Triple-head and Xinerama status (or lack thereof?)

[Fernando Cassia]

Hi there,

I´m new to this list (but not to Linux, started with Caldera OpenLinux
at the time of Xfree86 and 2.x kernels) so please bear with me.

My current setup includes an AMD Opteron server-workstation with one
PCI-X ATI X1600 board, which its dual DVI+VGA outputs. That card has
two 19' monitors connected, a DVI one and a VGA-only one, both LGs
(FWIW). I run the latest greatest Fedora (F17 Beta) with Xorg 1.12.0.

Now, for budget reasons suppose I don't want to buy another gfx board,
but rather connect an external USB-to-VGA framebuffer adapters like
these:
http://goo.gl/TqchG

Would current Xorg recognize the 3rd display (no matter it being much
slower due to the USB 2.0 interface) and put the 3rd screen alongside
the other two so I can move app windows from one monitor to the next,
just as the latest Xorg along with FOSS ATI drivers did with the two
current displays?

Or would it be a separate X display because it's handled by a different driver?

I have asked on the Fedora list and the answer hasn´t been encouraging.

---
The stumbling block will be to get the current Xorg to
span two framebuffers.  Back in the early days of X11 it did have an
extension called Xinerama ( http://en.wikipedia.org/wiki/Xinerama ).
That extension appears to have suffered bit-rot and no longer works for
me.  I tried to get two different Radeon frame buffers to work together
but ended up buying a new card that had at least three outputs.  Sadly
those are hard to come by and they charge an arm and a leg.
---

So, what is the real status of Xorg´s Xinerama support, and what can
the experts on this list tell me about my proposed usage scenario?.

Thanks!
FC
--
During times of Universal Deceit, telling the truth becomes a revolutionary act
- George Orwell