The purpose of the TLB Type Register is to return the number of lockable entries for both the instruction and data TLBs.
Each TLB has 32 entries organized as fully associative and lockable TLB.
The TLB Type Register is:
a read-only register common to the Secure and Nonsecure states
accessible in privileged modes only.
Figure 3.3 shows the bit arrangement of the TLB Type Register.
Table 3.9 shows how the bit values correspond with the TLB Type Register functions.
Reserved, Read-As-Zero (RAZ).
Instruction lockable size specifies the number of instruction TLB lockable entries:
Data lockable size specifies the number of unified or data TLB lockable entries:
Unified specifies if the TLB is unified or if there are separate instruction and data TLBs:
Table 3.10 shows the results of attempted access for each mode.
|Secure privileged||Nonsecure privileged||Secure User||Nonsecure User|
To access the TLB Type Register, read CP15 with:
MRC p15, 0, <Rd>, c0, c0, 3 ; Read TLB Type Register