| Message ID | 20220224125934.3461478-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/todo: Update panic handling todo | expand |
Hello Daniel, On 2/24/22 13:59, Daniel Vetter wrote: > Some things changed, and add two useful links. > > Cc: Javier Martinez Canillas <javierm@redhat.com> > Cc: Pekka Paalanen <ppaalanen@gmail.com> > Cc: gpiccoli@igalia.com > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > --- > Documentation/gpu/todo.rst | 21 +++++++++------------ > 1 file changed, 9 insertions(+), 12 deletions(-) > > diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst > index 7bf7f2111696..283d35a500bd 100644 > --- a/Documentation/gpu/todo.rst > +++ b/Documentation/gpu/todo.rst > @@ -475,8 +475,12 @@ This is a really varied tasks with lots of little bits and pieces: > achieved by using an IPI to the local processor. > > * There's a massive confusion of different panic handlers. DRM fbdev emulation > - helpers have one, but on top of that the fbcon code itself also has one. We > - need to make sure that they stop fighting over each another. > + helpers had their own (long removed), but on top of that the fbcon code itself > + also has one. We need to make sure that they stop fighting over each another. The "over each another" sounds a little bit off, shouldn't be "over each other" ? > + This is worked around by checking ``oops_in_progress`` at various entry points > + into the DRM fbdev emulation helpers. A much cleaner approach here would be to > + switch fbcon to the `threaded printk support > + <https://lwn.net/Articles/800946/>`_. > > * ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and > isn't a full solution for panic paths. We need to make sure that it only > @@ -488,16 +492,9 @@ This is a really varied tasks with lots of little bits and pieces: > even spinlocks (because NMI and hardirq can panic too). We need to either > make sure to not call such paths, or trylock everything. Really tricky. > > -* For the above locking troubles reasons it's pretty much impossible to > - attempt a synchronous modeset from panic handlers. The only thing we could > - try to achive is an atomic ``set_base`` of the primary plane, and hope that > - it shows up. Everything else probably needs to be delayed to some worker or > - something else which happens later on. Otherwise it just kills the box > - harder, prevent the panic from going out on e.g. netconsole. > - > -* There's also proposal for a simplied DRM console instead of the full-blown > - fbcon and DRM fbdev emulation. Any kind of panic handling tricks should > - obviously work for both console, in case we ever get kmslog merged. > +* A clean solution would be an entirely separate panic output support in KMS, > + bypassing the current fbcon support. See `[PATCH v2 0/3] drm: Add panic handling > + <https://lore.kernel.org/dri-devel/20190311174218.51899-1-noralf@tronnes.org/>`_. > Having these two links in the docs is very useful. Thanks a lot for adding that. Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Best regards,
diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 7bf7f2111696..283d35a500bd 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -475,8 +475,12 @@ This is a really varied tasks with lots of little bits and pieces: achieved by using an IPI to the local processor. * There's a massive confusion of different panic handlers. DRM fbdev emulation - helpers have one, but on top of that the fbcon code itself also has one. We - need to make sure that they stop fighting over each another. + helpers had their own (long removed), but on top of that the fbcon code itself + also has one. We need to make sure that they stop fighting over each another. + This is worked around by checking ``oops_in_progress`` at various entry points + into the DRM fbdev emulation helpers. A much cleaner approach here would be to + switch fbcon to the `threaded printk support + <https://lwn.net/Articles/800946/>`_. * ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and isn't a full solution for panic paths. We need to make sure that it only @@ -488,16 +492,9 @@ This is a really varied tasks with lots of little bits and pieces: even spinlocks (because NMI and hardirq can panic too). We need to either make sure to not call such paths, or trylock everything. Really tricky. -* For the above locking troubles reasons it's pretty much impossible to - attempt a synchronous modeset from panic handlers. The only thing we could - try to achive is an atomic ``set_base`` of the primary plane, and hope that - it shows up. Everything else probably needs to be delayed to some worker or - something else which happens later on. Otherwise it just kills the box - harder, prevent the panic from going out on e.g. netconsole. - -* There's also proposal for a simplied DRM console instead of the full-blown - fbcon and DRM fbdev emulation. Any kind of panic handling tricks should - obviously work for both console, in case we ever get kmslog merged. +* A clean solution would be an entirely separate panic output support in KMS, + bypassing the current fbcon support. See `[PATCH v2 0/3] drm: Add panic handling + <https://lore.kernel.org/dri-devel/20190311174218.51899-1-noralf@tronnes.org/>`_. Contact: Daniel Vetter
Some things changed, and add two useful links. Cc: Javier Martinez Canillas <javierm@redhat.com> Cc: Pekka Paalanen <ppaalanen@gmail.com> Cc: gpiccoli@igalia.com Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> --- Documentation/gpu/todo.rst | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-)