Messages in this thread | | | Date | Tue, 4 Mar 2008 15:58:30 -0700 | From | Alex Chiang <> | Subject | Re: [PATCH 4/4] ACPI PCI slot detection driver |
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* 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
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