From owner-freebsd-arch@FreeBSD.ORG Sat Sep 9 12:24:43 2006 Return-Path: X-Original-To: arch@freebsd.org Delivered-To: freebsd-arch@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6C75D16A417 for ; Sat, 9 Sep 2006 12:24:43 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id DDE7443D70 for ; Sat, 9 Sep 2006 12:24:38 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id CCEB546D1A; Sat, 9 Sep 2006 08:24:37 -0400 (EDT) Date: Sat, 9 Sep 2006 13:24:37 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: "M. Warner Losh" In-Reply-To: <20060908.001045.1683322424.imp@bsdimp.com> Message-ID: <20060909131907.G84834@fledge.watson.org> References: <20060907.153239.1219861549.imp@bsdimp.com> <20060908.001045.1683322424.imp@bsdimp.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: arch@freebsd.org, howard0su@gmail.com Subject: Re: Modularize kernel 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: Sat, 09 Sep 2006 12:24:43 -0000 On Fri, 8 Sep 2006, M. Warner Losh wrote: > In message: > "Howard Su" writes: > : On 9/8/06, M. Warner Losh wrote: > : > I routinely boot a minimal kernel and kldload everything. this gives > : > me a kernel about 1/3 the size of a full GENERIC build, but at the > : > price of needing to keep my modules up to date. > : > : For -STABLE tree, i think it is easy since ABI is fixed. However what > : I proposed is pushing this effort to let most user to use module > : instead of rebuilding the kernel. > > I guess what I'm saying is that with a minimal kernel + all the modules we > have, you have that today. One of the biggest concerns I have with moving towards a heavily modularized default kernel is that we may find we need to explore improving our automatic loading of modules. For example, if we want to de-populate the base kernel with respect to device drivers, which take up quite a lot of space, we'll want to look both at how to handle early boot, and later loading if hardware turns up -- issues we've largely avoided by virtue of compiling them in. We may, for example, want to look at Apple's approach of loading all the available modules sequentially early in the boot to see what attachs, unload the idle modules, and then provide demand loading later. Robert N M Watson Computer Laboratory University of Cambridge