[systemd-devel] Need help with a systemd/mdadm interaction.

[NeilBrown]

On Tue, 12 Nov 2013 00:10:28 -0800 Greg KH <gregkh at linuxfoundation.org> wrote:

> On Tue, Nov 12, 2013 at 11:31:45AM +1100, NeilBrown wrote:
> > Alternately, is there some "all devices have been probed, nothing new will
> > appear unless it is hot-plugged" event.  That would be equally useful (and
> > probably mirrors what hardware-RAID cards do).
> 
> No, there's no way to ever know this in a hotplug world, sorry.
> Especially with USB devices, they show up when they show up, there's no
> "oh look, the bus is all scanned now and all devices currently plugged
> in are found" type knowledge at all.
> 
> Then there are hotplug PCI systems where people slam in PCI cards
> whenever they feel like it (remember, thunderbolt is PCI express...)
> 
> Sorry,
> 
> greg k-h

Surely something must be possible.
Clearly a physical hot-plug event will cause more devices to appear, but
there must come a point at which no more (non-virtual) devices will appear
unless a physical event happens?  Or may unless "a physical event or a
deliberate configuration change" happens.

Maybe it is hard.  Maybe it is too hard.  But surely
it is at least theoretically possible.

NeilBrown
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