Re: [Qemu-devel] [RFC PATCH v0 2/2] spapr: Abort when HTAB of requested size isn't allocated

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Wed, Sep 23, 2015 at 01:29:51PM +1000, David Gibson wrote:
> On Tue, Sep 22, 2015 at 09:09:49AM +0530, Bharata B Rao wrote:
> > Terminate the guest when HTAB of requested size isn't allocated by
> > the host.
> > 
> > When memory hotplug is attempted on a guest that has booted with
> > less than requested HTAB size, the guest kernel will not be able
> > to gracefully fail the hotplug request. This patch will ensure that
> > we never end up in a situation where memory hotplug fails due to
> > less than requested HTAB size.
> > 
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> 
> > ---
> >  hw/ppc/spapr.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 4692122..66446af 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -992,6 +992,10 @@ static void spapr_alloc_htab(sPAPRMachineState *spapr)
> >  
> >      if (shift > 0) {
> >          /* Kernel handles htab, we don't need to allocate one */
> > +        if (shift != spapr->htab_shift) {
> > +            error_setg(&error_abort, "Failed to allocated requested HTAB size");

Do you think we should have a bit more verbose message here so that
use knows what action to take after this abortion ? Like

"Failed to allocate requested HTAB size, try with lower maxmem"

Regards,
Bharata.