Add support for lease transition

[src/drm-lease-manager.git] / README.md

diff --git a/README.md b/README.md
index 5368f6b..84af0a7 100644 (file)
--- a/README.md
+++ b/README.md
@@ -44,6 +44,26 @@ The names of the DRM leases will have the following pattern:
 So, for example, a DRM lease for the first LVDS device on the device `/dev/dri/card0` would be named
 `card0-LVDS-1`.
 
+### Dynamic lease transfer
+
+When `drm-lease-manager` is started with the `-t` option, the
+ownership of a leases resourses can be transfered from
+one client to another.
+
+This allows the ownership of the leased resources to be transferred
+without the display being closed and the screen blanking.
+`drm-lease-manager` handles the timing of the tranfser and manages the
+references to the DRM device, so that the last framebuffer of
+the old client stays on screen until the new client presents its first frame.
+
+The transition can be completed without direct communication between the old
+and new client applications, however, the client that the lease will be
+transitioned *from* must be able to handle unexpected lease revokation.
+Once the lease is revoked, all DRM API calls referring to the DRM
+resources managed by the lease will fail with -ENOENT.  The client
+should be able to gracefully handle this condition by, for example,
+pausing or shutting down its rendering operations.
+
 ## Client API usage
 
 The libdmclient handles all communication with the DRM Lease Manager and provides file descriptors that