradd siraben && passwd siraben. Ensure that you have passwordless SSH set up by using ssh-copy-id.

3. The root partition on the tablet has very limited space (22 MB), so, as root, mkdir -p /nix /opt/nix && mount --bind /opt/nix /nix. The bind can be made persistent by adding the following line to /etc/fstab

/opt/nix /nix none bind,nofail 0,0

4. Install Nix on the device. To do this, fetch the latest armv7l-linux Nix build from https://hydra.nixos.org/jobset/nix/master, then un-tar it (tar -xf ...) and run the installation script. For the multi-user installation, you may have to upgrade busybox or edit the script, as the flags provided to head in the script aren't available on the default binary available on the reMarkable.

5. Using nix-build and nix-copy-closure, one can cross-build from their machine and transfer it to the tablet, like so. The NIX_SSHOPTS is needed because nix isn't available unless .profile is sourced.

$ NIX_SSHOPTS="source .profile;" nix-copy-closure --to [email protected] "$(nix build -f '<nixpkgs>' pkgs.pkgsCross.remarkable1.hello)"

Happy hacking!

Cross-compiling using reMarkable's toolchain

Clone and navigate to this repository and run the following to cross-compile retris to the reMarkable tablet. If you want to use the binary cache (recommended), run cachix use nix-remarkable first.

nix build --arg release true -f . rmPkgs.retris

Description

This repository adapts reMarkable's toolchain to be compatible with Nix. The added benefits are;

• cross-compiling up to 60,000+ additional packages from Nixpkgs
• reproducible builds and deployment, check out the GitHub actions artifacts in this repository
• takes advantage of benefits from source and binary deployment by using Nix and a binary cache
• allows macOS users to cross-compile to the tablet when used in conjunction with nix-docker

Currently, it includes both a Nixpkgs cross configuration for the reMarkable, and Nix expressions for various tools, including

• appmarkable
• chessMarkable
• evkill
• gst-libvncclient-rfbsrc
• mxc_epdc_fb_damage
• plato
• rM-vnc-server
• remarkable-fractals
• remarkable_news
• retris
• rm-video-player

To build a local copy of the above packages, create a pkgs/ directory, clone the relevant repository into it, and run nix build in the resulting subdirectory.

To build release copies of any of the projects, run nix build --arg release true -f . <attribute path> from this repo (without needing to manually download anything else), where <attribute path> is one of:

• hostPkgs.gst-libvncclient-rfbsrc
• rmPkgs.appmarkable
• rmPkgs.chessmarkable
• rmPkgs.evkill
• rmPkgs.linuxPackages.mxc_epdc_fb_damage
• rmPkgs.plato
• rmPkgs.rM-vnc-server
• rmPkgs.remarkable-fractals
• rmPkgs.remarkable_news
• rmPkgs.retris
• rmPkgs.rm-video-player

To develop your own packages for the reMarkable, use the rmPkgs attribute of the set computed in default.nix as a nixpkgs appropriately configured for cross-compilation (e.g. its stdenv.mkDerivation will generate derivations that cross-build for the reMarkable).