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From: Alex Chiang <achiang@hp.com>
To: Greg KH <gregkh@suse.de>
Cc: 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 15:58:30 -0700	[thread overview]
Message-ID: <20080304225830.GC3694@ldl.fc.hp.com> (raw)
In-Reply-To: <20080304054927.GA15566@suse.de>

* 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.

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


  parent reply	other threads:[~2008-03-04 22:58 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 [this message]
2008-03-04 23:15           ` Greg KH
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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