Re: [Qemu-devel] [PATCH v2 00/38] Delay destruction of memory regions to instance_finalize

[Paolo Bonzini]

Il 03/09/2013 14:32, Paolo Bonzini ha scritto:
> QOM splits the destruction of a device in two phases:
> 
> - unrealize, also known as "exit" from qdev times, should isolate
>   the device from the guest.  After unrealize returns, the guest
>   should not be able to issue new requests.
> 
> - instance_finalize will reclaim the memory.  This is only called
>   after all requests terminate and drop the references on the
>   device.
> 
> Though overlooked, this is important even now: QEMU's little secret is
> that devices already do access memory out of the iothread mutex (with
> address_space_map/unmap and AIO), and this can be MMIO memory too
> through a bounce buffer.  This series prepares things so that, once
> we'll put the memory_region_ref/unref infrastructure to complete use,
> things will just work.
> 
> Of course this split will be particularly important for devices that
> will be able to do unlocked MMIO.
> 
> This series changes all PCI devices (the sole to support hotplug _and_
> use MemoryRegions) to do memory_region_del_subregion at unrealize time,
> and memory_region_destroy at instance_finalize time.  As it is mostly
> a PCI patch, it should go through mst's tree.

Ping.

Paolo