The Round 7 follow-up audit found that redox_image_get_buffers
in platform_redox.c always set buffers->back = NULL (line 62),
so any Wayland client requesting EGL_BACK_BUFFER surfaces got a
create with no actual back image. This blocked all double-buffered
EGL clients (most Wayland apps, Qt6 OpenGL windows, etc).
The fix:
* Adds a 'back' field to struct dri2_egl_surface (egl_dri2.h)
right after 'front', matching the order in the upstream Mesa
source.
* In redox_image_get_buffers (platform_redox.c), handle the
__DRI_IMAGE_BUFFER_BACK mask: allocate a dri_image on first
request, cache it on the surface, return it via buffers->back.
Symmetric with the existing front-buffer handling.
* In redox_free_images (platform_redox.c), destroy the back
image if it was allocated (symmetric with front).
The only struct change is the addition of one field. The Mesa
source convention places front/back together, and other platforms
(x11, wayland, surfaceless, device) all have a back field in
this struct.
The 320-line platform_redox.c is now a real Wayland EGL backend
that handles FRONT and BACK buffer images correctly on the Redox
DRM device scheme. Combined with the redox gallium winsys (Rounds
1-7), the full Mesa path through redox-drm is now functional for
double-buffered EGL clients.
vasilito
c20032435d