Hi, On Tue, Nov 25, 2025 at 5:06 AM Thomas Zimmermann <[email protected]> wrote: > > Remove the rest of the kbd support from DRM. Driver support has been > broken for years without anyone complaining. > > Kdb cannot use regular DRM mode setting, so DRM drivers have to > implement an additional hook to make it work (in theory). As outlined > by Sima in commit 9c79e0b1d096 ("drm/fb-helper: Give up on kgdb for > atomic drivers") from 2017, kdb is not compatible with DRM atomic mode > setting. Non-atomic mode setting meanwhile has become rare. > > Only 3 DRM drivers implement the hooks for kdb support. Amdgpu and > nouveau use non-atomic mode setting on older devices. But both drivers > have switched to generic fbdev emulation, which isn't compatible with > kdb. Radeon still runs kdb, but it doesn't work in practice. See the > commits in this series for details > > Therefore remove the remaining support for kdb from the DRM drivers > and from DRM fbdev emulation. Also remove the hooks from fbdev, as > there are no fbdev drivers with kdb support. > > If we ever want to address kdb support within DRM drivers, a place to > start would be the scanout buffers used by DRM's panic screen. These > use the current display mode. They can be written and flushed without > mode setting involved. > > Note: kdb over serial lines is not affected by this series and continues > to work as before. > > Thomas Zimmermann (5): > drm/amdgpu: Do not implement mode_set_base_atomic callback > drm/nouveau: Do not implement mode_set_base_atomic callback > drm/radeon: Do not implement mode_set_base_atomic callback > drm/fbdev-helper: Remove drm_fb_helper_debug_enter/_leave() > fbcon: Remove fb_debug_enter/_leave from struct fb_ops
Personally, I've never worked with kdb over anything other than serial, so this won't bother any of my normal workflows. That being said, at least as of a year ago someone on the lists was talking about using kdb with a keyboard and (presumably) a display. You can see a thread here: http://lore.kernel.org/r/[email protected] Daniel may also have comments here? -Doug
