969cb02de7
Venus implements guest WSI on host external memory and thus cannot transition guest wsi images to/from VK_IMAGE_LAYOUT_PRESENT_SRC_KHR. Thus, when a client would attempt to transition a Venus wsi image to/from VK_IMAGE_LAYOUT_PRESENT_SRC_KHR, Venus instead transitions to/from VK_IMAGE_LAYOUT_GENERAL and performs an explicit ownership transfer to/from VK_QUEUE_FAMILY_FOREIGN_EXT. Unfortunately, the read-only guarantee of VK_IMAGE_LAYOUT_PRESENT_SRC_KHR is lost. Upon the "acquire from foreign queue" side of that symmetry, when a client would attempt to retain the contents of the image (i.e. transition from VK_IMAGE_LAYOUT_PRESENT_SRC_KHR instead of VK_IMAGE_LAYOUT_UNDEFINED), Venus knows that the image's backing memory has not been modified. Thus, when those "acquire from FOREIGN queue" ownership transfers flow to the native driver, Venus can signal it to skip any acquisition-time validation of an image's internal data, obtaining the same optimization as native WSI. This is useful for drivers such as ARM's Mali (with Transaction Elimination) that would otherwise need to recompute costly per-tile checksums (CRCs) to ensure that they haven't gone stale during FOREIGN ownership of the image's memory. Signed-off-by: Ryan Neph <ryanneph@google.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29777>
`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library ====================================================== Source ------ This repository lives at https://gitlab.freedesktop.org/mesa/mesa. Other repositories are likely forks, and code found there is not supported. Build & install --------------- You can find more information in our documentation (`docs/install.rst <https://docs.mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://docs.mesa3d.org/meson.html>`_): .. code-block:: sh $ mkdir build $ cd build $ meson .. $ sudo ninja install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `OFTC's #dri-devel <irc://irc.oftc.net/dri-devel>`_, someone will redirect you if necessary. Remember that not everyone is in the same timezone as you, so it might take a while before someone qualified sees your question. To figure out who you're talking to, or which nick to ping for your question, check out `Who's Who on IRC <https://dri.freedesktop.org/wiki/WhosWho/>`_. The next best option is to ask your question in an email to the mailing lists: `mesa-dev\@lists.freedesktop.org <https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_ Bug reports ----------- If you think something isn't working properly, please file a bug report (`docs/bugs.rst <https://docs.mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://docs.mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.