Re: [Qemu-devel] [PATCH RFC 00/10] qdev: Hotplug handler chaining + virtio-pmem

[David Hildenbrand <david@redhat.com>]

On 16.01.19 12:35, David Hildenbrand wrote:
> This series implements supprt for hotplug handler chaining (proposed
> by Igor), something that is necessary to turn selected virtio devices into
> memory devices. Planned devices inlude virtio-mem and virtio-pmem. The
> current prototype of virtio-pmem is included.
> 
> The machine hotplug handler can intercept hotplug handler calls
> to properly prepare/teardown the memory device part of a device. Control
> is then passed on to the actual bus hotplug handler. So the default hotplug
> handler is effectively overwritten to make interception possible.
> 
> It is based on the following patches/series
> - [PULL v2 01/49] pci/pcie: stop plug/unplug if the slot is locked
> -- Soon upstream
> - [PATCH v1] pc: Use hotplug_handler_(plug|unplug|unplug_request)
> -- Queued by Paolo
> - [PATCH v2 0/6] s390x/pci: hotplug handler fixes and reworks
> -- Partially queued
> 
> Patch 1-3 are the preparations for hotplug handler chaining. The remaining
> patches are a modified prototype of virtio-pmem.
> 
> I modified Pankajs work to work with this series. virtio-pmem is included
> as it was requested during review of previous preparations to showcase a
> real user, so we can discuss if this is good enough for us or if we have
> to do further changes.
> 
> More details about virtio-pmem (including the Linux guest driver side)
> can be found at:
>     https://lkml.org/lkml/2018/7/13/102
>     https://lkml.org/lkml/2019/1/9/756
> 
> Example: defining a simple virtio-pmem device (on /dev/zero for simplicity):
> 
>     qemu-system-x86_64 \
>      -machine pc \
>      -monitor stdio \
>      -m 8G,maxmem=20G \
>      -object memory-backend-file,id=mem1,mem-path=/dev/zero,size=4G \
>      -device virtio-pmem-pci,id=vp1,memdev=mem1
> 
> QEMU 3.0.50 monitor - type 'help' for more information
> (qemu) info memory-devices
> Memory device [virtio-pmem]: "vp1"
>   memaddr: 0x240000000
>   size: 4294967296
>   memdev: /objects/mem1
> 
> (qemu) info memory_size_summary
> base memory: 8589934592
> plugged memory: 4294967296
> 

The current state can be found on:
https://github.com/davidhildenbrand/qemu.git : memory_device

-- 

Thanks,

David / dhildenb