[RFC][PATCH v2 0/2] drm/panic: Add a drm panic handler
Noralf Trønnes
noralf at tronnes.org
Mon Sep 18 23:19:19 UTC 2023
Hi,
On 9/15/23 10:28, Jocelyn Falempe wrote:
> This introduces a new drm panic handler, which displays a message when a panic occurs.
> So when fbcon is disabled, you can still see a kernel panic.
>
> This is one of the missing feature, when disabling VT/fbcon in the kernel:
> https://www.reddit.com/r/linux/comments/10eccv9/config_vtn_in_2023/
> Fbcon can be replaced by a userspace kms console, but the panic screen must be done in the kernel.
>
> This is a proof of concept, and works only with simpledrm, using a new get_scanout_buffer() api
>
There's a panic handling entry in Documentation/gpu/todo.rst pointing to
some work done in this area.
Noralf.
> To test it, make sure you're using the simpledrm driver, and trigger a panic:
> echo c > /proc/sysrq-trigger
>
> v2
> * Use get_scanout_buffer() instead of the drm client API. (Thomas Zimmermann)
> * Add the panic reason to the panic message (Nerdopolis)
> * Add an exclamation mark (Nerdopolis)
>
> I didn't reuse the fbdev functions yet, that would need some fbdev refactoring, because they rely on struct fb_info, and struct vc_data (for font/console). But I still plan to at least try it for v3.
>
> A few more though:
> 1) what about gpu with multiple monitor connected ?
> maybe get_scanout_buffer() could return a list of scanout buffers ?
> 2) I think for some GPU drivers, there might need a flush_scanout_buffer() function, that should be called after the scanout buffer has been filled ?
>
> Best regards,
>
> Jocelyn Falempe (2):
> drm/panic: Add a drm panic handler
> drm/simpledrm: Add drm_panic support
>
> drivers/gpu/drm/Kconfig | 11 ++
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/drm_drv.c | 3 +
> drivers/gpu/drm/drm_panic.c | 270 +++++++++++++++++++++++++++++++
> drivers/gpu/drm/tiny/simpledrm.c | 17 ++
> include/drm/drm_drv.h | 14 ++
> include/drm/drm_panic.h | 41 +++++
> 7 files changed, 357 insertions(+)
> create mode 100644 drivers/gpu/drm/drm_panic.c
> create mode 100644 include/drm/drm_panic.h
>
>
> base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
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