Epson ARM720T Manuel D’Utilisation

On an abort, the MMU places an encoded 4-bit value, FS[3:0], along with the 4-bit encoded 

domain number, in the data FSR, and the MVA associated with the abort is latched into the 

FAR. If an access violation simultaneously generates more than one source of abort, they are 

Table 7-9 describes the various access permissions and controls supported by the data MMU 

and details how these are interpreted to generate faults.

 

Alignment faults can write either b0001 or b0011 into FS[3:0]. Invalid values in 

domains [3:0] can occur because the fault is raised before a valid domain field has 

been read from a page table descriptor. Any abort masked by the priority encoding 

can be regenerated by fixing the primary abort and restarting the instruction. 

Table 7-9  Priority encoding of fault status

Highest

Alignment

-

b00x1

Invalid

MVA of access 
causing abort

Translation

Section
Page

b0101
b0111

Invalid
Valid

MVA of access 
causing abort

Domain

Section
Page

b1001
b1011

Valid
Valid

MVA of access 
causing abort

Permission

Section
Page

b1101
b1111

Valid
Valid

MVA of access 
causing abort

Lowest

External abort on noncachable 
nonbufferable access or 
noncachable bufferable read

Section
Page

b1000
b1010

Valid
Valid

MVA of access 
causing abort