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User-space applications can wait on so called endpoints. The kernel
can then send a message to this endpoint (using
lmp_deliver_notifications), which will trigger a handler-function to
be called. From the perspective of the user-space application, you
would then call event_dispatch(), which blocks until a notification
arrives.<br>
<br>
Have a look at how we implement support for performance counters.
The user-level code is in usr/tests/perfmontest. The kernel part of
the implementation is in the code for interrupt handling (to send to
endpoints when the counters overflow) and syscalls (we use
capabilities to register the endpoints).<br>
<br>
If you need more help I will have to give me some more concrete
information on what exactly you want to do.<br>
<br>
<br>
<div class="moz-cite-prefix">On 03/04/2013 11:01 AM, Zhiquan Lai
wrote:<br>
</div>
<blockquote
cite="mid:CAKP_FrPsDDwZ4nxp3EhcVnrK2ysTrra=n0tt069UxDgH_9GQwQ@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
Dear Stefan,
<div><br>
</div>
<div>Actually, I want to know the general method that we can use
to inform user applications in the Barrelfish kernel.</div>
<div><br>
</div>
<div>But you can assume that I receive a UMP-IPI notification.
Then how can I inform the a user application to handle this
event ?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Zhiquan</div>
<div><br>
</div>
<div><br>
<div class="gmail_quote">On Mon, Mar 4, 2013 at 5:47 PM, Stefan
Kästle <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:stefan.kaestle@inf.ethz.ch" target="_blank">stefan.kaestle@inf.ethz.ch</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Are you talking about
UMP-IPI notifications? <br>
<div>
<div class="h5"> <br>
<div>On 03/02/2013 10:29 AM, Zhiquan Lai wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div class="h5"> Hi all,
<div><br>
</div>
<div>When the kernel receive a certain notification,
I want to export some parameters to an user
application and inform it to handle this
notification.</div>
<div>How can I implement that in Barrelfish?</div>
<div><br>
</div>
<div>Should the application register a handler to
the kernel? But I think the kernel can not call
that handler directly.</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Zhiquan</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
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Stefan</pre>
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<pre class="moz-signature" cols="72">--
Stefan</pre>
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