shushos

An implementation of a real-time operating system.

How to build

In order to build the project, you have to have Rust toolchain installed on the system. The following commands will produce a bare binary targeted at x86-64 platform.

sudo apt-get update
sudo apt-get install qemu qemu-system qemu-kvm
cargo install bootimage
rustup component add rust-src
rustup component add llvm-tools-preview
cargo run

Run tests

To run tests, simply execute the following:

cargo test

Features

print! and println! macros

These macros are defined in the crate vga_buffer.rs, which also holds the VgaBuffer, Buffer, and Writer structs with safe interfaces. Printing is done by using a "static mut" WRITER object, which, upon writing into the Buffer and VgaBuffer, locks a spinlock mutex and prevents cpu from sending interrupts to prevent undefined behaviour caused by race conditions. Since the Rust's implementation of static mut struct is flawed, we emulate this behaviour by making WRITER a lazy_static object, and by locking a mutex when accessing it.

Scrolling

Using arrow keys (up/down) you can scroll the contents of the buffer. The implementation is inside interrupts.rs and vga_buffer.rs. During a keyboard interrupt, we execute a function that changes the position of the VgaBuffer inside Buffer and updates the screen view.

Panic

Panic situations are handled by the function defined in main.rs, panic.

Memory mapping

Using bootimage's initialized memory map, we introduce a FrameAllocator which, using the physical memory offset, returns usable frames specified in the memory map. The implementation is in memory.rs, we test virtual memory mapping in function basic_tests inside main.rs.

Keyboard

ps/2 keyboard interrupts are handled by functions inside interrupts.rs. The scan codes are transformed into characters via crate pc-keyboard's functions.

Shushpancheak / shushos