3 ms·

>More AMDGPU DRM driver DRM is a really unfortunate acronym here. It took me a while to figure out it refers to direct rendering manager.

xtf 10y ago
Direct Rendering Mode, yes
- cm3 10y ago
  And before that DRI back when we used to build our own X11 from CVS.
Unklejoe 10y ago
On a related note, I have a hard time understanding the layout of the Linux graphics stack as a whole. You have MESA, DRM, DAL, Gallium3D, etc... All these acronyms and systems that somehow relate to eachother. It seems like there are many layers, and there aren't many good references that really explain it "from the beginning".
- claudius 10y ago
  The wikipedia page at https://en.wikipedia.org/wiki/Free_and_open-source_graphics_device_driver https://en.wikipedia.org/wiki/Free_and_open-source_graphics_... has some somewhat helpful graphics at least explaining the relative abstraction levels of the different entities.
- exDM69 10y ago
  Here's a good writeup from a few years ago about the Linux graphics stack internals: http://blog.mecheye.net/2012/06/the-linux-graphics-stack/ http://blog.mecheye.net/2012/06/the-linux-graphics-stack/
- mlvljr 10y ago
  You are not alone (and above writeups don't help much many of us, sadly). The implementation-and-mailing-lists-are-documentation practice bites badly :)
- ZenoArrow 10y ago
  The collective name is DRI (Direct Rendering Infrastructure), perhaps this Wikipedia page will help? https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructure https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructur... I think the basic way to understand it all is that the decision was made to pull more of the graphics stack into the Linux kernel, and this has enabled thinner abstractions to be built on top for various purposes. For example, Wayland makes use of the underlying DRI infrastructure.
  - cm3 10y ago
    I've been wondering how Wayland actually works underneath. Seeing how Wayland window managers usually have a drawing layer that among others have a specific backend for Intel, I scratched my head wondering if people have to reinvent/reimplement parts of what xf86-video-intel provides in Xorg. Any insight?
    - ZenoArrow 10y ago
      I'm not an expert, but here's how I see it... There are different ways to create GPU drivers for Linux. In order to make use of DRI, the GPU has to have a DRM driver. This DRM driver is specific to the GPU hardware. The DRM is the interface that software can work with to make calls to the GPU. You could think of DRM as a way to have a standard interface for GPU calls, so other software will speak to this DRM layer, but the DRM driver will speak to the hardware, which is why the DRM driver needs to be device specific. The DRM driver is the part of the GPU driver that sits in the kernel, there will also be a userland part of the GPU driver. I believe the part of the driver that gets used will depend on what the software is targetting. Wayland will target the kernel side, but games would work with the userland side. These images from Wikipedia may help visualise what DRM is doing. Without DRM: https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/media/File:Access_to_video_card_without_DRM.svg https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/medi... With DRM: https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/media/File:High_level_Overview_of_DRM.svg https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/medi... As a side note, it's possible for GPU vendors to create more generic GPU drivers by using Gallium3D. This also creates drivers that work with DRI, but GPU drivers don't need to use Gallium3D to use DRI. I would suggest thinking of Gallium3D as a set of reusable GPU driver components, you could code a driver using these reusable components, or you could code something bespoke. https://en.wikipedia.org/wiki/Gallium3D https://en.wikipedia.org/wiki/Gallium3D In terms of Wayland in particular, you may be interested in this: https://wayland.freedesktop.org/architecture.html https://wayland.freedesktop.org/architecture.html Does this help?
CiPHPerCoder 10y ago
That acronym misled me too: "DRM? In Linux? :("

xtf 10y ago

Direct Rendering Mode, yes

cm3 10y ago
And before that DRI back when we used to build our own X11 from CVS.

Unklejoe 10y ago

On a related note, I have a hard time understanding the layout of the Linux graphics stack as a whole. You have MESA, DRM, DAL, Gallium3D, etc... All these acronyms and systems that somehow relate to eachother. It seems like there are many layers, and there aren't many good references that really explain it "from the beginning".

claudius 10y ago
The wikipedia page at https://en.wikipedia.org/wiki/Free_and_open-source_graphics_device_driver https://en.wikipedia.org/wiki/Free_and_open-source_graphics_... has some somewhat helpful graphics at least explaining the relative abstraction levels of the different entities.
exDM69 10y ago
Here's a good writeup from a few years ago about the Linux graphics stack internals: http://blog.mecheye.net/2012/06/the-linux-graphics-stack/ http://blog.mecheye.net/2012/06/the-linux-graphics-stack/
mlvljr 10y ago
You are not alone (and above writeups don't help much many of us, sadly). The implementation-and-mailing-lists-are-documentation practice bites badly :)
ZenoArrow 10y ago
The collective name is DRI (Direct Rendering Infrastructure), perhaps this Wikipedia page will help? https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructure https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructur... I think the basic way to understand it all is that the decision was made to pull more of the graphics stack into the Linux kernel, and this has enabled thinner abstractions to be built on top for various purposes. For example, Wayland makes use of the underlying DRI infrastructure.
- cm3 10y ago
  I've been wondering how Wayland actually works underneath. Seeing how Wayland window managers usually have a drawing layer that among others have a specific backend for Intel, I scratched my head wondering if people have to reinvent/reimplement parts of what xf86-video-intel provides in Xorg. Any insight?
  - ZenoArrow 10y ago
    I'm not an expert, but here's how I see it... There are different ways to create GPU drivers for Linux. In order to make use of DRI, the GPU has to have a DRM driver. This DRM driver is specific to the GPU hardware. The DRM is the interface that software can work with to make calls to the GPU. You could think of DRM as a way to have a standard interface for GPU calls, so other software will speak to this DRM layer, but the DRM driver will speak to the hardware, which is why the DRM driver needs to be device specific. The DRM driver is the part of the GPU driver that sits in the kernel, there will also be a userland part of the GPU driver. I believe the part of the driver that gets used will depend on what the software is targetting. Wayland will target the kernel side, but games would work with the userland side. These images from Wikipedia may help visualise what DRM is doing. Without DRM: https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/media/File:Access_to_video_card_without_DRM.svg https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/medi... With DRM: https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/media/File:High_level_Overview_of_DRM.svg https://en.wikipedia.org/wiki/Direct_Rendering_Manager#/medi... As a side note, it's possible for GPU vendors to create more generic GPU drivers by using Gallium3D. This also creates drivers that work with DRI, but GPU drivers don't need to use Gallium3D to use DRI. I would suggest thinking of Gallium3D as a set of reusable GPU driver components, you could code a driver using these reusable components, or you could code something bespoke. https://en.wikipedia.org/wiki/Gallium3D https://en.wikipedia.org/wiki/Gallium3D In terms of Wayland in particular, you may be interested in this: https://wayland.freedesktop.org/architecture.html https://wayland.freedesktop.org/architecture.html Does this help?

CiPHPerCoder 10y ago

That acronym misled me too: "DRM? In Linux? :("