[Libdlo] Tips for setting up displaylink with Xinerama

[B. Douglas Hilton]

On Tue, 05 Jan 2010 19:16:59 +0100
Christoph Rissner <c.r at visotech.at> wrote:

> Hi,
> 
> I'm trying to get the latest udlfb/xf86-video-displaylink combo
> working. I've managed to set things up months ago (using Robertos
> sources) but had to patch udlfb (X didn't read EDID data) and
> libxinerama (2 nvidia screens + 1 displaylink) for my purpose.
> 
> > Firstly, you need the newer udlfb sources which enable you to use
> > the xf86-driver-fbdev with Xorg. These can be fetched here:
> >
> > "git clonehttp://git.plugable.com/webdav/udlfb"
> >
> > To compile this, you will need to enable "Virtual Framebuffer" in
> > your kernel, and you will also want "VESA Framebuffer".
> 
> I just tried using kernel 2.6.30, enabled CONFIG_FB_VIRTUAL (as
> module, does it matter?) and made sure CONFIG_FB_VESA is set.
> 
> I still can't build udlfb:
> --%<------------------------------
> /home/resi/abs/udlfb-git/src/udlfb-build/udlfb.c: In function 
> 'dlfb_dpy_deferred_io':
> /home/resi/abs/udlfb-git/src/udlfb-build/udlfb.c:1022: error: 'struct 
> fb_info' has no member named 'fbdefio'
> --%<------------------------------
> 
> Looking into fb.h clears things up, I need to set
> CONFIG_FB_DEFERRED_IO. I couldn't find the option in make menuconfig,
> how do I enable it?
> 
> Btw, my distro switched to xorg 1.7 in the meantime, are there 
> experiences with xf86-video-displaylink? Will fbdev work?
> 
> Bye
> Christoph

Ok, I hoped that CONFIG_FB_VIRTUAL would set that. What I did was edit
the file:

/usr/src/linux/drivers/video/Kconfig

config FB_DEFERRED_IO
        bool
        depends on FB
        default y

Find that chunk and set "default y" like above, then run make
menuconfig again and it should be set. I don't know any other way to
set that flag.