cfenollosa_os-tutorial/11-kernel-crosscompiler

Concepts you may want to Google beforehand: cross-compiler

Goal: Create a development environment to build your kernel

If you're using a Mac, you will need to do this process right away. Otherwise, it could have waited for a few more lessons. Anyway, you will need a cross-compiler once we jump to developing in a higher language, that is, C. Read why

I'll be adapting the instructions at the OSDev wiki.

Required packages

First, install the required packages. On linux, use your package distribution. On a Mac, install brew if you didn't do it on lesson 00, and get those packages with brew install

• gmp
• mpfr
• libmpc
• gcc

Yes, we will need gcc to build our cross-compiled gcc, especially on a Mac where gcc has been deprecated for clang

Once installed, find where your packaged gcc is (remember, not clang) and export it. For example:

export CC=/usr/local/bin/gcc-4.9
export LD=/usr/local/bin/gcc-4.9

We will need to build binutils and a cross-compiled gcc, and we will put them into /usr/local/i386elfgcc, so let's export some paths now. Feel free to change them to your liking.

export PREFIX="/usr/local/i386elfgcc"
export TARGET=i386-elf
export PATH="$PREFIX/bin:$PATH"

binutils

Remember: always be careful before pasting walls of text from the internet. I recommend copying line by line.

mkdir /tmp/src
cd /tmp/src
curl -O http://ftp.gnu.org/gnu/binutils/binutils-2.24.tar.gz # If the link 404's, look for a more recent version
tar xf binutils-2.24.tar.gz
mkdir binutils-build
cd binutils-build
../binutils-2.24/configure --target=$TARGET --enable-interwork --enable-multilib --disable-nls --disable-werror --prefix=$PREFIX 2>&1 | tee configure.log
make all install 2>&1 | tee make.log

gcc

cd /tmp/src
curl -O https://ftp.gnu.org/gnu/gcc/gcc-4.9.1/gcc-4.9.1.tar.bz2
tar xf gcc-4.9.1.tar.bz2
mkdir gcc-build
cd gcc-build
../gcc-4.9.1/configure --target=$TARGET --prefix="$PREFIX" --disable-nls --disable-libssp --enable-languages=c --without-headers
make all-gcc 
make all-target-libgcc 
make install-gcc 
make install-target-libgcc 

That's it! You should have all the GNU binutils and the compiler at /usr/local/i386elfgcc/bin, prefixed by i386-elf- to avoid collisions with your system's compiler and binutils.

You may want to add the $PATH to your .bashrc. From now on, on this tutorial, we will explicitly use the prefixes when using the cross-compiled gcc.