doc: add note about SRIOV disable
Currently, Service VM may fail to shut down due to some enabled
VFs. ACRN doesn't disable VFs automatically.
In this patch, add a note for user to disable VFs before Service
VM shuts down.
@@ -338,3 +338,8 @@ ack message, and proceeds to shut itself down accordingly.
#. After receiving the ack message from all user VMs, the Lifecycle Manager
in the Service VM shuts down VM.
#. The hypervisor shuts down the system after all VMs have shut down.
+
+.. note:: If one or more virtual functions (VFs) of a SR-IOV device, e.g. GPU on Alder
+ Lake platform, are assigned to User VMs, extra steps should be taken by user to
+ disable all VFs before Service VM shuts down. Otherwise, Service VM may fail to
+ shut down due to some enabled VFs.
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