Re: Using quad or dual cards

[Helge H. <hel...@hi...>]

oregon wrote:

>Has anyone had any success getting multiple separate instances of X to
>run on separate screens of a quad or even dual-head graphics card?  I
>  
>
I've done this with a matrox G550 dualhead card. It has only
one busid, so the second X driver used the framebuffer
driver. That driver uses none of the cards accelearation features,
only the graphichs memory.  It was fast enough for 2D work
like word processing and 2D gaming anyway.  Very light
3D stuff worked too, using software rendering.
The first head used the matrox driver with all features
and nice speed.

I also tried to use two instances of the accelerated driver
on this single card.  That actually works - by luck I guess,
but still.  I didn't go for that solution because 3D didn't
work at all, only accelerated 2D.

These days I'm using two cards, with a radeon 9200SE in
addition to the G550.  This allows accelerated 2D and 3D
on both heads.  Unfortunately, the radeon driver in debian is
quite buggy and hangs that X server a lot of the time.  So
I'll probably have to replace the card.

>have a Matrox G200 MMS Quad, which gives you 4 separate bus IDs for
>the 4 different monitors, but I can't seem to get prefbusid to address
>any monitor except for the primary (first) one.
>
>  
>
Did you get prefbusid working in a test with actual separate cards?
Experiment with that first.  If it doesn't work, then you might need
a different xserver.  Not all of them support prefbusid.  Some,
such as debian, want "isolatedevice" instead of "prefbusid".

Also, some hardware drivers just don't work in dual/quad
setups, this limits what cards one can use.

Cards having separate bus IDs ought to behave just as a
bunch of separate cards, but you never know if they
cut some corners supporting this somewhat unusual feature.

>I'm trying to get as many as 6 or 8 touchscreens running from one PC,
>so I would really like to be able to use dual or quad head cards so I
>don't run out of PCI slots. Has anyone had success with any dual or
>quad head cards? If so, send me your recommendations, and maybe a copy
>of your config files too if you're feeling generous.
>  
>
My two-card setup isn't exactly what you want, but I can
mail you the config files if you think they may be useful anyway.

Helge Hafting