Francisco Jerez
fce905f613
The Vulkan specification indicates that if memory types have properties which are a strict subset of another type's, then they should appear before that memory type. Otherwise the specification does not require a specific ordering of memory types. But, it appears that Aztec Ruins and the Vulkan CTS make an assumption that the first host-accessible memory type is host-coherent and select it when they expect data written by the CPU to become visible without calling vkFlushMappedMemoryRanges(), even though flushing is required by the spec, which leads to misrendering and hangs on MTL platforms. We found that other drivers also put a host-coherent, but not cached memory type as the first host-accessible memory type, so let's do the same in order to match the expectations of such broken applications. Host-coherent uncached memory types are currently implemented with a WC CPU map on non-LLC platforms, so there shouldn't be a huge performance penalty from this: If an application intends to do heavy R/W CPU access on a memory range it's expected to loop over the available memory types and select one marked as host-cached -- If an application fails to do that and simply selects the first available type it seems more robust to stay on the safe side and give them a host-coherent type rather than a cached one. Rework: * Jordan: Add initial explanation to body of commmit message. * Curro: Add additional comments to commit message. Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22878>
`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://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://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://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.