[libvirt] [PATCH 0/2] memdev device: add share argument for type=file

[Daniel P. Berrange]

On Mon, Jun 30, 2014 at 10:39:05AM +0200, Martin Kletzander wrote:
> On Fri, Jun 27, 2014 at 10:53:10PM +0200, Michele Paolino wrote:
> >This patch enables the possibility to run a qemu virtual machine with the
> >share option for the memory-backend-file. The xml description looks like:
> >
> ><memdev type='file' share='on'>
> >   <name>ram0</name>
> >   <source mem-path='/hugetlbfs'/>
> >   <capacity unit='MiB'>1024</capacity>
> ></memdev>
> >
> >This work is based on the previous work of Chen Fan[1].
> >We are aware of the existing conflict with the previous numa patches[2].
> >We are sharing this because it is a dependency for some use cases of the
> >qemu vhost-user support(e.g. snabbswitch).
> >
> 
> There is one important thing left out.  What qemu uses as a memdev
> should not be exposed as such (a device) in the XML, that way the
> definition makes sense only for people aware of how qemu works, but
> we are trying to keep the XML as hypervisor-independent as possible.
> Of course only where applicable, many places must have
> hypervisor-dependent structures, but I don't think memory device is
> one of these exceptions.  All the options that qemu aspose as memdev
> options should be abstracted in the XML.  For example3, we already
> have an element in the XML that says "use hugepages as a backing for
> memory" and that element should be used for that.  I just skimmed the
> patches a bit, but it looks like none of the series works with that
> information or changes the behaviour based on that.

Agreed, we really don't want to expose memdev as a user visible
device, since it really isn't a guest device - this is entirely
host-side config information.


Regards,
Daniel
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