3.3.11 Shareable Override Register

This register overrides the shareability characteristics of Normal transactions that are received on the relevant interface. Overriding of the shareability settings does not occur for FIXED bursts, Device transactions, or DVM message transactions.

Usage constraints
This register is for ACE-Lite slave interfaces only.
Accessible using only Secure accesses, unless you set the Secure Access Register to permit Non-secure accesses.
Configurations
Available in all CCI-550 configurations.
An instance of this register exists for each slave interface.
Attributes
See 3.2 Register summary for more information.

Note

Exclusive accesses must not be issued on an interface that is being overridden as shareable. If the CCI-550 is programmed to override transactions as shareable, exclusive accesses are overridden to normal accesses. An exclusive write then receives an OKAY response to indicate that the slave does not support exclusive accesses.
The following figure shows the bit assignments.
Figure 3-9 share_ovr register bit assignments
To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.

The following table shows the bit assignments.

Table 3-12 share_ovr register bit assignments

Bits
Name
Function
[31:2]
Reserved
-
[1:0]
shareable_override
Shareable override for slave interface:
0b00-0b01Do not override AxDOMAIN inputs.
0b10
Override AxDOMAIN inputs to 0b00, meaning that all transactions are treated as Non-shareable:
  • ReadOnce becomes ReadNoSnoop.
  • WriteUnique and WriteLineUnique become WriteNoSnoop.
  • CleanShared, CleanInvalid, and MakeInvalid transactions do not generate snoops.
0b11
Override AxDOMAIN inputs to 0b01, meaning that all Normal transactions are treated as Shareable:
  • ReadNoSnoop becomes ReadOnce.
  • WriteNoSnoop becomes WriteUnique.
  • CleanShared, CleanInvalid, and MakeInvalid transactions generate snoops.
Related reference
3.3.2 Secure Access Register
Non-ConfidentialPDF file icon PDF versionARM 100282_0100_00_en
Copyright © 2015, 2016 ARM. All rights reserved.