On Fri, 10 Feb 2023, Jani Nikula jani.nikula@intel.com wrote:
On Tue, 07 Feb 2023, Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
On Tue, Feb 07, 2023 at 04:33:37PM +0200, Jani Nikula wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
CONFIG_DRM_USE_DYNAMIC_DEBUG breaks debug prints for (at least modular) drm drivers. The debug prints can be reinstated by manually frobbing /sys/module/drm/parameters/debug after the fact, but at that point the damage is done and all debugs from driver probe are lost. This makes drivers totally undebuggable.
There's a more complete fix in progress [1], with further details, but we need this fixed in stable kernels. Mark the feature as broken and disable it by default, with hopes distros follow suit and disable it as well.
[1] https://lore.kernel.org/r/20230125203743.564009-1-jim.cromie@gmail.com
Fixes: 84ec67288c10 ("drm_print: wrap drm_*_dbg in dyndbg descriptor factory macro") Cc: Jim Cromie jim.cromie@gmail.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard mripard@kernel.org Cc: Thomas Zimmermann tzimmermann@suse.de Cc: David Airlie airlied@gmail.com Cc: Daniel Vetter daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v6.1+ Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com
drivers/gpu/drm/Kconfig | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index f42d4c6a19f2..dc0f94f02a82 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -52,7 +52,8 @@ config DRM_DEBUG_MM config DRM_USE_DYNAMIC_DEBUG bool "use dynamic debug to implement drm.debug"
- default y
- default n
- depends on BROKEN depends on DRM depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE depends on JUMP_LABEL
Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Thanks Greg, any more acks from anyone?
Maxime, since there's going to be an -rc8, I suggest taking this via drm-misc-fixes. Is that okay with you? (You're doing drm-misc-fixes this round, right?)
Pushed to drm-misc-fixes with Maxime's IRC ack and Jim's ack elsewhere in the thread. Thanks.
BR, Jani.
BR, Jani.