• Locked Locked
  • Replies 6 replies
  • Subscribers 119 subscribers
  • Views 5929 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
Related
How was your experience today?
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

How to enter Secure mode

Zova Chou
Note: This was originally posted on 29th July 2011 at http://forums.arm.com

Hi all,
I want to use TCM in ARM1176ZJF-S core. It will be accessed in Non-secure world (cause I don't use TrustZone) but by default it's configured as secure TCM. So, it's not visible.  I need to change it to non-secure TCM which is indicated by the NS bit. According to the Ref, if I want to change the NS bit, I need to enter Secure privileged mode first.
My question is how can I enter that mode?
I tried the following, according to ARM1176JZF-S tech ref,

             asm("str     lr,[sp, #-4]!");
             asm("smc     #0");
             asm("mrc     p15, 0, %0, c9, c1, 2" 
                 : "=r" (tcm_secure));
             tcm_secure |= 1;
             asm("mcr     p15, 0, %0, c9, c1, 2"   /* set DTCM NS bit to 1 */
                 :
                 : "r" (tcm_secure));
             asm("movs    pc, lr");
             asm("ldr     lr, [sp, #0]!");


It doesn't work, however. Compiler says SMC is supported.
Please help, TCM troubles me for weeks.

Thanks for any input
Zova
Parents
  • Arm Employee Badge
    Note: This was originally posted on 29th July 2011 at http://forums.arm.com

    It is also worth noting that the "typical" user model is that the bootstrap (running in secure) sets up the platform, assigning periphals, TCM, etc to the correct worlds, and the proceeds with the boot of the higher levels of the system.

    It is unusual to want to re-partition resources after this point, especially things like TCM, so can't your bootloader do this?
Reply
  • Arm Employee Badge
    Note: This was originally posted on 29th July 2011 at http://forums.arm.com

    It is also worth noting that the "typical" user model is that the bootstrap (running in secure) sets up the platform, assigning periphals, TCM, etc to the correct worlds, and the proceeds with the boot of the higher levels of the system.

    It is unusual to want to re-partition resources after this point, especially things like TCM, so can't your bootloader do this?
Children
No data