I currently own the AMD A8-3850 APU (GPU+CPU), and I'm wondering if Ubuntu supports AMD's dual graphics, or if I should focus on buying a more powerful card that isn't compatible.
I have the A6-3400m APU (integrated 6520G, discrete 6470M) and my experience until now is:
The Ubuntu built-in "radeon" driver does NOT support "dual graphics". To get the radeon driver without dual graphics work properly, the discrete graphics card should be switched off in the BIOS (less power consumption, ...)
AMD provides a proprietary driver called "fglrx". This driver can be installed via the system settings "additional drivers" or the latest version directly downloaded from AMD. https://help.ubuntu.com/community/BinaryDriverHowto/ATI My experience: The Ubuntu fglrx version is much toooo old: I had a lot of problems with wine and the activated discrete graphics card because that driver recognised a wrong graphics card (7400m series instead of 64oom series). With the latest AMD driver (Catalyst 12.10): working.
The fglrx drivers for Linux/Ubuntu are provided with a graphical configuration application called Catalyst Control Center and can also be configured via command line via amdconfig. With both configuration tools it is possible to switch between the discrete und the integrated graphics engine. This is called PowerXpress. With Windows this switch can be done without reboot but X needs a restart. Therefore the powersaving feature called PowerPlay does not use PowerXpress under Linux but just other features like dynamic clock rate change, .... BUT: PowerXpress is NOT "dual graphics".
"dual graphics" means: Both graphics engine act like a single one using the CrossFireX-Technology. This is provided for Windows 7 DirectX 10+ but NOT for Windows XP or Linux! For more information compare the AMD dual graphics FAQ: http://www.amd.com/us/products/technologies/dual-graphics/pages/dual-graphics.aspx#4
If there is any newer information about dual graphics and Linux: Please let me know!
