Where possible, try to export the buffer rendered by the primary GPU as a
dmabuf and import it to the secondary GPU and turn it into a DRM FB for
scanout. If this works, we get a zero-copy path to secondary GPU outputs.
This is especially useful on virtual drivers like EVDI (used for DisplayLink
devices) which are not picky at all about what kind of FBs they can handle.
The zero-copy path is prioritised after the secondary GPU copy path, which
should avoid regressions for existing working systems. Attempting zero-copy
would have the risk of being less performant than doing the copy on the
secondary GPU. This does not affect the DisplayLink use case, because there is
no GPU in a DisplayLink device.
The zero-copy path is prioritised before the primary GPU and CPU copy paths. It
will be tried on the first frame of an output and the copy path is executed
too. If zero-copy fails, the result from the copy path will take over on that
frame. Furthermore, zero-copy will not be attemped again on that output. If
zero-copy succeeds, the copy path is de-initialized.
Zero-copy is assumed to be always preferable over the primary GPU and CPU copy
paths. Whether this is universally true remains to be seen.
This patch has one unhandled failure mode: if zero-copy path first succeeds and
then fails later, there is no fallback and the output is left frozen or black.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
With all the three paths this is quite a handful of code, and it was mostly
duplicated in two places. A follow-up patch would need to introduce a third
copy of it. Therefore move the code into a helper function.
There are two behavioral changes:
- The format error now prints the string code as well, because it is easy to
read.
- The g_debug() in init_dumb_fb() is removed. Did not seem useful.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
There will be another place where I need to release the dumb buffers but not
destroy the whole secondary_gpu_state, so extract this bit of code into a
helper.
The checks of fb_id are dropped as redundant with the check already in in
release_dumb_fb ().
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
release_dumb_fb () checks 'map' to see if anything needs freeing. Other places
are checking fb_id instead. The checks maybe redundant, but let's reset all
fields here while at it, so that all the checks work as expected.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
Simplify the bo freeing functions by not checking what the copy mode is. This
matches what swap_secondary_drm_fb () already does. g_clear_object () is safe
to call even if the value is already NULL.
The copy mode does not change mid-operation. If it did, this change would
ensure we still clean up everything. So this is more future-proof too.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
To mirror what happens in meta_onscreen_native_swap_buffers_with_damage(), warn
here too if next_fb is not NULL. This makes it clear to the reader of what the
expectations are inside this function.
Ensuring next_fb is NULL as the first thing in the function will make all error
paths equal: no longer some failures reset next_fb while others don't. Removing
such special cases should reduce surprises.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
If we end up trying to do a mode set on a DRM state that has already
changed behind our back without us yet having seen the hotplug event we
may fail with `EINVAL`. Since the renderer layer doesn't handle mode set
failure, it'll still try to page flip later on, which will then also
fail. When failing, it'll try to look up the cached mode set in order to
retry the mode set later on, as is needed to handle other error
conditions. However, if the mode set prior to the page flip failed, we
won't cache the mode set, and the page flip error handling code will get
confused.
Instead of asserting that a page flip always has a valid cached mode set
ready to look up, handle it being missing more gracefully by failing to
mode set. It is expected that things will correct themself as there
should be a hotplug event waiting around the the corner, to reconfigure
the monitor configuration setting new modes.
Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/917https://gitlab.gnome.org/GNOME/mutter/merge_requests/1007
The method `relative_motion_across_outputs` is used to adjust the
distance/delta of a mouse movement across multiple monitors to take the
different scale factors of those monitors into account. This works by
getting the adjacent monitors that the movement-line/vector intersects
with and adjusting the final position (or end point of the
movement-line) by multiplying the parts of the line spanning across
different monitors with the scale factors of those monitors.
In the end of this calculation, we always want to set the new end
coordinates of the relative motion to the new end coordinates of the
adjusted movement-line. We currently only do that if all adjacent
monitors the line is crossing actually exist, because only then we end
up inside the "We reached the dest logical monitor" else-block and set
`x` and `y` to the correct values. Fix that and make sure the returned
values are also correct in case an adjacent monitor doesn't exist by
adding separate `target_x` and `target_y` variables which we update during
each pass of the while loop so we're always prepared for the while loop
exiting before the destination monitor was found.
Thanks to Axel Kittenberger for reporting the initial bug and tracking
the issue down to `relative_motion_across_outputs`.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/774
Presumably this function is supposed to be like
meta_kms_impl_simple_handle_page_flip_callback() but the condition in the
if-statement is inverted. Fix the inversion to make these two functions look
alike.
This is part 2 of 2 fixing a complete desktop freeze when drmModePageFlip()
fails with EINVAL and the fallback to drmModeSetCrtc() succeeds but the success
is not registered correctly as completed "flip". The freeze occurs under
wait_for_pending_flips() which calls down into meta_kms_impl_device_dispatch()
which ends up poll()'ing the DRM fd even though drmModeSetCrtc() will not
produce a DRM event, hence the poll() never returns. The freeze was observed
when hotplugging a DisplayLink dock for the first time on Ubuntu 19.10.
This patch makes meta_set_fallback_feedback_idle() actually end up calling into
notify_view_crtc_presented() which decrements
secondary_gpu_state->pending_flips so that wait_for_pending_flips() can finish.
CC stable: gnome-3-34
https://gitlab.gnome.org/GNOME/mutter/merge_requests/953
mode_set_fallback() schedules a call to mode_set_fallback_feedback_idle(), but
it is possible for Mutter to repaint before the idle callbacks are dispatched.
If that happens, mode_set_fallback_feedback_idle() does not get called before
Mutter enters wait_for_pending_flips(), leading to a deadlock.
Add the needed interfaces so that meta_kms_device_dispatch_sync() can flush all
the implementation idle callbacks before it checks if any "events" are
available. This prevents the deadlock by ensuring
mode_set_fallback_feedback_idle() does get called before potentially waiting
for actual DRM events.
Presumably this call would not be needed if the implementation was running in
its own thread, since it would eventually dispatch its idle callbacks before
going to sleep polling on the DRM fd. This call might even be unnecessary
overhead in that case, synchronizing with the implementation thread needlessly.
But the thread does not exist yet, so this is needed for now.
This is part 1 of 2 fixing a complete desktop freeze when drmModePageFlip()
fails with EINVAL and the fallback to drmModeSetCrtc() succeeds but the success
is not registered correctly as completed "flip". The freeze occurs under
wait_for_pending_flips() which calls down into meta_kms_impl_device_dispatch()
which ends up poll()'ing the DRM fd even though drmModeSetCrtc() will not
produce a DRM event, hence the poll() never returns. The freeze was observed
when hotplugging a DisplayLink dock for the first time on Ubuntu 19.10.
CC stable: gnome-3-34
https://gitlab.gnome.org/GNOME/mutter/merge_requests/953
This is inspired by 98892391d7 where the usage of
`g_signal_handler_disconnect()` without resetting the corresponding
handler id later resulted in a bug. Using `g_clear_signal_handler()`
makes sure we avoid similar bugs and is almost always the better
alternative. We use it for new code, let's clean up the old code to
also use it.
A further benefit is that it can get called even if the passed id is
0, allowing us to remove a lot of now unnessecary checks, and the fact
that `g_clear_signal_handler()` checks for the right type size, forcing us
to clean up all places where we used `guint` instead of `gulong`.
No functional changes intended here and all changes should be trivial,
thus bundled in one big commit.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/940
Properly take the panel_orientation_transform into account in
update_monitor_crtc_cursor. This fixes us sometimes drawing the cursor
on two monitors at the same time as we did not properly swap the crtc
width/height when a panel_orientation_transform is active.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/927
Create the intermediate shadow framebuffer for use exclusively when a
shadowfb is required.
Keep the previous offscreen framebuffer is as an intermediate
framebuffer for transformations only.
This way, we can apply transformations between in-memory framebuffers
prior to blit the result to screen, and achieve acceptable performance
even with software rendering on discrete GPU.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/877
If we did a mode set, the gamma may have been changed by the kernel, and
if we didn't also update the gamma in the same transaction, we have no
way to predict the current gamma ramp state. In this case, read the
gamma state directly from KMS.
This should be relatively harmless regarding the race conditions the
state prediction was meant to solve, as the worst case is we get none or
out of date gamma ramps; and since this is for when gamma ramps are not
updated at mode setting time, we'd get intermediate gamma state to begin
with, so it's not worse than what we currently do anyway.
Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/851https://gitlab.gnome.org/GNOME/mutter/merge_requests/840
We can't just update the state of the connector and CRTC from KMS since
it might contain too new updates, e.g. from a from a future hot plug. In
order to not add ad-hoc hot plug detection everywhere, predict the state
changes by looking inside the MetaKmsUpdate object, and let the hot-plug
state changes happen after the actual hot-plug event.
This fixes issues where connectors were discovered as disconnected while
doing a mode-set, meaning assumptions about the connectedness of
monitors elsewhere were broken until the hot plug event was processed.
Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/782https://gitlab.gnome.org/GNOME/mutter/merge_requests/826
It was not the lack of forcing the shadow fb that caused slowness, but
rather due to the method the shadow fb content was copied onto the
scanout fb. With 'clutter: Use cogl_blit_framebuffer() for shadow FB'
we'll use a path that shouldn't be slow when copying onto the scanout
fb.
Also 437f6b3d59 accidentally enabled
shadow fb when using hw accelerated contexts, due to the cap being set
to 1 in majority of drivers. While the kernel documentation for the
related field says "hint to userspace to prefer shadow-fb rendering",
the name of the hint when exposed to userspace is
DRM_CAP_DUMB_PREFER_SHADOW, thus should only be taken into consideration
for dumb buffers, not rendering in general.
This reverts commit 437f6b3d59.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/818
The commit 'renderer/native: Use shadow fb on software GL if preferred'
attempted to force using a shadow fb when using llvmpipe in order to
speed up blending, but instead only did so when llvmpipe AND the drm
device explicityl asked for it.
Now instead always force it for llvmpipe and other software rendering
backends, and otherwise just query the drm device (i.e.
DRM_CAP_DUMB_PREFER_SHADOW).
https://gitlab.gnome.org/GNOME/mutter/merge_requests/807
When suspending, the devices are removed and the virtual device
associated with the corresponding core pointer is disposed.
Add the pointer accessibility virtual device to the core pointer
on resume to restore pointer accessibility on resume if enabled.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/761
The end goal is to have all clutter backend code in src/backends. Input
is the larger chunk of it, which is now part of our specific
MutterClutterBackendNative, this extends to device manager, input devices,
tools and keymap.
This was supposed to be nice and incremental, but there's no sane way
to cut this through. As a result of the refactor, a number of private
Clutter functions are now exported for external backends to be possible.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
Add meta-kms and meta-monitor-manager-kms listener for the udev
device-removed signal and on this signal update the device state /
re-enumerate the monitors, so that the monitors properly get updated
to disconnected state on GPU removal.
We really should also have meta-backend-native remove the GPU itself
from our list of GPU objects. But that is more involved, see:
https://gitlab.gnome.org/GNOME/mutter/issues/710
This commit at least gets us to a point where we properly update the
list of monitors when a GPU gets unplugged; and where we no longer
crash the first time the user changes the monitor configuration after
a GPU was unplugged.
Specifically before this commit we would hit the first g_error () in
meta_renderer_native_create_view () as soon as some monitor
(re)configuration is done after a GPU was unplugged.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/713
drmModeGetConnector may fail and return NULL, this may happen when
a connector is removed underneath us (which can happen with e.g.
DP MST or GPU hot unplug).
Deal with this by skipping the connector when enumerating and by
assuming it is disconnected when checking its connection state.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/713
drmModeGetCrtc may fail and return NULL. This will trigger when
meta_kms_crtc_update_state gets called from meta_kms_update_states_sync
after a GPU has been unplugged leading to a NULL pointer deref causing
a crash.
This commit fixes this by checking for NULL and clearing the current_state
when NULL is returned.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/713
Before this commit meta_kms_crtc_read_state was overwriting the
entire MetaKmsCrtcState struct stored in crtc->current_state including
the gamma (sub)struct.
This effectively zero-s the gamma struct each time before calling
read_gamma_state, setting the pointers where the previous gamma values
were stored to NULL without freeing the memory. Luckily this zero-ing
also sets gamma.size to 0, causing read_gamma_state to re-alloc the
arrays on each meta_kms_crtc_update_state call. But this does mean that
were leaking the old gamma arrays on each meta_kms_crtc_update_state call.
This commit fixes this by making meta_kms_crtc_read_state only overwrite
the other values in the MetaKmsCrtcState struct and leaving the gamma
sub-struct alone, this will make read_gamma_state correctly re-use the
gamma tables if the gamma table size is unchanged; or re-alloc them
(freeing the old ones) if the size has changed, fixing the memory leak.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/713
The "device-added" signal should use g_cclosure_marshal_VOID__OBJECT not
g_cclosure_marshal_VOID__VOID.
Instead of fixing this manually, simply replace the closure function for
both signals with NULL, glib will then automatically set the correct
va_marshaller.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/713
COPY_MODE_PRIMARY has two paths, automatically chosen. For debugging purposes,
e.g. why is my DisplayLink screen slowing down the whole desktop, it will be
useful to know which copy path is taken. Debug prints are added to both when
the primary GPU copy succeeds the first time and when it fails the first time.
This is not the full truth, because theoretically the success/failure could
change every frame, but we don't want to spam the logs (even in debug mode)
every frame. In practise, it should be rare for the success or failure to ever
change. Hence, saying what happened on the first time is enough. This does
indicate if it ever changes even once, too, so we know if that unexpected thing
happens.
The debug prints are per secondary GPU since there could be several.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/615
When the preferred path META_SHARED_FRAMEBUFFER_COPY_MODE_SECONDARY_GPU cannot
be used, as is the case for e.g. DisplayLink devices which do not actually have
a GPU, try to use the primary GPU for the copying before falling back to
read-pixels which is a CPU copy.
When the primary GPU copy works, it should be a significant performance win
over the CPU copy by avoiding stalling libmutter for the duration.
This also renames META_SHARED_FRAMEBUFFER_COPY_MODE_* because the new names are
more accurate. While the secondary GPU copy is always a GPU copy, the primary
copy might be either a CPU or a GPU copy.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/615
This bit of code was more or less duplicated in meta-renderer-native-gles3.c
and meta-wayland-dma-buf.c. Start consolidating the two implementations by
moving the *-gles3.c function into meta-egl.c and generalizing it so it could
also accommodate the meta-wayland-dma-buf.c usage.
The workaround in the *-gles3.c implementation is moved to the caller. It is
the caller's responsibility to check for the existence of the appropriate EGL
extensions.
Commit 6f59e4858e worked around the lack of
EGL_EXT_image_dma_buf_import_modifiers with the assumption that if the modifier
is linear, there is no need to pass it into EGL. The problem is that not
passing a modifier explicitly to EGL invokes implementation-defined behaviour,
so we should not have that workaround in meta-egl.c.
This patch intends to be pure refactoring, no behavioral changes. The one
change is the addition of g_assert to catch overwriting arbitrary memory.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/615
We currently don't handle the lack of DRM_CLIENT_CAP_UNIVERSAL_PLANES
KMS capability. Fail constructing a device that can't handle this up
front, so later made assumptions, such as presence of a primary plane,
are actually valid.
If we want to support lack of said capability, the required planes need
to be emulated by a dummy MetaKmsPlane object.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/665
There were fallbacks in place in case IN_FORMATS didn't yield any usable
formats: the formats in the drmModePlane struct, and a hard coded array.
The lack of these fallbacks in place could result in a segfault as code
using the supported plane formats assumed there were at least something
in there.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/662
Simplify the call site a bit and make the native renderer know it should
queue mode reset itself when views have been rebuilt. This is done
partly due to more things needing to be dealt with after views have been
rebuilt.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/630
When building without EGL device support, the following compiler warning
is seen:
```
src/backends/native/meta-renderer-native.c:2637:20: warning: unused
variable ‘cogl_renderer_egl’ [-Wunused-variable]
```
Fix the warning by placing the relevant variable declarations within the
`#ifdef HAVE_EGL_DEVICE/#endif` statement.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/656
We used to have wayland-specific paths for this in src/wayland, now we
have ClutterKeymap that we can rely on in order to do state tracking,
and can do this all on src/backend domain.
This accomodates the feature in common code, so will work on both
Wayland and X11.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/590
This commit introduces, and makes use of, a transactional API used for
setting up KMS state, later to be applied, potentially atomically. From
an API point of view, so is always the case, but in the current
implementation, it still uses legacy drmMode* API to apply the state
non-atomically.
The API consists of various buliding blocks:
* MetaKmsUpdate - a set of configuration changes, the higher level
handle for handing over configuration to the impl backend. It's used to
set mode, assign framebuffers to planes, queue page flips and set
connector properties.
* MetaKmsPlaneAssignment - the assignment of a framebuffer to a plane.
Currently used to map a framebuffer to the primary plane of a CRTC. In
the legacy KMS implementation, the plane assignment is used to derive
the framebuffer used for mode setting and page flipping.
This also means various high level changes:
State, excluding configuring the cursor plane and creating/destroying
DRM framebuffer handles, are applied in the end of a clutter frame, in
one go. From an API point of view, this is done atomically, but as
mentioned, only the non-atomic implementation exists so far.
From MetaRendererNative's point of view, a page flip now initially
always succeeds; the handling of EBUSY errors are done asynchronously in
the MetaKmsImpl backend (still by retrying at refresh rate, but
postponing flip callbacks instead of manipulating the frame clock).
Handling of falling back to mode setting instead of page flipping is
notified after the fact by a more precise page flip feedback API.
EGLStream based page flipping relies on the impl backend not being
atomic, as the page flipping is done in the EGLStream backend (e.g.
nvidia driver). It uses a 'custom' page flip queueing method, keeping
the EGLStream logic inside meta-renderer-native.c.
Page flip handling is moved to meta-kms-impl-device.c from
meta-gpu-kms.c. It goes via an extra idle callback before reaching
meta-renderer-native.c to make sure callbacks are invoked outside of the
impl context.
While dummy power save page flipping is kept in meta-renderer-native.c, the
EBUSY handling is moved to meta-kms-impl-simple.c. Instead of freezing the
frame clock, actual page flip callbacks are postponed until all EBUSY retries
have either succeeded or failed due to some other error than EBUSY. This
effectively inhibits new frames to be drawn, meaning we won't stall waiting on
the file descriptor for pending page flips.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
The MetaKmsImpl implementation may need to add a GSource that should be
invoked in the right context; e.g. a idle callback, timeout etc. It
cannot just add it itself, since it's the responsibility of MetaKms to
determine what is the impl context and what is the main context, so add
API to MetaKms to ensure the callback is invoked correctly.
It's the responsibility of the caller to eventually remove and destroy
the GSource.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
As with CRTC state, variable connector state is now fetched via the
MetaKmsConnector. The existance of a connector state is equivalent of
the connector being connected. MetaOutputKms is changed to fetch
variable connector state via MetaKmsConnector intsead of KMS directly.
The drmModeConnector is still used for constructing the MetaOutputKms to
find properties used for applying configuration.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
Move reading state into a struct for MetaCrtcKms to use instead of
querying KMS itself. The state is fetched in the impl context, but
consists of only simple data types, so is made accessible publicly. As
of this, MetaCrtcKms construction does not involve any manual KMS
interaction outside of the MetaKms abstraction.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
Represents drmModeConnector; both connected and disconnected. Currently
only provides non-changing meta data. MetaOutputKms is changed to use
MetaKmsConnector to get basic metadata, but variable metadata, those
changing depending on what is connected (e.g. physical dimension, EDID,
etc), are still manually retrieved by MetaOutputKms.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
A plane is one of three possible: primary, overlay and cursor. Each
plane can have various properties, such as possible rotations, formats
etc. Each plane can also be used with a set of CRTCs.
A primary plane is the "backdrop" of a CRTC, i.e. the primary output for
the composited frame that covers the whole CRTC. In general, mutter
composites to a stage view frame onto a framebuffer that is then put on
the primary plane.
An overlay plane is a rectangular area that can be displayed on top of
the primary plane. Eventually it will be used to place non-fullscreen
surfaces, potentially avoiding stage redraws.
A cursor plane is a plane placed on top of all the other planes, usually
used to put the mouse cursor sprite.
Initially, we only fetch the rotation properties, and we so far
blacklist all rotations except ones that ends up with the same
dimensions as with no rotations. This is because non-180° rotations
doesn't work yet due to incorrect buffer modifiers. To make it possible
to use non-180° rotations, changes necessary include among other things
finding compatible modifiers using atomic modesetting. Until then,
simply blacklist the ones we know doesn't work.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
Add MetaKmsCrtc to represent a CRTC on the associated device. Change
MetaCrtcKms to use the ones discovered by the KMS abstraction. It still
reads the resources handed over by MetaGpuKms, but eventually it will
use only MetaKmsCrtc.
MetaKmsCrtc is a type of object that is usable both from an impl task
and from outside. All the API exposed via the non-private header is
expected to be accessible from outside of the meta-kms namespace.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525
The intention with KMS abstraction is to hide away accessing the drm
functions behind an API that allows us to have different kind of KMS
implementations, including legacy non-atomic and atomic. The intention
is also that the code interacting with the drm device should be able to
be run in a different thread than the main thread. This means that we
need to make sure that all drm*() API usage must only occur from within
tasks that eventually can be run in the dedicated thread.
The idea here is that MetaKms provides a outward facing API other places
of mutter can use (e.g. MetaGpuKms and friends), while MetaKmsImpl is
an internal implementation that only gets interacted with via "tasks"
posted via the MetaKms object. These tasks will in the future
potentially be run on the dedicated KMS thread. Initially, we don't
create any new threads.
Likewise, MetaKmsDevice is a outward facing representation of a KMS
device, while MetaKmsImplDevice is the corresponding implementation,
which only runs from within the MetaKmsImpl tasks.
This commit only moves opening and closing the device to this new API,
while leaking the fd outside of the impl enclosure, effectively making
the isolation for drm*() calls pointless. This, however, is necessary to
allow gradual porting of drm interaction, and eventually the file
descriptor in MetaGpuKms will be removed. For now, it's harmless, since
everything still run in the main thread.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525