libguestfs VS QEMU

We started off doing this, but you end up with enormous diffs which are themselves confusing. Example, only about 5% of this change is non-generated:

https://github.com/libguestfs/libguestfs/commit/5186251f8f68...

And inside the registry. The apparently correct way to distinguish them is using the build ID:

https://github.com/libguestfs/libguestfs/commit/824c74574893...

NDB works great but another option is libguestfs. https://libguestfs.org/

Have a look here

Consider using libguestfs.

There's a lot of useful command-line tooling for KVM and QEMU-based virt. Here's a small selection of useful tools:

• virsh — This[1] is libvirt's shell interface; and gives you access to the rich set of libvirt APIs.

• virt-builder — Use this for rapidly building minimal or customized virtual machines; it's greatly flexible; check out its man page[2]. And here's[3] a quick example that connects both virt-builder and virsh together.

• virt-install — Use this if you don't like the default build of the template images from virt-builder; it lets you create "headless" servers via 'kickstart' and Linux OS trees from the command-line.

• guestfish and libguestfs suite[4] — This rich set of tools help you in a variety of use-cases: repairing your broken disk images, editing, cloning, debugging disk images, and more. It has saved my behind a lot of times.

• qemu-img[5] – This Swiss Army knife lets you powerfully manipulate disk images (QCOW2, raw, et al) offline. Example operations include: create images, backing chains, offline snapshots, disk image merging, and convert disk images from one format to another, and more.

[1] https://libvirt.org/manpages/virsh.html

[2] https://libguestfs.org/virt-builder.1.html

[3] https://developer.fedoraproject.org/tools/virt-builder/about...

[4] http://libguestfs.org/

[5] https://qemu.readthedocs.io/en/latest/tools/qemu-img.html

That's a good point. As long as the project has a setup.py or pyproject.toml available, it can usually be installed from the repo. For libguestfs it looks like they do some pre-processing on their setup.py so that wouldn't work, it's lucky that they had this alternative set up already. :)

Nah, this virt-install preseed script is faster, or even just run virt-builder debian-10 and they're both libvirt not hacky qemu scripts

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.