From owner-freebsd-current@FreeBSD.ORG Thu Sep 3 09:38:21 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3B8C3106566C; Thu, 3 Sep 2009 09:38:21 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 136BA8FC12; Thu, 3 Sep 2009 09:38:21 +0000 (UTC) Received: from fledge.watson.org (fledge.watson.org [65.122.17.41]) by cyrus.watson.org (Postfix) with ESMTPS id B600B46B29; Thu, 3 Sep 2009 05:38:20 -0400 (EDT) Date: Thu, 3 Sep 2009 10:38:20 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Tim Kientzle In-Reply-To: <4A9F4DC1.4010002@freebsd.org> Message-ID: References: <200909010931.16880.nick@van-laarhoven.org> <1251841416.1689.4458.camel@balrog.2hip.net> <200909021656.15747.nick@van-laarhoven.org> <2fd864e0909021645p735e22b8id7d41f4b5a0ee89e@mail.gmail.com> <4A9F4DC1.4010002@freebsd.org> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-current@freebsd.org, Astrodog Subject: Re: Reducing noise in dmesg output X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Sep 2009 09:38:21 -0000 On Wed, 2 Sep 2009, Tim Kientzle wrote: >>> FreeBSD has historically been producing very limited output on dmesg. >>> Linux is very noisy (ever noticed the copyright notices right in the >>> middle of your list of PCI devices?). Even they have decided that they >>> should hide this behind coloured 'ok/failed' texts in some distributions. >> >> I think this speaks more towards needing something between "Very Quiet" and >> "Give me everything every developer has ever wanted to know enough to >> include a print for it." > > Other possibilities: > > * Provide a per-driver control to determine verbosity. That would make it > easier for developers who really do want to see "everything there is to know > in my part of the world". > > * Put more information into the kernel buffers (and from there into dmesg) > and less on the screen. That would reduce visible boot verbosity while > retaining the post-hoc debugging value of dmesg(1). It's clear that part of the problem we're dealing with here is that dmesg remains the authoritative source for certain kinds of data that really should be in a machine-readable/reportable format. devinfo(8) captures some of this, but can't, for example, cleanly represent an IRQ being shared by multiple devices, and doesn't capture a lot of the device-driver specific data that appears in dmesg. dmesg is a useful log of events, and I'm not saying we should omit information there, but when inspecting the current state of the system, the kernel has a lot of information and it would be nice if more of it were accessible in userspace. To my mind, the main reason to look at dmesg should be to find out about *failed* device attaches, where there most likely won't be persisting state in the kernel, but the debugging information is invaluable. Robert N M Watson Computer Laboratory University of Cambridge