Re: [Qemu-devel] [PATCH 1/4] char: add a post_load callback

[Hans de Goede]

Hi,

On 03/20/2013 07:59 PM, Anthony Liguori wrote:
> Alon Levy <address@hidden> writes:
>
> > > Alon Levy <address@hidden> writes:
> > >
> > > > Signed-off-by: Alon Levy <address@hidden>
> > > > ---
> > > >   include/char/char.h | 12 ++++++++++++
> > > >   qemu-char.c         |  7 +++++++
> > > >   2 files changed, 19 insertions(+)
> > > >
> > > > diff --git a/include/char/char.h b/include/char/char.h
> > > > index 0326b2a..0fdcaf9 100644
> > > > --- a/include/char/char.h
> > > > +++ b/include/char/char.h
> > > > @@ -70,6 +70,7 @@ struct CharDriverState {
> > > >       void (*chr_set_echo)(struct CharDriverState *chr, bool echo);
> > > >       void (*chr_guest_open)(struct CharDriverState *chr);
> > > >       void (*chr_guest_close)(struct CharDriverState *chr);
> > > > +    void (*chr_post_load)(struct CharDriverState *chr, int
> > > > connected);
> > >
> > > The character device layer should *not* be messing around with
> > > notifying
> > > migration state.
> > >
> > > I thought we previously discussed this?  Just implement a migration
> > > hook
> > > in the spice code.
> >
> > The thing Gerd objected to when I sent a patch doing just that was the
> > way I used the vmstate, one possible way to not have to use vmstate at
> > all is adding api for querying the current front end connected status,
> > like qemu_fe_is_connected. Is that acceptable?
>
> To determine if the backend is connected?

No to query if the front-end is connected to the guest, with virtio-ports
just because they are there does not mean the guest is listening,
so qemu_fe_is_connected is the right name, or maybe
qemu_fe_is_guest_connected

  If so, it's fine, but I'd
> suggest being more explicit and calling it qemu_fe_is_be_connected().

Definitely not qemu_fe_is_be_connected that would mean asking if a chardev
backend is connected, which is not what we're interested in (we're calling
this from a backend, so we know we're connected ourselves).

Regards,

Hans