some changes to xpt to help make unloading sim modules safer

[Matthew Jacob]

On 8/9/2011 12:39 PM, Kenneth D. Merry wrote:
>
>> I added a few after that to guard against overrunning some counters so
>> that they would wrap.
> Just out of curiosity, have you seen instances where the counters have
> gone negative?

No- but it's one of those things you'd be unlikely to notice w/o unloads :-)

>
> I would think you'd want to wait until the periph is closed, but perhaps
> there is a way to get away with it if there aren't any commands outstanding
> in the SIM.
>
> You could send async notifications that all of the devices on the bus have
> gone away, and then once everything disappears, you could finish the
> unload.
>
> \

Either would work, but I'm inclined to think it'd be better if we finish 
newbusifying all of this.

> Ken