Author:

• Name: Sebastian Macke
  Location: DE - Federal Republic of Germany (Germany)

To build:

    make all

To use:

    ./prog

Try:

    ./try.sh

Judges’ remarks:

When we ran this entry the first time (in a virtual machine window), it felt like the VM has rebooted. Then, after the initial feeling had subsided, we were able to appreciate the entry in greater detail.

Have you ever wondered would what would happen if you recursively removed files starting from the root directory? Are you curious what happens when you launch a fork bomb? Within the safety of an virtual walls, can safely give those and other scenarios: just check out the “Things You Can Do(#todo”)” section below.

NOTE: For those who do not have a clang compiler environment that supports the wasm32 target, we provide a prog.wasm file.

SUGGESTION / REQUEST: Having a way to build custom boot-up images for this entry would be of interest.

Author’s remarks:

Emulator Running Linux

What It Does

This is an emulator capable of running a full modern Linux system with a minimal set of features. The system includes:

• An OpenRISC 32-Bit CPU
• A Memory Management Unit
• A UART connected to the Terminal
• An Interrupt Controller
• A Timer Controller

Look Up Specs

First, you can look up the specs of the emulated system. The following commands will give you a good overview:

    uname -a
    free -h
    cat /proc/cpuinfo
    cat /proc/meminfo
    cat /proc/interrupts
    cat /proc/timer_list

Fork Bomb Visualized

For educational purposes, type the following two lines and watch the process tree grow:

    b(){ sleep 2; b|b; }
    (b &) && watch -n1 pstree -p

Or just run:

    ./fork_bomb.sh

Note: You won’t be able to stop the emulator anymore and will need to kill the process.

Delete Filesystem

Ever wanted to know what happens when you delete your computer’s filesystem? Now is your chance to find out!

    rm -rf /

Even after removal, your system will still be in a well-defined state. For example, you can still run commands such as:

    cd /proc
    echo *

Be careful: You won’t be able to stop the emulation anymore and will need to kill the process.

Run C64 Emulation

A full-fledged C64 emulator is included. Run it via:

    ./c64

Since the C64 is little-endian and runs on a big-endian machine, which itself runs on a little-endian machine, it combines the best of both worlds into a cool intermediate format. Might this be the future of endianness? 🤔

Run Itself

With ./prog, you can run the emulator within itself. This is a bit meta, but it works. The emulator would be able to run Linux as well, but it is tweaked to run with less memory and on a big-endian machine.

Full scripting capabilities

With vi, you got an awesome editor and can write scripts in ash such as.

    i=1
    while [ "$i" -le 10 ]
    do
        echo "Hello World"
        i=$(expr "$i" + 1)
    done

Run in the Web Browser

Did you know that you can run this emulator in a web browser?

First, compile with Clang on systems that support a target of wasm32:

    make prog.wasm

Then, for example, run a local web server with the following command:

    python3 -m http.server 8000

Open your browser and go to http://localhost:8000/prog.html. You can now run the emulator in the browser.

Obsfucation

The obfuscation is mainly a result of compression, plus a healthy dose of recursion and the usual endian mischief. For some reason, LLMs might think that this is a Smoothed Particle Hydrodynamics (SPH) simulation.

Sigh, so much space left. More than enough for multi-core support, a full-fledged windowing system, or networking. Well, there’s always next year.

Primary files

• prog.c - entry source code
• Makefile - entry Makefile
• prog.orig.c - original source code
• try.sh - script to try entry
• wasm_include/stdio.h - wasm include file
• wasm_include/termios.h - wasm include file
• wasm_include/unistd.h - wasm include file

Secondary files

• 2024_macke.tar.bz2 - download entry tarball
• README.md - markdown source for this web page
• a - virtual machine
• .entry.json - entry summary and manifest in JSON
• .gitignore - list of files that should not be committed under git
• .path - directory path from top level directory
• prog.wasm - WebAssembly binary module
• index.html - this web page

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