From owner-freebsd-questions@FreeBSD.ORG  Mon Mar 14 02:13:23 2011
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C736F106566C
	for <freebsd-questions@freebsd.org>;
	Mon, 14 Mar 2011 02:13:23 +0000 (UTC)
	(envelope-from perryh@pluto.rain.com)
Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34])
	by mx1.freebsd.org (Postfix) with ESMTP id A99FF8FC13
	for <freebsd-questions@freebsd.org>;
	Mon, 14 Mar 2011 02:13:23 +0000 (UTC)
Received: from agora.rdrop.com (66@localhost [127.0.0.1])
	by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id p2E2DNEt074987
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT)
	for <freebsd-questions@freebsd.org>;
	Sun, 13 Mar 2011 19:13:23 -0700 (PDT)
	(envelope-from perryh@pluto.rain.com)
Received: (from uucp@localhost)
	by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id p2E2DNgr074986
	for freebsd-questions@freebsd.org; Sun, 13 Mar 2011 19:13:23 -0700 (PDT)
Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407)
	id AA07747; Sun, 13 Mar 11 18:08:23 PST
Date: Sun, 13 Mar 2011 19:08:20 -0700
From: perryh@pluto.rain.com
To: freebsd-questions@freebsd.org
Message-Id: <4d7d7894.ZVXy6HlL95xx+v0E%perryh@pluto.rain.com>
User-Agent: nail 11.25 7/29/05
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Subject: logging to dmesg from userland
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 14 Mar 2011 02:13:23 -0000

I am looking for a way to write into the kernel message buffer --
the one that dmesg prints out -- from a userland program, to help
in relating kernel printf messages to the userland operations which
provoked them.  (Yes, I am aware of the potential DoS implications:
the capability should be restricted to root, or at least to the
"operator" group.  I expect to use it only in single-user mode.)

Is there a program, or a system call, which can do this?  logger(1)
seemed a likely prospect, but either it doesn't have this capability
or I haven't found the formula.