Re: [PATCH v2 5/7] driver core: Add device location to "struct device" and expose it in sysfs

[Rafael J. Wysocki]

On Tue, Jun 30, 2020 at 2:52 PM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, Jun 30, 2020 at 01:49:48PM +0300, Heikki Krogerus wrote:
> > On Mon, Jun 29, 2020 at 09:49:41PM -0700, Rajat Jain wrote:
> > > Add a new (optional) field to denote the physical location of a device
> > > in the system, and expose it in sysfs. This was discussed here:
> > > https://lore.kernel.org/linux-acpi/20200618184621.GA446639@xxxxxxxxx/
> > >
> > > (The primary choice for attribute name i.e. "location" is already
> > > exposed as an ABI elsewhere, so settled for "site"). Individual buses
> > > that want to support this new attribute can opt-in by setting a flag in
> > > bus_type, and then populating the location of device while enumerating
> > > it.
> >
> > So why not just call it "physical_location"?
>
> That's better, and will allow us to put "3rd blue plug from the left,
> 4th row down" in there someday :)
>
> All of this is "relative" to the CPU, right?  But what CPU?  Again, how
> are the systems with drawers of PCI and CPUs and memory that can be
> added/removed at any point in time being handled here?  What is
> "internal" and "external" for them?
>
> What exactly is the physical boundry here that is attempting to be
> described?

Also, where is the "physical location" information going to come from?

If that is the platform firmware (which I suspect is the anticipated
case), there may be problems with reliability related to that.