I knew I wasn't going to get away with no explanation. Well, here goes: The ultimate problem is getting a dual head setup on my hybrid graphics [1,2] laptop. This should be a real multi-monitor desktop "The way it should workâ˘", where you can move windows between monitors (or half on either side if you so incline) and the maximize function maximizes across a monitor, not the entire screen. My laptop has an nVidia card attached to the DisplayPort and an Intel card attached to the internal LVDS port. Because the proprietary nVidia drivers use all kinds of OpenGL-library magic, you can't have OpenGL working on both cards in the same X server. My laptop has an option the BIOS to switch between three graphics modes. "Integrated" turns off the nVidia card, saving power, I'm not sure what this does to the DisplayPort. "Hybrid" works as I just described, and note that the nVidia card can still be powered down by software when not in use. "Discrete" turns off the Intel card and connects the LVDS port to the nVidia card as well. I understand not all laptops with hybrid graphics have these options in the BIOS.
Solution #1. Reboot and change the BIOS every time I switch from 'docked at my desk with an external monitor' to 'on-the-go with maximum power savings'. This is cumbersome and might not be possible for some people with different hardware setups. Solution #2. Find some way to copy the screen rendered by one chip to the other. This might involve running different X servers or not. Ideally, you want to leverage the power of the nVidia card to do the heavy 3D lifting. If you don't have separate X servers, you can't use OpenGL on one of the graphics cards. I have tried to use x11vnc [3], but the performance is really poor (<1fps). Today I came across two other attempts at a solution [4,5], I will try them out later, but since they still use XGetImage/XShmGetImage, I don't think the performance will be much better. I think this might be where VirtualGL can play an important role. Solution #3. Reverse engineering other software. Obviously the BIOS has a way to (dis)connect the LVDS screen to the nVidia card. If I could figure out how that works, I might be able to do that dynamically. Also, the Windows drivers seem to have all of this figured out, so may be there are some hidden gems in those drivers. Solution #4. Wait for nVidia to fix the problem in their proprietary drivers. They are supposedly working on that, but no one knows how long it is going to take and whether they will support older hardware once it is released. I hope this helps to provide some context to my question. Don't say tl;dr because you asked for it ;) Jethro [1] https://en.wikipedia.org/wiki/ATI_Hybrid_Graphics [2] https://en.wikipedia.org/wiki/Nvidia_Optimus [3] http://www.karlrunge.com/x11vnc/ [4] https://github.com/harp1n/hybrid-windump [5] https://github.com/liskin/hybrid-screenclone On Fri, 15 Jun 2012 03:23:03 -0500, DRC wrote: > On 6/15/12 1:36 AM, Jethro Beekman wrote: >> I want to capture part of my desktop, and since I'm using compiz as >> a window >> manager, I'd think I should be able to use VirtualGL to do this. Is >> that right? >> Just to be clear: I still want everything to appear on my attached >> monitor as well. > > That depends. I wasn't aware that compiz actually worked properly > with > VirtualGL yet, but I could be behind the curve on that. I've never > personally been able to bring it up with all of the 3D stuff enabled. > > Further, if remote delivery of the images is not necessary, then > VirtualGL may not be what you want. It's hard to say without knowing > more about what you're trying to do. VirtualGL is certainly not > intended as a session capture program. There are much better ways to > do > that. > > >> If the answer is yes, I assume I will need to write my own >> transport. Is there >> any developer documentation? Chapter 11 is not very elaborate. > > rrtransport.h (which is shipped in /usr/include if you are using our > binary packages) provides detailed API documentation. You could > probably just modify testplugin2.cpp and add a separate thread that > saves the images to disk rather than displaying them. > > I echo Arthur's comment, however, that VirtualGL may or may not be > the > best solution for this. We really need more information about what > you're trying to do, what format you need to output, etc. > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. > Discussions > will include endpoint security, mobile security and the latest in > malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > VirtualGL-Users mailing list > VirtualGL-Users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/virtualgl-users ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ VirtualGL-Users mailing list VirtualGL-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/virtualgl-users
