2.10. DVM messages

The ACE slave interfaces support DVM messages through their regular AC and CR channels. The ACE-Lite interfaces all contain AC and CR channels to support DVM messages only. Each slave interface has a programmable enable bit to determine whether it supports the issuing of AC requests for DVM messages. DVM messages are handled as regular transactions in the CCI-400, except that they are decoded based on the DVM message indicator, instead of the address, to ensure that multi-transaction DVM messages are correctly ordered.

The Snoop Control Registers and Control Override Register control the issuing of DVM message requests. See Snoop Control Registers and Control Override Register.

ACE and ACE-Lite, plus DVM slave interfaces support all types of DVM transaction. These are:

The R channel response to a DVM messages is sent immediately by the CCI-400. If the DVM message results in an error response, this is signaled imprecisely. For more information, see Error responses.

Note

A master that issues DVM messages must also be able to receive DVM messages. The slave interface through which the master connects must have DVM messages enabled.

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