powerpc/131548: ofw_syscons no longer supports 32-bit framebuffer

[Justin Hibbits]

>Number:         131548
>Category:       powerpc
>Synopsis:       ofw_syscons no longer supports 32-bit framebuffer
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-ppc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Feb 10 03:20:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Justin Hibbits
>Release:        8.0-CURRENT
>Organization:
>Environment:
FreeBSD narn.knownspace 8.0-CURRENT FreeBSD 8.0-CURRENT #2 r188149M: Mon Feb  9 18:45:09 EST 2009     root at narn.knownspace:/usr/obj/usr/src/sys/NARN  powerpc

>Description:
The change made in r186055 forces a display reset, which causes OpenFirmware to reset the display controller to boot-time settings.  Unfortunately, with a 32-bit color depth, OpenFirmware resets the display to 8-bit, causing the ofw_syscons code to draw 4 physical pixels for one logical pixel.  This causes lines to wrap, and also causes text to wrap below the visible screen.  Another bug, discussed on the ppc@ mailing list, is shown by this, as the system hangs very shortly after bootup, possibly due to memory corruption by overlapping pages in the video buffer and RAM.
>How-To-Repeat:
Add:

dev screen 32 set-depth

To sys/boot/powerpc/boot1.chrp/bootinfo.txt, or run at the OFW prompt.  ATI cards only (tested with Radeon 9600pro)
>Fix:
OpenBSD's console code might have something helpful.

>Release-Note:
>Audit-Trail:
>Unformatted: