I've a few problems with my Intel NUC (NUC6i7KYB / Intel Iris Pro Graphics 580).
Beginning with Mesa 17.3.3 I had several GPU hangs which I already reported upstream and of course to bos. As suggested upstream, I tried Mesa 18.0.0 RC3 and the described issue was gone.
But since my latest TW upgrade to 20180130 the login screen is complete white. There is only the mouse cursor. Nevertheless I'm able to login by entering my password and hit "Enter". If I downgrade Mesa to 17.3.3 the login screen is normal but then the GPU hangs come back :/
As Mesa 18.0.0 is not yet official I don't know what is causing this issue and - if necessary - to whom I should report it (I didn't want to spam the bos issue) :)