Re: [PATCH 07/10] xen/arm: intruduce alloc_domstatic_pages

[Julien Grall <julien@xxxxxxx>]

Hi Penny,

On 18/05/2021 09:57, Penny Zheng wrote:
> > -----Original Message-----
> > From: Jan Beulich <jbeulich@xxxxxxxx>
> > Sent: Tuesday, May 18, 2021 3:35 PM
> > To: Penny Zheng <Penny.Zheng@xxxxxxx>
> > Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>; Wei Chen
> > <Wei.Chen@xxxxxxx>; nd <nd@xxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx;
> > sstabellini@xxxxxxxxxx; julien@xxxxxxx
> > Subject: Re: [PATCH 07/10] xen/arm: intruduce alloc_domstatic_pages
> >
> > On 18.05.2021 07:21, Penny Zheng wrote:
> > > --- a/xen/common/page_alloc.c
> > > +++ b/xen/common/page_alloc.c
> > > @@ -2447,6 +2447,9 @@ int assign_pages(
> > >       {
> > >           ASSERT(page_get_owner(&pg[i]) == NULL);
> > >           page_set_owner(&pg[i], d);
> > > +        /* use page_set_reserved_owner to set its reserved domain owner.
> > */
> > > +        if ( (pg[i].count_info & PGC_reserved) )
> > > +            page_set_reserved_owner(&pg[i], d);
> > Now this is puzzling: What's the point of setting two owner fields to the same
> > value? I also don't recall you having introduced
> > page_set_reserved_owner() for x86, so how is this going to build there?
> Thanks for pointing out that it will fail on x86.
> As for the same value, sure, I shall change it to domid_t domid to record its 
> reserved owner.
> Only domid is enough for differentiate.
> And even when domain get rebooted, struct domain may be destroyed, but domid 
> will stays
> The same.
> Major user cases for domain on static allocation are referring to the whole 
> system are static,
> No runtime creation.
One may want to have static memory yet doesn't care about the domid. So 
I am not in favor to restrict about the domid unless there is no other way.
Cheers,

--
Julien Grall