KoalemOS

KoalemOS is a hobby project to explore OS development.

License

This software is copyright © 2020 Jonathan Räsch and is released under the GNU GPL v3 license (LICENSE), unless otherwise specified.

Portions of this software are copyright © 2020 The FreeType Project (www.freetype.org). All rights reserved. Those portions can be found in include/freetype and are released under the FreeType License (FTL.TXT).

The Roboto Mono font, designed by Christian Robertson, is released under the Apache License, Version 2 (APACHE-LICENSE). It can be found in the fonts directory. Other ttf files and more information can be found at fonts.google.com/specimen/Roboto+Mono.

Build Requirements

• qemu-system-x86_64
• ovmf
• x86_64-cross-toolchain (see below)
• mtools
• FreeType sources (set $LIBFTDIR appropriately)
• GNU gettext (for envsubst command)

Cross Compiler

To install the required gcc cross compiler run the install_cross_compiler.sh script. The configurable options are set by environment variables:

• $BUILD_PATH is the (temporary) build directory (default: build-cross)
• $PREFIX is the base directory where gcc and binutils are install (default: /usr/local/x86_64-elf-toolchain)
• $GCC_VER is the version of gcc to use (default: 10.2.0)
• $BINUTILS_VER is the version of binutils to use (default: 2.35)

ToDo

build system

• verify build requirements
• check header file dependency management in Makefile
• make separate debug build

error checking/prevention

• add tests
• specify dependencies between parts of kernel (e.g. init_acpi needing to be called before init_pci)
  • could likely be solved by implementing kernel modules
• check ACPI table checksums
• check kernel heap limit in kmalloc/krealloc
• possibly add static bounds checking for stacks
• detect stack overflow
• check if the spurious interrupt handler needs to do anything

memory

• fix memory leak from paging structures (if feasible, also from physical memory map)
• expand paging support
  • add memory typing using PAT/MTRRs
• improve memory manager
• create proper memory map, including:
  • system structures (MMIO, ACPI tables, ...)
  • userspace memory
  • kernel memory
• unmap ACPI tables when no longer needed
• maybe allocate phys_mmap dynamically
• add proper handling/removal of page sizes other than 4K
• free AP bootstrap memory after use

PCI

• add support for PCI 3.0 compatible PCIe configuration mechanism
• possibly add support for PCI-CardBus bridges
• possibly add support for deprecated <1MB PCI BAR encoding (bits[2:1]=1)

libc

• check for optimizations of str- and mem- functions in string.h
• improve qsort performance (change pivot to median of three, use introsort)

misc

• extend graphical capabilities
  • add support for other GOP pixel formats
  • add support for displaying bitmaps
  • add drivers for other graphics output interfaces
• improve performance of printing characters to screen (maybe improve cache / use FreeType cache)
• implement methods of timing CPU clocks using CPUID and/or MSRs (see Intel SDM Vol3 Ch10.5.4, Ch18.7.3)
  • these methods should work, but are currently not testable
  • may resolve timing issues when testing with KVM
• optimize mutex use / synchronization
• check synchronization of shared structures between CPUs