Feature level 12_2 exists as a means by which to standardize a set of features across the GPU ecosystem in a way that improves customers’ experience with graphical games and applications on the Windows platform.
The runtime queries the graphics driver for the 12_2 feature level in the same manner it queries for other feature levels.
Remark
While feature level 12_2 could be inferred based on the right set of caps being at the right values, the runtime does not do this because inferring feature levels goes against pre-existing designs. Feature level 12_2 is something explicitly reported by the driver.
The enumeration value for 12_2 is expressed as follows:
typedef
enum D3D_FEATURE_LEVEL
{
// ...
D3D_FEATURE_LEVEL_12_2 = 0xc200
} D3D_FEATURE_LEVEL;
Feature level 12_2 is requested in the same manner as other feature levels, e.g., when creating a device:
ComPtr<ID3D12Device> device;
D3D_FEATURE_LEVEL featureLevel = D3D_FEATURE_LEVEL_12_2;
HRESULT hr = D3D12CreateDevice(nullptr, featureLevel, IID_PPV_ARGS(&m_spDevice));
if (SUCCEEDED(hr))
{
// feature level is supported by default adapter
}
Feature level 12_2 is expressed in terms of capabilities and feature tiers directly queryable through CheckFeatureSupport.
If a device is feature level 12_2, it has
| Feature | 12_2 proposed minimum | Public spec |
|---|---|---|
| Required driver model | WDDM 2.0 | |
| Shader Model | 6.5 | Link |
| Raytracing tier | Tier 1.1 | Link |
| Variable shading rate | Tier 2 | Link |
| Mesh shader tier | Tier 1 | Link |
| Sampler feedback | Tier 0.9 | Link |
| Resource Binding Tier | Tier 3 | Link |
| Tiled Resources | Tier 3 | |
| Conservative Rasterization | Tier 3 | Link |
| RootSignatureTier | 1.1 | Link |
| DepthBoundsTestSupported | TRUE | Link |
| WriteBufferImmediateSupportFlags | Direct, Compute, Bundle | |
| MaxGPUVirtualAddressBitsPerResource | 40 | |
| MaxGPUVirtualAddressBitsPerProcess | 40 |
Additionally, it has the following flags set
| Feature | 12_2 proposed value |
|---|---|
| WaveOps | TRUE |
| OutputMergerLogicOp | TRUE |
| VPAndRTArrayIndexFromAnyShaderFeedingRasterizerSupportWithoutGSEmulation | TRUE |
| CopyQueueTimestampQueriesSupported | TRUE |
| CastingFullyTypedFormatSupported | TRUE |
| UnalignedBlockTexturesSuported | TRUE |
| Int64ShaderOps | TRUE |
Remark
Some specifications, especially those from before the May 2019 Update, are not migrated to the DirectX-Specs repo.
The Direct3D 12 UMD DDI has an enumeration, D3D12DDI_3DPIPELINELEVEL, for describing feature levels. This enumeration has a value for feature level 12.2:
typedef enum D3D12DDI_3DPIPELINELEVEL
{
// ...
D3D12DDI_3DPIPELINELEVEL_12_2 = 14,
} D3D12DDI_3DPIPELINELEVEL;
To find out which feature levels a driver supports, the runtime calls PFND3D12DDI_GETCAPS with
The difference between these two usages of GetCaps is as follows
| Selector | Data interpretation | Valid returnable feature levels |
|---|---|---|
| 3DPIPELINESUPPORT | D3D12DDI_3DPIPELINELEVEL, simple output value | 12.1 and earlier |
| 3DPIPELINESUPPORT1 | D3D12DDI_3DPIPELINESUPPORT1_DATA_0081, structure with an input and output field | any, including 12.2 and later |
The definition of D3D12DDI_3DPIPELINESUPPORT1_DATA_0081 is as follows
typedef struct D3D12DDI_3DPIPELINESUPPORT1_DATA_0081
{
D3D12DDI_3DPIPELINELEVEL HighestRuntimeSupportedFeatureLevel; // input
D3D12DDI_3DPIPELINELEVEL MaximumDriverSupportedFeatureLevel; // output
} D3D12DDI_3DPIPELINESUPPORT1_DATA_0081;
For 3DPIPELINESUPPORT1, the runtime sets the value of HighestRuntimeSupportedFeatureLevel. The driver returns a value for MaximumDriverSupportedFeatureLevel which does not exceed HighestRuntimeSupportedFeatureLevel.
Remark
In practice:
- Versions of Direct3D built into the operating system at or before Manganese (20H2) use 3DPIPELINESUPPORT.
- Versions of Direct3D built into Iron operating system or later use 3DPIPELINESUPPORT1, and fall back to 3DPIPELINESUPPORT if it fails.
The WriteBufferImmediateSupportFlags capability D3D12_COMMAND_LIST_SUPPORT_FLAG_BUNDLE is switched on at the API level for drivers which report D3D12DDI_COMMAND_QUEUE_FLAG_3D at the DDI level.
There is a Direct3D 12 conformance test to validate that a Direct3D 12 device created with feature level 12_2 capability satisfies at least the capabilities outlined in the Capabilities section of this document. This is a conformance test, not an HLK test because it exercises behaviors of the runtime not the driver. Other tests, external to the specific test for feature level 12_2, are in place to ensure that CheckFeatureSupport capabilities properly match with device behavior.