Comment by captainmuon
3 years ago
Does graphics on Linux work by loading the driver into your process? I assumed it works via writing a protocol to shared memory in case of Wayland, or over a socket (or some byzantine shared memory stuff that is only defined in the Xorg source) in case of X11.
From my experience, if you have the kernel headers and have all the required options compiled into your kernel, then you can go really far back and build a modern glibc and Gtk+ Stack, and use a modern application on an old system. If you do some tricks with Rpath, everything is self-contained. I think it should work the other way around, with old apps on a new kernel + display server, as well.
So there are two parts to this: the app producing the image in the application window and then the windowing system combining multiple windows together to form the final image you see on screen.
The former gets done in process (using e.g. GL/vulkan) and then that final image gets passed onto the windowing system which is a separate process and could run outside the container.
As an aside, with accelerated graphics you mostly pass a file descriptor to the GPU memory containing the image, rather than mucking around with traditional shared memory.
Does graphics on Linux work by loading the driver into your process?
Yes, it's called Direct Rendering (DRI) and it allows apps to drive GPUs with as little overhead as possible. The output of the GPU goes into the shared memory so that the compositor can see it.