> -----Original Message----- > From: Jürgen Groß <jgr...@suse.com> > Sent: 27 April 2020 16:14 > To: Paul Durrant <p...@xen.org>; xen-devel@lists.xenproject.org > Cc: Paul Durrant <pdurr...@amazon.com>; Andrew Cooper > <andrew.coop...@citrix.com>; George Dunlap > <george.dun...@citrix.com>; Ian Jackson <ian.jack...@eu.citrix.com>; Jan > Beulich <jbeul...@suse.com>; > Julien Grall <jul...@xen.org>; Stefano Stabellini <sstabell...@kernel.org>; > Wei Liu <w...@xen.org> > Subject: Re: [PATCH v3] docs/designs: re-work the xenstore migration > document... > > On 27.04.20 17:06, Paul Durrant wrote: > > From: Paul Durrant <pdurr...@amazon.com> > > > > ... to specify a separate migration stream that will also be suitable for > > live update. > > > > The original scope of the document was to support non-cooperative migration > > of guests [1] but, since then, live update of xenstored has been brought > > into > > scope. Thus it makes more sense to define a separate image format for > > serializing xenstore state that is suitable for both purposes. > > > > The document has been limited to specifying a new image format. The > > mechanism > > for acquiring the image for live update or migration is not covered as that > > is more appropriately dealt with by a patch to docs/misc/xenstore.txt. It is > > also expected that, when the first implementation of live update or > > migration > > making use of this specification is committed, that the document is moved > > from > > docs/designs into docs/specs. > > > > NOTE: It will only be necessary to save and restore state for active > > xenstore > > connections, but the documentation for 'RESUME' in xenstore.txt > > implies > > otherwise. That command is unused so this patch deletes it from the > > specification. > > > > [1] See > > https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/designs/non-cooperative-migration.md > > > > Signed-off-by: Paul Durrant <pdurr...@amazon.com> > > --- > > Cc: Juergen Gross <jgr...@suse.com> > > Cc: Andrew Cooper <andrew.coop...@citrix.com> > > Cc: George Dunlap <george.dun...@citrix.com> > > Cc: Ian Jackson <ian.jack...@eu.citrix.com> > > Cc: Jan Beulich <jbeul...@suse.com> > > Cc: Julien Grall <jul...@xen.org> > > Cc: Stefano Stabellini <sstabell...@kernel.org> > > Cc: Wei Liu <w...@xen.org> > > > > v3: > > - Address missed comments from Juergen > > Not all :-( > > > > > v2: > > - Address comments from Juergen > > --- > > ... > > > +### NODE_DATA > > + > > +For live update the image format will contain a `NODE_DATA` record for each > > +node in xenstore. For migration it will only contain a record for the nodes > > +relating to the domain being migrated. The `NODE_DATA` may be related to > > +a _committed_ node (globally visible in xenstored) or a _pending_ node > > (created > > +or modified by a transaction for which there is also a `TRANSACTION_DATA` > > +record previously present). > > > > -The `TRANSACTION_START` operation does not allow specification of a > > -`<domid>`; it is assumed that the transaction pertains to the domain that > > -owns the shared ring over which the operation is passed. Neither does it > > -allow a `<transid>` to be specified; it is always chosen by xenstored. > > -Hence, for the tool-stack to be able to open a transaction on behalf of a > > -domain a new operation is needed: > > > > ``` > > -START_DOMAIN_TRANSACTION <domid>|<transid>| > > + 0 1 2 3 octet > > ++-------+-------+-------+-------+ > > +| conn-id | > > ++-------------------------------+ > > +| tx-id | > > ++---------------+---------------+ > > +| access | perm-count | > > ++---------------+---------------+ > > +| perm1 | > > ++-------------------------------+ > > +... > > ++-------------------------------+ > > +| permN | > > ++---------------+---------------+ > > +| path-len | value-len | > > ++---------------+---------------+ > > > path-len and value-len are still after perm1...permN, which makes it > impossible to include them in a struct. > > Could you please either move them before the perm array or tell me why > not?
Gah, sorry, I meant to move them and then forgot again. I'll send v4. Paul > > > Juergen