On 07/10/2023 14:38, Noralf Trønnes wrote:
On 10/3/23 16:22, Jocelyn Falempe wrote:
This module displays a user friendly message when a kernel panic
occurs. It currently doesn't contain any debug information,
but that can be added later.
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)
v3
* Rework the drawing functions, to write the pixels line by line and
to use the drm conversion helper to support other formats.
(Thomas Zimmermann)
v4
* Use drm_fb_r1_to_32bit for fonts (Thomas Zimmermann)
* Remove the default y to DRM_PANIC config option (Thomas Zimmermann)
* Add foreground/background color config option
* Fix the bottom lines not painted if the framebuffer height
is not a multiple of the font height.
* Automatically register the device to drm_panic, if the function
get_scanout_buffer exists. (Thomas Zimmermann)
Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 22 ++
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/drm_drv.c | 8 +
drivers/gpu/drm/drm_panic.c | 413 ++++++++++++++++++++++++++++++++++++
include/drm/drm_drv.h | 14 ++
include/drm/drm_panic.h | 41 ++++
6 files changed, 499 insertions(+)
create mode 100644 drivers/gpu/drm/drm_panic.c
create mode 100644 include/drm/drm_panic.h
diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
new file mode 100644
+static void draw_panic_device(struct drm_device *dev, const char *msg)
+{
+ struct drm_scanout_buffer sb;
+
+ if (dev->driver->get_scanout_buffer(dev, &sb))
+ return;
+ if (!drm_panic_line_buf)
+ return;
+
Unless something has changed since 2019 we need to make sure fbcon
hasn't already printed the panic to avoid jumbled output. See [1] for
more info.
I think DRM_PANIC and fbcon are incompatible, so in Kconfig I prevent
them to be built together:
config DRM_PANIC
bool "Display a user-friendly message when a kernel panic occurs"
depends on DRM && !FRAMEBUFFER_CONSOLE
So DRM_PANIC should be used with a userspace console, either kmscon, or
some lightweight terminal emulator/wayland compositor, like cage/foot.
As fbcon has lost scrolling support, it's time to switch to something
better. [1]
--
Jocelyn
[1]
https://www.reddit.com/r/linux/comments/10eccv9/config_vtn_in_2023/
Noralf.
[1]
https://lore.kernel.org/dri-devel/20190312095320.GX2665@phenom.ffwll.local/
+ /* to avoid buffer overflow on drm_panic_line_buf */
+ if (sb.width > DRM_PANIC_MAX_WIDTH)
+ sb.width = DRM_PANIC_MAX_WIDTH;
+
+ draw_panic_static(&sb, msg);
+}
