[ale] (no subject)

[Pat Regan]

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On 03/26/10 09:55, Brandon Checketts wrote:
> I missed and have deleted the original post, so this may be completely
> irrelevant, but I spent several hours trying to get dual monitors working with
> an nVidia card on Ubuntu 9.10 and learned a lot.  My conclusion was that
> basically have two "drivers" that allow you to run two monitors: TwinView or
> Xinerama

I just set up a pair of external monitors on my new laptop, with an
nvidia card, this week so this is all fresh in my mind.  For the most
part, everything just works out of the box on a modern distro.

On Ubuntu with the open source nvidia driver I was able to just click on
the "display" application and add the second display.

Unforunately, the open source driver could not detect when something was
plugged into the laptop's HDMI port.  The port was in the list, though.

The proprietary driver works fine but it does not support xrandr.  That
made it a little more effort for me to script things so it automatically
did the right thing when I plug/unplug the monitors on my desk.  There's
a program called `disper` that made that easy.

If anyone is curious, the laptop will let me drive two 1920x1080
displays without a problem.  Either two external, one vga and one hdmi,
or the internal plus one external.  It can't mirror the laptop display
to one of the external heads, either.

> TwinView is the nVidia implimentation.  It essentially runs two separate
> desktops and allows your mouse to move between them.  Each desktop has its own
> toolbar. Since the desktops are separate, you can't drag a window from one to
> the other.  Compiz desktop effects works with this.

Twinview and Xinerama are functionally the same.  The proprietary driver
lets you use twinview and/or separate X servers.  I find the "and"
interesting.  10 years ago I wanted to drive 2 heads in Xinerama and one
head as a separate server and it wasn't possible.

Twinview used to be problematic.  Window managers thought it was one big
desktop.  Xinerama has always allowed discovery of the dimension and
position of each head.  Twinview either didn't used to do that or
software just didn't query it.  Hitting the maximize button and having a
window expand over 3 heads is rarely useful...

> Xinerama is the open source implementation.   It creates one big desktop so you
> can drag windows between screens, and you only have a toolbar on just one
> screen.  However nvidia+xinerama+compiz doesn't work, so you can't enable the
> cool effects.

I wasn't on the open source nvidia driver for long, but xinerama+compiz
should work fine on it.  It works fine here with the Radeon and Intel
drivers here as well.  I can't speak for the proprietary driver, but I
can't come up with a reason not to use Twinview since its functionally
equivalent.

The important thing for me is to be able to unplug and replug my
monitors without restarting X.  I definitely can't make that happen with
Xinerama+prorietary.


Pat
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