veryBadKernel

A very bad x86_64 kernel written in Rust. All information in this readme is meant for posix systems (*nix, *BSD, macOS). Windows support will be added in the future.

Features

These are all the current and planned features for this kernel. It is meant to be more of a learning opportunity instead of an actual usable kernel.

• Static Rust binary (no stdlib or dynamic linking)
• VGA text buffer interface
• Interrupt descriptor table
• Single and double fault handling
• Hardware interrupts (timer, keyboard, etc.)
• Memory paging
• Heap allocation
• Concurrency and multitasking

Running the Kernel

These instructions are for if you want to run the kernel without any of the fuss of compiling.

Prerequisites

• An installation of qemu OR
• A physical x86_64 machine and a USB drive

Head over to the releases section and download the boot image.

Running with QEMU

Use the qemu-system-x86_64 command with the path to the boot image you downloaded.

qemu-system-x86_64 -drive format=raw,file=path/to/bootimage-very_bad_kernel.bin

Running on Bare Metal

Use dd to write the boot image to a USB drive

dd if=path/to/bootimage-very_bad_kernel.bin of=/dev/<DISK_TO_WRITE>

After the USB is flashed, you can plug it into the machine, and select the USB drive as a boot option from your BIOS of boot manager.

Building from Source

Prerequisites

• Cargo and Rustup

To build and run the kernel from source, you will need a rust nightly version from 2021-12-13 or earlier. This is because in the inline asm stabilization PR, the location for the asm!() macro has changed and the `x86_64 crate has not been updated to support this change yet. This documentation will be irrelevant when that crate is updated.

$ rustup toolchain install nightly-2021-12-13
$ rustup default nightly-2021-12-13
$ rustup component add rust-src --toolchain nightly-2021-12-13-x86_64-unknown-linux-gnu

You will also need the bootimage tool, and the llvm-tools-preview component:

$ cargo install bootimage
$ rustup component add llvm-tools-preview --toolchain nightly-2021-12-13-x86_64-unknown-linux-gnu

Compile & Run

Once you have all the prerequisites and toolchains installed you can clone the repository and compile the boot image:

$ git clone https://github.com/zhooda/veryBadKernel
$ cd veryBadKernel

# compile boot image without running
# the resulting bootimage binary can be found in 
# `target/x86_64-very_bad_kernel/debug/bootimage-very_bad_kernel.bin`
$ cargo bootimage

# compile boot image and run with qemu-system-x86_64
$ cargo run

After compiling and running, you should be able to interact with the kernel via your keyboard. Currently, the kernel only displays the name of the key pressed (capturing keyboard interrupts), and prints a . on every timer interrupt.