From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sceptre.pobox.com (sceptre.pobox.com [207.106.133.20]) by ozlabs.org (Postfix) with ESMTP id 57572DDDFE for ; Fri, 31 Aug 2007 03:56:31 +1000 (EST) Date: Thu, 30 Aug 2007 12:56:09 -0500 From: Nathan Lynch To: Joachim Fenkes Subject: Re: [PATCH 2.6.23] ibmebus: Prevent bus_id collisions Message-ID: <20070830175609.GG23140@localdomain> References: <46D5BBFA.5060200@austin.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: Thomas Q Klein , Jan-Bernd Themann , Paul Mackerras , LKML , LinuxPPC-Dev , Christoph Raisch , Paul Mackerras , Stefan Roscher List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Joachim- Joachim Fenkes wrote: > Nathan Lynch wrote on 29.08.2007 20:12:32: > > Will anything break? > > Nope. Userspace programs should not depend on ibmebus' way of naming the > devices; especially since some overly long loc_codes tended to be > truncated and thus rendered useless. I have tested IBM's DLPAR tools > against the changed kernel, and they didn't break. Okay. > > Also, I dislike this approach of duplicating the firmware device tree > > path in sysfs. > > Why? Any specific reasons for your dislike? struct device's bus_id field is but 20 bytes in size. Too close for comfort? > > Are GX/ibmebus devices guaranteed to be children of > > the same node in the OF device tree? If so, their unit addresses will > > be unique, and therefore suitable values for bus_id. I believe this > > is what the powerpc vio bus code does. > > While there's no such guarantee (as in "officially signed document"), yes, > I expect future GX devices to also appear beneath the OFDT root node. For > the existing devices, the unit addresses are already part of the device > name, so I save the need to use sprintf() again. Plus, I rather like using > the full_name since it also contains a descriptive name as opposed to > being just nondescript numbers, helping the layman (ie user) to make sense > out of a dev_id. Okay, but your layman isn't supposed to be relying on any user-friendly properties of the name :) Hope he doesn't work on a distro installer. Anyway, if you're still confident in this approach, I relent. :)