Building GCC AVR Toolchain Cross Compiler

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Building GCC AVR Toolchain Cross Compiler

December 11, 2015 | Article, Labs | No Comments

In this article we will about how to build GCC AVR Toolchain, which is a cross compiler to build AVR program. The built GCC can be used to compile application into AVR’s machine codes. The toolchain then reside on /usr/local path.

For this article, I use:

  1. Slackware64 14.0
  2. GCC 4.9.0
  3. GDB 7.7
  4. Binutils 2.24
  5. AVR-libc 1.8
  6. GMP 6.0.0
  7. MPFR 3.1.2
  8. MPC 1.0.2


We will need some disk space (~2GB should be enough). We also need root access to install it on “system-wide”.

Slackware64 14.0 is optional. You can use any linux distribution you like.

We will create a working directory. We will refer it as $AVRGCC, so $AVRGCC/src should really be something like ~/AVRGCC/src (the ~ means your home directory). So go ahead and create following directory structure:

# set aliases
export TARGET=avr
export PREFIX=/usr/local

export BINUTILS_BUILD=${AVRGCC}/build/binutils-build
export GCC_BUILD=${AVRGCC}/build/gcc-build
export GDB_BUILD=${AVRGCC}/build/gdb-build

export BINUTILS_SRC=${AVRGCC}/src/binutils-2.24
export GCC_SRC=${AVRGCC}/src/gcc-4.9.0
export GDB_SRC=${AVRGCC}/src/gdb-7.7
export AVRLIBC_SRC=${AVRGCC}/src/avr-libc-1.8.0

# make base dir, original archives dir (orig), source code dir (src), 
# and working / building dir (build) 
mkdir ${AVRGCC}{,/{orig,src,build}}

# Make build directory for each component
mkdir ${AVRGCC}/build/{binutils,gcc,gdb}-build

Acquiring the Materials

Download latest packages of GCC, GDB, binutils, and Newlib.You can download it using wget or alternatively download via browser and move it to $AVRGCC/orig. The version we will use is GCC 4.9.0, GDB 7.7, binutils 2.24, and newlib 2.1.0.

cd ${AVRGCC}/orig


Then, extract them to src directory.

cd ${AVRGCC}/src

tar -jxf ${AVRGCC}/orig/gcc-4.9.0.tar.bz2
tar -jxf ${AVRGCC}/orig/gdb-7.7.tar.bz2
tar -jxf ${AVRGCC}/orig/binutils-2.24.tar.bz2
tar -jxf ${AVRGCC}/orig/avr-libc-1.8.0.tar.bz2

Next we need to download some prerequisites, especially GMP (GNU Multiple Precision), MPC (Multiple-Precision Complex), and MPFR (Multiple-Precision Floating Point Reliably) which is used for computation. The prerequisites can be downloaded by invoking following command:

The MPFR, GMP, and MPC is not the latest version, but at least we can build GCC. Suppose your working directory at /home/xathrya/AVRGCC, to obtain MPDR, GMP, and MPC invoke following command:

cd ${GCC_SRC}

However, the version of GMP, MPC, MPFR are not the latest version. We can switch to the latest version by link it to our downloaded one.

cd ${GCC_SRC}

rm {gmp,mpc,mpfr}

tar -Jxf ${AVRGCC}/orig/gmp-6.0.0a.tar.xz
tar -zxf ${AVRGCC}/orig/mpc-1.0.2.tar.gz
tar -zxf ${AVRGCC}/orig/mpfr-3.1.2.tar.gz

ln -s gmp-6.0.0 gmp
ln -s mpc-1.0.2 mpc
ln -s mpfr-3.1.2 mpfr

Building the Toolchains

Building stage is pretty simple. Honestly speaking, the tricky part is about how GCC and built concept and ordering them in correct order.


First, built binutils. This will provide lots of useful tools in building ARM libraries and binaries (like objdump, ld, ranlib, etc). Invoke following commands:

${BINUTILS_SRC}/configure --target=${TARGET} --prefix=${PREFIX} \
    --enable-interwork --enable-multilib --enable-shared 
make configure-host
make -j4 all
make install

You will notice a few configure options that are really critical for getting things to work properly.

  • –target=avr Says we want a compiler to generate binaries for the avr platform.
  • –enable-multilib Multilib allows the use of libraries that are compiled multiple times for different targets/build types
  • –enable-shared – enable the creation of the shared libraries.


Next we will build the GCC. But please note that we are only intereset on C and C++ so we will ignore other language. To built GCC, do this:

${GCC_SRC}/configure --target=${TARGET} --prefix=${PREFIX} --enable-interwork \
   --enable-multilib --enable-languages="c,c++" --with-dwarf2 --disable-libssp \
   --enable-c99 --enable-long-long --enable-__cxa_atexit --enable-shared
make -j4 all-gcc 
make -j4 all-target-libgcc

make install-gcc install-target-libgcc

Now, the important points are:

  • –enable-languages=”c,c++” – means build C and C++ only.
  • –with-headers – this adds a header inlude path during build time and will allow the build to find the newlib header files
  • –enable-__cxa_atexit – allows use of __cxa_atexit, rather than atexit, to register C++ destructors for local statics and global objects and is essential for fully standards-compliant handling of destructors. It also affects the C++ ABI and therefore results in C++ shared libraries and C++ programs that are interoperable with other Linux distributions.
  • –enable-c99 – enable C99 support for C programs.
  • –enable-long-long – enables long long support in the compiler.


Now build our avr-libc

./configure --host=avr --build=`./config.guess` --prefix=${PREFIX}
make install


Optionally you can build GDB. To do so, invoke following:

${GDB_SRC}/configure --target=${TARGET} --prefix=${PREFIX} \
  --enable-interwork --enable-multilib
make -j4 all 
make install

And that’s it. You should have them now.


The toolchain can be tested with the minimal code here:

int main()
   return 0;

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