This is a hobby OS project for learning more about low-level hardware.  See
the LICENSE file for details.

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Hardware Requirements:

- 64-bit x86 CPU
- Intel Gigabit Ethernet

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Setup and Installation for Windows:

- Install Cygwin (http://www.cygwin.com/) including the following packages
  and their dependencies:

    - bison
    - flex
    - gcc4
    - gdb
    - make
    - nasm
    - wget

- Build a 64-bit cross compiler for the kernel:
  - Setup
    - export PREFIX=/usr/local/cross
    - export TARGET=x86_64-elf
    - export PATH=$PATH:$PREFIX/bin
    - mkdir cross_gcc
    - cd cross_gcc
    - mkdir build_binutils build_gcc

  - Download and unpack source code
    - wget http://ftp.gnu.org/gnu/binutils/binutils-2.22.tar.bz2
    - wget http://ftp.gnu.org/gnu/gcc/gcc-4.7.0/gcc-4.7.0.tar.bz2
    - wget http://ftp.gnu.org/gnu/gmp/gmp-4.3.2.tar.bz2
    - wget http://www.mpfr.org/mpfr-2.4.2/mpfr-2.4.2.tar.bz2
    - wget http://www.multiprecision.org/mpc/download/mpc-0.8.1.tar.gz
    - tar xjf binutils-2.22.tar.bz2
    - tar xjf gcc-4.7.0.tar.bz2
    - tar xjf gmp-4.3.2.tar.bz2
    - tar xjf mpfr-2.4.2.tar.bz2
    - tar xzf mpc-0.8.1.tar.gz
    - mv gmp-4.3.2 gcc-4.7.0/gmp
    - mv mpfr-2.4.2 gcc-4.7.0/mpfr
    - mv mpc-0.8.1 gcc-4.7.0/mpc

  - Build binutils
    - cd build_binutils
    - ../binutils-2.22/configure --target=$TARGET --prefix=$PREFIX --disable-nls
    - make all
    - make install
    - cd ..

  - Build gcc
    - cd build_gcc
    - ../gcc-4.7.0/configure --target=$TARGET --prefix=$PREFIX --disable-nls --enable-languages=c --without-headers
    - make all-gcc
    - make install-gcc

- Install QEMU:
  - Precompiled Windows binaries are located at http://lassauge.free.fr/qemu/
  - Install http://lassauge.free.fr/qemu/release/Qemu-1.0.1-windows.zip
  - Copy bios.bin and vgabios-cirrus.bin from the Bios folder to QEMU's
    root directory.

- Install the TAP driver:
  - OpenVPN installers are located at http://openvpn.net/index.php/download.html
  - Install http://swupdate.openvpn.org/community/releases/openvpn-2.2.2-install.exe
  - Install only the "TAP Virtual Ethernet Adapter" component.
  - Modify the Network Connections:
    - Rename the TAP interface from "Local Area Connection (n)" to "tap"
    - Bridge the TAP interface with your active Local Area Connection.

- Update PATH:
  - Add QEMU and /usr/local/cross/bin to the PATH variable in .bash_profile

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Kernel configuration:

- Update the following globals in net_config.c as appropriate:
    - net_local_ip
    - net_subnet_mask
    - net_gateway_ip

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What to expect:

- The ethernet driver is initialized in promiscuous mode, so it will display
  all packets on the LAN.

- The network stack will reply to ICMP requests (i.e. ping).

- There is rudimentary console support, but no commands yet.

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Emulator steps:

  $ make
  $ qemu.bat

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Hardware steps:

  Format a FAT16 drive, update the boot sector and copy the loader and kernel
  binaries.

  $ make
  $ tools/set_boot.exe //./<drive letter>: boot/boot.bin
  $ cp boot/loader.bin <drive letter>:/
  $ cp kernel/kernel.bin <drive letter>:/

  Boot!