Hi,
Fusion definitely support the "switchable graphics card". Sometimes you may notice that Fusion diagnostics dialog still reports that Intel GPU is used but underneath the ATI card is actually used if you configure you ATI control panel correctly. The reason is described below (it is directly from AMD developers):
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The truth behind this issue is that AMD is using LDA mode in this case. On the contrary, there is a MDA (Multiple Display Adapter) mode.
Linked Display Adapters
A linked display adapter (LDA) is a mode of operation in which multiple physical adapters are merged, thus appearing as a single logical adapter. From an application’s point of view, only the logical adapter is visible. However, the underlying WDDM driver uses all the physical adapters within the link to improve the performance of the logical adapter.
With LDA mode, Intel iGPU is the Master GPU and AMD dGPU is the Slave GPU. All regular DirectX APIs will see Master GPU, i.e., Intel iGPU only. That’s to say, OS only expose the Intel iGPU as the logical adapter at the API level.
Underneath the app and DirectX runtime, AMD’s graphics driver takes over the control and dispatch the work to Intel GPU or AMD GPU based on some policies.
So AMD GPU is doing work behind but unfortunately it is not exposed by standard DirectX APIs.
The positive side of LDA mode is that app doesn’t need to care how many display adapters in the system so the programming is much simplified. The down side is that app lose the control to select specific adapter if it wants to do so.
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-Chengyun
