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Date: Mon, 27 Jul 2015 18:38:02 +0100
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20150727173802.GC27613@work-vm>
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Subject: Re: [Qemu-devel] [PATCH v7 21/42] postcopy: OS support test
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To: Amit Shah <amit.shah@redhat.com>
Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, liang.z.li@intel.com, qemu-devel@nongnu.org, luis@cs.umu.se, pbonzini@redhat.com, david@gibson.dropbear.id.au

* Amit Shah (amit.shah@redhat.com) wrote:
> On (Tue) 16 Jun 2015 [11:26:34], Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Provide a check to see if the OS we're running on has all the bits
> > needed for postcopy.
> > 
> > Creates postcopy-ram.c which will get most of the other helpers we need.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> > @@ -1165,6 +1166,10 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
> >          return -1;
> >      }
> >  
> > +    if (!postcopy_ram_supported_by_host()) {
> > +        return -1;
> > +    }
> > +
> 
> So this is just advise: if we receive this, and we can't handle
> postcopy, we're going to abort migration?  Shouldn't we continue and
> let src know that we can't accept postcopy?  ie the problem is
> currently punted to higher levels, should we try to handle it
> ourselves?

We could, although it happens right at the start of migration, and it only
happens if you explicitly enabled the postcopy capability, so I'm not
sure there's any advantage in trying to fall back when you've been told
to use it.

Dave

> 
> 
> 
> 		Amit
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK