pseudo multi-seat with dual head

[Yan Seiner]

Richard Morton wrote:
> On 2 April 2011 16:46, Yan Seiner <yan at seiner.com> wrote:
>   
>> Richard Morton wrote:
>>     
>>> ok, thanks for that. the issue, with using a single dual head display
>>> rather than using multi-seat is that power management will turn on
>>> both screens if one screen is in use. I would rather have only the
>>> screens being used being switched on via powermanagement.
>>>
>>>       
>> AFAIK there's no way to turn each screen on independently.  I have three
>> heads; one running myth on a separate card and two running Xephyr on top of
>> a singe X session.  I had to disable power management on all of them to make
>> it work.
>>
>>     
>
> oh! so if you wiggle one of the mice all three screens turn on?
>   
I think so.... Xephyr doesn't do DPMS so it would have to be on the 
underlying screen.  In that case you wiggle an input device and all 
screens turn on.


>   
>>> So, I guess I go back to asking how I setup multi-seat.. I have played
>>> with it all day, looking at using kdm and multi-seat display manager
>>> (mdm, it doesnt mention anything after ubuntu 8.04) and I cant get
>>> either to work with 10.10 on my laptop (although I would of course be
>>> looking to implement on 10.04LTS on the server.
>>>
>>>       
>> mdm is a few scripts that do some fancy stuff to find the root window and to
>> hook the right input devices to the right screen.  They don't work with the
>> proprietary nvidia drivers.
>>     
>
> oh
>
>   
>>  I hacked mdm to work with nvidia; there's a
>> page in their wiki on that.
>>
>>     
>
> phew! you got  me worried there; even so, this is quite a pa-larva
> isnt it? I know multi-seat is still a little niche but I thought it
> would be used quite a lot in education and training environments so I
> thought there would be something out there... on some niche distro,
> but I cant find anything! ;-)
>   
It's disappointing, no?  It makes sense for me; my server has to be on 
24/7 so I hang myth off of it as well and get a "free ride" as far as 
power and hardware goes.  The two workstations are gravy at that point.  
I've even though about getting one of those mobos with 5 PICe-16 slots 
and stuffing it full of video cards.  Our usage is so low that a single 
computer should be able to handle all 6 heads.

I don't know that much about X innards; I think there are some 
underlying architecture issues that prevent independent heads on a 
single card. A binary blob driver that's not fully compliant with the 
latest X stuff is probably a big part of it.
>   
>>
>> Single remote for both screens?  Or single remote for each screen?
>>
>>     
>
> sorry, yeah I should have been more clear; a single remote (a ps3 bd
> remote) for each viewing location; and control it all through it;
> volume, watching, music, pictures, etc. all through myth, controlling
> video and if the system is left on the menu screen for a couple of
> minutes the screen goes into standby / power management on that screen
> only. the other screens that are in use would stay on!
>
>   
If it's a uinput device you will have problems with that.  You can map 
the uinput devices to Xephyr or X but AFAICT bluetooth devices cannot be 
mapped to a single X session.

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