Re: [PATCH] virtio-spec: balloon: MUST_TELL_HOST is optional

[Rusty Russell <rusty@rustcorp.com.au>]

"Michael S. Tsirkin" <mst@redhat.com> writes:
> On Sun, Sep 09, 2012 at 02:36:50PM +0300, Michael S. Tsirkin wrote:
>> Drivers treat MUST_TELL_HOST as optional: windows drivers do not ack it
>> and expect this means they can tell host *after* deflate.  This was not
>> the intent but the documentation was not very clear on this point.
>> 
>> Luckily hyprevisors did not implement this feature yet so to provide
>> guidance for future devices make spec match drivers expectations, and
>> clarify that this feature only has effect if negotiated.
>> This is needed as recent developments in kvm (memory
>> region rework and the addition of vfio) finally make
>> it practical to implement this in devices.
>> 
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>
> ping

OK, I just s/set/negotiated:

--- virtio-spec.txt.old	2013-06-17 16:03:51.875066122 +0930
+++ virtio-spec.txt	2013-06-17 16:07:42.291063924 +0930
@@ -2411,9 +2411,9 @@
     it has previously given to the balloon, as described above. 
     This descriptor is added to the deflateq.
 
-  (b) If the VIRTIO_BALLOON_F_MUST_TELL_HOST feature is set, the 
-    guest may not use these requested pages until that descriptor 
-    in the deflateq has been used by the device.
+  (b) If the VIRTIO_BALLOON_F_MUST_TELL_HOST feature is 
+    negotiated, the guest may not use these requested pages until 
+    that descriptor in the deflateq has been used by the device.
 
   (c) Otherwise, the guest may begin to re-use pages previously 
     given to the balloon before the device has acknowledged their 

I'm think we get rid of the output queue for balloon in future.

Cheers,
Rusty.