On Mon, Feb 1, 2016 at 9:21 AM, Jan Beulich <jbeul...@suse.com> wrote:
> >>> On 01.02.16 at 15:45, <ian.campb...@citrix.com> wrote:
> > On Fri, 2016-01-29 at 09:47 -0700, Jan Beulich wrote:
> >> > > > On 29.01.16 at 17:32, <tleng...@novetta.com> wrote:
> >> > On Fri, Jan 29, 2016 at 9:19 AM, Jan Beulich <jbeul...@suse.com>
> wrote:
> >> > > > > > On 29.01.16 at 17:12, <tleng...@novetta.com> wrote:
> >> > > > On Fri, Jan 29, 2016 at 4:03 AM, Jan Beulich <jbeul...@suse.com>
> >> > > > wrote:
> >> > > > > > > > On 28.01.16 at 21:58, <tleng...@novetta.com> wrote:
> >> > > > > > --- a/xen/include/public/memory.h
> >> > > > > > +++ b/xen/include/public/memory.h
> >> > > > > > @@ -423,11 +423,14 @@ struct xen_mem_access_op {
> >> > > > > > /* xenmem_access_t */
> >> > > > > > uint8_t access;
> >> > > > > > domid_t domid;
> >> > > > > > + uint16_t altp2m_idx;
> >> > > > > > + uint16_t _pad;
> >> > > > > > /*
> >> > > > > > * Number of pages for set op
> >> > > > > > * Ignored on setting default access and other ops
> >> > > > > > */
> >> > > > > > uint32_t nr;
> >> > > > > > + uint32_t _pad2;
> >> > > > >
> >> > > > > Repeating what I had said on v1: So this is a tools only
> >> > > > > interface,
> >> > > > > yes. But it's not versioned (other than e.g. domctl and sysctl),
> >> > > > > so
> >> > > > > altering the interface structure is at least fragile.
> >> > > >
> >> > > > Not sure what I can do to address this.
> >> > >
> >> > > Deprecate the old interface and introduce a new one. But other
> >> > > maintainers' opinions would be welcome.
> >> >
> >> > That seems like a very heavy handed solution to me.
> >>
> >> I understand that - hence the request for others' opinions.
> >
> > It's unfortunate that we've found ourselves here, but I think rather than
> > deprecating the current and adding a new op alongside we should just
> accept
> > the one-time fragility this time around, add the version field as part of
> > this set of changes and try and remember to include a version number for
> > next time we add a tools only interface. I don't think xenaccess is yet
> > widely used outside of Tamas and the Bitdfender folks, who I would assume
> > can cope with such a change.
> >
> > I could accept changing the op number would make sense, but I don't think
> > we should deprecate the old one (which implies continuing to support it
> in
> > parallel)
>
Supporting the two versions in parallel is not much effort, we would just
have to add an extra check to the current version to fail if altp2m is
enabled.
Tamas
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