• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 83 subscribers
  • Views 1231 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Is it possible to re-purpose of BOOT_RSVD memory?

Igor Kordunsky
Intellectual 835 points

In F28M35, M3 core, there is "idling" hole in C2 memory, according to cmd file:

    BOOT_RSVD (RX)  : origin = 0x20004000, length = 0x0900   // 2'304 bytes

the map file shows it is not used for the main program, but it is fairly large chunk of memory :

BOOT_RSVD    size: 0x900        unused: 0x900        max hole: 0x900

I know, the M3 boot code uses this memory DURING BOOT.

But, as soon as program pointer reaches _c_int00() this memory could be re-used, could not it?

Or if  _c_int00() uses it, (to initialize defined initial values for some variables), we can re-use BOOT_RSVD when program pointer reaches main()?

Thanks, Igor

  • 0
    TI__Guru 57255 points

    Hi Igor,

    Yes, you should be able to re-purpose this memory if you wish. 

    However, note a few things:
    1) The ROM will overwrite whatever is here during boot-up.
    2) After boot, the BOOT STATUS is located at word 0x2000 4000 if you wish to make use of this information.
    3) If the device goes through any reset (even a watchdog reset), the Boot ROM will run after the reset and any information stored in BOOT_RSVD will be overwritten.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Guru 12350 points

    Hi, Brett

    I guess Boot ROM have to use stack(BOOT_RSVD) if vector fetch error.
    This is correct ?

    Best Regards
    Hiroyasu

  • 0 in reply to Hiroyasu Tazawa1
    TI__Mastermind 19810 points
    on a vector fetch error , stack will be whatever was before the error happened. However if the handler in ROM is being executed because user application has not initialized interrupts/NVIC then the ROM handler might write something into the RAMs which is part of BOOT_RSVD. This use case is unlikely because almost all of the applications will have to have NVIC initialized to point to the user handlers.

    otherwise, what Brett suggested is correct.

    Best Regards
    Santosh Athuru
  • 0 in reply to Santosh Athuru
    Guru 12350 points

    Hi, Santosh

    Thank you for your reply.
    I wanna make sure I understand Boot ROM Handler in C28x may write something
    into part of BOOT_RSVD too.

    This understanding is correct?

    Best Regards
    Hiroyasu