Please note: We are aware of an issue affecting replies on the Arm Community forums, which may not be loading as expected.

We apologize for any inconvenience and appreciate your patience while we investigate and work to resolve the issue.

Thank you for your understanding.

  • State Accepted Answer
  • Locked Locked
  • Replies 2 replies
  • Subscribers 346 subscribers
  • Views 4957 views
  • Users 0 members are here
Options
Related
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Secure world memory access with MMU disabled

Zizhu

Hi,

I am a newbie to the TrustZone architecture. I learned that, in secure world, whether a memory access is secure or not is determined by the NS field in the translation descriptor and, in non-secure world, the NS field will be ignored. I am wondering that what type of memory access will be issued from secure world if the MMU hasn't been enabled? Secure or non-secure? What about from non-secure world?

I am asking this is because I am trying to initialize GIC and Generic Timer before my translation table and MMU get initialized. Both of there two components contain memory mapped registers which are banked for secure and non-secure accesses. Not sure if it's correct way to do this. Correct me if I am wrong.

Thanks,

Zizhu

Parents
  • 0 Arm Employee Badge

    With the MMU disabled:

    • Secure world accesses will always be made as secure bus accesses

    With the MMU enabled:

    • Secure world accesses may optionally be made as non-secure via secure world page table entries

    Non-secure world accesses will always be made as non-secure accesses, irrespective of MMU settings, for obvious reasons ...

Reply
  • 0 Arm Employee Badge

    With the MMU disabled:

    • Secure world accesses will always be made as secure bus accesses

    With the MMU enabled:

    • Secure world accesses may optionally be made as non-secure via secure world page table entries

    Non-secure world accesses will always be made as non-secure accesses, irrespective of MMU settings, for obvious reasons ...

Children