With 8x MSAA, read from multisample texture in D3D 11 silently fails on Intel Haswell-generation GPUs

[Konstantin_G_]

With 8x MSAA, read from multisample texture in D3D 11 silently fails on Intel Haswell-generation GPUs. Here’s the HLSL code:

Texture2DMS<uint2> depthStencilTexture : register( t0 );
cbuffer ReadDepthInput : register( b2 )
{
    int2 readPosition;
}
// Produces vector3( x, y, stencilValue )
float4 main() : SV_Target0
{
    uint2 res = depthStencilTexture.Load( readPosition, 1 );
    float stencil = res.y;
    // Scale the result from integers to 0..1
    stencil /= 255.0f;
    return float4( float( readPosition.x ) / 65535.0f, float( readPosition.y ) / 65535.0f, stencil, 0 );
}

CheckFormatSupport API says D3D11_FORMAT_SUPPORT_MULTISAMPLE_LOAD is supported, CheckMultisampleQualityLevels says 8X MSAA is supported, and yet it doesn’t work. The physical texture format is DXGI_FORMAT_R24G8_TYPELESS, interpreted as DXGI_FORMAT_D24_UNORM_S8_UINT for the depth+stencil view, and as DXGI_FORMAT_X24_TYPELESS_G8_UINT by the affected pixel shader above.

[Konstantin_G_]

Forget to tell I’ve reproduced that on my i5-4460 with HD 4600 GPU, and before that our customer found the bug on their 4-generation Intel NUC with i5 4250U and Intel HD 5000 GPU. Both running Windows 10, latest graphic driver 20.19.15.4531.

[Michael_C_Intel2]

Hi, 

There are no driver releases planned for that generation of Intel Graphics.So if it s a driver issue there is not much I can do I'm afraid. Is it seen on newer graphics?

[Konstantin_G_]

Hi. I have another PC here with later generation of Intel graphics, namely Iris 550 inside i3-6157U. I can confirm my code works on that just fine, with 8x MSAA. Personally, I’ve already found a workaround for the software I’m working on: http://stackoverflow.com/a/43437289/126995 But I still think you better fix the issue on your side. Ideally, in the next version of GPU driver, you should decrease the value CheckMultisampleQualityLevels reports from 8 to 4 for that hardware.