Re: [Qemu-devel] [PATCH v3 11/29] vhost+postcopy: Transmit 'listen' to client

[Dr. David Alan Gilbert]

* Peter Xu (address@hidden) wrote:
> On Fri, Feb 16, 2018 at 01:16:07PM +0000, Dr. David Alan Gilbert (git) wrote:
> 
> [...]
> 
> >  typedef struct VuVirtqElement {
> > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> > index 621543e654..bdec9ec0e8 100644
> > --- a/docs/interop/vhost-user.txt
> > +++ b/docs/interop/vhost-user.txt
> > @@ -682,6 +682,12 @@ Master message types
> >        the slave must open a userfaultfd for later use.
> >        Note that at this stage the migration is still in precopy mode.
> >  
> > + * VHOST_USER_POSTCOPY_LISTEN
> > +      Id: 27
> > +      Master payload: N/A
> > +
> > +      Master advises slave that a transition to postcopy mode has happened.
> 
> Could we add something to explain why this listen needs to be
> broadcasted to clients?  Since I failed to find it out quickly
> myself. :(

I've changed this to:

 * VHOST_USER_POSTCOPY_LISTEN
      Id: 29
      Master payload: N/A

      Master advises slave that a transition to postcopy mode has happened.
      The slave must ensure that shared memory is registered with userfaultfd
      to cause faulting of non-present pages.

      This is always sent sometime after a VHOST_USER_POSTCOPY_ADVISE, and
      thus only when VHOST_USER_PROTOCOL_F_PAGEFAULT is supported.

Dave

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