>Number:         13117
>Category:       kern
>Synopsis:       cursor off is not always cursor off
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 05 12:34:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Onno van der Linden
>Release:        <NetBSD-current source date> 21-May-2001
>Organization:
	
>Environment:
	
System: NetBSD sheep 1.5V NetBSD 1.5V (SHEEP) #6: Tue Jun 5 14:39:33 MEST 2001 onno@sheep:/usr/src/sys/arch/i386/compile/SHEEP i386
Architecture: i386
Machine: i386
>Description:
This bug only is visible in kernels *without* the PCDISPLAY_SOFTCURSOR option.
Although a userland program (e.g. mutt) sets the cursor to off, the normally
absent blinking cursor appears. Not always, see below why.

>How-To-Repeat:
	repeat start mutt and quit. And after some time the cursor *will*
        appear.
>Fix:
	cursor off is currently done by setting it to a non-visible position.
pcdisplay_subr.c line 118 says: pos = 0x1010.
*BUT*, instead of a fix 4K display window, scrolling upwards is done by
manipulating the start of display offset in the 6845 register. It's
therefore possible with the right display offset to have a display window
in which position 0x1010 is between the start and end of the display.
The appended diff fixes this, unless someone implements a 128x64 tty
screen mode. (Maybe it should really be fixed by setting curend to
a smaller value than curbegin and use cursortmp from the pcdisplayscreen
structure to store curstart and curend, but that requires some more
modifications).

*** /sys/dev/ic/pcdisplay_subr.c.orig	Tue Jun  5 20:55:01 2001
--- /sys/dev/ic/pcdisplay_subr.c	Tue Jun  5 20:52:08 2001
***************
*** 115,121 ****
  
  	if (scr->active) {
  		if (!on)
! 			pos = 0x1010;
  		else
  			pos = scr->dispoffset / 2
  				+ row * scr->type->ncols + col;
--- 115,121 ----
  
  	if (scr->active) {
  		if (!on)
! 			pos = 0x3fff;
  		else
  			pos = scr->dispoffset / 2
  				+ row * scr->type->ncols + col;
>Release-Note:
>Audit-Trail:
>Unformatted: