Clarity on the requirement of pCmdList for resource tagging

[FakeMichau]

I've encountered an issue where I'm unable to tag a resource without providing a command list. The resource is marked as valid until present and is already in the prefer (D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE) state.
Trying to tag this resource with a nullptr passed as a command list results in XEFG_SWAPCHAIN_RESULT_ERROR_INVALID_ARGUMENT despite the header file saying pCmdList is optional for my case.

xess/inc/xess_fg/xefg_swapchain_d3d12.h

Lines 194 to 196 in c159ef4

	* @param pCmdList Optional command list utilized to manage the resource
	* lifetime. It is only required if the resource is not valid until the next
	* present call.

Doing the sin of passing this (ID3D12GraphicsCommandList*) 1 does get around this issue and the resource seems to be successfully tagged.

I would like to get some clarification on when exactly command list is optional.

[mike-intel]

This is a defect in the parameter validation and the function will always complain about null command list pointer. Sorry about that.

Our next patch will address the problem.

The comment is correct in the way that the command list is not going to be used for resources tagged with XEFG_SWAPCHAIN_RV_UNTIL_NEXT_PRESENT - that's why (ID3D12GraphicsCommandList*)1 works.

Going forward we will maintain the following contract:

• resource valid now - command list is required (XeSS-FG will record state transitions and copy)
• resource valid until present - command list is optional and it won't be accessed
• back buffer tagging for letterboxing - command list is optional and it won't be accessed

XeSS-FG maintains a history of input resources and may need to copy some of them. Application can use xefg_swapchain_resource_validity_t to control when the copy happens:

• valid now - copy is recorded to the provided command list and the application must execute this command list before the matching present
• valid until present - copy is recorded (to an internal command list) and executed during present

With the current version of SDK, a named constant may make life a bit easier:

// Workaround for https://github.com/intel/xess/issues/45
constexpr auto kXessFgCommandListPlaceholder = (ID3D12GraphicsCommandList*)1;
xefgSwapChainD3D12TagFrameResource(xefg_handle, kXessFgCommandListPlaceholder, frame_id, &resource_data);

[FakeMichau]

Thank you for a quick response. I assume there are no public ETAs for when a fixed version might be released?

[mike-intel]

Unfortunately, I cannot provide a specific ETA. Historically patch iterations have been happening much faster than minor version bumps.

[mike-intel]

@FakeMichau fix is available in https://github.com/intel/xess/releases/tag/v2.1.1

We've also updated the basic sample to tag UNTIL_PRESENT resources without command list:

xess/samples/basic_sample_frame_generation/basic_sample.cpp

Line 1112 in b2e8f70

xefgSwapChainD3D12TagFrameResource(m_xefgSwapChain, nullptr, m_frameCounter, &hudlessColor);

[FakeMichau]

Can confirm that this and other issues are resolved. Thank you!

[mike-intel]

Thank you for the feedback!