Re: [Qemu-devel] [RFC PATCH qemu 2/4] memory: Prepare for shared flat views

[Alexey Kardashevskiy]

On 09/09/17 17:18, David Gibson wrote:
> On Thu, Sep 07, 2017 at 07:20:08PM +1000, Alexey Kardashevskiy wrote:
>> We are going to share flat views and dispatch trees between address
>> spaces. This moves bits around but no change in behaviour is expected
>> here. The following patch will implement sharing.
>>
>> This switches from AddressSpace to AddressSpaceDispatch as in many
>> places this is what is used actually. Also, since multiple address
>> spaces will be sharing a flat view, MemoryRegionSection cannot store
>> the address space pointer, this changes it to AddressSpaceDispatch
>> as well. As a not very obvious result, IOMMUTLBEntry also switched
>> from AddressSpace to AddressSpaceDispatch to make
>> address_space_get_iotlb_entry() work.
> 
> So, mostly this seems to be exposing AddressSpaceDispatch in more
> places.  It's not obvious to me why that's useful.


It is mostly for IOMMUs - since dispatch tree and flat view is shared among
address spaces, I cannot use address spaces in iommu_ops::translate - too
ambiguous - "use any attached to this flatview/dispatch" is just  confusing.


-- 
Alexey

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