GENFB(4) Device Drivers Manual GENFB(4)

genfb
generic framebuffer console driver

genfb* at pci?
genfb* at sbus?
genfb* at intvid? (mac68k)
genfb* at macvid? (mac68k)
wsdisplay* at genfb?

The genfb driver provides support for generic framebuffers that have no native driver. All it needs are some parameters to describe the framebuffer and an address.

When attaching to a pci(4) bus the driver is configured via device properties:
(uint32)
Width in pixels.
(uint32)
Height in pixels.
(uint32)
Line size in bytes.
(uint32)
Bits per pixel.
(bool)
If true, genfb will try to become the system console.
(uint32)
Bus address of the framebuffer.

When attaching to sbus(4) all those parameters are retrieved from the firmware.

All those parameters are configured with Mac OS, and retrieved from the boot loader.

mac68k/intro(4), pci(4), sbus(4), wscons(4), wsdisplay(4)

There is no way to change the color map even when the firmware supports it. The pci(4) bus frontend has only been tested on macppc, i386, and amd64 and requires machine dependent code to pass the properties mentioned above. So far only macppc, i386, and amd64 provides them.
July 26, 2019 NetBSD 9.4