[cgl_discussion] Re: questions on AEM article

Frederic Rossi (LMC) Frederic.Rossi at ericsson.ca
Fri Mar 21 06:14:48 PST 2003

Dave Olien wrote:

>OK, so there is a way to block event delivery.
>Code for libraries routines in libc for example,
>won't be modified to block events.

I hope not. It would too much complicated and not really interesting. Which
one should be blocked and why. It depends on event types.

>So the application would have to block event delivery before
>calling a library routine that might be vulnerable to
>event delivery.  Vulnerable library routines are ones
>that are called from within both event handler context
>and from "main level" context.
>Likewise, any user-mode lock that's acquired both
>in "main level" context and from within an event
>handler, should block event delivery before acquiring
>the lock.

When running a handler a process cannot be interupted to execute
another handler. But it can be interupted when running the main code.

Stopping and starting events are especially usefull during the process 
startup. So that
an application can register as many events as it wants without being 
interrupted and
start the all thing at the end (or whenever it wants).

>On Thu, Mar 20, 2003 at 03:20:51PM -0500, Frederic Rossi (LMC) wrote:
>>Yes it is possible to control event delivery from user space. throught the
>>evctl system call. It is possible to start/stop events. Although I don't 
>>call it 'defer'  because it implies queueing and AEM doesn't perform 
>>by itself.
>>cgl_discussion mailing list
>>cgl_discussion at lists.osdl.org

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