Welcome to FoolOS
=================

Disclaimer
----------

THIS IS A WORK IN PROGRESS.

This is a simple and useless "operating system", with very basic 
features, sorry. It is the fruit of my fundamental explorations of 
the x86 architectures,  32-bit protected mode, interrupt handling, 
memory management, scheduling, the floppy disk controller, networking 
as well as VESA and a couple of other things.

![Screenshot of FoolOS](/screenshots/foolos.png?raw=true "FoolOs Kernel")

Copyright M.Idziorek 2014 <m.i@gmx.at> unless stated otherwise!

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


Usage
-----

Attach the FoolOS.img or FoolOS.vdi image in your favourite emulator and 
boot or create a bootable USB stick by copying the raw data in the 
following way:

$ cat FoolOS.img > /dev/sdX

You will require some dependencies (as newlib) in order to build.

adapt libgloss/libnosys 

uncomment environ.c and add stubwarnings for sbrk and exit
Build newlib with: --target=i686-elf to use the crosscompiler


Supported Platforms
-------------------

FoolOS is tested/developed on the following emulators/machines

* bochs 2.6.6 (compiled with: ./configure --enable-clgd54xx --enable-a20-pin --enable-debugger --enable-disasm --enable-e1000 --with-x --with-x11 --with-term --enable-smp) (add -lpthread to LIBS in the Makefile!)
* qemu 1.1.2
* virtual box 4.1.18
* Acer Aspire 1810TZ (Notebook)
* Q6600 on Asus p5n32-e sli plus (Desktop PC)

Features
--------

Please note that all features are only very rudimentary and buggy.
Some might be disabled temporarily due to conflicts or regressions.

* Bootloader (2 stages)
* ELF binaries
* PIT support / Timing
* PIC support & Interrupt handling framework
* PCI bus scanning
* Physical memory management
* Virtual memory management
* Multitasking
* Symmetric Multiprocessing
* ACPI / MP
* Floppy disk driver
* PS2 Mouse driver
* Keyboard driver
* VESA Support
* Spinlocks
* Simple Shell
* Simple Ext2 driver (read-only)

Todos
-----

* Allow GRUB as alternative bootloader (multiboot spec/ grub-mkrescue)
* Begin to worry about reentrancy of clib!
* Support some TTY standard
* Real User space

* USB driver
* E1000 driver
* Networking stack 

* Port (ncurses, vim, coreutils, gcc, apache?)

Issues
------

* ESP collisions!?
* implement posix(?) getdents instead of our own readdir.
* Turning on some gcc optimizations breaks the kernel
* Assumed support for VESA mode 0x114 with linear addressing.


Organization
------------

* screenshots/ - latest screenshot

* userspace/ - userspace related code

* boot1/ - 2nd stage bootloader
* boot2/ - 1st stage bootloader

* asm/	- kernel assembler code

* kernel/ - kernel source

* lib/ - some helper sources and includes
* fs/	- file system related source
* video/ - screen output (VESA and text)

* font/ - Fonts for VESA

* bochs/ -Bochs config files


REFERENCES
==========

* http://www.brokenthorn.com/Resources/OSDev17.html
* http://www.jamesmolloy.co.uk/tutorial_html/9.-Multitasking.html
* http://pdos.csail.mit.edu/6.828/2011/labs/lab6/
* http://pdos.csail.mit.edu/6.828/2011/xv6.html
* http://www.nongnu.org/ext2-doc/
* http://www.osdever.net/tutorials/view/multiprocessing-support-for-hobby-oses-explained
* http://forum.osdev.org/viewtopic.php?f=1&t=10944
* http://wiki.osdev.org/Virtual_8086_Mode
* http://wiki.xomb.org/index.php?title=ACPI_Tables
* and many many more...

NOTES
=====
in freestanding mode we can just use this c lib headers: 
stdbool,sddef,stdint,
float,iso646,limits,stdarg