Re: [PATCH V2] Add flag to start info regarding virtual mapped p2m list

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2015-03-04 at 08:58 +0000, Jan Beulich wrote:
> >>> On 03.03.15 at 11:32, <JGross@suse.com> wrote:
> > On 03/03/2015 11:27 AM, Jan Beulich wrote:
> >>>>> On 03.03.15 at 10:29, <"jgross@suse.com".non-mime.internet> wrote:
> >>> In order to indicate the Xen tools capability to support the virtual
> >>> mapped linear p2m list instead the 3 level mfn tree add a flag to the
> >>> start_info page.
> >>>
> >>> Signed-off-by: Juergen Gross <jgross@suse.com>
> >>> ---
> >>>   xen/include/public/xen.h | 2 ++
> >>>   1 file changed, 2 insertions(+)
> >>>
> >>> diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
> >>> index 3703c39..36c6d62 100644
> >>> --- a/xen/include/public/xen.h
> >>> +++ b/xen/include/public/xen.h
> >>> @@ -777,6 +777,8 @@ typedef struct start_info start_info_t;
> >>>   #define SIF_INITDOMAIN    (1<<1)  /* Is this the initial control domain? */
> >>>   #define SIF_MULTIBOOT_MOD (1<<2)  /* Is mod_start a multiboot module? */
> >>>   #define SIF_MOD_START_PFN (1<<3)  /* Is mod_start a PFN? */
> >>> +#define SIF_VIRT_P2M      (1<<4)  /* Does Xen understand a virt. mapped P->M 
> > */
> >>> +                                  /* making the 3 level tree obsolete?      
> >  */
> >>>   #define SIF_PM_MASK       (0xFF<<8) /* reserve 1 byte for xen-pm options */
> >>>
> >>>   /*
> >>
> >> Is there any reason why this can't be part of the tools patch (series)
> >> actually going to make use of it?
> > 
> > The main reason is I want to make use of it in the related kernel
> > series first. And this requires the Xen header implementation.
> 
> I was about to apply v3, but I'm still unconvinced: How would you
> test those kernel side changes without having anything to set the
> flag?

It does seem odd to be committing to an ABI with no xen.git side
implementation having been posted yet. Normally we ask that things go
into xen.git first before any guests start using them.

Ian.