From owner-freebsd-stable Wed Mar 21 1:24:58 2001 Delivered-To: freebsd-stable@freebsd.org Received: from mail.wipol.uni-bonn.de (data.wipol.uni-bonn.de [131.220.47.161]) by hub.freebsd.org (Postfix) with ESMTP id 669E237B71F for ; Wed, 21 Mar 2001 01:24:55 -0800 (PST) (envelope-from noel@koethe.net) Received: by mail.wipol.uni-bonn.de (Postfix, from userid 506) id E29BF3D13; Wed, 21 Mar 2001 10:24:53 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by mail.wipol.uni-bonn.de (Postfix) with ESMTP id D7743B6DF; Wed, 21 Mar 2001 10:24:53 +0100 (CET) Date: Wed, 21 Mar 2001 10:24:53 +0100 (CET) From: Noel Koethe X-Sender: noel@data.wipol.uni-bonn.de To: Thomas Moestl Cc: freebsd-stable@freebsd.org Subject: Re: dmesg output In-Reply-To: <20010320181117.A2347@crow.dom2ip.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 20 Mar 2001, Thomas Moestl wrote: Hello Thomas, > > Why it is here normal on one machine and cutted on the other? > > And why does it work before ( I'm sure in December it doesn't work like > > now )? > > OK, I'll go into details a little more. Not too long ago, a patch was > MFCed that allows logging console output. To allow this, this ouput is > written into the kernel message buffer, where it can be picked up by > syslog using the /dev/klog interface. Normal kernel output is written > to the message buffer as is, while console output is prefixed with a > string in the form "", where category is a number (118 in > this case, LOG_CONSOLE|LOG_INFO). dmesg will ignore messages that > start with such a string indicating that the message didn't come from > the kernel unless it is invoked with the -a option. If syslogd is > configured to echo some messages to the console, those messages will > be appended to the kernel message buffer, and if this happens too > often, this will overwrite all the kernel messages. A common situation > is that a lot of kernel messages are generated that fill up the message > buffer, syslog snarfs those a little later, writes them to the console > and thus overwrites the original kernel messages in turn. dmesg > will show nothing in this case, or, more often, a line that came from > the console, but of which the first character(s) were overwritten by a > new message (they don't start with a "" magic string then, and > dmesg will print them). > So, dmesg will work as expected on machines that didn't generate > enough messages yet, or on systems from before the MFC. Thanks for this long explanation. Maybe the daily "security check output" will be correct: host.domain.de kernel log messages: > ia tun0 Again. Thanks for your answers. -- Noch einen schoenen Tag Noel To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message