Re: port-sparc64/52060: ifb driver for Sun XVR-1200

[Michael <macallan%netbsd.org@localhost>]

The following reply was made to PR port-sparc64/52060; it has been noted by GNATS.

From: Michael <macallan%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-sparc64/52060: ifb driver for Sun XVR-1200
Date: Sat, 11 Mar 2017 12:11:47 -0500

 There is no Xorg driver for the XVR-1200 or any other wildcat-based
 cards, not in NetBSD or anywhere else that I'm aware of. It wouldn't be
 too hard to write one though, we have limited documentation for at
 least a few chips.
 The problem is that we get the hardware in a rather weird state - two
 framebuffers and a control plane which ( likely among other things )
 selects which pixel's colour info is taken from what framebuffer. This
 control plane contains garbage and we don't know how to access it. 
 Currently the kernel's wcfb driver works around this by writing into
 both framebuffers.
 An Xorg driver would either need to use a shadow framebuffer with a
 specialized update routine that writes both framebuffers ( not hard to
 do, I did something similar for the mgx board ) or, on boards where we
 know how to use the blitter, one could write a simple exa driver with
 an UploadToScreen() method that takes care of this.
 
 have fun
 Michael