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Date: Wed, 20 Mar 2013 13:05:21 -0400 (EDT)
From: Alon Levy <alevy@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/4] char: add a post_load callback
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To: Anthony Liguori <aliguori@us.ibm.com>
Cc: amit shah <amit.shah@redhat.com>, hdegoede@redhat.com, kraxel@redhat.com, qemu-devel@nongnu.org

> Alon Levy <alevy@redhat.com> writes:
> 
> > Signed-off-by: Alon Levy <alevy@redhat.com>
> > ---
> >  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?

> 
> Regards,
> 
> Anthony Liguori
> 
> >      void *opaque;
> >      int idle_tag;
> >      char *label;
> > @@ -144,6 +145,17 @@ void qemu_chr_fe_open(struct CharDriverState
> > *chr);
> >  void qemu_chr_fe_close(struct CharDriverState *chr);
> >  
> >  /**
> > + * @qemu_chr_fe_post_load:
> > + *
> > + * Indicate to backend that a migration has just completed. Must
> > be called when
> > + * the vm is in the running state.
> > + *
> > + * @connected true if frontend is still connected after migration,
> > false
> > + * otherwise.
> > + */
> > +void qemu_chr_fe_post_load(struct CharDriverState *chr, int
> > connected);
> > +
> > +/**
> >   * @qemu_chr_fe_printf:
> >   *
> >   * Write to a character backend using a printf style interface.
> > diff --git a/qemu-char.c b/qemu-char.c
> > index 4e011df..42c911f 100644
> > --- a/qemu-char.c
> > +++ b/qemu-char.c
> > @@ -3390,6 +3390,13 @@ void qemu_chr_fe_open(struct CharDriverState
> > *chr)
> >      }
> >  }
> >  
> > +void qemu_chr_fe_post_load(struct CharDriverState *chr, int
> > connected)
> > +{
> > +    if (chr->chr_post_load) {
> > +        chr->chr_post_load(chr, connected);
> > +    }
> > +}
> > +
> >  void qemu_chr_fe_close(struct CharDriverState *chr)
> >  {
> >      if (chr->chr_guest_close) {
> > --
> > 1.8.1.4
> 
> 
>