yggdrasil/README.md

yggdrasil-kernel

Rust Unix-like operating system kernel.

See also:

• ABI for kernel-user communication
• Rust fork to use with the kernel
• Userspace programs
• yboot — x86-64 UEFI bootloader

Main features

• Architecture support: aarch64 and 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 (no plans for legacy boot)
• PCIe, with plans to extend to aarch64 as well
• 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, 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.