Setting up the Contiki toolchain in Arch Linux is a 2 step process. Step 1 is to clone the Contiki repository from GitHub https://github.com/contiki-os/contiki). Step 2 is to install the packages that are required to run and build Contiki's examples/simulations. The packages that Contiki depends on are 32-bit, although 64-bit processors are backwards compatible with 32-bit, thus running 32-bit software is possible on 64-bit Arch Linux. All except one of Contiki's dependencies can be installed from Arch Linux's official repositories (core, extra, community, multilib). The one package... (see bellow).

In order to use MSP430 based platforms you need to install the gcc-msp430 package VERSION <= 4.7.x (version used in this guide: 4.7.2) which is available in Ubuntu. Arch has package mspgcc-ti from the aur which contains msp430-elf-gcc. This package is essentially the GNU toolchain for the Texas Instruments msp430 embedded processors that TI has in its website (you can verify the version by comparing the line: _installer=msp430-gcc-full-linux-installer-x.x.x.xx.run from the PKGBUILD with the version number that Texas Instruments has in its website http:https://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/MSPGCC/latest/index_FDS.html). Unfortunately, mspgcc-ti doesn't work with Contiki. However, you can find in this repository a precompiled version of the mspgcc-4.7.2.

Clone the Contiki GitHub repository to a local directory:

git clone 'url-contiki-repository'

Once cloned, run:

cd contiki/
git submodule update --init

The above command will check out the submodules that are included in the contiki repository (e.g. mspsim).

Install the required packages. First though, the multilib repository must be enabled in /etc/pacman.conf. To do this uncomment the lines:

[multilib]
Include = /etc/pacman.d/mirrorlist

Mirrors can be out of sync so pacman needs to be forced to refresh the package lists. The following command forces pacman to refresh all package lists even if they are considered to be up to date:

pacman -Syy

Now, install the packages:

pacman -S libmpc zlib apache-ant jdk8-openjdk arm-none-eabi-gcc arm-none-eabi-gdb lib32-gcc-libs lib32-glibc lib32-libstdc++5 lib32-zlib lib32-fakeroot

Finally "install" the mspgcc-4.7.2 package:

tar xjf mspgcc-4.7.2-compiled.tar.bz2
sudo cp -r -f msp430/* /usr/local/

Verify:

msp430-gcc --version

An alternate solution in case you prefer not to copy the contents of msp430/ would be to create symbolic links from msp430/* to /usr/local/.

Try opening a simulation in cooja and see if it runs.

If cooja fails to open the simulation and outputs an error in the console complaining about the size of .text file or something similar, download the contiki.zip file from this repository which contains the contiki directory from Instant Contiki 3.0 and test cooja in this version which is the same as the one used in this guide. Don't forget to checkout the submodules (git submodule update --init).

Instead of doing cd /path/to/cooja and then ant run each time you run cooja, you could create an alias in your .bashrc like this: alias cooja='sh -c "cd /path/to/cooja && ant run"'.