Re: [Xen-devel] What runtime states to be preserved across save / restore?

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Apr 29, 2014 at 12:40:15PM +0200, Daniel Kiper wrote:
> On Tue, Apr 29, 2014 at 10:05:26AM +0100, Wei Liu wrote:
> > On Tue, Apr 29, 2014 at 09:29:10AM +0200, Daniel Kiper wrote:
> > > On Mon, Apr 28, 2014 at 03:16:17PM +0100, Ian Campbell wrote:
> > > > On Mon, 2014-04-28 at 14:57 +0100, Wei Liu wrote:
> > > >
> > > > > > Other things I can think of right now:
> > > > > >
> > > > > >       * The devid of each device -- for some classes these can be
> > > > > >         automatically assigned, I'm not really sure if that needs
> > > > > >         preserving or not.
> > > > >
> > > > > I don't think so. The receiving end should make its own decision.
> > > >
> > > > Having eth0 become eth1 over migrate would be surprising though,
> > > > wouldn't it?
> > > >
> > > > > >       * Hotplug of devices more generally
> > > > > >
> > > > >
> > > > > Scripts? If so, they, with the things you mentioned below ...
> > > >
> > > > Not script, I meant e.g. xl block-attach and stuff like that.
> > >
> > > Do not forget about memory hotplug and in general memory != maxmem.
> > > This stuff is also important in migration case.
> > >
> >
> > I think max memory and target memory are easy -- I can retrieve them
> > from xenstore. But where can I get information about memory hotplug?
> > If the relevant bits are missing in libxl then I think we need another
> > series to address this problem.
> 
> I think that target and max memory should be sufficient. I mentioned

Cool!

> about that because when I tested migration with xm a few years ago
> I was not able to migrate machine which had hotplugged memory. IIRC
> it happened because migration process refered to config file instead
> of checking relevant values in xenstore. Acording to my knowledge save
> and restore machinery is (or was) used for migration. Correct me
> if I am wrong.
> 

You're right about this. ;-)

Wei.

> Daniel

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