nix: Make nix the root

Which means now I'll have to think about real prefixes in commit names.

unprocessed/config/scripts/arch-kexec

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+# Set variables
+name="${1:-linux}"
+kernel="/boot/vmlinuz-$name"
+initrd="/boot/initramfs-$name.img"
+
+# Test if required files are present
+[ -f $kernel ]
+[ -f $initrd ]
+command -v kexec &> /dev/null
+
+# Configure the next kernel to load
+sudo kexec -l $kernel --initrd=$initrd --reuse-cmdline
+# Gracefully restart on the next kernel
+sudo systemctl kexec