[U-Boot] [PATCH] armv7: Fix to mistake clean the memory space

[Andreas Bießmann]

Dear Zhong Hongbo,

this is arm related and should therefore apply to all the different
arch/arm/cpu/*/start.S (as long as they have SPL support).

On 05.07.2012 16:35, Zhong Hongbo wrote:
> From: Zhong Hongbo <bocui107 at gmail.com>
> 
> In currently, when __bss_start is equal to __bss_end__,
> The bss loop will clear all the things in memory space.

I ask myself why there is no bss at all. Have you just initialized data
in your spl code?

> 
> But just only when __bss_end__ greater than __bss_start__,
> we do the clear bss section operation.
> 
> Signed-off-by: Hongbo Zhong <bocui107 at gmail.com>
> ---
>  arch/arm/cpu/armv7/start.S |    9 ++++++---
>  1 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index 22a3ced..2e583ee 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -259,10 +259,13 @@ clear_bss:
>  #endif
>  	mov	r2, #0x00000000		/* clear			    */
>  
> -clbss_l:str	r2, [r0]		/* clear loop...		    */
> +clbss_l:
> +	cmp	r1, r0
> +	bls	clbss_end
> +	str	r2, [r0]		/* clear loop...		    */
>  	add	r0, r0, #4
> -	cmp	r0, r1
> -	bne	clbss_l
> +	b	clbss_l
> +clbss_end:

Looks sane, I maybe had checked before clbss_l, jumped over clear loop
if r0 and r1 equal (to emphasize the fact that this is a check for entry
correctness) and wouldn't change the loop at all. To be more precise we
could also check if end is after start.

>  
>  /*
>   * We are done. Do not return, instead branch to second part of board
> 

Best regards

Andreas Bießmann