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Cortex-A8 Technical Reference Manual - ARM Information Center

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Design for Test<br />

Not all row settings are valid for all RAMs in all L2 cache size configurations. Table 11-12<br />

shows the range of values from Table 11-11 on page 11-8, that is possible for each RAM type,<br />

and for each cache size.<br />

L2ValSer<br />

By default, the MBIST tests the L2 tag RAM and L2 valid RAM at the same time. Table 11-13<br />

shows that you can select serial testing of the tag and valid RAMs by setting the L2ValSer bit<br />

to 1. The reset value of the L2ValSer bit is 0.<br />

When L2ValSer is 0, that is, parallel testing is selected, the address scramble configuration for<br />

the valid RAM is the same as that of the tag RAM. This means that the valid RAM uses the tag<br />

RAM address scramble configuration, even if the tag RAM is not selected for test. The L2ValSer<br />

bit is provided to enable you to serially test the tag RAM with different address scramble<br />

configurations.<br />

L2AdLSB[3:0]<br />

Cache size (KB)<br />

Valid range<br />

Table 11-12 Valid L2 array row numbers<br />

Data/parity RAM (rows) Tag/valid RAM (rows)<br />

128 32-512 16-128<br />

256 32-512 16-128<br />

512 32-512 16-128<br />

1024 64-512 16-256<br />

Table 11-13 Selecting the L2ValSer test type<br />

L2ValSer Testing of L2 tag RAM and L2 valid RAM<br />

1 Serial testing<br />

0 Parallel testing<br />

Use the L2AdLSB[3:0] field to select how to increment or decrement the two LSBs of the<br />

column address of L2 valid, tag, parity and data RAM accesses. This field is provided as a way<br />

to configure non-linear address sequences found in some compiled RAMs. Table 11-14 shows<br />

the L2 array controlled by each L2AdLSB[3:0] bit.<br />

Table 11-14 Selecting L2 RAMs for LSB control<br />

L2AdLSB[3:0] bit Selected RAM<br />

[0] L2 valid RAM<br />

[1] L2 tag RAM<br />

[2] L2 parity RAM<br />

[3] L2 data RAM<br />

<strong>ARM</strong> DDI 0344K Copyright © 2006-2010 <strong>ARM</strong> Limited. All rights reserved. 11-9<br />

ID060510 Non-Confidential

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