On 2019-03-11 6:42 p.m., Noralf Trønnes wrote:
This adds support for outputting kernel messages on panic(). A kernel message dumper is used to dump the log. The dumper iterates over each DRM device and it's crtc's to find suitable framebuffers.
All the other dumpers are run before this one except mtdoops. Only atomic drivers are supported.
Signed-off-by: Noralf Trønnes noralf@tronnes.org
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diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h index f0b34c977ec5..f3274798ecfe 100644 --- a/include/drm/drm_framebuffer.h +++ b/include/drm/drm_framebuffer.h @@ -94,6 +94,44 @@ struct drm_framebuffer_funcs { struct drm_file *file_priv, unsigned flags, unsigned color, struct drm_clip_rect *clips, unsigned num_clips);
- /**
* @panic_vmap:** Optional callback for panic handling.** For vmapping the selected framebuffer in a panic context. Must* be super careful about locking (only trylocking allowed).** RETURNS:** NULL if it didn't work out, otherwise an opaque cookie which is* passed to @panic_draw_xy. It can be anything: vmap area, structure* with more details, just a few flags, ...*/- void *(*panic_vmap)(struct drm_framebuffer *fb);
FWIW, the panic_vmap hook cannot work in general with the amdgpu/radeon drivers:
Framebuffers are normally tiled, writing to them with the CPU results in garbled output.
With a discrete GPU having a large amount of VRAM, the framebuffer may not be directly CPU accessible at all.
There would need to be a mechanism for switching scanout to a linear, CPU accessible framebuffer.