Bug 13764

>>Number:         13764
>>Category:       kern
>>Synopsis:       [PATCH] Stop syscons from flushing history buffer when changi
>ng video mode
[...]
>>Arrival-Date:   Wed Sep 15 11:00:01 PDT 1999
>>Closed-Date:
>>Last-Modified:
>>Originator:     Mark Ovens
>>Release:        FreeBSD 3.1-RELEASE i386
>>Organization:
>>Environment:
>
>	FreeBSD marder-1 3.1-RELEASE FreeBSD 3.1-RELEASE #33:
>	Wed Sep 15 18:12:58 BST 1999
>	mark@marder-1:/usr/src/sys/compile/MARDER-1  i386
>
>>Description:
>
>	When the console video mode is changed, with vidcontrol,
>	syscons free()s the current history buffer and malloc()s
>	a new one which means that the scroll-back buffer is lost.
>
>	This can be a problem if the video mode is set in /etc/rc.conf
>	(e.g. ``allscreens_flags="80x43"'') and a process which is started
>	from an rc* file fails to start as you cannot scroll back to look
>	at the error messages.

This has been brought up several times before.  I will work on
this.  Thank you.

Kazu

Comment 2 Sheldon Hearn 1999-09-16 09:13:23 UTC

Responsible Changed
From-To: freebsd-bugs->yokota

Over to Mr Syscons. 

>Submitter-Id:   current-users
>Originator:     Mark Ovens
>Organization:   
>Confidential:   no
>Synopsis:       [PATCH] Stop syscons from flushing history buffer when changing video mode
>Severity:       non-critical
>Priority:       low
>Category:       kern
>Release:        FreeBSD 3.1-RELEASE i386
>Class:          change-request
>Environment: 

	

>Description: 

	I just discovered a couple of careless yank and pastes in my code.
	It doesn't affect the logic, just redundant assignments.

	New diff below:

>How-To-Repeat: 

	

>Fix: 
	

*** syscons.c.orig	Wed Sep  8 18:42:25 1999
--- syscons.c	Fri Sep 17 17:33:53 1999
***************
*** 3320,3347 ****
  void
  sc_alloc_history_buffer(scr_stat *scp, int lines, int extra, int wait)
  {
!     u_short *usp;
  
!     if (lines < scp->ysize)
! 	lines = scp->ysize;
  
!     usp = scp->history;
!     scp->history = NULL;
!     if (usp != NULL) {
! 	free(usp, M_DEVBUF);
! 	if (extra > 0)
  	    extra_history_size += extra;
      }
  
      scp->history_size = lines * scp->xsize;
      if (lines > imax(sc_history_size, scp->ysize))
  	extra_history_size -= lines - imax(sc_history_size, scp->ysize);
!     usp = (u_short *)malloc(scp->history_size * sizeof(u_short), 
  			    M_DEVBUF, (wait) ? M_WAITOK : M_NOWAIT);
!     if (usp != NULL)
! 	bzero(usp, scp->history_size * sizeof(u_short));
!     scp->history_head = scp->history_pos = usp;
!     scp->history = usp;
  }
  
  static scr_stat
--- 3320,3380 ----
  void
  sc_alloc_history_buffer(scr_stat *scp, int lines, int extra, int wait)
  {
!     u_short *new, *old;
!     u_short head_offset = 0, pos_offset = 0;
!     int i, j;
!     int old_size = 0;
  
!     old = NULL;
! 
!     if (scp->history != NULL) {
! 
! 	/* Save pointer offsets and size of the old buffer */
  
!     	head_offset = scp->history_head - scp->history;
!     	pos_offset = scp->history_pos - scp->history;
!     	old_size = scp->history_size;
!     	if (extra > 0)
  	    extra_history_size += extra;
      }
  
+     if (lines < scp->ysize)
+ 	lines = scp->ysize;
+ 
      scp->history_size = lines * scp->xsize;
      if (lines > imax(sc_history_size, scp->ysize))
  	extra_history_size -= lines - imax(sc_history_size, scp->ysize);
!     new = (u_short *)malloc(scp->history_size * sizeof(u_short), 
  			    M_DEVBUF, (wait) ? M_WAITOK : M_NOWAIT);
!     if (new != NULL)
! 	bzero(new, scp->history_size * sizeof(u_short));
! 
!     /* Copy contents of old buffer to the new one, but start at
!      * the end and work back. This ensures that if the new buffer
!      * is smaller than the old one then the oldest data is
!      * truncated rather than the latest.
!      */
! 
!     if (scp->history != NULL) {
! 	    i = scp->history_size - 1;
! 	    j = old_size - 1;
! 
! 	    while (i >= 0 && j >= 0)
! 		    *(new + i--) = *(scp->history + j--);
! 
! 	    old = scp->history;
! 	    scp->history = new;
! 
! 	    scp->history_head = scp->history + head_offset;
! 	    scp->history_pos = scp->history + pos_offset;
! 
!     } else
! 	    scp->history = scp->history_head = scp->history_pos = new;
! 
!     if (old != NULL) {
! 	free(old, M_DEVBUF);
! 
!     }
  }
  
  static scr_stat
*** scvidctl.c.orig	Tue Sep  7 20:53:19 1999
--- scvidctl.c	Wed Sep 15 00:44:55 1999
***************
*** 86,91 ****
--- 86,107 ----
      int s;
      int i;
  
+     /* Copy screen into the top of the history buffer. This must
+      * be done here so that scp->{x,y}size are still set to the
+      * old mode values. Any later and we will copy too few or too
+      * many (the extra will be garbage) lines.
+      */
+ 
+     for (i = 0; i < scp->ysize; i++) {
+ 	bcopy(scp->scr_buf + (scp->xsize * i), scp->history_head,
+ 			scp->xsize * sizeof(u_short));
+ 
+ 	scp->history_head += scp->xsize;
+ 
+ 	if (scp->history_head + scp->xsize > scp->history + scp->history_size)
+ 	    scp->history_head=scp->history;
+     }
+ 
      if ((*vidsw[scp->ad]->get_info)(scp->adp, mode, &info))
  	return ENODEV;
   
***************
*** 138,153 ****
      scp->xpixel = scp->xsize*8;
      scp->ypixel = scp->ysize*fontsize;
  
      /* allocate buffers */
      sc_alloc_scr_buffer(scp, TRUE, TRUE);
      if (ISMOUSEAVAIL(scp->adp->va_flags))
  	sc_alloc_cut_buffer(scp, FALSE);
      sc_alloc_history_buffer(scp, sc_history_size, i, FALSE);
      splx(s);
- 
-     if (scp == cur_console)
- 	set_mode(scp);
-     scp->status &= ~UNKNOWN_MODE;
  
      if (tp == NULL)
  	return 0;
--- 154,173 ----
      scp->xpixel = scp->xsize*8;
      scp->ypixel = scp->ysize*fontsize;
  
+     /* We need to call set_mode() before sc_alloc_history_buffer()
+      * or the history buffer will get screwed up.
+      */
+ 
+     if (scp == cur_console)
+ 	set_mode(scp);
+     scp->status &= ~UNKNOWN_MODE;
+ 
      /* allocate buffers */
      sc_alloc_scr_buffer(scp, TRUE, TRUE);
      if (ISMOUSEAVAIL(scp->adp->va_flags))
  	sc_alloc_cut_buffer(scp, FALSE);
      sc_alloc_history_buffer(scp, sc_history_size, i, FALSE);
      splx(s);
  
      if (tp == NULL)
  	return 0;

I reckon that this PR can be closed now. syscons(4) has had a major
re-write in 4.0 and this functionality is now included.

Comment 5 Poul-Henning Kamp 2001-06-22 16:43:55 UTC

State Changed
From-To: open->closed

done