Re: [Qemu-devel] [PATCH v4 24/47] Allow savevm handlers to state whether they could go into postcopy

[Dr. David Alan Gilbert]

* David Gibson (address@hidden) wrote:
> On Fri, Oct 03, 2014 at 06:47:30PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> > 
> > Use that to split the qemu_savevm_state_pending counts into postcopiable
> > and non-postcopiable amounts
> > 
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > ---
> >  arch_init.c                 |  7 +++++++
> >  include/migration/vmstate.h |  2 +-
> >  include/sysemu/sysemu.h     |  4 +++-
> >  migration.c                 |  9 ++++++++-
> >  savevm.c                    | 23 +++++++++++++++++++----
> >  5 files changed, 38 insertions(+), 7 deletions(-)
> > 
> > diff --git a/arch_init.c b/arch_init.c
> > index 6970733..44072d8 100644
> > --- a/arch_init.c
> > +++ b/arch_init.c
> > @@ -1192,6 +1192,12 @@ static int ram_load(QEMUFile *f, void *opaque, int 
> > version_id)
> >      return ret;
> >  }
> >  
> > +/* RAM's always up for postcopying */
> > +static bool ram_can_postcopy(void *opaque)
> > +{
> > +    return true;
> > +}
> > +
> >  static SaveVMHandlers savevm_ram_handlers = {
> >      .save_live_setup = ram_save_setup,
> >      .save_live_iterate = ram_save_iterate,
> > @@ -1199,6 +1205,7 @@ static SaveVMHandlers savevm_ram_handlers = {
> >      .save_live_pending = ram_save_pending,
> >      .load_state = ram_load,
> >      .cancel = ram_migration_cancel,
> > +    .can_postcopy = ram_can_postcopy,
> 
> Is there actually any plausible device for which you'd need a callback
> here, rather than just having a static bool?
> 
> On the other hand, it does seem kind of plausible that there might be
> situations in which some data from a device must be pre-copied, but
> more can be post-copied, which would necessitate extending the
> per-handler callback to return quantities for both.

It's cheap enough and I couldn't make a strong argument about
any possible device, so I just used the function.

Dave

> -- 
> David Gibson                  | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au        | minimalist, thank you.  NOT _the_ 
> _other_
>                               | _way_ _around_!
> http://www.ozlabs.org/~dgibson


--
Dr. David Alan Gilbert / address@hidden / Manchester, UK