QEMU VS k8s-lab-terraform-libvirt

My most-wanted QEMU feature: https://github.com/qemu/qemu/commit/a2260983c6553

Using `gic-version=3` on macOS you can now use more than 8 cores on ARM chips.

A better solution is just to write a plain ass shell script that tests if various C snippets compile.

https://github.com/oilshell/oil/blob/master/configure

https://github.com/oilshell/oil/blob/master/build/detect-pwe...

Not an unholy mix of m4, shell, and C, all in the same file.

---

These are the same style as a the configure scripts that Fabrice Bellard wrote for tcc and QEMU.

They are plain ass shell scripts, because he actually understands the code he writes.

https://github.com/qemu/qemu/blob/master/configure

https://github.com/TinyCC/tinycc/blob/mob/configure

OCaml’s configure script is also “normal”.

You don’t have to copy and paste thousands of lines of GNU stuff that you don’t understand.

(copy of lobste.rs comment)

Related:

A fast Pascal (Delphi) WebAssembly interpreter:

https://github.com/marat1961/wasm

WASM-4:

https://github.com/aduros/wasm4

Curated list of awesome things regarding WebAssembly (wasm) ecosystem:

https://github.com/mbasso/awesome-wasm

Also, it would be nice if there was a WASM (soft) CPU for QEMU, which (if it existed!) would go here:

https://github.com/qemu/qemu/tree/master/target

> architectural registers are always updated

In tiny code, the guest registers (global TCG variables) are stored in the host's registers until you either call an helper which can access the CPU state or you return (`git grep la_global_sync`). This is the reason why QEMU is not so terribly slow.

But after a check, this also happens when you access the guest memory address space! https://github.com/qemu/qemu/blob/master/include/tcg/tcg-opc... (TCG_OPF_SIDE_EFFECTS is what matters)

But still, in the end, it's the same problem. What QEMU does, can be done in LLVM too. You could probably be more efficient in LLVM by using the exception handling mechanism (invoke and friends) to only serialize back to memory when there's an actual exception, at the cost of higher register pressure. More or less what we do here: https://rev.ng/downloads/bar-2019-paper.pdf

Um, in case you don't know, UTM (based on QEMU) is out for quite a while.

Some of these tools include Oracle VM VirtualBox (that I've used since before the acquisition of Sun Microsystems by Oracle), VMWare Workstation Player, and QEMU, but last year, I found out about Multipass.

For C/C++ projects that use meson as the build system, there is an excellent way to manage dependencies:

https://mesonbuild.com/Wrapdb-projects.html

https://mesonbuild.com/Wrap-dependency-system-manual.html

meson will download and build the libraries automatically and give you a variable which you pass as a regular dependency into the built target:

https://github.com/qemu/qemu/tree/005ad32358f12fe9313a4a0191...

https://github.com/harfbuzz/harfbuzz/tree/main/subprojects

https://github.com/harfbuzz/harfbuzz/blob/37457412b3212463c5...

Or, if you're using proper operating systems, they're managed by the usual package manager, just like everything else.

For all the users of the Linux platform, QEMU is the VM that you should go for. This software comes without any price tag and works as an emulator of various machines with utmost ease and completion; the software uses dynamic translations to emulate hardware peripherals and enhances its overall performance. If you are using QEMU as a virtualizer, then it will function exactly like the host system (provided you have the right set of hardware).

In this tutorial, we set up macOS and Windows virtual machines on UTM, a macOS application that provides a GUI wrapper for QEMU, a powerful open-source emulator and virtualizer. UTM allows you to easily manage and run virtual machines without memorizing complex commands. It also has special handling for macOS, making it simpler to install compared to other virtual machine software.

https://blog.ruanbekker.com/blog/2020/10/08/using-the-libvir...

I include the blog link because there is some nuance in how to get the path right for community Terraform providers that aren't in the Hashicorp registry. The documentation on the GitHub project isn't quite up to date with respect to how the latest versions of Terraform expect the plugin paths to be set up.

I've done this pretty successfully with all the major Linux distros minus Arch, which requires some bootstrapping to get an iso that Packer can work with (no such thing as an answers file for Arch). It's not that big a deal, though. Just find some instructions on how to create and mount a cloud-init iso in addition to the installer iso and use that to add an ssh public key so you can script the installation steps externally. I actually think Packer can do this, but I just haven't gotten it to work yet and have relied on shell scripts.

Hyper-V actually has a very comprehensive PowerShell module that is pretty well documented, by the way: https://docs.microsoft.com/en-us/powershell/module/hyper-v/?.... I've found it pretty easy to use and actually got the Arch auto-provision working on Hyper-V in Windows before I got it working in KVM in Linux.

Another thing is you can just use the cloud images and cloud-init for bootstrapping everything pretty easily, even on-prem. cloud-init has a "no cloud" config option, as mentioned above, where you just mount an iso with the config data as a DVD drive and cloud-init will find it automatically when the distro iso boots.

This guy has a pretty comprehensive example of how to set up a kubernetes homelab entirely using the libvirt Terraform provider from Ubuntu cloud images bootstrapped with cloud-init: https://github.com/zloeber/k8s-lab-terraform-libvirt