Re: [gentoo-user] Xinerama vs TwinView for dual monitor setup

[YoYo siska]

On Mon, Oct 13, 2008 at 09:10:34AM +0200, Alan McKinnon wrote:
> On Monday 13 October 2008 04:02:19 Iain Buchanan wrote:
>
> > [snip]
> >
> > > I've configured it with TwinView
> >
> > as in:
> >       Option         "TwinView" "True"
>
> Yes. Some output :
>
> $ sudo grep -i -e xinerama -e twinview /var/log/Xorg.0.log
> (**) Option "Xinerama" "1"
> (**) Xinerama: enabled
> (**) NVIDIA(0): Option "TwinView" "1"
> (**) NVIDIA(0): Option "TwinViewXineramaInfoOrder" "DFP-0"
> (**) NVIDIA(0): TwinView enabled
> (II) Initializing built-in extension XINERAMA
>
> $ sudo grep -i -e xinerama -e twinview /etc/X11/xorg.conf
>         Option          "Xinerama"      "1"
>         Option          "TwinView"              "1"
>         Option          "TwinViewXineramaInfoOrder"     "DFP-0"
>
>
> > > The viewports are aligned along the top edge
> >
> > you mean move the mouse up and it appears on the next screen?  Don't you
> > want them aligned left / right of each other?
>
> My description wasn't clear. I mean the screens are physically and logically
> laid out like so:
>
> +------------------------------+
> |                  |           |
> |        1         |     2     |
> |                  |-----------+
> +------------------+
>
> 1 is the notebook screen
> 2 is the external lcd
> below 2 is dead space. The mouse works correctly.
>
> > >  and the
> > > panel/kicker/plasma/whatever on every desktop environment insists on
> > > trying to stretch across both monitors, into dead space on the right hand
> > > one.
> >
> > Sounds like you haven't compiled stuff with the xinerama USE flag.  I
> > put it in make.conf, and then did a emerge --newuse.
>
> OK, I did that. The packages that got rebuilt are:
>
> $ equery hasuse xinerama
> [ Searching for USE flag xinerama in all categories among: ]
>  * installed packages
> [I--] [ ~] x11-apps/xdpyinfo-1.0.3 (0)
> [I--] [ ~] x11-libs/qt-3.3.8b (3)
> [I--] [ ~] x11-libs/gtk+-2.14.3-r2 (2)
> [I--] [ ~] x11-libs/qt-gui-4.4.2 (4)
> [I--] [  ] x11-misc/engage-9999 (0)
> [I--] [ ~] kde-base/ksplash-4.1.2 (4.1)
> [I--] [ ~] kde-base/plasma-workspace-4.1.2 (4.1)
> [I--] [ ~] kde-base/ksplashml-3.5.10 (3.5)
> [I--] [ ~] kde-base/systemsettings-4.1.2 (4.1)
> [I--] [ ~] kde-base/kwin-4.1.2 (4.1)
> [I--] [ ~] kde-base/libplasma-4.1.2 (4.1)
> [I--] [ ~] kde-misc/knetworkmanager-0.2.2_p20080528 (0)
> [I--] [ ~] kde-misc/filelight-1.0-r1 (0)
> [I--] [  ] media-libs/libsdl-1.2.13 (0)
> [I--] [  ] media-libs/xine-lib-1.1.15-r1 (1)
> [I--] [  ] net-libs/xulrunner-1.8.1.17 (1.8)
> [I--] [ ~] media-sound/kid3-1.0 (0)
> [I--] [ ~] media-sound/amarok-1.4.10-r1 (0)
> [I--] [ ~] media-video/mplayer-1.0_rc2_p27725-r1 (0)
> [I--] [  ] media-video/xine-ui-0.99.5-r1 (0)
> [I--] [ ~] media-video/gxine-0.5.903 (0)
> [I--] [ ~] app-cdr/k3b-1.0.5-r3 (0)

tabletka ~ # equery hasuse xinerama | wc -l
285

most of them are apps from kde-base/* (3.5.9), seems that it changed between
3.5.9 and 3.5.10, plus iwndow managers like fluxbox, openbox... 

>
> Seems like the only things that would affect kde-3 apps is qt-3.3.8b.
> Plus x11-libs/libXinerama and x11-proto/xineramaproto (both latest unstable)
> are installed.
>
> [snip]
>
> > > I'd appreciate some pros and cons feedback from the list before I embark
> > > on a huge emerge -e world to include Xinerama support.
> >
> > Why would you do -e world?  How about `emerge -uN world` The N being
> > --newuse.  or `emerge -vauDN world`.
>
> I was running
> /bin/think --exaggerate --frustrated --logic-level -3
> when I typed that :-)
>
> > check out my blog for how I did it:
> >
> > http://nthrbldyblg.blogspot.com/2008/08/nvidia-xinerama-on-dell-m6300.html
>
> Nice blog :-)
>
> I'll fiddle some more with these tips later in the day, but first a conceptual
> question: I read that huge collection of docs from nvidia-drivers, and
> concluded that Xinerama and TwinView are fundamentally different and
> incompatible. i.e. Xinerama starts with two classic X screens and joins them
> in software to make one big display - an abstraction layer if you will.
> TwinView rips out the guts of X, dispenses with the notion of separate
> screens for a TwinView display and gives you one giant screen with no API for
> an app to see how this big screen is composed. So, you either use Xinerama or
> TwinView, but not both.
>
> Obviously, this understanding of mine is flawed. Which bit did I get wrong?

Xinerama consists basically of two parts, the protocol to communicate the
position/sizes of screen between the Xserver and the applications (which
you usually get by enabling the xinerama use flag) and an xserver part
(module?) that you can use to set up the screens. What you said is
correct for the Xserver setup part...
You use either xinerama setup to put together completely different
displays (might be different cards, such as one nvidia, one ati, ...) 
or twinview in case of a dualhead nvidia setup. But both this setups use
the xinerama protocol to let the apps/wm know the placement of the monitors.
>
> -- alan dot mckinnon at gmail dot com
>
>

-- 
      _
      |            
YoYo () Siska      
===================
http://www.ksp.sk/