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Re: [Xen-devel] notification in xen

On Wed, Mar 21, 2012 at 2:17 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>> On 21.03.12 at 07:20, Nupur Ghatnekar <nupurghatnekar@xxxxxxxxx> wrote:
> For event notification there are 2 functions that i came across.
> notify_remote_via_irq(int irq)
> notify_remote_via_evtchn(int port)
> I tried to use those, but didnt know how to check whether notification has
> occurred. Is there a way in which i can check the success of the commands.

While the function could be made return an error indication, there's
little point in doing so - the only possibility for things going wrong is
that you pass in bad arguments.


>> But is there no other way to find out what happens at the remote end after
> it receives the notification?



Then how does inter-domain communication happen??
A simple split device driver implementation

Âblkfront wants to access data
-queue a âread requestâ into memory it shares with blkback
-notify blkback in dom0 using an event channel

blkback experiences an âinterruptâ as a result of the event sent to it
-looks in the shared memory to find the request
-executes the read operation
-puts a response in shared memoryÂ
-notifies blkfront in the domU using an event channel

blkfront experiences an âinterruptâ due to the event sent to it
-completes processing of the new data

How does thisÂnotificationÂwork?
Could you please explain? if there are any sample codes i can refer to, that would be great!

Nupur Ghatnekar
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