Re: [Xen-devel] notification in xen

[Nupur Ghatnekar <nupurghatnekar@xxxxxxxxx>]

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.

Jan

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

No.

Jan

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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