X and Modesetting: Atrophy illustrated. Modesetting is ... Getting - - PowerPoint PPT Presentation

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Jun 13, 2023 168 likes •255 views

X and Modesetting: Atrophy illustrated. Modesetting is ... Getting pixels on a screen. Modesetting is ... Boring. Hard. Slow. Requires a lot of hardware to do properly. Tseng ET4000W32p: DAC bus (8bit) R/W Clock Select

SLIDE 1

X and Modesetting: Atrophy illustrated.

SLIDE 2

Modesetting is ... Getting pixels on a “screen”.

SLIDE 3

Modesetting is ...

Boring.
Hard.
Slow.
Requires a lot of hardware to do properly.

SLIDE 4

Tseng ET4000W32p:

CRTC DAC

Pixel Bus (8/16bit) Blank

CRT CRT

Clock Select R/W DAC bus (8bit) HSync/VSync RGB

SLIDE 5

Unichrome:

CRTC1 CRTC2 Panel Scaler DAC CRT TTL Panel External Encoder External Encoder

SLIDE 6

Encoder

External encoder

Pixel Bus H/VSync I²C Blank / Data Enable

“Screen”

SLIDE 7

Enemy: VBE

Extension of IBMs VGA BIOS:

Selfmodifying binary.
Always loaded at 0xC0000
Hooked into interrupt vector table (int10)

VBE:

1991: v1.2
meant to get past VGA limitations, forgood.
meant to alleviate the burden of modesetting on complex

hardware.

SLIDE 8

Modesetting for 7.1:

cvt (committed)
bug #5386: Getting a mode without a Modes directive.
cvts xf86CVTMode() -> common/xf86cvt.c (attached).
xf86SetDDCproperties becomes useful (attached).
adjust drivers to new xf86SetDDCproperties (todo / trivial).
filter resulting modeslist based on type. (todo / discuss / pending).
multiple ClockRanges:
tseng fixup (committed).
xf86mode.c cleanup (pending).
non-programmable dotclocks:
trident fixup (test).
c&t fixup (redo).
vga fixup (todo / discuss).
atimisc fixup (scared).
xf86mode.c cleanup (pending).