From: Jan Kneschke <Jan.Kneschke@kiel.netsurf.de>
  To  : ggi-develop@eskimo.com
  Date: Sun, 2 Aug 1998 01:13:55 +0200 (MEST)

bughunting II

here is my next attempt to trigger as much bugs as possible. (this isn't
planned it just happens .) )

this time i go into the kernel (my first oops-tracking). i tried to get one
driver running in the kgicon-enviroment. virge-gx or vision-968. everytime i
get an oops in fbcon_open.

here is the tracked code-line: driver/video/fbcon.c:416:

    if (!fontwidthvalid(p,p->fontwidth)) {

this means

if (!(p->dispsw->fontwidthmask & (1 << ((p->fontwidth) - 1)))) {

after some translating to c i found out that p->dispsw is ZERO. 
yeah. this has cost me one hour to find out, but i did it. :)

next question: why is p->dispsw == NULL ??

here is some text from fbcon.c:115

/*
 * Emmanuel: fbcon will now use a hardware cursor if the
 * low-level driver provides a non-NULL dispsw->cursor pointer,
 * in which case the hardware should do blinking, etc.
 *
 * if dispsw->cursor is NULL, use Atari alike software cursor
 */

dispsw is set in fbcon-kgi.c:977-1019. if someone looks here he will see
that 

# CONFIG_FBCON_CFB2 is not set
# CONFIG_FBCON_CFB4 is not set
CONFIG_FBCON_CFB8=y
CONFIG_FBCON_CFB16=y
# CONFIG_FBCON_CFB24 is not set
CONFIG_FBCON_CFB32=y

should have been set.

solution:
1. write a HOWTO-kgicon
2. think about this bug.

two great hours bughunting are finished now.

thats all
  Jan

--- 
       Project: GGI - S3-Vision-driver -- http://www.ggi-project.org/
         -)=  Jan (Weigon) Kneschke -- Kiel -- Northern Germany =(-