Board Initialisation Flow:
--------------------------

This is the intended start-up flow for boards. This should apply for both
SPL and U-Boot proper (i.e. they both follow the same rules).

Note: "SPL" stands for "Secondary Program Loader," which is explained in
more detail later in this file.

At present, SPL mostly uses a separate code path, but the function names
and roles of each function are the same. Some boards or architectures
may not conform to this.  At least most ARM boards which use
CONFIG_SPL_FRAMEWORK conform to this.

Execution typically starts with an architecture-specific (and possibly
CPU-specific) start.S file, such as:

     - arch/arm/cpu/armv7/start.S
     - arch/powerpc/cpu/mpc83xx/start.S
     - arch/mips/cpu/start.S

and so on. From there, three functions are called; the purpose and
limitations of each of these functions are described below.

lowlevel_init():
     - purpose: essential init to permit execution to reach board_init_f()
     - no global_data or BSS
     - there is no stack (ARMv7 may have one but it will soon be removed)
     - must not set up SDRAM or use console
     - must only do the bare minimum to allow execution to continue to
          board_init_f()
     - this is almost never needed
     - return normally from this function

board_init_f():
     - purpose: set up the machine ready for running board_init_r():
          i.e. SDRAM and serial UART
     - global_data is available
     - stack is in SRAM
     - BSS is not available, so you cannot use global/static variables,
          only stack variables and global_data

     Non-SPL-specific notes:
     - dram_init() is called to set up DRAM. If already done in SPL this
          can do nothing

     SPL-specific notes:
     - you can override the entire board_init_f() function with your own
          version as needed.
     - preloader_console_init() can be called here in extremis
     - should set up SDRAM, and anything needed to make the UART work
     - these is no need to clear BSS, it will be done by crt0.S
     - must return normally from this function (don't call board_init_r()
          directly)

Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
this point the stack and global_data are relocated to below
CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
memory.

board_init_r():
     - purpose: main execution, common code
     - global_data is available
     - SDRAM is available
     - BSS is available, all static/global variables can be used
     - execution eventually continues to main_loop()

     Non-SPL-specific notes:
     - U-Boot is relocated to the top of memory and is now running from
          there.

     SPL-specific notes:
     - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
          CONFIG_SPL_STACK_R_ADDR points into SDRAM
     - preloader_console_init() can be called here - typically this is
          done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
          spl_board_init() function containing this call
     - loads U-Boot or (in falcon mode) Linux

victor@victor-HP:~/master$ lunch xxx-eng 

Already installed latest Toochain
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=3.0.0
TARGET_PRODUCT=xxx
TARGET_BUILD_VARIANT=eng
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm64
TARGET_ARCH_VARIANT=armv8-a
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=master
============================================