[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 7/7] xl: allow domid to be preserved on save/restore or migrate
On Sat, Feb 01, 2020 at 11:56:19AM +0000, Durrant, Paul wrote: > > -----Original Message----- > > From: Wei Liu <wl@xxxxxxx> > > Sent: 31 January 2020 16:08 > > To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > > Cc: Durrant, Paul <pdurrant@xxxxxxxxxxxx>; Ian Jackson > > <ian.jackson@xxxxxxxxxx>; Anthony Perard <anthony.perard@xxxxxxxxxx>; xen- > > devel@xxxxxxxxxxxxxxxxxxxx; Wei Liu <wl@xxxxxxx> > > Subject: Re: [Xen-devel] [PATCH v4 7/7] xl: allow domid to be preserved on > > save/restore or migrate > > > > On Thu, Jan 30, 2020 at 06:20:08PM +0000, Andrew Cooper wrote: > > > On 30/01/2020 17:42, Durrant, Paul wrote: > > > >> -----Original Message----- > > > >> From: Ian Jackson <ian.jackson@xxxxxxxxxx> > > > >> Sent: 30 January 2020 17:29 > > > >> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx> > > > >> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Wei Liu <wl@xxxxxxx>; Anthony > > Perard > > > >> <anthony.perard@xxxxxxxxxx> > > > >> Subject: Re: [PATCH v4 7/7] xl: allow domid to be preserved on > > > >> save/restore or migrate > > > >> > > > >> Paul Durrant writes ("[PATCH v4 7/7] xl: allow domid to be preserved > > on > > > >> save/restore or migrate"): > > > >>> This patch adds a '-D' command line option to save and migrate to > > allow > > > >>> the domain id to be incorporated into the saved domain configuration > > and > > > >>> hence be preserved. > > > >> Thanks. > > > >> > > > >> In response to v3 6/6 I wrote: > > > >> > > > >> I wonder if this should be done more in libxl. Should this be a > > > >> domain property ? Wei, Anthony ? > > > >> > > > >> This question remains unanswered. I'm sorry that neither Wei nor > > > >> Anthony had a chance to answer yet... > > > >> > > > >> Paul, do you have a reason for doing it this way ? My inclination is > > > >> that think doing it at the libxl layer would make more sense. Do you > > > >> think that would be possible ? > > > >> > > > > I'm not sure how it would work at the libxl level as the domid is > > > > part of create_info and that it transferred by xl on migration. IIUC > > > > we'd need a new libxl save record to transfer it at that level, and > > > > then I'm not sure whether we'd hit an ordering problem as we'd have > > > > to dig that save record out before we could actually create the > > > > domain. > > > > > > There is definitely an ordering problem. > > > > > > I agree that it should logically be part of the libxl level of the > > > stream, but none of that is even parsed until after the domain has been > > > created on the destination side. > > > > > > I have no idea how easy/difficult it would be to rearrange libxl to > > > start parsing the migration stream before creating the domain. I think > > > there will be a lot of code relying on the domid already being valid. > > > > This. > > > > The other way I can think of is to specify something (domid policy??) in > > create_info and apply it during domain creation. But that reeks like a > > layering violation to me. > > > > That's basically what this series does, but I don't see it as a > layering violation. It has always been the case that xl is in control > of the domain creation and then passes the migration stream into > libxl. Passing in a 'domid policy' (specific value, 'random', or > 'allocated by Xen') as part of create_info, and not messing with the > libxl migration data, seems like the right approach to me... which is > why I've done it that way. Going through the code more carefully I think your implementation should be fine. Wei. > > Paul _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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