<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>For a few weeks now I am working on implementing Vulkan for VideoCore 6 AKA 42 (using V3D/DRM). Don't hold you breath ;)<br/> <br/> Currently I am trying to understand what is necessary or how to interact with V3D. So I am looking at TransformFeedback because it interacts with quite a few other parts of the pipeline and still seems less mangled into the big logic than other features. So I am comparing how Gallium (V3D) is handling TF in the state tracker VS how Vulkan (Intel) is handling the Extension.<br/> <br/> The following is what I so far think I gathered:<br/> 1. GV3D is handling TransformFeedback directly with other bound parts of the pipeline (e.g. `emit_state` in _v3dx_emit.c_). It seems to look into the shader and associated TF specs. It seems to use "streamout targets", although I do not yet understand what these are really. Then it passes all the offsets, indices and finally resources to V3D.<br/> 2. The Vulkan Extension only knows about CounterBuffers and iterates over these. Intel seems to call TF -> XF? and subsequently the buffers XFB. Have also not yet gathered what is the difference and what all the gazillion acronyms mean.<br/> <br/> So far my idea would be to implement TF similar to Intel and instead of iterating over "streamout targets" I would iterate XFBs.<br/> The problem with this approach is, that it will not be easy to mimic `cl_emit` calls similar to Gallium.<br/> My question now is which parts of V3D emits have a dependency.<br/> <br/> I would assume that I can move TRANSFORM_FEEDBACK_SPECS and TRANSFORM_FEEDBACK_ENABLE to cmd state flush in Vulkan.<br/> `vkCmdBeginTransformFeedbackEXT` shoudl then only need TRANSFORM_FEEDBACK_BUFFER and TRANSFORM_FEEDBACK_OUTPUT_ADDRESS.<br/> <br/> Sorry if this is a bit confusing - I am really just trying to figure this out one by one.<br/> <br/> Any information would be appreciated.</div> <div> </div> <div class="signature"> </div></div></body></html>