Hi,

Please correct me if I'm wrong, but text-console emulation/scrolling on DRM is
currently unaccelerated and bound to Truecolour modes only,

Yes.  Adding support for formats beside argb8888 to the drm fbcon
emulation shouldn't be that much of a problem though.

Acceleration is harder.  The scroll acceleration had issues nobody
addressed for years, and on modern hardware it is simply not used, which
is probably the reason nobody stepped up fixing things and it ended up
being dropped.  Bringing it back is much more work than just reverting
the commits removing it.

Also note that using a shadow framebuffer allows to decouple fbcon
updates and scanout framebuffer updates.  Can be used to speed up
things without depending on the 2d blitter.

take care,
  Gerd