iMX535 Fuse Setting boot MMU enabled with security open

[sherry_zahid]

Question on the subject of iMX535 fuses:

Would the following fuse settings result in any issues / problems / risks?
If boot MMU/Cache is enabled (BT_MMU_ENABLE=1) but security config is left open (SEC_CONFIG=01)

Additional info:
Setting up to boot via eMMC

BT_MMU_ENABLE IIM address:080C[0]

SEC_CONFIG IIM address:0810[1:0]

Thanks

SZ

[igorpadykov]

Hi sherry

no, it will not cause any problems or issues

Best regards
igor
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[sherry_zahid]

Hi Igor,

Thanks for the quick response. The reason I asked was because the reference manual recommends that boot MMU/cache should be disabled if security config is left open:-

From IMX53RM Rev2.1 (Section 7.4.4)

"Enabling the MMU when booting non-securely by setting, SEC_CONFIG=Open and
setting the CSF pointer in the Image Vector Table set to NULL, has no impact on the
boot performance. With this configuration it is recommended not to blow the MMU_EN
fuse."

Would there be any technical reason for the above recommendation? 

Thanks,

SZ

[igorpadykov · Accepted solution]

Hi sherry

there is no special technical reason for the above recommendation,

it just points that with SEC_CONFIG=Open this setting is useless, 

as will not improve boot performance.

Best regards
igor