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Date: Fri, 29 Nov 1996 00:48:30 -0600 (CST)
From: Jimbo Bahooli <moke@winternet.com>
Reply-To: moke@winternet.com
To: FreeBSD-gnats-submit@freebsd.org
Subject: failure to write to vc w/o input
X-Send-Pr-Version: 3.2

>Number:         2118
>Category:       kern
>Synopsis:       writing to virtual consoles fails to display until input
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    sos
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Nov 28 22:50:00 PST 1996
>Closed-Date:    Tue Oct 13 01:19:23 PDT 1998
>Last-Modified:  Tue Oct 13 01:21:43 PDT 1998
>Originator:     Jimbo Bahooli
>Release:        FreeBSD 3.0-CURRENT i386
>Organization:
none
>Environment:

	
	FreeBSD-current updated on 11/28/96, and make world'd shortly
	after.


>Description:

	Text written to virtual consoles that are not waiting for input is
	not displayed. However once input is asked for, all lines pending
	will display.

>How-To-Repeat:

	( as root )
	./MAKEDEV vty12
	( assuming no active getty is on ttyv8 )
	echo display me > /dev/ttyv8
	( try switching to ttyv8, you can't, text is not displayed )
	add a line to /etc/ttys to start a getty on ttyv8, 'display me'
	will display, and then the login prompt will show up.

	this first showed up in syslog when trying to log to /dev/ttyvb
	which i had been doing for quite sometime.

>Fix:
	
	

>Release-Note:
>Audit-Trail:

From: Bruce Evans <bde@zeta.org.au>
To: j@uriah.heep.sax.de, moke@winternet.com
Cc: freebsd-bugs@freebsd.org, sos@freebsd.org
Subject: Re: kern/2118: failure to write to vc w/o input
Date: Fri, 29 Nov 1996 21:18:36 +1100

 >> 	Text written to virtual consoles that are not waiting for input is
 >> 	not displayed. However once input is asked for, all lines pending
 >> 	will display.
 >
 >Uh, so perhaps _this_ is the reason why the emergency holographic
 >shell of 2.2's sysinstall vanishes when typing a command while the
 >installation is in progress?
 
 The tty plumbing for this is very strange:
 
 	$ cat >/dev/ttyv9		# on unused ttyv9
 	1
 	2
 	3
 	[pause]
 
 This gives no output on /dev/ttyv9.  Then on another tty:
 
 	$ cat /dev/ttyv9
 	1
 	2
 	3
 	$
 
 ttyv9 is acting like a pty.
 
 	$ cat /dev/ttyv9
 	1
 	2
 	3
 	$
 
 A buggy pty :-).  Now with the first cat terminated by ^D:
 
 	$ cat /dev/ttyv9
 	1
 	2
 	3
 	$
 
 A very buggy pty :-).
 
 Bruce
Responsible-Changed-From-To: freebsd-bugs->sos 
Responsible-Changed-By: wosch 
Responsible-Changed-When: Wed Aug 27 15:00:22 PDT 1997 
Responsible-Changed-Why:  
sos is Mr. syscons. 
State-Changed-From-To: open->closed 
State-Changed-By: yokota 
State-Changed-When: Tue Oct 13 01:19:23 PDT 1998 
State-Changed-Why:  
syscons does not allow the user to switch to a vty which is not opened. 
This is a feature, not a bug.  The PR originator was able to switch 
to ttyv8 after `login' started in that vty, because `login' opened the vty, 
not because it was requesting input. 
>Unformatted:
