Re: [Qemu-devel] [RFC PATCH qemu] exec: Destroy dispatch immediately

[Paolo Bonzini]

On 25/08/2017 15:19, David Gibson wrote:
> On Fri, Aug 25, 2017 at 11:57:26AM +0200, Paolo Bonzini wrote:
>> On 25/08/2017 11:22, Peter Maydell wrote:
>>> On 25 August 2017 at 09:53, Paolo Bonzini <address@hidden> wrote:
>>>> The solution is to: 1) share the FlatView structures if they refer to
>>>> the same root memory region; 2) have one AddressSpaceDispatch per
>>>> FlatView instead of one per AddressSpace, so that FlatView reference
>>>> counting takes care of clearing the AddressSpaceDispatch too.  Neither
>>>> is particularly hard.
>>> If we did this we could get rid of address_space_init_shareable(),
>>> right? (It's a bit of a cheesy hack aimed at avoiding having duplicate
>>> address space structures for the same root memory region, but if
>>> the underlying code is better at not duplicating all the data
>>> structures unless necessary then the benefit of having the
>>> separate API goes away I think.)
>>
>> Yes, indeed.
> 
> Hm.  Why do we need to construct full ASes for virtio-blk, rather than
> just MRs?

It's an artifact of how virtio_address_space_read and
virtio_address_space_write are implemented.

Paolo

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