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

[George Dunlap <george.dunlap@citrix.com>]

On 22/02/16 17:01, Paul Durrant wrote:
>> What you did in an earlier version of this series (correct me if I'm
>> wrong) is to make a separate hypercall for memory, but still keep using
>> the same internal implementation (i.e., still having a write_dm p2m type
>> and using rangesets to determine which ioreq server to give the
>> notification to).  But since the interface for memory looks exactly the
>> same as the interface for MMIO, at some point this morphed back to "use
>> xen_hvm_io_range but with a different range type (i.e., WP_MEM)".
>>
> 
> Yes, and that's now pointless since we're going to use purely p2m types for sending memory accesses to ioreq servers.
> 
>> From an *interface* perspective that makes sense, because in both cases
>> you want to be able to specify a domain, an ioreq server, and a range of
>> physical addresses.  I don't have any objection to the change you made
>> to hvm_op.h in this version of the series.
>>
> 
> No, if we are intercepting 'memory' purely by p2m type then there is no need for the additional range type.

So here seems to be the crux of our disagreement.

I don't understand why you think that the WP_MEM interface described in
patch 2 of this series can't be implemented using p2m types rather than
rangesets.

 -George