Aphrodite

An operating system written in C17 (gnu17), for x86_64, aarch64, and riscv64.

Migrated from older repository: https://github.com/suhas-pai/operating-system-old Check older repository for full commit history

Features

The kernel has the following implemented:

• UART drivers; uart8250 on x86_64, riscv64 and pl011 on aarch64
• Physical memory buddy allocator using a vmemmap of struct page
• General memory allocation with kmalloc() using a slab allocator
• RTC (google,goldfish-rtc on riscv64) and LAPIC Timer, HPET on x86_64
• Keyboard (ps2) driver
• Parsing ACPI Tables and DTB (Flattened Device Tree) (when available)
• Local APIC and I/O APIC
• PCI(e) Device Initialization with drivers

The following is currently being worked on.

• AHCI, SATA, IDE controllers to read disks
• VirtIO drivers
• Virtual File System (VFS)
• Full SMP support with scheduler
• User processes and threads

In addition, the system comes with a basic standard library that includes:

• Abstract printf() formatter
  • Used to implement kprintf() and format_to_string(), and more
• Abstract strftime() formatter
  • Used to implement a very basic kstrftime()
• Integer Conversion APIs
  • Can convert to and from strings, with the following configurable integer formats:
    • Binary (with 0b prefix)
    • Octal (with 0 or 0o prefix)
    • Decimal
    • Hexadecimal (with 0x prefix)
    • Alpbabetic (with 0a prefix)
  • Used by printf() formatter for converting integers to strings
• AVL Trees
  • Used to create abstract struct address_space type

And more

Building

It is recommended to build this project using a standard Linux distro, using a Clang/LLVM toolchain capable of cross compilation.

This project can be built using Clang/LLVM for all architectures.

This project can also be built using the host GCC toolchain on x86_64 when targetting x86_64 (KARCH=x86_64), but it is recommended to set up an *-elf cross compiler for the chosen target, or use a native cross toolchain such as Clang/LLVM.

The KARCH make variable determines the target architecture to build the kernel and image for. The all target (the default one) builds the kernel for the given architecture, and a bootable .iso image containing it. The all-hdd target builds a flat hard disk/USB image instead.

The system currently supports the x86_64, aarch64 (arm64), and riscv64 architectures. x86_64 is the most feature complete, while aarch64 and riscv64 are catching up

Several variables are available to configure launching in QEMU:

• MEM= to configure memory size (in QEMU units) (By default 4G)
• SMP= to configure amount of cpus (By default 4)
• DEBUG=1 to build in debug mode and to start in QEMU in debugger mode (By default 0)
• RELEASE=1 to build in release mode with full optimizations (though ubsan is still enabled) (By default 0)
• CONSOLE=1 to start in QEMU's console mode (By default 0)
• DISABLE_ACPI=1 to start QEMU's machine without ACPI, relying exclusively on the DTB (Flattened Device Tree) (by default 0)
• DISABLE_FLANTERM=1 to disable flanterm, the terminal emulator used. This option helps improve kernel performance (by default `0)
• TRACE="" to trace certain logs in qemu to log.txt. Takes a space separated string and provides qemu with the correct argumentd (by default "")
• CHECK_SLABS=1 to enable pervasive slab checks in kmalloc() and other allocators (by default 0)

The all target (default target) builds the system for the given architecture, creating a bootable .iso image containing the built system. The all-hdd target builds a flat hard disk/USB image instead.

For example, to build for aarch64 run:

make KARCH=aarch64 KCC="clang" KLD="ld.lld"

The image can then be tested with the one of the run or run-hdd targets.

make KARCH=aarch64 KCC="clang" KLD="ld.lld" run