From 32355dbc285f67e717abd70cbf78ba256a894904 Mon Sep 17 00:00:00 2001
From: Carlos Fenollosa <carlos.fenollosa@gmail.com>
Date: Wed, 15 Oct 2014 11:19:16 +0200
Subject: [PATCH] lesson 11, cross-compiler

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 11-kernel-crosscompiler/README.md | 76 +++++++++++++++++++++++++++++++
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+*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 one we jump to developing in a higher
+language, that is, C. [Read why](http://wiki.osdev.org/Why_do_I_need_a_Cross_Compiler%3F)
+
+I'll be adapting the instructions [at the OSDev wiki](http://wiki.osdev.org/GCC_Cross-Compiler). 
+
+
+Required packages
+-----------------
+
+First, install the required packages. On linux, use your package distribution. On a Mac, [install brew](http://brew.sh/) 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
+--------
+
+Rember: always be careful before pasting walls of text from the internet. I recommend copying line by line.
+
+```sh
+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
+---
+```sh
+cd /tmp/src
+curl -O http://mirror.bbln.org/gcc/releases/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.