From owner-freebsd-stable@FreeBSD.ORG Wed Jan 21 04:25:47 2004 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 222F416A4CE for ; Wed, 21 Jan 2004 04:25:47 -0800 (PST) Received: from geminix.org (gen129.n001.c02.escapebox.net [213.73.91.129]) by mx1.FreeBSD.org (Postfix) with ESMTP id B91DE43D1D for ; Wed, 21 Jan 2004 04:25:45 -0800 (PST) (envelope-from gemini@geminix.org) Message-ID: <400E6FC6.6010801@geminix.org> Date: Wed, 21 Jan 2004 13:25:42 +0100 From: Uwe Doering Organization: Private UNIX Site User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.6) Gecko/20040119 X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-stable@freebsd.org References: <20040120132533.GA24163@neuron.tuke.sk> <400E3628.8050601@geminix.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Received: from gemini by geminix.org with asmtp (TLSv1:AES256-SHA:256) (Exim 3.36 #1) id 1AjHQW-000MnU-00; Wed, 21 Jan 2004 13:25:44 +0100 Subject: Re: Where are defaults for kernel variables? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Jan 2004 12:25:47 -0000 Dag-Erling Smørgrav wrote: > Uwe Doering writes: >>Jozef Babjak wrote: >>>options PMAP_SHPGPERPROC=201 >>>or options KVA_PAGES=260 >>>but are these default values? >> >>No, these are usually not the defaults, just examples. I haven't >>found a complete list so far. I could be wrong, but I think part of >>the problem is that the majority of kernel developers doesn't feel >>obligated to document the variables they introduced somewhere outside >>the kernel. > > The defaults are generally computed at boot time as a function of > physical memory size. While there are a number of variables that get derived from the physical memory size (if not overridden), claiming that kernel variable defaults are _generally_ computed at boot time is certainly an exaggeration. There are still tons of variables and C preprocessor defines that have nothing to do with physical memory size, have fixed defaults and have to be set explicitly where necessary. And many of those are unfortunately sparsely documented, if at all. Now, before someone gets me wrong on this, I don't complain about the lack of documentation, since the FreeBSD project is a voluntary effort and I don't have the time to solve this problem, either. I just describe the current state of affairs, as I see it. Uwe -- Uwe Doering | EscapeBox - Managed On-Demand UNIX Servers gemini@geminix.org | http://www.escapebox.net