On Nov 22, 2015 12:13 PM, "Bharath R" <[email protected]> wrote:
>
> Hi,
>
> As per my knowledge, MLO(SPL) does basic operation like clock
configuration, initialization of external eMMC, ext RAM and copy the u-boot
image from eMMC to RAM(DDR3) and jumps to RAM locate where it has copied
the u-boot.
> But the u-boot startup code seems to mislead me.
>
> Here is the code of u-boot start.S:
>
> #ifndef CONFIG_SKIP_RELOCATE_UBOOT
> relocate:                               /* relocate U-Boot to
RAM           */
>         adr     r0, _start              /* r0 <- current position of
code   */
>         ldr     r1, _TEXT_BASE          /* test if we run from flash or
RAM */
>         cmp     r0, r1                  /* don't reloc during
debug         */
>         beq     stack_setup
>
>         ldr     r2, _armboot_start
>         ldr     r3, _bss_start
>         sub     r2, r3, r2              /* r2 <- size of
armboot            */
>         add     r2, r0, r2              /* r2 <- source end
address         */
>
> copy_loop:
>         ldmia   r0!, {r3-r10}           /* copy from source address
[r0]    */
>         stmia   r1!, {r3-r10}           /* copy to   target address
[r1]    */
>         cmp     r0, r2                  /* until source end addreee
[r2]    */
>         ble     copy_loop
> #endif  /* CONFIG_SKIP_RELOCATE_UBOOT */
>
> why is u-boot's start.S copying itself to ext RAM(DDR3)?

This is a standard procedure for u-boot, why don't you go ask them...

Regards,

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