LinuxCon Brazil: Q&A with Linus and Andrew
Posted Sep 2, 2010 14:04 UTC (Thu) by michaeljt
In reply to: LinuxCon Brazil: Q&A with Linus and Andrew
Parent article: LinuxCon Brazil: Q&A with Linus and Andrew
> The DRM stuff that's in kernel space is hardware-bashing mode-setting and memory-management stuff. So we have hardware-bashing, arbitration among many processes and security (because the video card has access to all of memory and can be told to do stuff to it). Seems like stuff that belongs in the kernel to me.
It is particularly the arbitration between processes that I am thinking of. As far as I know, the main reason that indirect rendering is significantly slower than direct rendering is due to the need to pass large structures through, mainly textures and arrays of vertices. So to me it would make sense for direct rendering to work mostly like indirect rendering, except for additional mechanisms - say mechanisms based on shared memory in some way, like giving the process with actual access to the video card device a means to selectively share portions of video RAM - for passing those data structures more efficiently. This would also remove the need for memory management of video RAM in the kernel, as it could be done by the process managing the rendering - i.e. the X server - which mapped the VRAM.
As usual, feel free to point out why this would never work, I am always happy to learn something new.
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