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From: Greg KH <gregkh@suse.de>
To: Alex Chiang <achiang@hp.com>, Matthew Wilcox <matthew@wil.cx>,
	Gary Hade <garyhade@us.ibm.com>,
	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
Subject: Re: [PATCH 4/4] ACPI PCI slot detection driver
Date: Tue, 4 Mar 2008 15:15:25 -0800	[thread overview]
Message-ID: <20080304231525.GA25125@suse.de> (raw)
In-Reply-To: <20080304225830.GC3694@ldl.fc.hp.com>

On Tue, Mar 04, 2008 at 03:58:30PM -0700, Alex Chiang wrote:
> * Greg KH <gregkh@suse.de>:
> > 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 <foo>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.

But that is what the current code does, so I know a lot of userspace
programs assume that all slots there are valid hotplug slots.

I know I sure don't want to go fix up a lot of horrible Java
closed-source code in IBM's huge system management toolkits :(

> 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.

Ok, care to resend them with the requested updates?

thanks,

greg k-h

  reply	other threads:[~2008-03-04 23:21 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29  0:23 [PATCH 0/4, v7] PCI, ACPI: Physical PCI slot objects Alex Chiang
2008-02-29  0:26 ` [PATCH 1/4] Remove path attribute from sgi_hotplug Alex Chiang
2008-03-03 18:48   ` Jesse Barnes
2008-03-03 18:54     ` Prarit Bhargava
2008-03-05  0:19       ` Alex Chiang
2008-02-29  0:27 ` [PATCH 2/4] Construct one fakephp slot per pci slot Alex Chiang
2008-02-29  0:28 ` [PATCH 3/4] Introduce pci_slot Alex Chiang
2008-03-01  5:24   ` Greg KH
2008-03-03 20:56     ` Alex Chiang
2008-03-04  5:58       ` Greg KH
2008-03-04 23:30   ` [PATCH 3/4, v8] " Alex Chiang
2008-02-29  0:29 ` [PATCH 4/4] ACPI PCI slot detection driver Alex Chiang
2008-03-01  5:25   ` Greg KH
2008-03-01 14:43     ` Matthew Wilcox
2008-03-04  5:49       ` Greg KH
2008-03-04 18:18         ` Jesse Barnes
2008-03-04 19:30           ` Greg KH
2008-03-04 20:02             ` Jesse Barnes
2008-03-04 20:12             ` Kristen Carlson Accardi
2008-03-04 23:09             ` Alex Chiang
2008-03-05  1:11               ` Kenji Kaneshige
2008-03-05 20:20                 ` Alex Chiang
2008-03-05 20:34                   ` Matthew Wilcox
2008-03-06  2:07                   ` Kenji Kaneshige
2008-03-11 13:10                   ` Kenji Kaneshige
2008-03-11 13:13                     ` [PATCH 3/(3+1)] " Kenji Kaneshige
2008-03-11 13:17                       ` Kenji Kaneshige
2008-03-11 13:19                     ` [PATCH 4/(3+1)] Add quirks for " Kenji Kaneshige
2008-03-11 13:28                     ` [PATCH 4/4] " Matthew Wilcox
2008-03-11 16:56                       ` Jesse Barnes
2008-03-12  5:51                         ` Kenji Kaneshige
2008-03-12  4:08                       ` Kenji Kaneshige
2008-03-11 18:04                     ` Kristen Carlson Accardi
2008-03-11 19:14                       ` Alex Chiang
2008-03-12 11:33                         ` Kenji Kaneshige
2008-03-13  3:24                           ` Alex Chiang
2008-03-14  2:16                             ` Gary Hade
2008-03-14  5:34                               ` Kenji Kaneshige
2008-03-18 20:49                                 ` Alex Chiang
2008-03-12 10:50                       ` Kenji Kaneshige
2008-03-11 23:34                     ` Kristen Carlson Accardi
2008-03-12 12:59                       ` Kenji Kaneshige
2008-03-04 22:58         ` Alex Chiang
2008-03-04 23:15           ` Greg KH [this message]
2008-03-04 23:46             ` Alex Chiang
2008-03-01  5:12 ` [PATCH 0/4, v7] PCI, ACPI: Physical PCI slot objects Greg KH
2008-03-03 23:35   ` Alex Chiang
2008-03-04  5:56     ` Greg KH
2008-03-25  4:13 [PATCH 0/4, v11] " Alex Chiang
2008-03-25  4:17 ` [PATCH 4/4] ACPI PCI slot detection driver Alex Chiang
2008-03-25  4:50   ` Kenji Kaneshige
2008-03-25 17:09 [PATCH 0/4, v12] PCI, ACPI: Physical PCI slot objects Alex Chiang
2008-03-25 17:14 ` [PATCH 4/4] ACPI PCI slot detection driver Alex Chiang

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