Re: [Qemu-devel] [PATCH 56/56] docs/interop/qmp-spec: How to force known good parser state

[Eric Blake]

On 08/17/2018 06:16 AM, Markus Armbruster wrote:

> > > +2.7 QGA Synchronization
> > >    -----------------------
> > >      When using QGA, an additional synchronization feature is built
> > > into
> > > -the protocol.  If the Client sends a raw 0xFF sentinel byte (not valid
> > > -JSON), then the Server will reset its state and discard all pending
> > > -data prior to the sentinel.  Conversely, if the Client makes use of
> > > -the 'guest-sync-delimited' command, the Server will send a raw 0xFF
> > > -sentinel byte prior to its response, to aid the Client in discarding
> > > -any data prior to the sentinel.
> > > +the protocol. If the Client makes use of the 'guest-sync-delimited'
> > > +command, the Server will send a raw 0xFF sentinel byte prior to its
> > > +response, to aid the Client in discarding any data prior to the
> > > +sentinel.
> >
> > Maybe worth mentioning "including error messages reported about any
> > lexical errors received prior to the guest-sync-delimited command"
> >
> > >        3. QMP Examples
>
> What about:
>
>      2.7 QGA Synchronization
>      -----------------------
>
>      When a client connects to QGA over a transport lacking proper
>      connection semantics such as virtio-serial, QGA may have read partial
>      input from a previous client.  The client needs to force QGA's parser
>      into known-good state using the previous section's technique.
>      Moreover, the client may receive output a previous client didn't read.
>      To help with skipping that output, QGA provides the
>      'guest-sync-delimited' command.  Refer to its documentation for
>      details.

That works for me.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org