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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[18]; FREEMAIL_TO(0.00)[linux.intel.com,ffwll.ch,gmail.com,amd.com,redhat.com,kernel.org,gmx.de,windriver.com,chromium.org]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com,gmx.de]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.com:url] X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" Hi Am 25.11.25 um 17:25 schrieb Maarten Lankhorst: > Hey, > > I'm glad to see the old kdb handler gone. > > Could we perhaps extend the drm panic handler somehow for this to work? > Restore could potentially be simply duplicating and committing the current state. Yeah, I briefly outlined this in the cover letter. If we wanted to support kdb, we could get the scanout buffer and use the buffer's simple display update for showing the debugger. I think this still requires quite some work, but would avoid all the issues with the current approach. Best regards Thomas > > Kind regards, > ~Maarten Lankhorst > > Den 2025-11-25 kl. 13:52, skrev Thomas Zimmermann: >> 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 >> >> Documentation/process/debugging/kgdb.rst | 28 ----- >> drivers/gpu/drm/amd/amdgpu/dce_v10_0.c | 35 ++----- >> drivers/gpu/drm/amd/amdgpu/dce_v6_0.c | 35 ++----- >> drivers/gpu/drm/amd/amdgpu/dce_v8_0.c | 35 ++----- >> drivers/gpu/drm/drm_fb_helper.c | 108 -------------------- >> drivers/gpu/drm/nouveau/dispnv04/crtc.c | 24 +---- >> drivers/gpu/drm/radeon/atombios_crtc.c | 74 ++++---------- >> drivers/gpu/drm/radeon/radeon_legacy_crtc.c | 23 ++--- >> drivers/gpu/drm/radeon/radeon_mode.h | 10 +- >> drivers/video/fbdev/core/fbcon.c | 24 ----- >> drivers/video/fbdev/core/fbcon.h | 1 - >> include/drm/drm_fb_helper.h | 21 ---- >> include/drm/drm_modeset_helper_vtables.h | 23 ----- >> include/linux/fb.h | 4 - >> 14 files changed, 63 insertions(+), 382 deletions(-) >> >> >> base-commit: 0a21e96e0b6840d2a4e0b45a957679eeddeb4362 -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)