Re: hotpluggable ide cd-rom drive?

[Greg KH <greg@kroah.com>]

On Tue, Mar 18, 2003 at 07:17:33AM -0600, Kari Karhi wrote:
> Hi,
> so let me try to summarize for my own understanding.  Comments are welcome.
> 
> 1. The mechanism used to probe the hardware for new devices during boot can
> not be used later during normal operation of the os.  This prevents linux
> from running the ide-probe again and updating the device maps.  Therefore
> there can be no user level commands one could run after plugging in a
> hot-pluggable device, that would find the device and add it to the device
> maps.

Not necessarily true.  I think that the ide code does not support this
kind of behavior right now, this is not held back by the rest of the
kernel.  See the many queries about hotplug ide drives in the
linux-kernel mailing list archives for a better answer to this.

> 2. The hot-plug mechanism is specific to the system hardware and is not
> standardised.  This prevents linux from finding out that new hardware has
> been added, and automagically adding the hot-plugged devices.

Not true.  The hotplug mechanism is specific to the individual bus
types, but from a user's point of view, the mechanism is standardized to
always interact through the same interface (/sbin/hotplug).

> 3. It is not possible to guess the device map and to build it from some
> static file at boot time (e.g. boot hdc=hotplug fd0=hotplug).  This would
> allow the device to always be there, but if you try to access it before it
> is plugged in, you would get failures and time-outs.

That is a ide specific question, I do not know.  But the current kernel
code does not support such a "hcd=hotplug" mechanism, yes.

> So none of the above mechanisms would work?

They could, if someone implemented them :)

thanks,

greg k-h


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