diff --git a/qemu-options.hx b/qemu-options.hx
index ec356f6..cde3fb5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1124,6 +1124,13 @@ card.
 QXL paravirtual graphic card.  It is VGA compatible (including VESA
 2.0 VBE support).  Works best with qxl guest drivers installed though.
 Recommended choice when using the spice protocol.
+
+You will need to add the agent port (and install vdagent in guest) for the
+dynamic resolution change to work:
+
+-device virtio-serial
+-chardev spicevmc,id=vdagent,debug=0,name=vdagent
+-device virtserialport,chardev=vdagent,name=com.redhat.spice.0
 @item tcx
 (sun4m only) Sun TCX framebuffer. This is the default framebuffer for
 sun4m machines and offers both 8-bit and 24-bit colour depths at a