Re: removable media revalidation - udev vs. devfs or static /dev

[Linus Torvalds]

On Thu, 8 Jan 2004, Robert Love wrote:
> 
> I like the idea of a hotplug event on media change (basically, a hotplug
> event for partitions).  And, in fact, I am loath not to do it.

The thing is, you won't actually get a "media changed" event with almost 
any normal hardware. 

What you will get is "somebody tried to open the media, and we realized 
that it has changed since the last open".

> The current direction with the kernel and udev is letting us move _away_
> from polling.

.. but this isn't actually the case for media change. You'd still not get 
the media change when the change _occurs_. You'd only get it much later.

> But I hear you loud and clear about dumb devices that cannot detect
> media change.  They pose a problem.

No, even the smart devices pose a problem - but at least for those the 
test whether the media has changed is pretty simple. 

The really _dumb_ devices just assume the media has changed every time the 
device is opened.

			Linus
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