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The specification mentions that AxPROT[2] information is just a hint. Is the information given by the other AxPROT bits always accurate?

Applies to: AXI

Answer

The use of a cache can cause of misleading information on the AxPROT signals where data with different AxPROT values (such as instruction and data) resides in the same cache line. This can also be true where a write-back cache line holds both privileged and user data. Typically when a line is evicted from such a cache it will be written with privileged access although it may contain non-privileged data.

The security information given by AxPROT[1] will always be accurate and any cache used in a system that make use of the security features must be able to generate accurate AxPROT[1] information.

Article last edited on: 2008-09-09 15:47:45

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