Black Screen on Login

[David Edmundson]

On Fri, Jan 2, 2015 at 6:14 PM, Lukáš Tinkl <lukas at kde.org> wrote:

> Dne 2.1.2015 v 16:47 Aleix Pol napsal(a):
>
>  On Fri, Jan 2, 2015 at 4:41 PM, David Edmundson
>> <david at davidedmundson.co.uk> wrote:
>>
>>>
>>>
>>> On Fri, Jan 2, 2015 at 4:30 PM, Aleix Pol <aleixpol at kde.org> wrote:
>>>
>>>>
>>>> On Fri, Jan 2, 2015 at 4:23 PM, David Edmundson
>>>> <david at davidedmundson.co.uk> wrote:
>>>>
>>>>> I have a new theory as to what might be wrong.
>>>>>
>>>>> With KScreen's backend being out of process it could be signalling that
>>>>> there's a new screen before plasmashell has processed the X events and
>>>>> be
>>>>> trying to look for the relevant QScreen object before plasmashell has
>>>>> made
>>>>> it.
>>>>>
>>>>> Could someone put in some debug on shellcorona.cpp:851 before it
>>>>> returns
>>>>> a
>>>>> nullptr in ShellCorona::outputToScreen and see if that gets triggered.
>>>>>
>>>>> You may need to use printf() as plasmashell has this somewhat odd
>>>>> --shutup
>>>>> mode that suppresses all qDebug in an effort to make fixing this as
>>>>> difficult as possible.
>>>>>
>>>>
>>>> My theory, is that ::load is not being executed though. Otherwise we'd
>>>> be seeing things when this happens, instead of just a black screen.
>>>>
>>>
>>>
>>> I'm back to thinking you're right.
>>> load would call addOutput. addOutput would assert if outputToScreen
>>> failed.
>>>
>>> With the exception of being completely 100% wrong, it was a good theory.
>>>
>>
>> I appreciate a good theory. <3
>>
>> I just added a warning that will output something if the
>> GetConfigOperation fails.
>>
>> All those of you who can reproduce it, should rebuild and run again.
>> Maybe we'll see the answer there.
>>
>
> Can you update to the most recent powerdevil and try to reproduce the
> black screen problem again? My theory is that there lies the problem;
> plasmashell is starting up and requesting the config while kded is (also)
> waiting for plasmashell to show up (because of the notifications it wants
> to display). Eventually the dbus calls time out, plasmashell start but as
> there is no config, you just get a black screen.
>
After updating powerdevil, I can no longer reproduce this; kscreen is
> broken in a different way (doesn't apply the config) but that's another
> story


That theory doesn't make sense - plasmashell doesn't query kded for the
config.
plasmashell links libkscreen, libkscreen starts it's own unique backend
process for the current config then we query that.

This might delay kscreen setting the screen config, but it shouldn't
prevent reading the current state unless there's something else going on...


>
> --
> Lukáš Tinkl <lukas at kde.org>
>
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