diff --git a/virtio-spec.lyx b/virtio-spec.lyx
index 5c76a87..5da4fde 100644
--- a/virtio-spec.lyx
+++ b/virtio-spec.lyx
@@ -7267,6 +7267,20 @@ VIRTIO_BALLOON_F_STATS_VQ
 \end_inset
 
 (1) A virtqueue for reporting guest memory statistics is present.
+\change_inserted 1531152142 1347020627
+
+\end_layout
+
+\begin_layout Description
+
+\change_inserted 1531152142 1347020648
+VIRTIO_BALLOON_F_SILENT_DEFLATE
+\begin_inset space ~
+\end_inset
+
+(2) Guest need not tell host before pages from the balloon are used.
+\change_unchanged
+
 \end_layout
 
 \end_deeper
@@ -7627,6 +7641,168 @@ VIRTIO_BALLOON_S_MEMFREE The amount of memory not being used for any purpose
 VIRTIO_BALLOON_S_MEMTOT The total amount of memory available (in bytes).
 \end_layout
 
+\begin_layout Description
+
+\change_inserted 1531152142 1368005515
+Silent
+\begin_inset space ~
+\end_inset
+
+deflation
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+
+\series medium
+Some implementation of the balloon device may not require the guest to deflate
+ the balloon explicitly; instead, the guest may just take a page from its
+ reserve and start using it.
+ This is called 
+\begin_inset Quotes eld
+\end_inset
+
+silent deflate
+\begin_inset Quotes erd
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+In order to use this feature effectively, both the guest and the host need
+ to know how the other part intends to use the balloon.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+
+\series medium
+Guests may benefit from silent deflate by aggressively inflating the balloon;
+ they know that they will be able to use ballooned pages without issuing
+ a (blocking) request to the device.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+Knowing that the guest will 
+\emph on
+not
+\emph default
+ deflate silently also benefits the host.
+ For example, if the host is pinning the guest's memory, it may unpin ballooned
+ pages and pin them again upon deflation.
+ This allows cooperative memory overcommit even if the guest's memory is
+ pinned.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+Thus, there are two possibilities for the host (either it does not support
+ silent deflate, or it does), and three for the guest (it doesn't need silent
+ deflate, it may choose to use it if available, it requires it).
+ Because there are three possibilities for the guest, support for silent
+ deflate is represented by two different feature bits.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005515
+The feature bits are used as follows:
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1368005671
+if the host does not support silent deflate, it must propose the
+VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+CAN_\SpecialChar \-
+TELL_\SpecialChar \-
+HOST feature.
+ If the guest does 
+\emph on
+not
+\emph default
+ negotiate it, the host should assume that the guest will use silent deflate.
+ A host that does not support silent deflate then must do nothing on attempts
+ of the guest to deflate/inflate the balloon, except put the descriptors on
+ the used ring.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1368005515
+a guest that 
+\emph on
+must
+\emph default
+ use silent deflation does not need to negotiate any feature.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1368005676
+a guest that 
+\emph on
+will never
+\emph default
+ use silent deflation only has to propose VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+CAN_\SpecialChar \-
+TELL_\SpecialChar \-
+HOST.
+ It need not do anything if the host does not negotiate the feature.
+\end_layout
+
+\begin_layout Itemize
+
+\change_inserted 1531152142 1368005686
+a guest that 
+\emph on
+can optionally
+\emph default
+ use silent deflation should propose both VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+CAN_\SpecialChar \-
+TELL_\SpecialChar \-
+HOST
+ and VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+SILENT_\SpecialChar \-
+DEFLATE.
+ The guest driver can then use silent deflation if and only if the host
+ has negotiated VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+SILENT_\SpecialChar \-
+DEFLATE too.
+\end_layout
+
+\begin_layout Standard
+
+\change_inserted 1531152142 1368005690
+Hosts are free to propose the VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+CAN_\SpecialChar \-
+TELL_\SpecialChar \-
+HOST feature even if they support silent deflation.
+ It will
+ not affect operation of a well-behaving guest; such a guest
+ should never check if the host proposed the feature, and
+ should not assume that lack of this feature implies support
+ for silent deflation. The only bit to check for this purpose is
+ VIRTIO_\SpecialChar \-
+BALLOON_F_\SpecialChar \-
+SILENT_\SpecialChar \-
+DEFLATE.
+\end_layout
+
 \begin_layout Chapter*
 Appendix H: Rpmsg: Remote Processor Messaging
 \end_layout
