Re: [Qemu-devel] [RFC 21/29] migration: new cmd MIG_CMD_RECV_BITMAP

[Peter Xu <peterx@redhat.com>]

On Fri, Aug 04, 2017 at 02:08:33PM +0800, Peter Xu wrote:
> On Thu, Aug 03, 2017 at 10:49:02AM +0100, Dr. David Alan Gilbert wrote:
> > * Peter Xu (peterx@redhat.com) wrote:
> > > Add a new vm command MIG_CMD_RECV_BITMAP to request received bitmap for
> > > one ramblock.
> > > 
> > > Signed-off-by: Peter Xu <peterx@redhat.com>
> > > ---
> > >  migration/savevm.c     | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  migration/savevm.h     |  1 +
> > >  migration/trace-events |  1 +
> > >  3 files changed, 61 insertions(+)
> > > 
> > > diff --git a/migration/savevm.c b/migration/savevm.c
> > > index 386788d..0ab13c0 100644
> > > --- a/migration/savevm.c
> > > +++ b/migration/savevm.c
> > > @@ -78,6 +78,7 @@ enum qemu_vm_cmd {
> > >                                        were previously sent during
> > >                                        precopy but are dirty. */
> > >      MIG_CMD_PACKAGED,          /* Send a wrapped stream within this stream */
> > > +    MIG_CMD_RECV_BITMAP,       /* Request for recved bitmap on dst */
> > >      MIG_CMD_MAX
> > >  };
> > >  
> > > @@ -95,6 +96,7 @@ static struct mig_cmd_args {
> > >      [MIG_CMD_POSTCOPY_RAM_DISCARD] = {
> > >                                     .len = -1, .name = "POSTCOPY_RAM_DISCARD" },
> > >      [MIG_CMD_PACKAGED]         = { .len =  4, .name = "PACKAGED" },
> > > +    [MIG_CMD_RECV_BITMAP]      = { .len = -1, .name = "RECV_BITMAP" },
> > >      [MIG_CMD_MAX]              = { .len = -1, .name = "MAX" },
> > >  };
> > >  
> > > @@ -929,6 +931,19 @@ void qemu_savevm_send_postcopy_run(QEMUFile *f)
> > >      qemu_savevm_command_send(f, MIG_CMD_POSTCOPY_RUN, 0, NULL);
> > >  }
> > >  
> > > +void qemu_savevm_send_recv_bitmap(QEMUFile *f, char *block_name)
> > > +{
> > > +    size_t len;
> > > +    char buf[512];
> > 
> > Only needs to be 256 bytes?
> 
> Yes, it is.
> 
> Even, I guess I should use dynamic allocation, since 256 has the
> assumption of block_name size.

Oh wait - we will put the length into first byte, which cannot be
bigger than 255... I'll use 256 directly, then I guess I can keep the
r-b.   Thanks,

-- 
Peter Xu