14.4 Splittable Main Regions

Each IDAU region is associated with one MAIN region. When more than one IDAU regions are derived from a single MAIN region, this MAIN region is said to be splittable.

The following MAIN region types are not splittable:

  • MR_INVALID
  • MR_SEC
  • MR_NONSEC
  • MR_SECnNONSEC
  • MR_EXEMPT

The following IDAU region types are splittable:

  • MR_SEC_NSC_W
  • MR_SEC_NSC_NONSEC_W
  • MR_SEC_NONSEC_W

The following figure shows how the split is done for each MAIN region type. The vertical arrow shows which IDAU region size is configurable. The size of each MAIN region is fixed.

Figure 14-1. Splittable Main Regions
Table 14-3. Splittable Main Regions Configuration
SPLITTABLE MAIN REGION TYPE DESCRIPTION
MR_SEC_NSC_W

NSC_W size is configurable using the RCTRL.CMD = WRSZ.

Minimum size is 0 so that the SEC IDAU region size equals to the MAIN region size.
MR_SEC_NSC_NONSEC_W

NONSEC_W size is configurable using the RCTRL.CMD = WRSZ.

The NSC_W and SEC IDAU regions occupy the rest of the main region.

Minimum size is 0 allowing the SEC and NSC_W IDAU regions to occupy the whole MAIN region space.

NSC_W size is configurable using the RCTRL.CMD = WRSZ and occupies the space left by the NONSEC_W region inside the main region. The SEC IDAU region occupies the space left by the NONSEC_W and NSC_W IDAU regions.

Minimum size for the NSC_W is 0 allowing the SEC IDAU region size to occupy the MAIN region size when both NSC_W and NONSEC_W sizes are 0.
MR_SEC_NONSEC_W

NONSEC_W size is configurable using the RCTRL.CMD = WRSZ.

Minimum size is 0 so that the SEC IDAU region size equals to the MAIN region size.
Figure 14-2. Splittable Main Regions Configurations
Note:
  1. Impossible configuration due to subregion1 maximum size constraint (legal values are integers in the range of [1,decoding_size-subregion1_granularity]), refer to the “IDAU Main Regions Map”.
  2. Impossible configuration due to subregion2 maximum size constraint (legal values are integers in the range of [1,decoding_size-subregion2_granularity]), refer to the “IDAU Main Regions Map”.
  3. NSC_W can overlap the SEC region when the NONSEC_W region size is not null and NSC_W size is greater than 0. Even if the NSC_W size exceeds the remaining space not occupied by the NONSEC_W region in the MAIN region, the NSC_W will only overlap the SEC region, it cannot overlap contiguous MAIN regions.