Black screen, UI lock up, when starting Xserver,

[Adam Jackson]

On Thu, 2018-09-13 at 19:21 +0100, John Talbut wrote:

> The only errors that show in Xorg.0.log are:
> 
> [  420,876](EE) modeset(0): [DRI2] No driver mapping found for PCI
> device 0x8086 / 0x0be1
> [  42.877] (EE) modeset(0): Failed to initialize the DRI2 extension
> 
> I.e. the graphic controller is a VGA compatible controller: Intel
> Corporation Atom Processor D2xxx/N2xxx Integrated Graphics Controller
> (rev 09)
> 
> Questions, for a start:
> 1. What is supposed to provide the mapping for PCI device 0x8086 / 0x0be1?

There's a table built into the X server. In this case, you have the
misfortune to own a Cedarview chip, which is of the Poulsbo family of
"not really Intel, actually PowerVR" of devices and thus there is no
open source 3D support. That the code considers this an "error"
condition is perhaps unwarranted.

> 2. Is this error likely to be causing the UI to lock up?

Probably not, no. The fact that lightdm seems to be restarting makes me
suspect there is some other error in the X log that simply doesn't
begin with (EE). The complete log might be useful. It's possible that
what's really happening is the _session_ is failing to initialize, and
the X server is terminating normally because the last client
disconnected.

A quick thing to check is to run 'X -retro' from a vt. If that brings
up the classic root weave and X pointer, then X is working fine and the
session is to blame. You may need to boot to runlevel 3 to test this,
as otherwise lightdm would win the race.

- ajax