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.
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);
> +}
