DRM Text Mode Proposed As Alternative To FBDEV/FBCON

Written by Michael Larabel in Linux Kernel on 29 July 2016 at 08:56 AM EDT. Add A Comment
There's long been talk on killing FBDEV and getting rid of CONFIG_VT with a modern replacement making more use of DRM/KMS drivers, but so far none of those efforts have fully panned out. The latest proposal is a "DRM text mode" as an alternative to FBDEV/FBCON.

Noralf Trønnes published a set of patches on Thursday experimenting with a DRM text mode. It's designed as an interim solution for VT console support while waiting for a suitable user-space consome, like the stalled KMSCON that for a short time lived within systemd.

Trønnes explained, "The idea is that the driver provides a modeset like with the fbdev emulation code, and from this a text buffer representation is made. The console code can now write to this text buffer and ask for the text buffer to be flushed/rendered to the pixel buffer. In this hack/implementation of the idea, I have just hijacked a CMA backed fbdev framebuffer to keep it simple. I have reused the default buffer format that VT uses."

This DRM text mode currently amounts to just over one thousand lines of code.

Daniel Vetter, Intel's DRM driver maintainer, so far commented, "I guess some simpler drm console with vt support which would allow us to get rid of fbdev could make sense. And there's definitely going to be a lot of overlap with a full userspace solution using something like kmscon." But Daniel noted that much more prep work is needed from getting SimpleDRM in better shape and merged plus solving some other logistics around restructuring the VT code and getting the older frame-buffer code on its way out the door.

Hopefully something will be able to come of this in the not too distant future.
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