[TUHS] Re: Origins of the frame buffer device

Thanks for this. My question was unclear: I wasn't thinking of the hardware, but of the software abstraction, i.e. the device files living in /dev I’ve now read through SunOS man pages and it would seem that the /dev/fb file was indeed similar to /dev/fbdev on Linux 15 years later. Not quite the same though, as initially it seems to have been tied to the kernel part of the SunWindows software. My understanding of the latter is still limited though. The later Linux usage is designed around mmap() and I am not sure when that arrived in SunOS (the mmap call exists in the manpages of 4.2BSD, but was not implemented at that time). Maybe at the time of the Sun-1 and Sun-2 it worked differently. The frame buffer hardware is exposed differently in Plan9. Here there are device files (initially /dev/bit/screen and /dev/bit/bitblt) but these are not designed around mmap(), which does not exist on Plan9 by design. It later develops into the /dev/draw/... files. However, my understanding of graphics in Plan9 is also still limited. All in all, finding a conceptually clean but still performant way to expose the frame buffer (and acceleration) hardware seems to have been a hard problem. Arguably it still is.