1. Install ROCm

Disclaimer: This potentially could harm tour devices. Use at your own risk.

Using ROCm avoids having to install proprietary AMDGPUpro driver.

wget -q -O - https://repo.radeon.com/rocm/rocm.gpg.key | sudo apt-key add -
echo 'deb [arch=amd64] https://repo.radeon.com/rocm/apt/debian/ xenial main' | sudo tee /etc/apt/sources.list.d/rocm.list
sudo apt install libnuma-dev
sudo apt install build-essential dkms
sudo apt install rocm-dkms
sudo usermod -a -G video $LOGNAME
sudo usermod -a -G render $LOGNAME
reboot

/opt/rocm/bin/rocminfo should find the card.

2. Build ethminer with ROCm support

CPATH=/opt/rocm/opencl/include cmake --build .
cmake .. -DETHASHCUDA=OFF -DETHASHCL=ON -DUSE_SYS_OPENCL=ON -DAPICORE=ON -DOpenCL_INCLUDE_DIR=/opt/rocm/opencl/include -DOpenCL_LIBRARY=/opt/rocm/opencl/lib/libOpenCL.so.1.2

build/ethminer  ./ethminer should output something like:

ethminer 0.19.0-16+commit.47ae149e
Build: linux/release/gnu

 Id Pci Id    Type Name                          CL    Total Memory  Cl Max Alloc  Cl Max W.Grp 
--- --------- ---- ----------------------------- ----  ------------  ------------  ------------ 
  0 08:00.0   Gpu  gfx803                        Yes        8.00 GB       8.00 GB      256.00 B 

3. Monitor

/opt/rocm/bin/rocm-smi --showfan --showtemp --showvoltage --showclock

4. Mine

./ethminer ...options