Nix

In order to enable reproducible builds, experimental flowey features are being built to utilize the Nix package manager for dependency management and environment isolation. The root of the nix configuration lives in shell.nix. If you're unsure where the Nix definition is for a dependency, you should be able to track it down from there.

Updating Nix Packages

Nix dependencies require a hash of their contents to ensure integrity and reproducibility. When updating a dependency, you'll need to update the release that's being pulled and its corresponding hash.

For instance, let's say we have a new release of the OpenHCL Kernel and we want to update it in our Nix configuration:

1. Go to the corresponding .nix file (in this case, openhcl_kernel.nix)
2. Clear the hash to an empty string
3. Update the version
4. Run nix-shell --pure and use the printed error to get the new hash

Warning: Because Nix caches dependencies based on the hash, if you don't clear the hash to an empty string before updating the version, nix-shell --pure will run without error even though the dependency hasn't actually been updated.

Here's an example of what the error will look like when done correctly:

error: hash mismatch in fixed-output derivation '/nix/store/cc7hhyslx1dnw01nmjx11zqim2l50awp-source.drv':
         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
            got:    sha256-wUDWFazJM80oztKqpuRwj8Wvto2Uo/OuVGvhpszIw+A=
error: Cannot build '/nix/store/spg5vbm6mzmsxpg5v2ibg97qrz8khc70-openhcl-kernel-x64-6.12.52.4.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/kv8s7pld70yvzxzd77swz9hb3pygkrhl-openhcl-kernel-x64-6.12.52.4

Given this error, you would update the corresponding hash to sha256-An1N76i1MPb+rrQ1nBpoiuxnNeD0E+VuwqXdkPzaZn0= in the openhcl_kernel.nix file.