Re: [Qemu-devel] [PATCH 4/5] Disable XBZRLE during migrate to file if it is active

[Paolo Bonzini]

> On 01/30/2013 12:49 PM, Paolo Bonzini wrote:
> >> XBZRLE is not effective when migrating to file.
> >>
> >> Disabling it automatically will remove the need to update the
> >> command line to allow loading a guest from a file that was in
> >> XBZRLE format.
> > 
> > What about savevm?
> I think a user that activate the XBZRLE capability before doing
> savevm
> can do that also before doing loadvm so I leave it up to him.
> The problem with exec is that we load the file from command line and
> than the user can't activate XBZRLE from the monitor or QMP.
> So he gets an error at the moment.

Honest question: why do we need to activate XBZRLE at load time?
The stream should just work, you do not need a cache do you?

In other words, can you simply remove the "if" from

         } else if (flags & RAM_SAVE_FLAG_XBZRLE) {
-            if (!migrate_use_xbzrle()) {
-                return -EINVAL;
-            }
             void *host = host_from_stream_offset(f, addr, flags);
             if (!host) {
                 return -EINVAL;
             }
 
             if (load_xbzrle(f, addr, host) < 0) {
                 ret = -EINVAL;
                 goto done;
             }

?

Paolo