[U-Boot-Users] clarifications u-boot for arm

Ram vshrirama at gmail.com
Fri Jul 14 15:51:09 CEST 2006


Hi,
   Thanks for your response. I have gone much further and would like to know If

      ldr pc, _start_armboot
     _start_armboot:
         .word start_armboot


    Does this really invoke start_armboot?.  This is because
_start_armboot is what is
    stored in pc and not start_armboot and there is also a branch
point _start_armboot (underscore start_armboot) Please see above.

   Actually the above declares a variable start_armboot and does not
invoke the function
   start_armboot. If this is true, then who calls start_armboot?


    According to me start_armboot ( ) which is present in
lib_arm/board.c never returns until u reset the board and probably
should be one of the last functions that needs to be called.

    Correct?.


   Rest agreed, What i have understood is
         First,  reset is called which set the cpu to SVC32 mode and
calls cpu_init_crit
         which inturn calls lowlevel_init to setup memory and board
specific register values.

          Then stack is setup and start_amboot is called.


          start_armboot is the point of entry where code is C. ie
(Assembly to C) begins from start_armboot.


          am i Correct?.


        This is the function which does some remaining initialisation
and then starts initialising the for pheripherals.


     am i Correct?


  I didnt understand the things relating interrupt and thier processing though.

Thanks and Regards,
sriram




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