Re: [Xen-devel] [PATCH 0/2] Bulk mem-share identical domains

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Oct 08, 2015 at 03:07:19PM -0600, Tamas K Lengyel wrote:
> In case you miss it, there is now soft-reset support which dumps all
> > memory plus various states from one domain to another, and toolstack
> > will take care of QEMU and various userspace bits. This might be useful
> > to you?
> >
> > To be clear, this is just FYI, not suggesting we block this series.
> >
> > Wei.
> >
> 
> Hi Wei,
> it might be very useful but on a casual scan I couldn't really find much on
> the soft-reset option (no xl cmdline option and only a single call to
> xc_domain_soft_reset in libxl.c). For cloning I would need the origin
> domain to remain loaded as before (at least the memory, qemu can be killed)
> and then I would only need the QEMU setup bits from soft-reset. Any
> pointers on how to go about this would be very helpful ;)
> 

Soft-reset is in fact a slightly modified version of save / restore.  I
don't think you can directly use soft-reset to clone a domain.  What I
meant was you might be able to reuse some of the code in soft-reset, at
least on toolstack side.

For example, you can invent a hypercall to share all pages and transfer
states from a guest to another. In toolstack, you create a new domain,
save original domain's QEMU state, issue aforementioned hypercall (*),
and restore QEMU. It would still require some coding to disentangle
toolstack code to do what you need, but these different phases already
exist in toolstack code for soft-reset except for the hypercall.

What makes your need different from soft-reset is that, a) the hypercall is
different b) you don't destroy the original domain afterwards.

YMMV.

Wei.

> Thanks,
> Tamas

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