When we change the required dependencies for the DRM backend,
Meson might auto-disable the backend for users missing the new
requirements. This results in confused users [1] because they don't
notice the "drm-backend: NO" line burried in the Meson logs, and
then get a black screen when starting the compositor.
Update wlr_backend_autocreate() to refuse to create a backend with
only libinput (without DRM).
Users really wanting to start their compositor with a libinput
backend and without a DRM backend can manually set WLR_BACKENDS.
[1]: https://github.com/swaywm/sway/issues/7457
Up until now, wlr_backend_autocreate() created the wlr_session and
then stuffed it into struct wlr_multi_backend so that compositors
can grab it later.
This is an abuse of wlr_multi_backend and the wlr_backend API:
wlr_backend_get_session() and wlr_multi_backend.session only exist
to accomodate the needs of wlr_backend_autocreate(). What's more,
the DRM and libinput backends don't implement
wlr_backend_impl.get_session.
Instead, return the struct wlr_session to the compositor in the
wlr_backend_autocreate() call. wlr_backend_get_session() will be
removed in the next commit.
The libinput backend is now optional. However, this means that a
user building wlroots without the correct libinput dependencies
will end up with a compositor which doesn't respond to input events.
wlr_backend_autocreate is supposed to return a sensible setup, so in
this case let's just error out and explain what happened. Users can
suppress the check by setting WLR_LIBINPUT_NO_DEVICES=1 (already used
to suppress the zero input device case inside the libinput backend).
Compositors which really want to create a bare DRM backend can easily
create it manually instead of using wlr_backend_autocreate.
Since libinput is an optional dependency the libinput backend is possibly undeclared.
wlr_backend_destroy(backend) below will clean up the child libinput backend if any.
This commit adds two error-handling cases to the function
attempt_dmr_backend. Specifically:
- In the case where the number of found GPUs is zero, we now
print a log message indicating this and return a NULL pointer
- In the case where we could not successfully create a backend
on any GPU, we now log a message indicating this and return
a NULL pointer
This allows us to provide more descriptive error messages,
as well as avoid a SEGFAULT (the function
`ensure_primary_backend_renderer_and_allocator` dereferences the pointer
given, which could be NULL until this patch) when these cases arise.
After 70fb21c35b made libinput optional the include prevents
building without libinput package installed.
backend/backend.c:4:10: fatal error: 'libinput.h' file not found
#include <libinput.h>
^~~~~~~~~~~~
Instead of ensuring the renderer and allocator are initialized in each
backend, do it in wlr_backend_autocreate. This allows compositors to
create backends without any renderer/allocator if they side-step
wlr_backend_autocreate.
Since the wlr_backend_get_renderer and backend_get_allocator end up
calling wlr_renderer_autocreate and wlr_allocator_autocreate, it sounds
like a good idea to centralize all of the opimionated bits in one place.
This new functions cleans up the common backend state. While this
currently only emits the destroy signal, this will also clean up
the renderer and allocator in upcoming patches.
The get_drm_fd was made available in an internal header with a53ab146f. Move it
now to the public header so consumers opting in to the unstable interfaces can
make use of it.
Sometimes wlr_session_find_gpus will encounter an error. This is
different from finding zero GPUs.
On error, wlr_session_find_gpus already returns -1. However, this is
casted to size_t, so callers uncorrectly assume this is a success.
Instead, make wlr_session_find_gpus return a ssize_t and allow callers
to handle the error accordingly.
This callback allowed compositors to customize the EGL config used by
the renderer. However with renderer v6 EGL configs aren't used anymore.
Instead, buffers are allocated via GBM and GL FBOs are rendered to. So
customizing the EGL config is a no-op.
Instead of operating on FDs in {open,close}_device, operate on
wlr_devices. This avoids the device lookup in wlr_session and allows
callers to have access to wlr_device fields.
For now, we use it to remove wlr_session_signal_add and replace it with
a more idiomatic wlr_session.events.change field. In the future, other
events will be added.
I'm not sure what this was used for, but it's not used by libwayland.
Setting _WAYLAND_DISPLAY would result in the Wayland backend being
picked but would ignore the actual value of the env variable.
The documentation for wayland-server.h says:
> Use of this header file is discouraged. Prefer including
> wayland-server-core.h instead, which does not include the server protocol
> header and as such only defines the library PI, excluding the deprecated API
> below.
Replacing wayland-server.h with wayland-server-core.h allows us to drop the
WL_HIDE_DEPRECATED declaration.
The noop backend is similar to headless, but it doesn't contain a
renderer. It can be used as a place to stash views for when there's no
physical outputs connected.
