putting-the-you-in-cpu VS QEMU

Thanks to cpu.land , I grew an uncanny interest in how cpu works and got me deep into operating systems from there, it’s fascinating to see the deep down of your computer to the levels of registers and ALUs(arithmetic logical units). Nand2tetris and OSTEP is the greatest resource for starting with operating systems.

OrbStack | Founding Engineer | US/Europe REMOTE | Full-time | https://orbstack.dev

OrbStack is making Docker containers & development environments delightful. Our app replaces Docker Desktop and makes containers faster, lighter, and easier to work with. It's the tool of choice for PlanetScale, Replicate, and other hot companies.

Containers should be a joy to use, not something you have to put up with. Let's build the future of dev envs.

As a founding engineer, you'll mainly work on breaking high-level ideas down into tough systems problems, solving them, and taking ownership of projects. If https://cpu.land and https://docs.orbstack.dev/architecture excite you, you'll be right in place.

Email: jobs orbstack dev

Hi! I'm Lexi. I'm 17, and one of the things I'm interested in is gaining a deeper understanding of how computers work and showing that in new ways. A few months ago I published https://cpu.land (discussion: https://news.ycombinator.com/item?id=37062422).

After cpu.land, I felt a lot of pressure to make another Big Giant Thing but didn't really have anything compelling. So I just hacked away on personal projects and, through some coincidental learning on how the Internet works, ended up hacking together a traceroute program that could live stream to a website from scratch!

I realized I had never seen this sort of thing on the web before, and it was actually a kind of cool and novel way of visualizing the structure of the Internet, so I polished it up and built a pretty site around it. In the process, I learned some really interesting things about how BGP and the structure of The Internet, so I melted the traceroute tool with an article sharing that knowledge.

I'm still hacking on this and I'm sure my code will manage to break somehow, so please let me know if you have any suggestions! :)

(Side note: why Rust? I don’t think programming language choice matters that much, but I wanted to quickly write a very dependable low-level program, and I really like Rust’s error handling primitives.

https://cpu.land/

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.