Re: [xmonad] How to manage three monitors on two graphics cards?

On Thu, Jan 05, 2012 at 05:08:29PM -0800, Mike Meyer wrote:

On Thu, 5 Jan 2012 19:16:28 -0500 Wolfram Kahl wrote:

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On Thu, Jan 05, 2012 at 03:53:47PM -0400, Norbert Zeh wrote: I am running to equal ATI cards with the radeon driver.

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(2) In xorg.conf ServerFlags: Option "Xinerama" "true"

Now xrandr does not work anymore, and xmonad sees one big area.

Indeed, xrandr and xinerama are incompatible. Do you need xrandr? I just knew no other tool that produces that kind of information...

Xrandr is the preferred solution. Xinerama has missing functionality and vague specs.

However: * With Xinerama on, xrandr is not available. * With Xinerama off, I have two displays, and it appears that not only xmonad cannot move windows between the two.

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Right now, with Xinerama off, I get: On DISPLAY :0.0: $ xrandr Screen 0: minimum 320 x 200, current 3968 x 1200, maximum 8192 x 8192 DVI-0 connected 1920x1200+2048+0 (normal left inverted right x axis y axis) 495mm x 310mm 1920x1200 59.9*+ DVI-1 connected 2048x1152+0+0 (normal left inverted right x axis y axis) 510mm x 287mm 2048x1152 59.9*+ ... $ ghc -e "Graphics.X11.openDisplay [] >>= Graphics.X11.Xinerama.getScreenInfo" Xlib: extension "XINERAMA" missing on display ":0.0". [Rectangle {rect_x = 0, rect_y = 0, rect_width = 3968, rect_height = 1200}]

I consider this as wrong and would expect two separate rectangles to be reported for the two outputs DVI-0 and DVI-1. (That was probably the case while the second card was deactivated.)

This is correct for an xrandr config.

I wanted to say, more precisely, that I consider the output of Graphics.X11.Xinerama.getScreenInfo to be either wrong, or inappropriate for xmonad to base its screen subdivisions on.

The two monitors (DVI-1 and DVI-1) are views into a single logical screen (0). DVI-0 is a 1920x1200 view whose left edge is at 2048 in the logical screen. DVI-1 is a 2048x1152 view whose left edge is at the left edge of the logical screen. Programs that properly support xrandr will get all that information and work properly.

I'm on an extended trip, and can't really play with multiple cards, but with one card and two monitors, I get that kind of list (one logical screen with two monitors) from xrandr. Xmonad seems to work ok. Not sure I like it, but I switched from wmii to xmonad while on the trip, so haven't configured it for a multihead system, and probably won't be doing that anytime soon.

Anyway, the mouse will move between the two displays correctly when I move the mouse. Using the "switch screen" commands in the default config switches focus. The two screens do seem to be using the same stack, which causes some interesting behaviors.

That is what I consider ``normal xmonad behaviour'', and I had that with two monitors on one card as well. Now I would like that with three monitors, and I just happen to have them on two cards... Wolfram