Chaos: Hardly An Operative System

Chaos is my rendition of the xv86 project, ported to Zig so I learn the language as part of the process.

How to Run It

Prerequisites:

• Zig compiler: version 0.13.0. As Zig is still evolving a lot, a newer version might require patching the code. Older versions will definitely not work.
• Qemu: version 9.1.1.

Once you have Zig and Qemu installed, you can run zig build with any of the following:

• install: produce kernel binaries.
• userland: build user programs, assumed to be in src/userland folder.
• mkfs: userland + create file system image with user programs. The filesystem's name will be fs.img, and it will be located in the project's root folder.
• quickrun: install + run the kernel with fs.img (assumed to exist) mounted as the first IDE device. Useful if you previously built the file system and just changed kernel code. A qemu i386 instance will boot the kernel from ROM.
• run: install + mkfs + run the kernel as explained above. This is what you should execute if you changed userland code and want to check how it is executed by the kernel.

Note: the kernel is theoretically bootable from grub. Yet, I didn't try making a grub rescue disk because I don't feel like installing grub on my development laptop.

What to Expect

On execution you will find a console executing a shell. The console supports scrolling, clearing up the current line with Crtl+U and getting the list of processes with Ctrl+P. The control sequence Ctrl+D is interpreted as EOF, as usual. The shell allows to execute the following commands, bundled in the file system by the build process:

• cat
• echo
• grep
• kill
• ln
• ls
• mkdir
• rm
• sleep

In addition, the shell supports:

• Redirecting stdin and stdout: cat < in.txt > out.txt.
• Piping: ls | grep zombie | wc
• Sequencing: sleep 100 ; echo Done sleeping
• Background: (sleep 100; echo Done seeping) & ; cat

Credits

This is not, by any means, the first port of xv86 to Zig. At its beginnings, this project was based on xv86-zig. Albeit quite incomplete, the cited project gave me an idea of where to start the port and in which order to do things.