yggdrasil-kernel
================

Rust Unix-like operating system kernel.

See also:

* [ABI for kernel-user communication](https://git.alnyan.me/yggdrasil-abi)
* [Rust fork to use with the kernel](https://git.alnyan.me/yggdrasil/yggdrasil-rust)
* [Userspace programs](https://git.alnyan.me/yggdrasil/yggdrasil-userspace)
* [yboot — x86-64 UEFI bootloader](https://git.alnyan.me/yggdrasil/yboot)

Main features
-------------

* Architecture support: [aarch64](/src/arch/aarch64) and [x86_64](/src/arch/x86_64)
* Kernel/userspace preemptive multithreading
* Kernel-space multitasking with `async`/`await` runtime
* Symmetric Multiprocessing
* Unix-like virtual filesystem:
	files, directories, block/char devices, symlinks, mounts
* In-memory read-write filesystem for tar-based initrd
* sysfs/devfs
* Binary formats: ELF + `#!/...` shebangs
* Rust-style interfaces for most of the stuff like memory management, devices etc.

aarch64-specific:

* PSCI for SMP start-up and power control
* PL011 serial port
* ARM generic timer as system/monotonic timer
* GICv2 IRQ controller

x86_64-specific:

* UEFI boot through [yboot](https://git.alnyan.me/yggdrasil/yboot)
	(no plans for legacy boot)
* PCIe, with plans to extend to aarch64 as well
    * NVMe drive support (read/write)
    * AHCI SATA drive support (read/write)
* I/O and Local APIC IRQ controllers
* PS/2 keyboard,
* i8253-based timer (got some problems with HPET on
	real hw, had to revert, lol)
* COM ports
* ACPI, [work in progress](https://github.com/rust-osdev/acpi), mostly broken
	on real hardware
	* ACPI shutdown
	* PCI IRQ pin routing
	* Events like power button, etc.
* Fancy framebuffer console

Userspace features:

* Sanitized system calls better suited for Rust
* Userspace threads
* Synchronization primitives through futex-like interface
* Unix-like signals and exceptions

General plans (in no particular order)
--------------------------------------

* Better unification of architecture code
* `async` for VFS (?)
* PCIe NVMe block device
* PCIe SATA block device
* PCIe XHCI USB devices
* Better algorithms for memory management

Navigation
----------

* `src/arch` — architecture-specific code
* `src/device` — device driver implementations
	* `bus` — bus devices like USB, PCIe etc.
	* `display` — everything related to graphic displays
	* `power` — power and reset controllers
	* `serial` — serial transceiver drivers
	* `devtree.rs` — stuff related to ARM DeviceTree
	* `tty.rs` — Unix-style terminal driver implementation
* `src/fs` — in-kernel filesystems (sysfs/devfs)
* `src/mem` — memory management
* `src/proc` — process information management
* `src/syscall` — system call handling
* `src/task` — kernel and userspace tasks, processes and threads
* `src/util` — utilities used within the kernel
* `src/init.rs` — kernel init thread impl.