Re: [Qemu-devel] [PATCH] migrate: Migration aborts abruptly for machine "none"

[Daniel P. Berrange]

On Fri, Jan 27, 2017 at 03:22:38PM +0530, Ashijeet Acharya wrote:
> Okay
> 
> On Friday, 27 January 2017, Daniel P. Berrange <address@hidden> wrote:
> 
> > On Thu, Jan 26, 2017 at 02:46:52PM +0530, Ashijeet Acharya wrote:
> > > Migration of a "none" machine with no RAM crashes abruptly as
> > > bitmap_new() fails and thus aborts. Instead, place a check for
> > > last_ram_offset() being '0' at the start of ram_save_setup() and
> > > error out with a meaningful error message.
> > >
> > > Signed-off-by: Ashijeet Acharya <address@hidden
> > <javascript:;>>
> > > ---
> > >  migration/ram.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > >
> > > diff --git a/migration/ram.c b/migration/ram.c
> > > index ef8fadf..bf05d69 100644
> > > --- a/migration/ram.c
> > > +++ b/migration/ram.c
> > > @@ -1947,6 +1947,11 @@ static int ram_save_setup(QEMUFile *f, void
> > *opaque)
> > >  {
> > >      RAMBlock *block;
> > >
> > > +    if (last_ram_offset() == 0) {
> > > +        error_report("Failed to migrate: No RAM available!");
> > > +        return -1;
> > > +    }
> > > +
> >
> > If we're merely going to block migration, as opposed to making it work,
> > then IMHO we should use migration blockers registered at machine setup
> > for this task.
> >
> > We have a new cli arg added to QEMU to tell it to abort startup if the
> > machine configuration is not migratable. That only works if using
> 
> 
> Are you referring to the new "--only-migratable" option I added along with
> John last week?
> 
> migration blockers - this check you've added is too late to be detected
> > at startup.
> 
> 
> I think that the machine is not completely 'non-migratable' because if I
> boot qemu with "-m 1G" (say) the migration actually completes successfully.

Of course - you would only add the migration blocker when ram size is 0


Regards,
Daniel
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