Re: [PATCH v6 09/18] libxl: add save/restore support for qemu-xen in stubdomain

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Mon, May 18, 2020 at 10:24 AM Ian Jackson <ian.jackson@xxxxxxxxxx> wrote:
>
> Jason Andryuk writes ("[PATCH v6 09/18] libxl: add save/restore support for 
> qemu-xen in stubdomain"):
> > From: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> ...
> >      if (state->saved_state) {
> > -        /* This file descriptor is meant to be used by QEMU */
> > -        *dm_state_fd = open(state->saved_state, O_RDONLY);
> > -        flexarray_append(dm_args, "-incoming");
> > -        flexarray_append(dm_args, GCSPRINTF("fd:%d",*dm_state_fd));
> > +        if (is_stubdom) {
> > +            /* Linux stubdomain must replace $STUBDOM_RESTORE_INCOMING_ARG
> > +             * with the approriate fd:$num argument for the
> > +             * STUBDOM_CONSOLE_RESTORE console 2.
> > +             */
> > +            flexarray_append(dm_args, "-incoming");
> > +            flexarray_append(dm_args, "$STUBDOM_RESTORE_INCOMING_ARG");
> > +        } else {
> > +            /* This file descriptor is meant to be used by QEMU */
> > +            *dm_state_fd = open(state->saved_state, O_RDONLY);
> > +            flexarray_append(dm_args, "-incoming");
> > +            flexarray_append(dm_args, GCSPRINTF("fd:%d",*dm_state_fd));
>
> Hrk.  The stubdom script is expected to spot this particular value in
> the dm_args array and seddery it.  OK.  This is, at leasst, sound.
> I'm happy with the code and the protocol.
>
> I think this needs a change to this doc:
>
>   Subject: [PATCH v6 01/18] Document ioemu MiniOS stubdomain protocol
>
>   +Toolstack to MiniOS ioemu stubdomain protocol
>   +---------------------------------------------
>
> Provided that you update the docs commit and take my ack off that,
> please add my ack to this code :-).

I updated "[PATCH v6 02/18] Document ioemu Linux stubdomain protocol"
to mention $STUBDOM_RESTORE_INCOMING_ARG as well as the xenstore
directory change to "dm-argv" in this v6, but I left your Ack on it.
Sorry about that.  I'll remove your Ack from 02/18 when I post v7,
but I'll add the Ack to this 09/18.

-Jason