3 ms·

I wonder if there could be a X server implementation that ran fully on the GPU.

p_l 2y ago
Pure-CPU is side effect of XFree86 being essentially "lowest common denominator" platform (and even then some stuff was accelerated) - it comes from X.Org X11 releases being "base code" for vendors to built their own. For comparison, SGI used a wildly different architecture underneath, which heavily impacted performance - it's also why "xsgi" would default to indexed colour and you'd use 24bit/32bit visuals only for some windows - the server would use indexed colour visuals on the actual framebuffer to reduce memory bandwidth and composite everything together in hardware. It's also why there were "X11 Overlays" for GL - it meant you could easily implement parts of the GUI in X11 and still render on-top of direct-rendered visuals that bypassed X11.
- fulafel 2y ago
  Interesting! I wonder if there are any writeups around with more details on the SGI X architecture? But I was really thinking about going further with all or nearly all of the X server executing on the GPU with only cpu shims for input peripherals, networking etc.
  - p_l 2y ago
    The closest to this idea was less X11 and more the never actually fulfilled to my knowledge promise of NeXTDimension color board for NeXT Cube - which was supposed to implement the entire graphics stack on the embedded CPU. X11 could be implemented similarly - essentially sticking a complete standalone "X11 terminal" on an Add-In Card - the current GPU architectures aren't necessarily fitting for implementing it directly, but combine essentially an embedded OS running on extra CPU handling the protocol interactions and I/O then use a possibly more tailored interface to talk to GPU (compare with AMD's promise of HSA, or Xbox post 360 or PS4/PS5 architectures where GPU and CPU are on common memory). NeWS-style engine (possibly with something simpler than full postscript) would work great with that, especially if you had properly shared interface libs on it.
    - fulafel 2y ago
      We could run a OS on current GPUs I think, hardware-wise. And we know from history that compilers can make up for various hardware shortcomings on OS support side. Eg multi-task scheduling and concurrency can be done at the compiler level.

p_l 2y ago

Pure-CPU is side effect of XFree86 being essentially "lowest common denominator" platform (and even then some stuff was accelerated) - it comes from X.Org X11 releases being "base code" for vendors to built their own. For comparison, SGI used a wildly different architecture underneath, which heavily impacted performance - it's also why "xsgi" would default to indexed colour and you'd use 24bit/32bit visuals only for some windows - the server would use indexed colour visuals on the actual framebuffer to reduce memory bandwidth and composite everything together in hardware. It's also why there were "X11 Overlays" for GL - it meant you could easily implement parts of the GUI in X11 and still render on-top of direct-rendered visuals that bypassed X11.

fulafel 2y ago
Interesting! I wonder if there are any writeups around with more details on the SGI X architecture? But I was really thinking about going further with all or nearly all of the X server executing on the GPU with only cpu shims for input peripherals, networking etc.
- p_l 2y ago
  The closest to this idea was less X11 and more the never actually fulfilled to my knowledge promise of NeXTDimension color board for NeXT Cube - which was supposed to implement the entire graphics stack on the embedded CPU. X11 could be implemented similarly - essentially sticking a complete standalone "X11 terminal" on an Add-In Card - the current GPU architectures aren't necessarily fitting for implementing it directly, but combine essentially an embedded OS running on extra CPU handling the protocol interactions and I/O then use a possibly more tailored interface to talk to GPU (compare with AMD's promise of HSA, or Xbox post 360 or PS4/PS5 architectures where GPU and CPU are on common memory). NeWS-style engine (possibly with something simpler than full postscript) would work great with that, especially if you had properly shared interface libs on it.
  - fulafel 2y ago
    We could run a OS on current GPUs I think, hardware-wise. And we know from history that compilers can make up for various hardware shortcomings on OS support side. Eg multi-task scheduling and concurrency can be done at the compiler level.