Re: [Xen-devel] [RFC Design Doc v2] Add vNVDIMM support for Xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.08.16 at 12:08, <haozhong.zhang@xxxxxxxxx> wrote:
> On 08/03/16 03:47, Jan Beulich wrote:
>> >>> On 03.08.16 at 11:37, <haozhong.zhang@xxxxxxxxx> wrote:
>> > By using the file name, e.g. if I specify vnvdimm = [ 'file=/mnt/dax/foo' ]
>> > in a domain config file, SPA occupied by /mnt/dax/foo are mapped to
>> > the domain.  If the same file is used every time the domain is created,
>> > the same virtual device will be seen by that domain.
>> 
>> So what if the file got deleted and re-created in between? Since
>> I don't think you can specify the SPAs to use when creating such
>> a file, such an operation would be quite different from removing
>> and re-adding e.g. a specific PCI device (to be used by a guest)
>> on a host (while the guest is not running).
> 
> If modified in between, guest will see a virtual pmem device of
> different data. But the usage of pmem is similar to disk: if a file of
> the same content is given every time, the guest can get a virtual
> pmem/disk of the same data as last reboot/shutdown; keeping the data
> unchanged between multiple boots is out of the scope of Xen.

Except that here we're talking of handing a piece of hardware to a
guest, which to me is more like a PCI device than a (virtual) disk. But
anyway ...

Jan


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