libavf: Clarify what the “instanceId” is.
Bug: 383776459
Test: N/A
Change-Id: I504cbaef3e862f8233d0d7b28929ce90931b9c3b
diff --git a/libs/libavf/include/android/virtualization.h b/libs/libavf/include/android/virtualization.h
index 6b54bf7..ef57325 100644
--- a/libs/libavf/include/android/virtualization.h
+++ b/libs/libavf/include/android/virtualization.h
@@ -70,7 +70,13 @@
const char* _Nonnull name) __INTRODUCED_IN(36);
/**
- * Set an instance ID of a virtual machine.
+ * Set an instance ID of a virtual machine. Every virtual machine is identified by a unique
+ * `instanceId` which the virtual machine uses as its persistent identity while performing stateful
+ * operations that are expected to outlast single boot of the VM. For example, some virtual machines
+ * use it as a `Id` for storing secrets in Secretkeeper, which are retrieved on next boot of th VM.
+ *
+ * The `instanceId` is expected to be re-used for the VM instance with an associated state (secret,
+ * encrypted storage) - i.e., rebooting the VM must not change the instanceId.
*
* \param config a virtual machine config object.
* \param instanceId a pointer to a 64-byte buffer for the instance ID.