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

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 08/04/16 03:25, Jan Beulich wrote:
> >>> On 04.08.16 at 10:52, <haozhong.zhang@xxxxxxxxx> wrote:
> > On 08/03/16 17:25, Konrad Rzeszutek Wilk wrote:
> >> Anyhow, wouldn't this 'sizeof(struct page_info)' depend on the ndctl
> >> tool and what version was used to create this? What if one version
> >> used 32-bytes for a PAGE, while another used 64-bytes for a PAGE too?
> >> It would be a bit of catching up .. wait, this same problem MUST
> >> be with Linux? How does it deal with this?
> > 
> > Good question. Linux chooses a size (64 bytes) larger than its current
> > sizeof(struct page) (40 bytes). We may also do in the same way,
> > e.g. 32 bytes vs. 64 bytes?
> 
> I don't understand this: These structures aren't meant to be
> persistent, so their size shouldn't matter?
> 

But the size of the reserved area is persistent. If the size of struct
page_info increases in future versions, the reserved area which is
just enough for old version struct page_info would not be enough for
the new version.

Haozhong

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel