Is there documentation anywhere on glamor internals? And if there isn't, does anyone on this list know how glamor decides whether or not to upload pixmap contents to a texture (and/or fbo) when used as the source Picture to a CompositePictures request?
This might end up being an X/Y question, so I'll say why I'm asking. I'm writing a Wayland compositor that runs on X, and so far the "fast path" of using PresentPixmap to display the contents of a buffer is working fine. However, XRender is used to composite buffer contents to the window when there are multiple subsurfaces attached, and I'm running into a problem where partially drawn contents from shared memory buffers end up displayed by the X server while glamor is enabled. exa and the Render acceleration in xf86-video-intel work fine, but the former is slow. The only way this can make sense is if wl_buffer.release is sent before the buffer contents are uploaded to the fbo, resulting in the Wayland client scribbling over the contents of the buffer before the X server has a chance to display them. So what I need to know is whether or not the pixmap contents have been uploaded (or copied somewhere) by the time an XSync after the Composite request completes, or if not, when the pixmap contents will have been uploaded. Thanks.
