2.2. Snoop connectivity and control

The CCI-400 has a fully-connected snoop topology, so if they are enabled:

Snooping and DVM message broadcast are disabled at reset, so you must enable the appropriate masters for snooping and DVM messages using the Snoop Control Registers before shareable or DVM messages are sent to the CCI-400. See Snoop Control Registers.

Each ACE slave interface has programmable bits in the Snoop Control Registers. These bits control the issuing of snoop and DVM message requests on that interface.

Note

ACE-Lite slave interfaces have programmable bits to enable DVM messages only.

These programmable bits of the Snoop Control Registers are tied LOW at reset so you must program them HIGH for each master in the shareable domain before shareable transactions or DVM messages are sent to the CCI-400. Before disabling a master, you must disable snoop and DVM messages to that master by programming the relevant Snoop Control Register bits LOW.

To avoid deadlock through having AC requests enabled to interfaces where masters are not present, or not able to process them, the CCI-400 has the following hardware and software override mechanisms:

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