add README

README.md

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+# GayBSD Kernel
+
+This is the source tree of the GayBSD kernel.
+There isn't much to see here yet -- only the most basic boot routine is
+implemented at the moment.
+
+## Building
+
+The kernel compiles to a binary i686 image that implements the GNU
+[Multiboot 2](https://www.gnu.org/software/grub/manual/multiboot2/multiboot.html)
+specification.
+
+### Required Tools
+
+- A POSIX operating system (use WSL if you find yourself in the unfortunate
+  situation of running Windows)
+- CMake >= 3.14
+- clang, with support for the `i686-none` target
+  * You probably won't need to recompile clang as it has cross compiling
+    capabilities built in, at least it works fine on my Arch Linux machine
+  * GCC should work in theory, but this isn't tested at all and you'll most
+    likely need to compile it manually to make it spit out i686 ELFs
+- A linker that is able to work with GNU LinkerScripts (clang, GNU ld should
+  work too but as already stated you should avoid GNU stuff if possible)
+- Git
+
+### Actually Compiling the Thing
+
+```
+cmake -B build -S .
+cmake --build build
+```
+
+The compiled kernel image will be in `./build/gaybsd_image`.
+You may want to tweak come configuration values in `build/CMakeCache.txt`,
+either using a plain text editor or `cmake-gui(1)`.
+See `cmake/config.cmake` for all configuration options.
+
+## Running
+
+In its current state, GayBSD is barely more than a simple program writing stuff
+to the BIOS character framebuffer, so you probably don't want to be running it
+on bare metal.
+Seriously, *please* don't do this, i have virtually no experience with x86
+and no idea if what i'm doing could damage your hardware.
+Instead, you are way better off using QEMU or something similar.
+You will need a Multiboot 2 compliant bootloader, preferrably GRUB
+(you can use a 32-bit Linux ISO to set everything up, like Arch Linux 32).
+Install GRUB for the i386-pc target, and add the following entry to `grub.cfg`:
+
+```
+menuentry 'GayBSD' {
+        insmod part_gpt
+        search --no-floppy --fs-uuid --set=root <root partition uuid>
+
+        multiboot2 /boot/gaybsd_image
+}
+```
+
+Copy `./build/gaybsd_image` to `/boot/gaybsd_image` on the virtual disk that
+you are booting off of.  After that, you should be ready to go!