3.4.4. PROT[1:0]

The PROT[1:0] bus encodes information about the transfer. A memory management unit uses this signal to determine whether an access is from a privileged mode, and whether it is an opcode or a data fetch. This can therefore be used to implement an access permission scheme. The encoding of PROT[1:0] is shown in Table 3.4.

Table 3.4. PROT[1:0] encoding

PROT[1:0]

Mode

Opcode or data

b00

User

Opcode

b01

User

Data

b10

Privileged

Opcode

b11

Privileged

Data

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