Re: [PATCH] tools/xenstore: set maximum number of grants needed

[Wei Liu <wl@xxxxxxx>]

On Wed, Sep 30, 2020 at 04:30:16PM +0100, Andrew Cooper wrote:
> On 30/09/2020 16:28, Wei Liu wrote:
> > On Wed, Sep 30, 2020 at 05:23:58PM +0200, Jürgen Groß wrote:
> >> On 30.09.20 17:14, Wei Liu wrote:
> >>> On Thu, Sep 24, 2020 at 04:36:48PM +0200, Juergen Gross wrote:
> >>>> When running as a stubdom Xenstore should set the maximum number of
> >>>> grants needed via a call of xengnttab_set_max_grants(), as otherwise
> >>>> the number of domains which can be supported will be 128 only (the
> >>>> default number of grants supported by Mini-OS).
> >>>>
> >>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >>>> ---
> >>>> This is a backport candidate IMO.
> >>>> ---
> >>>>   tools/xenstore/xenstored_domain.c | 2 ++
> >>>>   1 file changed, 2 insertions(+)
> >>>>
> >>>> diff --git a/tools/xenstore/xenstored_domain.c 
> >>>> b/tools/xenstore/xenstored_domain.c
> >>>> index 06359503f0..f740aa02f5 100644
> >>>> --- a/tools/xenstore/xenstored_domain.c
> >>>> +++ b/tools/xenstore/xenstored_domain.c
> >>>> @@ -630,6 +630,8 @@ void domain_init(void)
> >>>>          *xgt_handle = xengnttab_open(NULL, 0);
> >>>>          if (*xgt_handle == NULL)
> >>>>                  barf_perror("Failed to open connection to gnttab");
> >>>> +        /* Allow max number of domains for mappings. */
> >>>> +        xengnttab_set_max_grants(*xgt_handle, DOMID_FIRST_RESERVED);
> >>> Why DOMID_FIRST_RESERVED as the count argument? Is the expectation here
> >>> xenstored maps one grant per domain?
> >> Yes. This is the theoretical maximum.
> >>
> > In that case:
> >
> > Acked-by: Wei Liu <wl@xxxxxxx>
> >
> > I will also add that information to the commit message.
> 
> And the comment if possible please.  That's where it will be most useful
> to the next person doing a doubletake at this code.  :)

Yes sure.

Wei.

> 
> ~Andrew