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SDRAM Controller (SDRC) Subsystem
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When all
[31:0] REQINFO bits are set to 0 the access to the region is not allowed.
Set the REQINFO[0] bit to 1 when NonHost-User-Functional-Data accesses are permitted in this region.
Set the REQINFO[1] bit to 1 when NonHost-User-Debug-Data accesses are permitted in this region.
Set the REQINFO[31] bit to 1 when Host-Supervisor-Debug-Opcode accesses are permitted in this region.
Any bit of the
[31:0] REQINFO field corresponds to a particular combination of the five
attribute bits. When all
[31:0] REQINFO bits are set to 1 the region is full-access allowed.
The firewall unit performs the following checks to authorize or reject an access to the external memory:
•
Compute the Region ID based on the transaction address.
•
Generate a violation if overlapping of firewall regions is detected.
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From the Region ID, get the attributes for the region that has been hit.
•
Check the transaction REQINFO attributes with respect to the region attributes (debug, privilege, type,
and host).
•
Reject the transaction if the attributes are not compatible.
•
From the Region ID and the transaction qualifiers (MCmd, ConnID), check the initiator permissions for
performing the access (read, write).
•
Reject the transaction if there is no permission.
The protection regions are organized in priority levels (from Level 0 to Level 2) to prevent problems with
overlapping region and corner cases associated with them; the lowest level has the lowest priority (see
).
2242
Memory Subsystem
SWPU177N – December 2009 – Revised November 2010
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