Day 2: Conferences: The Linux Frame Buffer Device Subsystem



Geert Uytterhoeven ported the frame buffer abstraction to the Amiga back in 1994 and then did more work like porting all this in the main linux source tree, merge that finally happened in 2.1.107

[picture]

[picture] While you can view his slides (you can find them in the middle of picture gallery and you can get the postscript version from Geert's web site), here are a few highlights from his talk:
  • In 1993 the need first came up with the initial port to linux/68k and that's when the frame buffer device was first written. Later, the same need came up on other architectures linux was ported to, and which didn't have a text mode.
  • Some video cards on PC now don't support textmode, or some don't even support VGA on PCs (like the Cyrix MediaGX)
  • They have to use a trick to get output at the beginning of the boot process because they can't display anything before the PCI bus is initialized, but they have to display messages earlier than that. The trick is to write in a dummy console and copy the result back to the virtual console once the card has been initialized
  • The little endian/big endian issues can be a pain when you have to swap bytes around on a big endian machine with a little endian only PCI board (some video cards support both BE and LE, but unfortunately others don't)
  • While there have been some disagreements with the GGI folks, they were credited for their work which helped a lot for the frame buffer code on Intel.



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99/05/23 (15:37): Version 1.0
99/05/26 (09:02): Version 1.1. Added link to Geert's slides on his web page
99/05/26 (18:44): Version 1.2. Fixed typo