[Xen-tools] Re: [Fwd: Question about use of xenstore]

[harry <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

> For block drivers, it works like this:
> 1) tool deletes frontend dir
> 2) frontend domain: xenbus calls driver cleanup
> 3) backend domain: sees frontend go away and deletes backend dir, calls
> xenbus to do driver cleanup.
> 
> That model seems to work well, and requires very little from the tools.
> I would recommend pursuing the same model for USB, although your
> frontend driver cleanup would leave the watch active, and page mapped,
> waiting to see that final backend delete.

That seems broken to me: where is the interlock that guarantees that the
shared memory page is not reused by the front-end whilst the back-end is
servicing an interrupt which is reading from the page?

> 
> Hope that clarifies!
> Rusty.


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