Re: [virtio-dev] [PATCH] content: reserve device ID for virtio-pmem devices

[David Hildenbrand <david@redhat.com>]

On 22.05.2018 11:42, Stefan Hajnoczi wrote:
> On Fri, May 18, 2018 at 10:11:06AM +0530, Pankaj Gupta wrote:
>> We need a device ID for virtio-pmem devices. As 24 is already 
>> requested by virtio-mem, so requesting next available(25)
>>
>> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
>> ---
>>  content.tex | 2 ++
>>  1 file changed, 2 insertions(+)
> 
> virtio-mem is designed for hotplug.  Does it make sense to merge
> virtio-pmem into virtio-mem since you'll need hotplug too?
> 
> Stefan
> 
Hi Stefan,

Initially I had (and even proposed during some discussion) the same
idea. But it turns out that they are fundamentally different.

They are memory devices, yes, but that's the point where they stop being
similar.

While virtio-pmem wants to expose a memory region as persistent memory
and adding a flushing interface, virtio-mem is all about managing
(add/remove/online/offline) sub-chunks and applying protection
mechanisms on the hypervisor side to make sure unplugged memory cannot
(or only in some limited sense) be accessed.

-- 

Thanks,

David / dhildenb