diff --git a/qemu/include/exec/exec-all.h b/qemu/include/exec/exec-all.h
index 134c7214..7de531ee 100644
--- a/qemu/include/exec/exec-all.h
+++ b/qemu/include/exec/exec-all.h
@@ -212,7 +212,23 @@ static inline void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr)
 {
 }
 #endif
-
+/**
+ * probe_access:
+ * @env: CPUArchState
+ * @addr: guest virtual address to look up
+ * @size: size of the access
+ * @access_type: read, write or execute permission
+ * @mmu_idx: MMU index to use for lookup
+ * @retaddr: return address for unwinding
+ *
+ * Look up the guest virtual address @addr.  Raise an exception if the
+ * page does not satisfy @access_type.  Raise an exception if the
+ * access (@addr, @size) hits a watchpoint.  For writes, mark a clean
+ * page as dirty.
+ *
+ * Finally, return the host address for a page that is backed by RAM,
+ * or NULL if the page requires I/O.
+ */
 void *probe_access(CPUArchState *env, target_ulong addr, int size,
                    MMUAccessType access_type, int mmu_idx, uintptr_t retaddr);