Re: Dual screen framebuffer development advice

[Andrew Walrond <andrew@walrond.org>]

I asked this a few months ago:

On Saturday 19 Jun 2004 21:25, Antonino A. Daplas wrote:
> On Saturday 19 June 2004 21:55, Andrew Walrond wrote:
> > I need to setup a machine to develop a framebuffer based application. I'd
> > like to use two graphics devices; The first an ati agp chipset on the
> > motherboard which will run X11 with X11's ati driver, the second a PCI
> > card running a fb driver and displaying my framebuffer application.
> >
> > Is this possible/sensible?
>
> Sure, it's possible and actually not hard to do.  Just make sure that the
> driver of your primary card is fbdev, and the secondary X11.  X happens to
> do a fine job of initializing non-primary cards whereas fbdev is mostly
> restricted to cards initialized by the firmware.
>

I've got this working nicely now. I have a recent agp nvidia card and an old 
pci matrox millenium in this dual opteron machine running 64bit linux. I boot 
into a console on the matrox using the built-in matroxfb driver, then startx 
which runs on the nvidia card using the nv driver. I can then work on my fb 
application in X, viewing the output on the second monitor via the matrox 
card. Nice!

> Note: You wont' be able to see both displays simultaneously, switching from
> one blanks the other.   If you do want multi-seat, see the Ruby project of
> linuxconsole.
>

This is wrong; I can indeed see both displays simultaneously :)

The matrox fb is pretty slow (being on a pci bus); it can only manage 5fps at 
1600x1200-16bpp. The rivafb is much faster (36fps) so I might try switching 
roles (X on matrox, fb on nvidia) at some point. I think X might accelerate 
the matrox card quite well enough for running xemacs etc.

Andrew Walrond


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