RE: [Xen-devel] event_lock not initialized in the idle domain (permitted actions in a tasklet?)

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>]

Well, [prepare_]wait_on_xen_event_channel() makes no sense to call on another 
domain, certainly given their current implementation. But 
notify_via_xen_event_channel() could, and you could add a domain parameter to 
it.

I don't know what dom0 does while the page is paged in? Probably just throws an 
error code and carries on? In which case thinking about 
[prepare_]wait_on_xen_event_channel() further would not be necessary, as a dom0 
code path can just notify on teh channel and carry on its way.

 -- Keir
________________________________________
From: Byrne, John (HP Labs) [john.l.byrne@xxxxxx]
Sent: Saturday, April 24, 2010 1:30 AM
To: Keir Fraser
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel] event_lock not initialized in the idle domain 
(permitted actions in a tasklet?)

Unfortunately, in the page sharing case as of now, p2m_mem_paging_populate() 
(which will eventually want to send the event) can be called from dom0 in the 
grant code. (Maybe you can see a way to re-engineer this, but it is not obvious 
to me.)  So, I need an interface that allows me to specify the domain. I don't 
see one for Xen event channels and the cleanest way I see to implement this is 
to simply add one. I'm certainly open to suggestions.

The handling in the grant code for paging is pretty ugly. There are a couple of 
holes. The biggest is that I don't see an obvious way to keep mapped grant 
pages from being evicted, again. However, I think it will work well enough for 
me to test what I need.

John




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