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

[Paolo Bonzini]

On 25/08/2017 10:31, Alexey Kardashevskiy wrote:
> 
> Interestingly, mem_add() from exec.c is called twice:
> as as->dispatch_listener.region_add() and
> as as->dispatch_listener.region_nop() - I did not understand
> the trick but it does not work if I remove the .region_nop() hook.
> How does it work? :)

Didn't note this.

The hooks are:

- region_add: a new MemoryRegionSection appeared compared to the
previous FlatView

- region_nop: a region that was in the previous FlatView stayed there

- region_del: a MemoryRegionSection disappeared compared to the previous
FlatView

Because the AddressSpaceDispatch is rebuilt from scratch, it cares about
both new (region_add) and existing (region_nop) regions.

Paolo