b1086889ed
The functions xwl_glamor_dmabuf_import_sync_file and
xwl_glamor_dmabuf_export_sync_file are used to ensure proper
synchronization between clients using PresentPixmapSynced and
compositors that do not support the wp_linux_drm_syncobj_v1 protocol
when presenting by flipping. The acquire point's fence will be imported
as the DMA-BUF's implicit fence before handing it off to the compositor,
and then, after the DMA-BUF has been released, its new implicit fence
will be exported and become the release point's fence which the client
is expected to wait for before re-using the buffer.
Both functions currently set the flags arguments of their respective
ioctls to DMA_BUF_SYNC_READ. When importing a sync file, this means that
any subsequent implicitly synchronized reads from the buffer will not
wait for the fence, and when exporting a sync file it means that the
returned fence may be signaled before preceeding reads from the buffer
have completed.
While this is correct for xwl_glamor_dmabuf_export_sync_file since the
compositor will never write to the buffer, it is incorrect for
xwl_glamor_dmabuf_import_sync_file. To avoid corruption, we need any
reads from the buffer by the compositor to wait on the acquire point's
fence.
As a fix, instead of setting the DMA_BUF_SYNC_READ flag in
xwl_glamor_dmabuf_import_sync_file, we set the DMA_BUF_SYNC_WRITE flag.
This *does* provide the necessary guarantees.
Signed-off-by: Erik Kurzinger <ekurzinger@nvidia.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1509>
(cherry picked from commit
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| dri3 | ||
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| fb | ||
| glamor | ||
| glx | ||
| hw | ||
| include | ||
| man | ||
| mi | ||
| miext | ||
| os | ||
| present | ||
| pseudoramiX | ||
| randr | ||
| record | ||
| render | ||
| test | ||
| Xext | ||
| xfixes | ||
| Xi | ||
| xkb | ||
| .appveyor.yml | ||
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| .gitignore | ||
| .gitlab-ci.yml | ||
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| COPYING | ||
| meson.build | ||
| meson_options.txt | ||
| README.md | ||
| xorg-server.m4 | ||
| xorg-server.pc.in | ||
| xserver.ent.in | ||
X Server
The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.
Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.
For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server
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