[Libdlo] Tips for setting up displaylink with Xinerama

[Mulchman]

Hi list,

I was able to use this post to get a Fedora 12 (32 bit) virtual machine
up and running with the display stretched across the vm's monitor and
the monitor attached to my Sewell USB External Video Card DisplayLink
device. Unfortunately, because it was inside a virtual machine, one
can't actually move the mouse to the display link screen because the
host operating system - and the virtual machine tools (in this case
VMware Workstation 7) - doesn't know there's a screen there. Perhaps
without the tools installed it would work but I didn't try. This was
more of a proof of concept thing before attempting on another machine.

I wanted to comment on a couple of items, though (I've snipped out some
of the xorg.conf settings just to try and condense the email length):

On 1/4/2010 08:35, B. Douglas Hilton wrote:
> To compile this, you will need to enable "Virtual Framebuffer" in your
> kernel, and you will also want "VESA Framebuffer". Configuring vesafb
> is beyond the scope here, but you want it to load up at boot time by
> passing it a vga=0xNNN command appropriate for your primary display,
> and be sure to select a 16-bit color depth.
>   
These options already seem to be compiled into the Fedora 12 kernel (or
at least what I thought were the two options were already marked with
asterisks or "M"'s when inside "make menuconfig" so I didn't have to
recompile the kernel. The vga=0xNNN was important, too, and supplying an
invalid value at boot gave me a list of available values. I picked
something like 1024x768 with 16 bit depth and stuck with it.
> Section "ServerLayout"
>         Screen      0  "RadeonScreen" 0 0
>         Screen      1  "DisplayLinkScreen" LeftOf "RadeonScreen"
>         Option         "Xinerama" "true"
> EndSection
>   
I used similar settings - screen names were changed, of course...
> Section "Device"
>         Driver      "fbdev"
> 	Option      "fbdev" "/dev/fb0"
>         BusID       "PCI:1:0:0"
> EndSection
>   
I used similar settings here. The key "a-ha" part here was adding the
BusID line to my xorg.conf. Fedora 12 doesn't ship w/ any xorg.conf so I
had to make my own and without the BusID line only the vm's monitor
would work and the DisplayLink monitor would stay green. This had me
puzzled for a while.
> Section "Device"
>         Identifier  "DisplayLinkDevice"
>         Driver      "displaylink"
>         Option      "fbdev" "/dev/fb1"
> EndSection
>   
And again I used similar settings here (basically a copy/paste from my
mulchman.org blog).

After getting the vm up and running in VMware Workstation 7 I then tried
to replicate things on a laptop but have run into some other problems
that I haven't worked out yet. It seems like the fbdev driver wants to
run @ 1280x800 but I can't find a vga=0xNNN # that works for the laptop
and is also 1280x800.

In short, thanks for the writeup B. Douglas Hilton as it provided a good
base to venture out from. I just need to spend more time on the laptop
and maybe I'll get it working.

-Pat O'Leary