diff --git a/src/include/ipc/header.h b/src/include/ipc/header.h
index 436b150a3..d2734ecf7 100644
--- a/src/include/ipc/header.h
+++ b/src/include/ipc/header.h
@@ -19,7 +19,10 @@
 #include <stdint.h>
 
 /** \addtogroup sof_uapi uAPI
- *  SOF uAPI specification.
+ * SOF uAPI specification
+ *
+ * Message structure
+ * -----------------
  *
  * IPC messages have a prefixed 32 bit identifier made up as follows :-
  *
@@ -28,9 +31,36 @@
  * - C is command type (12 bits)
  * - N is the ID number (16 bits) - monotonic and overflows
  *
- * This is sent at the start of the IPM message in the mailbox. Messages should
- * not be sent in the doorbell (special exceptions for firmware).
-
+ * IPC ABI version compatibility rules
+ * -----------------------------------
+ *
+ * 1. FW binaries will only support one MAJOR ABI version which is advertised
+ *    to host at FW boot.
+ *
+ * 2. Host drivers will support the current and older MAJOR ABI versions of
+ *    the IPC ABI (up to a certain age to be determined by market information).
+ *
+ * 3. MINOR and PATCH ABI versions can differ between host and FW but must be
+ *    backwards compatible on both host and FW.
+ *
+ *    IPC messages sizes can be different for sender and receiver if MINOR or
+ *    PATCH ABI versions differ as new fields can be added to the end of
+ *    messages.
+ *
+ *    i) Sender > receiver: receiver only copies its own ABI structure size.
+ *
+ *    ii) Receiver > sender: receiver copies its own ABI size and zero pads
+ *                           new fields. i.e. new structure fields must be non
+ *                           zero to be activated.
+ *
+ * Guidelines for extending ABI compatible messages :-
+ *
+ * - i) Use reserved fields.
+ *
+ * - ii) Grow structure at the end.
+ *
+ * - iii) Iff (i) and (ii) are not possible then MAJOR ABI is bumped.
+ *
  *  @{
  */
 
diff --git a/src/ipc/handler.c b/src/ipc/handler.c
index 276f1e2aa..17a411ae8 100644
--- a/src/ipc/handler.c
+++ b/src/ipc/handler.c
@@ -59,35 +59,6 @@
 #define iGS(x) ((x) & SOF_GLB_TYPE_MASK)
 #define iCS(x) ((x) & SOF_CMD_TYPE_MASK)
 
-/*
- * IPC ABI version compatibility rules :-
- *
- * 1) FW binaries will only support one MAJOR ABI version which is advertised
- *    to host at FW boot.
- *
- * 2) Host drivers will support the current and older MAJOR ABI versions of
- *    the IPC ABI (up to a certain age to be determined by market information).
- *
- * 3) MINOR and PATCH ABI versions can differ between host and FW but must be
- *    backwards compatible on both host and FW.
- *
- *    IPC messages sizes can be different for sender and receiver if MINOR or
- *    PATCH ABI versions differ as new fields can be added to the end of
- *    messages.
- *
- *    i) Sender > receiver: receiver only copies it's own ABI structure size.
- *
- *    ii) Receiver > sender: receiver copies its's own ABI size and zero pads
- *                           new fields. i.e. new structure fields must be non
- *                           zero to be activated.
- *
- *    Guidelines for extending ABI compatible messages :-
- *
- *    i) Use reserved fields.
- *    ii) Grow structure at the end.
- *    iii) Iff (i) and (ii) are not possible then MAJOR ABI is bumped.
- */
-
 #define _IPC_COPY_CMD(rx, tx, rx_size)					\
 	do {								\
 		int ___ret;						\