Create DRM drivers for VESA and EFI framebuffers
a project by tdz
Updated about 24 hours ago. 3 hacker ♥️. 2 followers.

Description

We already have simpledrm for firmware framebuffers. But the driver is originally for ARM boards, not PCs. It is already overloaded with code to support both use cases. At the same time it is missing possible features for VESA and EFI, such as palette modes or EDID support. We should have DRM drivers for VESA and EFI interfaces. The infrastructure exists already and initial drivers can be forked from simpledrm.

Goals

  • Initially, a bare driver for VESA or EFI should be created. It can take functionality from simpledrm.
  • Then we can begin to add additional features. The boot loader can provide EDID data. With VGA hardware, VESA can support paletted modes or color management. Example code exists in vesafb.

Join this project

Looking for hackers with the skills:

graphics drivers kernel drm grub2

This project is part of:

Hack Week 24

Activity

  • about 23 hours ago: tdz added keyword "graphics" to this project.
  • about 23 hours ago: tdz added keyword "drivers" to this project.
  • about 23 hours ago: tdz added keyword "kernel" to this project.
  • about 23 hours ago: tdz added keyword "drm" to this project.
  • about 23 hours ago: tdz added keyword "grub2" to this project.
  • 1 day ago: michals liked this project.
  • 1 day ago: llansky3 liked this project.
  • 1 day ago: tdz liked this project.
  • 1 day ago: tdz started this project.
  • 1 day ago: tdz originated this project.


    • Comments

    • tdz
      1 day ago by tdz | Reply

      Day 1: I forked of simpledrm into a new vesadrm driver. This immediately works well on non-EFI PC hardware. I further added support for EDID information. This data has to be provided by the boot loader. There's already a field in Linux's boot parameters. It is not set by grub. So a patch there seems required.

      See: https://gitlab.suse.de/tzimmermann/linux/-/commits/vesadrm-day1

    • tdz
      about 17 hours ago by tdz | Reply

      Day 2: With vesadrm in place and the EDID property attached, it was time to fill it with data. As mentioned, there's already such a field in the kernel's boot params on x86. It has never been used; or at least i could not find any related code in grub2, grub(-legacy) or even LiLo.

      But grub2 already reads out the EDID for its graphics backends. And all we have to do is to copy is to the Linux boot parameters. We cannot transfer EDID extension headers, so we have to clear the extension field. Still, the result is EDID data for the firmware drivers. A patch for grub2 is on OBS at https://build.opensuse.org/package/show/home:tdz:branches:Base:System/grub2.

      Here's a screenshot of my test system's GNOME, where it correctly names the monitor from the provided data.

      This was on Wayland. I also have a patch pending for Xorg, so that it accepts vesadrm as driver.

      Overall, this project is going nicely and I'm very happy with the progress being made.

      See: https://gitlab.suse.de/tzimmermann/linux/-/commits/vesadrm-day2

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