Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 24 Oct 2002 13:40:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 24 Oct 2002 13:40:41 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:10246 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Thu, 24 Oct 2002 13:40:40 -0400 Message-ID: <3DB831FF.4000900@pobox.com> Date: Thu, 24 Oct 2002 13:46:39 -0400 From: Jeff Garzik User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.1) Gecko/20021003 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Mark Peloquin CC: linux-kernel@vger.kernel.org, mochel@osdl.org, viro@math.psu.edu Subject: Re: Switching from IOCTLs to a RAMFS References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1921 Lines: 44 Mark Peloquin wrote: > Based on the feedback and comments regarding > the use of IOCTLs in EVMS, we are switching to > the more preferred method of using a ram based > fs. Since we are going through this effort, I > would like to get it right now, rather than > having to switch to another ramfs system later > on. The question I have is: should we roll our > own fs, (a.k.a. evmsfs) or should we use sysfs > for this purpose? My initial thoughts are that > sysfs should be used. However, recent discussions > about device mapper have suggested a custom ramfs. > Which is the *best* choice? (cc'd viro and mochel, as I feel they are 'owners' in the subject area) Let's jump back a bit, for a second. Why is procfs bad news? There are minor issues with the implementation of single-page output and lack of pure file operations, but the big issue is lack of a sane namespace. sysfs is no better than procfs if we keep heaving junk into it without thinking about proper namespace organization. I personally prefer a separate filesystem for what you describe. That gives the EVMS team control over their own portion of the namespace, while giving complete flexibility. I do _not_ see sysfs as simply a procfs replacement -- sysfs IMO is more intended as a way to organize certain events and export internal kernel structure. To tangent a bit, WRT a private evmsfs, make sure that (a) you prefer ASCII over binary interfaces where reasonable, and (b) any binary interfaces you have are fixed-endian and 64-bit safe from the get-go. Consider crazy cases like someone exporting evmsfs over NFS, from a 32-bit IA32 server to a big-endian 64-bit client. Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/