在 2026-02-26四的 17:01 +0100，Thomas Zimmermann写道： > Hi > > Am 26.02.26 um 07:37 schrieb Icenowy Zheng: > > Although the current DRM_IOCTL_MODE_CREATE_DUMB interface design > > only > > suits linear buffers, some KMS drivers abuse it for AFBC > > framebuffers. > > > > Mention it in the interface document, and clarifying that it's not > > recommended. > > > > Signed-off-by: Icenowy Zheng <[email protected]> > > --- > > include/uapi/drm/drm_mode.h | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/include/uapi/drm/drm_mode.h > > b/include/uapi/drm/drm_mode.h > > index cbbbfc1dfe2b8..02b6fa7ade355 100644 > > --- a/include/uapi/drm/drm_mode.h > > +++ b/include/uapi/drm/drm_mode.h > > @@ -1256,6 +1256,10 @@ struct drm_mode_crtc_page_flip_target { > > Since you're at it, you should move the line at [1] right here as the > first sentence of this paragraph. Then continue with 'Do not > attempt'. > > With that change, the previous paragraphs refer to pixel formats and > the > final one refers to framebuffer layout. > > > > * Do not attempt to allocate anything but linear framebuffer > > memory > > * with single-plane RGB data. Allocation of other framebuffer > > * layouts requires dedicated ioctls in the respective DRM > > driver. > > + * There exists drivers exploiting this interface for framebuffers > > 'exists user-space software'
Ah the drivers seem to be also criminal to accept this kind of usage, it's why I thought about writing "drivers" here. Thanks Icenowy > > > + * with modifiers other than DRM_FORMAT_MOD_LINEAR, but this is > > Rather 'with non-linear layout'. The reference to MOD_LINEAR seems > out > of place here. > > > + * incorrect usage with undefined behavior, and should not be > > + * replicated. > > Best regards > Thomas > > [1] > https://elixir.bootlin.com/linux/v6.19/source/include/uapi/drm/drm_mode.h#L1216 > > > */ > > struct drm_mode_create_dumb { > > __u32 height;
