Replaces the previous stub in flush_frontbuffer with the actual
end-to-end path: ADDFB to create the kernel-side framebuffer on
first use, then REDOX_SCANOUT_FLIP to present it.
Three new functions:
redox_drm_bo_get_fb() in redox_drm_bo.{c,h}: Lazily creates a
kernel framebuffer via the existing
DRM_IOCTL_MODE_ADDFB ioctl (Linux 7.1's
drm_mode_addfb_ioctl, drivers/gpu/drm/
drm_ioctl.c). Caches fb_id and stride on
the BO so the second call is a no-op.
redox_drm_bo_flip_to_crtc() in redox_drm_surface.{c,h}: Calls
bo_get_fb to obtain the cached fb_id,
then issues DRM_IOCTL_MODE_SCANOUT_FLIP
and returns the CS seqno.
flush_frontbuffer in redox_drm_winsys.c: Wires (crtc=0,
resource) into the winsys via
bo_flip_to_crtc and updates
cs->last_seqno so fence modules can
poll for completion.
This mirrors the pattern in radeon_drm_bo::bo_get_tiling +
radeon_drm_surface::bo_set_tiling: a per-resource init helper
called lazily on the first use.
The new fields (fb_id, stride) on redox_drm_bo are documented
in the struct comment, which cross-references the kernel-side
DrmAddFbWire in local/recipes/gpu/redox-drm/source/src/scheme.rs.
Limitation (preserved as comment): ctrc_id is hardcoded to 0.
Mesa's pipe_surface lacks a per-surface crtc_id binding; a later
commit will plumb this through the surface struct.
This closes Phase 6+'s 'real flush_frontbuffer' gap. The
remaining 'real fence' work is Phase 6.4 (real eventfd for
fence_eventfd, replacing the synthetic stand-in).
vasilito
a506e62055