kern/48528: wsfb/genfb - display dramatically off center if GENFB_SHADOWFB is enabled

[nathanialsloss%yahoo.com.au@localhost]

>Number:         48528
>Category:       kern
>Synopsis:       wsfb/genfb - display dramatically off center if GENFB_SHADOWFB 
>is enabled
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jan 16 23:45:00 +0000 2014
>Originator:     Nat Sloss
>Release:        NetBSD 6.1.1
>Organization:
>Environment:
NetBSD beast 6.1.1_PATCH NetBSD 6.1.1_PATCH (SHADOWTEST) #6: Thu Jan 16 
18:39:48 EST 2014  
build@microrusty:/usr/src/sys/arch/i386/compile/obj/SHADOWTEST i386
>Description:
If "options GENFB_SHADOWFB" is built into the kernel and the computer is booted 
in a VESA mode then as soon as genfb attaches the screen text
is really off center.

If GENFB_SHADOWFB is not enabled then all is OK.

The problem seems to be that rasops_reconfig in genfb.c must be starting
with an offset in ri_bits, I have checked elements of the ri structure after 
rasops_reconfig and they seem OK.

I tried booting a current kernel (6.99.28) with GENFB_SHADOWFB enabled 
but it paniced as soon as genfb attached in rasops_erasecols.
>How-To-Repeat:
Refer to above.
>Fix:
I applied this patch as this is what is done in 
sys/arch/x86/x86/genfb_machdep.c:

Index: src/sys/dev/wsfb/genfb.c
===================================================================
RCS file: /cvsroot/src/sys/dev/wsfb/genfb.c,v
retrieving revision 1.51
diff -u -r1.51 genfb.c
--- src/sys/dev/wsfb/genfb.c    9 Oct 2013 17:20:54 -0000       1.51
+++ src/sys/dev/wsfb/genfb.c    16 Jan 2014 23:08:20 -0000
@@ -544,7 +544,7 @@
                ri->ri_flg |= RI_ENABLE_ALPHA | RI_8BIT_IS_RGB;
 
 
-       rasops_init(ri, 0, 0);
+       rasops_init(ri, sc->sc_height / 8, sc->sc_width / 8);
        ri->ri_caps = WSSCREEN_WSCOLORS;
 
        rasops_reconfig(ri, sc->sc_height / ri->ri_font->fontheight,

Regards,

Nat.