I'm trying to enable dual monitors in Ubuntu. This is working fine, but every time I do it, desktop effects is disabled. I think I've found
the reason why, though:
https://wiki.ubuntu.com/X/Config/Multihead/
As with
the GNOME XRandR configuration
method, setting Virtual to too large a
value may result in a loss of hardware
acceleration, and thus an inability to
use Compiz and its desktop effects.
When I use
the GNOME monitor applet, or
the Monitors configuration in
the System menu,
the default xrandr settings puts
the second monitor to
the right of
the first, and, as I found with this bug, for most monitors this creates a virtual desktop larger than
the maximum 2048 horizontal resolution needed for hardware acceleration on my netbook hardware.
So, it seems like if I can modify xrandr's default settings so that it places
the new desktop above or below (north or south of)
the main LVDS display, then hardware acceleration, and therefore compiz will continue to work. Can anyone tell me, what is
the easiest way to achieve this?
UPDATE:
I have confirmed that multihead support with desktop effects and hardware acceleration works when I move
the external monitor display north of
the main LVDS display. Right now this involves
the following process: plugging in
the external monitor, starting
the Monitors configuration menu, desktop effects are disabled automatically (and all of
the windows on my workspaces are moved to
the first workspace), repositioning
the external display so that it is north of LVDS display and clicking apply, and then navigating to
the Appearance menu and telling it to reenable desktop effects. Is there a simpler way do this?
UPDATE 2:
OK, so I thought that perhaps
the GNOME Monitors configuration screen was trying to be clever, and might be disbling desktop effects. So, I just tried using
the xrandr command-line client instead, as follows:
xrandr --output VGA1 --above LVDS1
When I do that, desktop effects are still disabled, and I need to manually reenable them. This, despite
the fact that hardware acceleration works, and there is never a point where hardware acceleration stops working because
the horizontal dimension of
the virtual display is too large. So what program is trying to be clever, and is turning off desktop effects when it doesn't need to? And how do I make it stop?
If there were a way to re-enable desktop effects from
the command line, which I could then put into a script along with
the proper xrandr invocation, I would accept that as a workaround.
UPDATE 3:
OK, here's my script to enable a second monitor with desktop effects. It might be evil, I'm not sure:
second-monitor.sh
xrandr --output VGA1 --above LVDS1
sleep 3
compiz --replace &
The sleep statement might not be necessary.
If there's a better way to do this, please let me know.
UPDATE 4:
This is a Dell
Mini Inspiron 1012.
Here are my system specifications:
lspci -vv
00:02.0 VGA compatible controller: Intel Corporation N10 Family Integrated Graphics Controller
Subsystem: Dell Device 041a
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Interrupt: pin A routed to IRQ 29
Region 0: Memory at f0b00000 (32-bit, non-prefetchable) [size=512K]
Region 1: I/O ports at 18d0 [size=8]
Region 2: Memory at d0000000 (32-bit, prefetchable) [size=256M]
Region 3: Memory at f0900000 (32-bit, non-prefetchable) [size=1M]
Capabilities: <access denied>
Kernel driver in use: i915
Kernel modules: i915
00:02.1 Display controller: Intel Corporation N10 Family Integrated Graphics Controller
Subsystem: Dell Device 041a
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Region 0: Memory at f0b80000 (32-bit, non-prefetchable) [size=512K]
Capabilities: <access denied>
lsmod | grep i915
i915 287458 2
drm_kms_helper 29329 1 i915
drm 162409 3 i915,drm_kms_helper
intel_agp 24375 2 i915
i2c_algo_bit 5028 1 i915
video 17375 1 i915
