flix

A kernel written in C++.

Why?

This is a kernel I wrote mostly for fun (and no profit). I tried to make use of modern C++ features to make the code clearer and easier to write.

This kernel is a work in progress that I stopped developing in the end. I tried to make use of most open-source code as possible. This includes a fork of libc++ for kernel-space and Android's bionic libc implementation for user-space. There are no drivers and the VFS part is very poor in features. My plan was to make use of open-source code for this too and maybe integrate filesystems from Linux or some micro-kernel.

Features

• Supports only x86_64 CPUs
• Works on real hardware (I could only test on one computer)
• Memory protection
• Multi-process support
• ABI-compatible syscalls with Linux
• Can run a very light busybox
• Unit-tested

How to compile

This kernel is only tested with Clang 3.8. You will need to find where your distro has installed your compiler's headers. This includes the files stddef.h and stdint.h. For me, they are in /usr/lib/clang/3.8/include.

I use ninja to compile, but you can use make if you prefer.

To compile:

$ mkdir build
$ cd build
$ CC=clang CXX=clang++ cmake .. -DCXX_COMPILER_INCLUDE=<path to your compiler's headers> -GNinja
$ ninja

This will create an image that you can run in bochs, qemu or your hardware.

A module is bundled inside the image with the root filesystem, in which there is currently a compiled busybox.

Running tests

The tests run on the bochs emulator. The one bundled in Debian doesn't have all the features needed, so you will need to compile your's.

I compiled mine from Debian sources of bochs-2.6:

$ apt source bochs
$ cd bochs-2.6
$ ./configure --prefix=$HOME/.local --with-nogui  --with-x11  --with-rfb  --with-term  --with-sdl  --with-wx  --disable-docbook  --enable-cdrom  --enable-pci  --enable-usb  --enable-usb-ohci  --enable-a20-pin  --enable-cpu-level=6  --enable-x86-64  --enable-avx  --enable-vmx=2  --enable-fpu  --enable-debugger  --enable-debugger-gui  --enable-disasm  --enable-idle-hack  --enable-all-optimizations  --enable-repeat-speedups  --enable-plugins  --enable-compressed-hd  --enable-clgd54xx  --enable-sb16  --enable-es1370  --enable-ne2000  --enable-pnic
$ make
$ make install

After you have compiled the kernel, you can run the unit tests with:

$ ctest -VV

How to run

You can run the compiled kernel with its module in qemu with the following command, inside the build directory:

$ ninja run_flixmain

You can run it in bochs with the following command, inside the source directory:

$ bochs -f debug/bochsrc -q

You can make a bootable USB drive with the following command, inside the build directory:

$ dd if=build/source/flix_flixmain.img of=/dev/<your drive> bs=1M

How to compile something for flix

You need to compile a libc and then you can compile my fork of busybox.