From: Brian Julin <bri@forcade.calyx.net>
  To  : Paananen Osmo <odie@cs.tut.fi>
  Date: Thu, 2 Jul 1998 09:07:06 -0400 (EDT)

Re: Multiheaded Linux

On Thu, 2 Jul 1998, Paananen Osmo wrote:

> > >  I don't know where the framebuffer device names will be used in, but
> > >  my guess is that this wouldn't be as big problem as it is with disks.
> > Yeah, no real problems.  (Having two will be rare, having three or more
> > will be very rare indeed).
> 
> I already have two (vga+mda) and I most certainly will put in another VGA if 
> thats possible.  

Should be technically "possible" with one VLB VGA and one older ISA
VGA (One card needs to not have the 0x46e8 register).  But it will
require several modifications to the drivers -- simultaneous access
to framebuffers and the CRTC can be arranged but in order to set modes
and access the GRC ATC and SEQ you have to disable the other chipset.
The next WD driver set will support adding an older PVGA chipset in a docking
station with a localbus wd90c2x laptop.

And it's definitely possible and being done with PCI.  In fact on
a stock kernel I almost got X running on my second PCI Mach32 just
by mapping the first one's IO space out and the new one in and running
startx -- however the chipset had not been sufficiently initialized 
so the mode was screwed.

> Last time I check (about three months ago) I tried to use Matrox Millenium I 
> and Matrox Millenium I cards together in order to get multiheaded.  
> Do I need two identical cards to get multiheaded?  

Right now sort of but not really -- easier to just write a driver that 
handles multiple displays than coordinate between drivers, so support 
will probably be better for this scenario.  However some developers 
have gotten different drivers working together already as there's support
in KGI manager for this.  Multi-adaptor use will be the sugar to encourage
people to try KGI-manager/EvStacks.

--
Brian S. Julin