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

[Alan McKinnon <alan.mckinnon@gmail.com>]

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)


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?

-- 
alan dot mckinnon at gmail dot com