I have two different Debian Buster/sid systems. The first is a desktop
PC with AMD RX 580 graphics. It used to work ok until July, then I
updated it sometime in August, and Xorg broke.
The second is an Acer Aspire5 notebook I've just bought, with AMD RX 540
graphics. I've installed Debian using the latest Debian Buster testing
ISO (August 27th, as today's one wasn't available yet), and Xorg doesn't
start.
Both Xorg.0.log show the same error:
Fatal server error:
Cannot run in framebuffer mode please supply the busIds for all
framebuffer devices
Both systems run the 4.17 amd64 kernel, but I've also tried a custom
4.18 kernel on the desktop system, with the same results.
I could find a number of references to that error out there, but all of
them point either to a solution that does not work in my cases (e.g.
adding "amdgpu.cik_support=1 radeon.cik_support=0" to the kernel
comdline) or to a old and already closed bug report, (e.g.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=508476)
I'd suspect fbdev was somehow guilty, but the fbdev module isn't even
listed by lsmod.
I've already tried creating a /etc/X11/xorg.conf file, using
# Xorg -configure
but it didn't solve the problem.
Any clues?
