James Bottomley wrote:
>>n Advanced TCA (what spawned this work) a button is pressed to
>>indicate hotswap removal which makes for easy detection of hotswap
>>events. This is why there are kernel interfaces for removal and
>>insertion (so a kernel driver can be written to detect the button
>>press and remove the devices from the os data structures and then
>>light a blue led indicating safe for removal).
>>
>>
>
>OK, I understand what's going on now. It's no different from those hotplug
>PCI busses where you press the button and a second or so later the LED goes
>out and you can remove the card. 10ms sounds rather a short maximum time for
>a technician to wait for a light to go out....I suppose Telco technicians are
>rather impatient.
>
>I really think you need to lengthen this interval. The kernel is moving
>towards this type of hotplug infrastructure which you can easily leverage (or
>even help build), but it's definitely going to be mainly in user space.
>
>
Caveat coder -- you also have to handle the case where the device is
already gone, by the time you are notified of the hot-unplug event.
Some ejections are less friendly than others... though from a SCSI
standpoint, hopefully that case is easier -- error out all I/Os in
flight, and unregister the host and device structures associated with
the recently-removed host. The devil, of course, is in the details ;-)
Jeff
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This archive was generated by hypermail 2b29 : Thu Oct 31 2002 - 22:00:25 EST