ASpeed DRM Driver Adding DMA-BUF/PRIME Sharing For Use With Servers Having dGPUs

[phoronix]

Phoronix: ASpeed DRM Driver Adding DMA-BUF/PRIME Sharing For Use With Servers Having dGPUs

The ASpeed "AST" DRM driver that is for use with ASpeed BMCs on server platforms for display capabilities is preparing to see DMA-BUF and PRIME sharing support. This is useful so the ASpeed BMC can see the screen contents even if the server is relying on a discrete GPU rather than the baseboard management controller's monitor output...

https://www.phoronix.com/news/AST-DMA-BUF-PRIME-Sharing

[illwieckz]

Excellent, Threradripper PRO motherboards usually features this kind of ASpeed graphic chip.

Does that mean that:

1. We would be able to plug secondary screens using the motherboard video port while displaying on a discrete card?
2. We would be able to see the a screen rendered by a discrete card using the motherboard web interface?

[binarybanana]

Does that mean that:[*]We would be able to plug secondary screens using the motherboard video port while displaying on a discrete card?

To me it looks like it (only) allows importing buffers into the ast side, i.e. using dGPU to render and ast for output. That means if you use ast as primary GPU you won't be able to use the dGPU outputs at all, but you can use it to render. If you use the dGPU as primary GPU you'll be able to use both's outputs or just ast's if you like. At least on Xorg. Wayland compositors might be more flexible. Note that this has nothing to do with which GPU is used for booting. The boot GPU doesn't have to be the "primary" one as far as Xorg is concerned.

We would be able to see the a screen rendered by a discrete card using the motherboard web interface?[/LIST]

Maybe once the system is booted up, but I'm not sure how those interfaces grab the output. If it copies whatetever ast is currently scanning out it should work because the code copies the imported framebuffer which might let the webui see it. Same if there is some special handling in the driver that explicitly uploads new frames. But I'm just speculating. I'm a pleb using cheap consumer hardware.

[DanaG]

Hallelujah, I've been wanting this feature for one of my machines, so I can actually use ASPEED+AMD and have the machine be usable!
Currently, it tends to do one of the following:

• fail to show the login window content
• break Wayland sessions
• crash the desktop environment
• require logging out completely to switch from remotely viewed AST to a display connected to the AMD GPU

[intelfx]

Typos:

The intention with it is all about offloading of reendering in one direction and outputss in the other.