This is the Translation Table Base (TTB) register, for the currently active first-level translation table. The contents of register 2 are shown in Table 2.12.

Reading from register 2 returns the pointer to the currently active first-level translation table in bits [31:14]. Writing to register 2 updates the pointer to the first-level translation table from bits [31:14] of the written value.

Bits [13:0] should be zero when written, and are unpredictable when read.

You can use the following instructions to access the TTB:

MRC p15, 0, Rd, c2, c0, 0       ; read TTB register

MCR p15, 0, Rd, c2, c0, 0       ; write TTB register