Overview of SPL on OMAP3 devices
  ================================
  
  Introduction
  ------------
  
  This document provides an overview of how SPL functions on OMAP3 (and related
  such as am35x and am37x) processors.
  
  Methodology
  -----------
  
  On these platforms the ROM supports trying a sequence of boot devices.  Once
  one has been used successfully to load SPL this information is stored in memory
  and the location stored in a register.  We will read this to determine where to
  read U-Boot from in turn.
  
  Memory Map
  ----------
  
  This is an example of a typical setup.  See top-level README for documentation
  of which CONFIG variables control these values.  For a given board and the
  amount of DRAM available to it different values may need to be used.
  Note that the size of the SPL text rodata and data is enforced with a CONFIG
  option and growing over that size results in a link error.  The SPL stack
  starts at the top of SRAM (which is configurable) and grows downward.  The
  space between the top of SRAM and the enforced upper bound on the size of the
  SPL text, data and rodata is considered the safe stack area.  Details on
  confirming this behavior are shown below.
  
  A portion of the system memory map looks as follows:
  SRAM: 0x40200000 - 0x4020FFFF
  DDR1: 0x80000000 - 0xBFFFFFFF
  
  Option 1 (SPL only):
  0x40200800 - 0x4020BBFF: Area for SPL text, data and rodata

  0x4020E000 - 0x4020FFFC: Area for the SPL stack.

  0x80000000 - 0x8007FFFF: Area for the SPL BSS.
  0x80100000: CONFIG_SYS_TEXT_BASE of U-Boot
  0x80208000 - 0x80307FFF: malloc() pool available to SPL.
  
  Option 2 (SPL or X-Loader):
  0x40200800 - 0x4020BBFF: Area for SPL text, data and rodata

  0x4020E000 - 0x4020FFFC: Area for the SPL stack.

  0x80008000: CONFIG_SYS_TEXT_BASE of U-Boot
  0x87000000 - 0x8707FFFF: Area for the SPL BSS.
  0x87080000 - 0x870FFFFF: malloc() pool available to SPL.
  
  For the areas that reside within DDR1 they must not be used prior to s_init()
  completing.  Note that CONFIG_SYS_TEXT_BASE must be clear of the areas that SPL
  uses while running.  This is why we have two versions of the memory map that
  only vary in where the BSS and malloc pool reside.