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Re: [Xen-devel] [PATCH v3 3/3] tools: introduce parameter max_wp_ram_ranges.

> From: Paul Durrant [mailto:Paul.Durrant@xxxxxxxxxx]
> Sent: Wednesday, February 17, 2016 4:58 PM
> >
> > btw does this design consider the case where multiple ioreq servers
> > may claim on same page?
> Yes it does and there are currently insufficient page types to allow any more 
> than a single
> ioreq server to claim a type. My plan is that, in future, we can add a p2t 
> mapping table to
> allow for more types and then introduce HVMMEM_ioreq_1, HVMMEM_ioreq_2, etc.

so these new types actually represent ioreq server ID, right? If yes I can then
understand your earlier explanations.

> > For example, different usages may both
> > want to capture write requests on the same set of pages (say XenGT
> > selectively write-protects a subset of pages due to shadow GTT, while
> > another agent wants to monitor all guest writes to any guest memory
> > page).
> Monitoring is a different thing altogether. Emulation is costly and not 
> something you'd want
> to use for that purpose. If you want to monitor writes then log-dirty already 
> exists for that
> purpose.


> >
> > Thanks
> > Kevin
> I hope my explanation helped. I think things will be clearer once I've had 
> chance to actually
> put together a design doc. and hack up a PoC (probably only for EPT at first).

Thanks for the help. Let's see whether we can have some solution ready for 4.7. 


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