From owner-freebsd-arch@FreeBSD.ORG Wed Jan 19 20:59:48 2011 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0C927106566C; Wed, 19 Jan 2011 20:59:48 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id D601B8FC17; Wed, 19 Jan 2011 20:59:47 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id 920D646B89; Wed, 19 Jan 2011 15:59:47 -0500 (EST) Received: from jhbbsd.localnet (smtp.hudson-trading.com [209.249.190.9]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id A97DC8A01D; Wed, 19 Jan 2011 15:59:46 -0500 (EST) From: John Baldwin To: freebsd-arch@freebsd.org Date: Wed, 19 Jan 2011 15:59:07 -0500 User-Agent: KMail/1.13.5 (FreeBSD/7.4-CBSD-20110107; KDE/4.4.5; amd64; ; ) References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201101191559.07713.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (bigwig.baldwin.cx); Wed, 19 Jan 2011 15:59:46 -0500 (EST) X-Virus-Scanned: clamav-milter 0.96.3 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-1.9 required=4.2 tests=BAYES_00 autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on bigwig.baldwin.cx Cc: mdf@freebsd.org Subject: Re: Weed-whacking sysctl(8) X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Jan 2011 20:59:48 -0000 On Wednesday, January 19, 2011 3:28:19 pm mdf@freebsd.org wrote: > As bde@ mentioned, there's very little actual use of the sysctl format > strings. I recently changed it so the use is even smaller, but I've > got a quandary as to how to finish the job. > > I agree with Bruce that the formatted structs can just be removed. Hmm, I've actually used 'sysctl kern.clockrate' in the past. > This leaves just the "IK" format, which shows up in just a few files: > > sys/dev/acpica/acpi_thermal.c: > sys/dev/amdtemp/amdtemp.c > sys/dev/acpi_support/atk0110.c > sys/dev/coretemp/coretemp.c > sys/dev/iicbus/max6690.c > sys/dev/iicbus/ds1775.c > > I see two solutions to "IK". The first is to preserve the interface > as experienced by sysctl(8) users, and add some functions to push a > string buffer back to userspace, and parse a string in the kernel. > The second is to preserve the binary interface as experienced by > sysctl(3) users, and either have the values be dumped in the slightly > obscure 10ths of Kelvin values, or add a new CTLTYPE_KELVIN so > sysctl(8) can also keep showing things as it does today. > > Given how infrequent the use is CTLTYPE_KELVIN seems a non-starter. > So who is the worse client to break: those who use sysctl(8) to look > at temperatures, or those who have a utility to manipulate these > values using sysctl(3)? So what is sufficiently broken elsewhere that requires us to break the existing sysctls? Many people use the output of sysctl(8) for coretemp, and the ACPI thermal zones and breaking that gratuitously would be unfortunate. I've no idea if there is existing code reading these sysctls in userland for things like gkrellm, but I wouldn't be surprised if there were. Even CTLTYPE_KELVIN would require changes to user apps, but I also would rather present an actual number to userland rather than a string so userland doesn't have to parse it just to get back to the original number. I guess I fail to see why sysctl giving a hint about the semantic type of the data ("temperature", "struct foo") which is separate from the "physical" type (e.g. 32-bit or 64-bit) is such a bad thing. -- John Baldwin