Hybrid-graphics is a concept involving two graphics cards on same computer, it was first designed to control power consumption in laptops and is extending to desktop computers as well
About Hybrid-graphics Technologies
The laptop manufacturers developed new technologies involving two graphic cards in an single computer, enabling both high performance and power saving usages. This technology is well supported on Windows but it's still quite experimental with Linux distributions.
We call hybrid graphics a set of two graphic cards with different abilities and power consumptions. There are a variety of technologies and each manufacturer developed it's own solution to this problem. Here we try to explain a little about each approach and models and some community solutions to the lack of GNU/Linux systems support.
The "Old" Hybrid Model (Basic Switching)
This approach involves a two graphic card setup with a hardware multiplexer (MUX). It allows power save and low-end 3D rendering by using an Integrated Graphics Processor (IGP); or a major power consumption with 3D rendering performance using a Dedicated Graphics Processor (DGP). This model makes the user choose (at boot time or at login time) within the two power/graphics profiles and is almost fixed through all the user session. The switch is done by a similar workflow:
- Turn off the display
- Turn on the DGP
- Switch the multiplexer
- Turn off the IGP
- Turn on agin the display
This switch is somewhat rough and adds some blinks and black screens in laptops that could do it "on the fly". Later approaches made the transition a little more user-friendly.
The New Dynamic Switching Model
Most of the new Hybrid-graphics technologies involves two graphic cards as the basic switching but now the DGP and IGP are plugged to a framebuffer and there is no hardware multiplexer. The IGP is always on and the DGP is switched on/off when there is a need in power-save or performance-rendering. In most cases there is no way to use only the DGP and all the switching and rendering is controlled by software. At startup, the Linux kernel starts using a video mode and setting up low-level graphic drivers which will be used by the applications. Most of the Linux distributions then use X.org to create a graphical environment. Finally, a few other softwares are launched, first a login manager and then a window manager, and so on. This hierarchical system has been designed to be used in most of cases on a single graphic card.
- Switching between cards when possible.
- Switching on/off the discrete card.
- Be able to use the discrete card for 3D render.
- Be able to use both cards for 3D render (problem arised in this post).
Solutions So Far
ATI Dynamic Switchable Graphics
This is a new technology similar to the one of Nvidia. There is no hardware multiplexer and gone into the market a few weeks/months ago.
To be filled
Solutions So Far
To be filled