From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Chiang Subject: Re: [PATCH 4/4] ACPI PCI slot detection driver Date: Tue, 4 Mar 2008 15:58:30 -0700 Message-ID: <20080304225830.GC3694@ldl.fc.hp.com> References: <20080229002341.GA21420@ldl.fc.hp.com> <20080229002938.GE21420@ldl.fc.hp.com> <20080301052542.GD19353@suse.de> <20080301144307.GD24386@parisc-linux.org> <20080304054927.GA15566@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from g1t0028.austin.hp.com ([15.216.28.35]:7069 "EHLO g1t0028.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752324AbYCDW6c (ORCPT ); Tue, 4 Mar 2008 17:58:32 -0500 Content-Disposition: inline In-Reply-To: <20080304054927.GA15566@suse.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Greg KH Cc: Matthew Wilcox , Gary Hade , kaneshige.kenji@jp.fujitsu.com, warthog19@eaglescrag.net, kristen.c.accardi@intel.com, rick.jones2@hp.com, linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, linux-acpi@vger.kernel.org * Greg KH : > On Sat, Mar 01, 2008 at 07:43:07AM -0700, Matthew Wilcox wrote: > > On Fri, Feb 29, 2008 at 09:25:42PM -0800, Greg KH wrote: > > > What is the guarantee that the names of these slots are correct No guarantee there. We report whatever firmware tells us. > > > and do not happen to be the same as the hotpluggable ones? Stronger guarantee here, since both pci_slot and hp driver will be getting the name of the slot from the same place. > > That would be a bug -- and yes, bugs happen, and we have to deal with > > them. > > My main concern is that BIOS vendors will not fix these bugs, as no > other OS cares/does this kind of thing today. The ammount of bad > information out there might be quite large, and I think this was > confirmed by some initial testing of IBM systems, right? We saw problems on Fujitsu machines, where they return an error code when the _SUN method is called on a slot that exists in the namespace but isn't actually present. After discussing with Kenji-san about specs, we came to the agreement that he was ok with this behavior because he had the option to not load pci_slot on his machines. I agree that there might be lots of buggy firmwares out there, but we won't know for certain until we get some exposure. And I think the upside is worth it. Kristen suggested the linux-next tree. That sounds viable to me... > > > Why show this information on machines that can not do > > > anything with these slots at all? Will that not just > > > confuse people? > > > > Only for people who think that /sys/bus/pci/slots/ is for > > hotpluggable slots only. There is plenty of useful > > information available for slots that aren't hotpluggable (eg > > bus address, speed, width, error status). > > Can the userspace tools that are using the existing directories > thinking that only hotplug slots are there, handle > "non-hotplug" slots showing up in this location? Of course we shouldn't break userspace, no one wants that. But nothing about that name (/sys/bus/pci/slots/) implies "hotplug only", and we have no idea how big the problem might be. Again, I'm thinking more exposure in linux-next might be a reasonable way for us to figure out how bad (or good) the situation might really be out there. Thanks. /ac