[Xen-devel] Re: [PATCH] xen: reduce severity of message about using v1 grant tables.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2009-12-02 at 19:33 +0000, Jeremy Fitzhardinge wrote: 
> On 12/02/09 11:28, Ian Campbell wrote:
> > From: Ian Campbell <ijc@xxxxxxxxxxxxxx>
> >
> > It's hardly the end of the world...
> >
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
> > Cc: Steven Smith <Steven.Smith@xxxxxxxxxxxxx>
> > ---
> >  drivers/xen/grant-table.c |   19 ++++++++++---------
> >  1 files changed, 10 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> > index 2240adf..85ce951 100644
> > --- a/drivers/xen/grant-table.c
> > +++ b/drivers/xen/grant-table.c
> > @@ -699,21 +699,22 @@ static void gnttab_request_version(void)
> >  
> >     gsv.version = 2;
> >     rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
> > -   if (rc == 0) {
> > +   if (rc == 0)
> >             grant_table_version = 2;
> > -           printk(KERN_NOTICE "Using V2 grant tables.\n");
> > -   } else {
> > +   else {
> >             if (grant_table_version == 2) {
> > -                   /* If we've already used version 2 features,
> > -                      but then suddenly discover that they're not
> > -                      available (e.g. migrating to an older
> > -                      version of Xen), almost unbounded badness
> > -                      can happen. */
> > +                   /*
> > +                    * If we've already used version 2 features,
> > +                    * but then suddenly discover that they're not
> > +                    * available (e.g. migrating to an older
> > +                    * version of Xen), almost unbounded badness
> > +                    * can happen.
> > +                    */
> >                     panic("we need grant tables version 2, but only version 
> > 1 is available");
> >   
> 
> Does it really need to be a panic?  Can't we just start failing all
> future operations?  Seems bad to take out the whole machine if we can
> just get away with crippling one device (especially if it can be
> recovered by downing it and re-upping a new one with nc1 and/or gt1).

Wouldn't there be (failing) grant table ops on the down path?

In any case doesn't it effect all devices since they all use the same
grant table?

Ian.

> 
>     J



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