Re: [Xen-devel] Memory Sharing

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Thu, Feb 4, 2016 at 2:04 PM, hanji unit <hanjiunit@xxxxxxxxx> wrote:

Hello, does Xen support sharing memory pages between multiple domains
(such as as Dom0, DomU1, DomU2)? The Grant Table hypercalls seem
limited to:

IOCTL_GNTALLOC_ALLOC_GREF
IOCTL_GNTALLOC_DEALLOC_GREF
IOCTL_GNTALLOC_SET_UNMAP_NOTIFY

Is there any mechanism to not allocate, but only share existing pages?

There is, it's call mem_share in Xen, but it's not very well (khm at all) documented. You can take a look at http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/tests/mem-sharing/memshrtool.c;h=437c7c9c472c0eff29b60e54f3de90e878de6d34;hb=HEAD to see an outline of the tools-side functions that control it. I also have a simple clone routine that deduplicates (clones) two identical VMs here https://github.com/tklengyel/drakvuf/blob/master/src/xen_helper/xen_helper.c#L197.

Cheers,

Tamas

Â

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