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ARM1176 boot code issue

sathishpkumar sathishpkumar
Note: This was originally posted on 5th June 2009 at http://forums.arm.com

Hi
I got an issue while writing the ARM1176 bootcode.

I used DCI 0xE1600071 instruction to switch from secure priviliged mode to monitor mode.
After ARM executed this instruction , tarmac.log file is not updated i.e., ARM is not switching to monitor mode but r14_mon and spsr_mon is updated

please let me know what could be the issue


Thanks,
Sathish
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  • Arm Employee Badge
    Note: This was originally posted on 9th June 2009 at http://forums.arm.com

    > one more question.. why we need to program the stack of the monitor mode before executing SMI??

    Just like most of the other exception modes in ARM, monitor has a local stack pointer stored in r13_mon. If you monitor code does anything with r13 then you need to make sure that it is initialized to a sensible location before using it. You could structure the SMI handler to initialize it to something sensible - so this will depend on how you have structured your monitor-mode code.

    When you say "in my case ARM is not executing any instruction after this" what behavior are you seeing in the core - it shouldn't just "not work", I would expect to be seeing an exception of some kind occurring.
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  • Arm Employee Badge
    Note: This was originally posted on 9th June 2009 at http://forums.arm.com

    > one more question.. why we need to program the stack of the monitor mode before executing SMI??

    Just like most of the other exception modes in ARM, monitor has a local stack pointer stored in r13_mon. If you monitor code does anything with r13 then you need to make sure that it is initialized to a sensible location before using it. You could structure the SMI handler to initialize it to something sensible - so this will depend on how you have structured your monitor-mode code.

    When you say "in my case ARM is not executing any instruction after this" what behavior are you seeing in the core - it shouldn't just "not work", I would expect to be seeing an exception of some kind occurring.
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