[gentoo-user] Re: KDE and the new plasma 5 thing

[Jonathan Callen <jcallen@gentoo.org>]

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On 04/14/2016 03:39 PM, Mick wrote:
> On Thursday 14 Apr 2016 11:21:39 Yuri K. Shatroff wrote:
>> 14.04.2016 10:43, J. Roeleveld wrote:
>>> On Thursday, April 14, 2016 10:33:10 AM Yuri K. Shatroff
>>> wrote:
>>>> 14.04.2016 00:49, Dale wrote:
>>>>> Yuri K. Shatroff wrote:
>>>> Hi Dale,
>>>> 
>>>>> I'm not sure on where you got the black screen.  If it is
>>>>> when X started, did you switch to sddm or some other
>>>>> compatible display manager?  The old kdm isn't supported
>>>>> and from what I read, doesn't work.  That may explain the
>>>>> black screen.
>>>> 
>>>> Sddm worked as expected, not to mention its veeery slow
>>>> interface (for that nvidia drivers can be blamed, but
>>>> whatever). The black screen appeared after logging in.
>>> 
>>> Slow interface? It works quite well on my laptop. Did you add
>>> the "sddm" user to the "video" group as mentioned in the
>>> upgrade guide?
>> 
>> No I didn't because I had a much more blatant issue with the
>> whole desktop than the 'SDDM display issues', I just didn't get
>> to that. Thanks for pointing it out, next time I'll give it a
>> try.
> 
> I don't have NVidia or use the full plasma desktop environment on
> my laptop (I use enlightenment instead with a Radeon card).
> However, I have not added sddm to the video group and have not
> noticed anything undue in my logs.  I have however noticed that
> sddm is slightly slower than kdm.
> 
> Why is the video group needed?  What does it do?
> 

The sddm user only needs to be in the video group if using the
proprietary NVIDIA driver, as it controls access to some low-level
device nodes created by that driver for the use of the NVIDIA driver's
userspace component.  It may be possible to use those device nodes to
perform certain privileged actions (the code behind them is in a
binary blob in the kernel with no source), so they are protected such
that only members of the video group can use them.

- -- 
Jonathan Callen
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