Re: Dual head: no xinerama

[Cameron Hutchison <camh+dl@xdna.net>]

Once upon a time Nick Hastings said...
> Hi,
> 
> * Cameron Hutchison <camh+dl@xdna.net> [041110 17:11]:
> > Once upon a time Nick Hastings said...
> > > 
> > > I think you missed my point: I don't use xinerama nor do I want to.
> > > I'm using a dual head setup with a *single* matrox card.
> > > 
> > > What I want is to somehow have my window manager or desktop
> > > environment to behave as described in chapter 9 of the xinermama howto.
> > 
> > I dont think you're being very clear.
> > 
> > You seem to be saying you want the features of xinerama, but not use
> > xinerama.
> > 
> > If you want to move windows between heads, then you want xinerama.
> 
> I already do this: as I said I have a have an X display of 2560x1024
> running over two monitors. I am _not_ using xinerama, I am using mtx
> driver from matrox.

Now I understand your setup. It was not clear you were using the mtx
driver and that it had the capability within it to join the heads.

I dont know much about how xinerama works, and just how an application
becomes xinerama-aware, but unless mtx emulates xinerama from an API
perspective, I dont see that current xinerama-aware applications would
know that you had two screens and behave accordingly.

> The features I mention (as listed in chapter 9) are suggestions to window
> manger coders on what they should include to play nicely with xinerama
> systems. They are not features *of* xinerama.

What I meant to say was that they are features that would only be
available under a xinerama display, and therefore it would be necessary
to be running xinerama to get those features. I was unaware of the 
matrox mtx drivers that performed a similar function.

> > Why do you say you do not want xinerama?
> 
> Because as I understand it xinerama, controls the X system of the two
> heads: I'm happy letting the mtx driver do that. I only want control over
> the window manager.

If you have no particular attachment to having the mtx driver joining
the screens into a single screen, I would think that xinerama would be a
better option, only because more software will be aware of xinerama that
the mtx driver's method of joining screens.

> > If you already have a working XF86Config-4 setup with two heads as
> > separate screens (:0.0 and :0.1), you should simply be able to add
> > Option "Xinerama" "true"
> > to you ServerLayout section.
> 
> I have a single screen section. I guess this is the point.

I would try adding a second device section to drive the two heads
independently, add a second monitor section referencing the new device
and then reference them both from the serverlayout section.

The device sections in my XF86Config-4 looks like:

Section "Device"
        Identifier      "Matrox G400 32MB Head 1"
        Driver          "mga"
        Option          "AGPMode" "4"
        BusID           "PCI:1:5:0"
        Screen          0
EndSection

Section "Device"
        Identifier      "Matrox G400 32MB Head 2"
        Driver          "mga"
        Option          "AGPMode" "4"
        BusID           "PCI:1:5:0"
        Screen          1
EndSection

Looking at the samples that come with the mtx driver, the above "Screen"
option should be accepted by the driver. You'll obviously need to
replace the BusID with yours, and change the mga driver to mtx,
and maybe leave out the AGPMode option.

My monitor sections look like:

Section "Monitor"
        Identifier      "EIZO FlexScan F77S"
        HorizSync       30-110
        VertRefresh     50-160
        Option          "DPMS"
EndSection

Section "Monitor"
        Identifier      "MAG XJ810"
        HorizSync       30-100
        VertRefresh     50-160
        Option          "DPMS"
EndSection

And the ServerLayout section

Section "ServerLayout"
        Identifier      "Dual-Head Matrox"
        Screen          "EIZO" 
        Screen          "MAG" RightOf "EIZO"
        InputDevice     "Generic Keyboard"
        InputDevice     "Configured Mouse"
EndSection

Add Option "Xinerama" "true" to that and you should get what you want.

Or you could add this section:

Section "ServerFlags"
    Option "Xinerama"
EndSection

That is how it is done in the mtx driver sample configuration.

If you haven't got the samples lying around anymore, let me know and
I'll email you them.

> I guess I'll try running with two screen sections and using xinerama. I
> guess it will work, but it just feels like an ugly way to control window
> management.

I dont think there's any other way than running xinerama for 
xinerama-aware apps to work. Whether the heads are joined in the x
server or the display driver makes little difference to me from a
technically asthetic perspective, but from a practical perspective a
working setup is better than a non-working one :-) (for various
definitions of working).