Black screen, UI lock up, when starting Xserver,

[Adam Jackson]

On Wed, 2018-09-19 at 06:53 +0100, John Talbut wrote:
> OK Adam, thanks for the suggestion about ssh, which I have now got working.
> 
> So, I boot to runlevel 3, log into tty1 as root and run 'X -retro' the
> UI locks up.  The keyboard is completely unresponsive.
> 
> However, I can see using ssh that the system is still running but I
> cannot see any sign of X running.  There are no message in journalctl
> during the attempt to start X. ps -C Xorg shows nothing.

'ps -C X' might.

> Xorg.0.log attached.

This bit of the log is pretty wild:

(II) modeset(0): glamor X acceleration enabled on llvmpipe (LLVM 6.0, 128 bits)

I'm really struggling to think of a world in which that would be a good
thing, fb's almost certainly going to be faster, and as the llvmpipe-
on-gbm support is pretty new I can easily imagine it being buggy. What
happens if you run with this in (or as) your /etc/X11/xorg.conf:

---
Section "Device"
    Identifier "modesetting"
    Driver "modesetting"
    Option "AccelMethod" "none"
EndSection
---

- ajax