mkdir risc-v-gcc
cd risc-v-gcc
git clone https://github.com/crosstool-ng/crosstool-ng.git
apt-get install build-essential zlib1g-dev pkg-config libglib2.0-dev binutils-dev libboost-all-dev autoconf libtool libssl-dev libpixman-1-dev libpython-dev python-pip python-capstone virtualenv
cd ..
git clone https://github.com/riscv/riscv-qemu.git
cd riscv-qemu
sudo apt install iverilog gtkwave
Here is a good starting point:
http://iverilog.wikia.com/wiki/Getting_Started
http://iverilog.wikia.com/wiki/GTKWAVE