From nobody  Tue Jan  5 20:51:46 1999
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Date: Tue, 5 Jan 1999 20:51:46 -0800 (PST)
From: kowkn@asia1.com.sg
To: freebsd-gnats-submit@freebsd.org
Subject: tty-level buffer overflows
X-Send-Pr-Version: www-1.0

>Number:         9341
>Category:       i386
>Synopsis:       tty-level buffer overflows
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Jan  5 21:00:01 PST 1999
>Closed-Date:    Sun May 21 00:44:21 PDT 2000
>Last-Modified:  Sun May 21 00:50:01 PDT 2000
>Originator:     Kow Kee Nge
>Release:        FreeBSD 2.2.2-RELEASE
>Organization:
Singapore Press Holdings Ltd
>Environment:
lewis:/usr/home/kowkn:/var/log> uname -a
FreeBSD lewis.asia1.com.sg 2.2.2-RELEASE FreeBSD 2.2.2-RELEASE #0: Fri Apr  3 17:22:33 SGT 1998     root@lewis.asia1.com.sg:/usr/src/sys/compile/LEWIS  i386
>Description:
Have wrote a C program constanly capturing data from 
/dev/cuaa0. Very often get the following messages in
/var/log/messages.
Jan  5 16:22:13 lewis /kernel: sio0: 646 more tty-level buffer overflows (total 24
16)  
Jan  5 16:22:14 lewis /kernel: sio0: 952 more tty-level buffer overflows (total 33
68)  
Jan  5 16:22:15 lewis /kernel: sio0: 952 more tty-level buffer overflows (total 43
20)  
Jan  5 16:22:16 lewis /kernel: sio0: 966 more tty-level buffer overflows (total 52
86)  
Jan  5 16:22:17 lewis /kernel: sio0: 616 more tty-level buffer overflows (total 59
02)  

What system parameters should we tune to increate the tty-level
buffer?
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:

From: Tim Vanderhoek <tim@localhost.nowhere>
To: freebsd-gnats-submit@FreeBSD.org, kowkn@asia1.com.sg
Cc: vanderh@ecf.toronto.edu
Subject: Re: i386/9341: tty-level buffer overflows
Date: Sat, 20 May 2000 04:24:29 -0400 (EDT)

 >Jan  5 16:22:16 lewis /kernel: sio0: 966 more tty-level buffer overflows (total 5286)
 >Jan  5 16:22:17 lewis /kernel: sio0: 616 more tty-level buffer overflows (total 5902)
 >
 >What system parameters should we tune to increate the tty-level
 >buffer?
 
 I once adjusted sys/isa/sio.c, the siosetwater() function to try and
 make this go away.  I adjusted ibufsize to something ridiculously high.
 Try say 4096 or so.  I can't remember if that made the problem go away.
 I found in practice that I lost little bandwidth to the overflows so I
 decided not to fight cvsup over my changes.  If it did work, my knowledge
 of sio.c is low enough that it was probably coincidence.  :)
 
 I just went browsing through the mail archives to see what they say.
 
 In turns-out that there are many references to this in the archives.
 You should have searched them before filing a PR.
 
 However, it seems that some of the suggestions in the mail archives
 are less than useful.  Again, see caveat about my little knowledge
 or interest in sio.c, but I don't believe that increasing your port
 speed will solve this problem.  Neither do I believe that one of the
 rather elaborate (and, to me, sub-comprehensible) suggestions will
 work, either.
 
 Credible mail archive
 
 Bruce Evans: 199705080354.NAA02619@godzilla.zeta.org.au
 Doug White: Pine.BSF.4.03.9810220936040.12898-100000@resnet.uoregon.edu
 
 Try also the command `man 4 sio`.  Note the explanation of error
 messages at the end of the manpage.
 
 In the event that you choose to ignore the error messages, you
 are mortally harming yourself.  Nor are they due to an unknown
 bug in FreeBSD.
 
 Good luck.
 
 
 
State-Changed-From-To: open->closed 
State-Changed-By: hoek 
State-Changed-When: Sun May 21 00:44:21 PDT 2000 
State-Changed-Why:  
As stated in sio(4): tty-level overflows are usually, rightly or 
wrongly, attributed to overly slow computers and thus dismissed.  Once 
again, rightly or wrongly, I see no reason not to thus dismiss this 
bugreport.  If you try one of the suggestions, I hope they work. 
If not, you can safely ignore the messages.  If they bother you, 
they can be disabled in the relevant source file and you'll never 
be the better except for your past. 

Good luck! 

From: Tim Vanderhoek <tim@localhost.nowhere>
To: freebsd-gnats-submit@FreeBSD.org, kowkn@asia1.com.sg
Cc: vanderh@ecf.toronto.edu
Subject: Re: i386/9341: tty-level buffer overflows
Date: Sun, 21 May 2000 03:44:13 -0400 (EDT)

 >
 > In the event that you choose to ignore the error messages, you
 > are mortally harming yourself.  Nor are they due to an unknown
 
 Uh, urg.  That was meant to be "you are _not_ mortally harming
 yourself."
 
 Mind you, you're quite mortal either way.  But ignoring them won't
 make you more mortal.  Not much more, anyways.
 > bug in FreeBSD.
 >
 > Good luck.
 >
 >
 >
 >   [4]Submit Followup
 >     _________________________________________________________________
 >   
 >   
 >    [5]www@FreeBSD.org
 
>Unformatted:
