The lastest Radeon™ Software for Linux® Driver for RHEL 7.6 / CentOS 7.6 cannot
be installed on my Fedora 29 with both Radeon RX480 and Radeon VII. I need to
have at least one GPU (e.g. RX480) being recognized by Fedora 29. 

I'm quite frustrated. I just want to install AMD driver, and it turned out to
be a subscription problem, which simply does not working after trying various
menthods. 

Registering to: subscription.rhsm.redhat.com:443/subscription
Username: xxxxx
Password: 
module 'os' has no attribute 'errno'
It seems Password cannot be typed

So I have no choice but to mount the downloaded rhel 7 and done everything
accordingly step by step without errors. 
https://access.redhat.com/solutions/1355683 
https://amdgpu-install.readthedocs.io/en/latest/install-prereq.html

But when I execute $ ./amdgpu-install -y, there still remains the same prompt: 
"No match for argument: amdgpu-dkms 
No match for argument: amdgpu"