Nix with its ecosystem is amazing tooling and the library functions in nixpkgs provide great builders to package certain programs, scripts, and stuff. But in this jungle of options, it’s also sometimes not clear which option is the best or most pragmatic solution. In this blog post, I’m going to present you the most pragmatic and easiest way to package a shell script in Nix from my year-long experience of packaging things. In...
Read moreUpdate: The original post is from November 2024. I updated the post in the meantime a couple of times to reflect my latest knowledge. During my work as virtualization engineer at Cyberus Technology, I work from time to time with libvirt. Specifically, I am working with live-migration of QEMU/KVM VMs (QEMU as VMM and KVM as hypervisor). I want to share what I’ve learned, highlight the caveats I’ve encountered, and discuss the solutions...
Read moreUPDATE: Turns out, I googled the wrong thing/keywords. There is a helpful answer on StackOverflow. It was surprisingly difficult to programmatically start a long-running command via SSH in background and disconnect the SSH session immediately. So, in case you need help, here’s how I did it. The final solution is ridiculously simple. Goal My goal is to programmatically (i.e., from a script) start a command on a remote server. So far so good,...
Read moreThis post is roughly a summary of the obscure knowledge I learned about toolchains and relocatable code in the last couple of years by studying the code of the microkernels NOVA and Hedron, my professional hands-on experience with kernel development, and several learning projects. I present some of the “hard and not obvious” properties of producing kernel binaries, information that only stands “between the lines” in existing projects, and topics I didn’t find Read more…
For various reasons, such as OS development, it is convenient to quickly start up an instance of QEMU or Cloud Hypervisor with a custom kernel and initrd. However, often the major struggle is to get some kernel and some initrd, i.e., the boot items, quickly and easily. Scope Foremost, this blog post is a guideline for direct (Linux) kernel boot, possibly along with a matching initrd. If you can boot an ISO installer Read more…
nixos-rebuild –target-host <user@host> is a powerful tool to remotely deploy a NixOS configuration. However, there are scenarios where you can’t reach a machine directly but need an SSH jump host. Suppose you want to deploy to the host 192.168.124.42, which is only reachable from the host ssh-gate. Then your nixos-rebuild invocation might look as follows: It’s simple as that. Using -J <jumphost> option (see man page), we instruct SSH to find the right Read more…
Recently, I’ve bought a TP-Link Archer TX20U Nano WiFi USB dongle (vendor website) for my desktop PC. The driver for Windows is provided by the stick itself, as it exposes a storage volume with the Windows driver on it. On Linux, the Windows driver doesn’t work, of course. However, with only minor modifications to the system’s NixOS configuration, we can leverage the already packaged out-of-tree driver for this device and use it for Read more…
