From owner-freebsd-hackers@FreeBSD.ORG Fri Feb 25 09:39:32 2005 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3C15E16A4CE for ; Fri, 25 Feb 2005 09:39:32 +0000 (GMT) Received: from mail04.syd.optusnet.com.au (mail04.syd.optusnet.com.au [211.29.132.185]) by mx1.FreeBSD.org (Postfix) with ESMTP id 58B9943D5A for ; Fri, 25 Feb 2005 09:39:31 +0000 (GMT) (envelope-from PeterJeremy@optushome.com.au) Received: from cirb503493.alcatel.com.au (c211-30-75-229.belrs2.nsw.optusnet.com.au [211.30.75.229]) j1P9dO9s031027 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Fri, 25 Feb 2005 20:39:27 +1100 Received: from cirb503493.alcatel.com.au (localhost.alcatel.com.au [127.0.0.1])j1P9dO7l090727; Fri, 25 Feb 2005 20:39:24 +1100 (EST) (envelope-from pjeremy@cirb503493.alcatel.com.au) Received: (from pjeremy@localhost)j1P9dHVa090726; Fri, 25 Feb 2005 20:39:17 +1100 (EST) (envelope-from pjeremy) Date: Fri, 25 Feb 2005 20:39:17 +1100 From: Peter Jeremy To: Scott Long Message-ID: <20050225093917.GA90508@cirb503493.alcatel.com.au> References: <421E7867.9060101@samsco.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <421E7867.9060101@samsco.org> User-Agent: Mutt/1.4.2i cc: hackers@freebsd.org Subject: Re: Driver Update Disk discussion X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Feb 2005 09:39:32 -0000 On Thu, 2005-Feb-24 17:59:19 -0700, Scott Long wrote: >- kernel option support. How do we support vendor modules in a kernel >that might be compiled with PAE (rather common these days), SMP, MAC, >etc. The loader and /boot infrastructure has no concept of this. It's >highly important, though. AFAIK, PAE is only relevant on iA32. I second the suggestion that PAE be treated as a distinct architecture for these purposes. INVARIANTS and WITNESS are the other options that impact ABI. These are probably unnecessary on -RELEASE but it would be nice if people could build a kernel with WITNESS and not have it panic if they loaded a module that wasn't compiled with WITNESS (which I think it the current behaviour). >- kernel api/abi. We are trying to keep the kernel api/abi stable now, ... >don't have the right hash. Should we follow with something similar, or >should we have runtime checks that check symbol/structure signatures? It would be wonderful if we could have a mechanism that did load-time validation that the module was compatible with the kernel. Unfortunately, I don't think there's any sane way to verify data structure compatability. (Verifying function call APIs is reasonably easy). Run-time checking adds overheads which may be significant for commonly used interfaces. >Or should we say that we make no guarantees about a binary-only module >working on anything but a -RELEASE kernel? At the very least we need to support errata branches. The RE team has expended a lot of effort to provide a mechanism to handle critical problems found post-release. We don't want to negate this by telling users that they have a choice of either using driver X or fixing hole Y. Unfortunately, in the rare case where an errata fix affects a kernel API/ABI, the change is probably critical to fixing the problem. This would require the FreeBSD fix to be co-ordinated with the driver vendor. I think that guaranteeing operation in -STABLE is probably impractical - though API/ABI changes would need to be flagged to vendors so they could test drivers for the next FreeBSD release. -- Peter Jeremy