[U-Boot] [PATCH v5] arm: Fix clear bss loop for zero length bss

[Christian Riesch]

Hi Albert,

On Wednesday, November 30, 2011, Albert ARIBAUD <albert.u.boot at aribaud.net>
wrote:
> Hi Christian,
>
> Le 29/11/2011 11:58, Christian Riesch a écrit :
>>
>> This patch fixes the clear bss loop for bss sections that have
>> zero length, i.e., where __bss_start == __bss_end__.
>
> Just out of curiosity, did you actually hit a scenario when you had a
really empty BSS? Not that I intend to reject this patch because of this,
mind.

Yes, I did. The patchset in [1] (which is not a complete SPL but was for
testing only, it hangs after initialization of the hardware) results in an
empty bss.
It took me quite some time to find out why my board didn't get out of the
relocation code... ;-)

[1] http://lists.denx.de/pipermail/u-boot/2011-November/109886.html

>
>> Signed-off-by: Christian Riesch<christian.riesch at omicron.at>
>> Cc: Albert Aribaud<albert.u.boot at aribaud.net>
>> ---
>> Hi,
>> this is v5 of a patch out of my recent patchset
>>
>> [PATCH v3 00/15] Add an SPL to boot the da850evm from SPI
>> http://lists.denx.de/pipermail/u-boot/2011-November/111182.html
>>
>> Changes for v5:
>> - correct subject line
>>
>> Changes for v4:
>> - split the patchset since it is getting quite big
>>
>> Regards, Christian
>>
>>  arch/arm/cpu/arm926ejs/start.S |    8 +++++---
>>  1 files changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/cpu/arm926ejs/start.S
b/arch/arm/cpu/arm926ejs/start.S
>> index 8b5355b..772793c 100644
>> --- a/arch/arm/cpu/arm926ejs/start.S
>> +++ b/arch/arm/cpu/arm926ejs/start.S
>> @@ -299,10 +299,12 @@ clear_bss:
>>  #endif
>>        mov     r2, #0x00000000         /* clear
   */
>>
>> -clbss_l:str    r2, [r0]                /* clear loop...
   */
>> +clbss_l:cmp    r0, r1                  /* clear loop...
   */
>> +       beq     clbss_e
>
> For safety, you had better use a bge here, in case r1-r0 is not a
multiple of 4.

Ok, I'll change that.

>
>> +       str     r2, [r0]
>>        add     r0, r0, #4
>> -       cmp     r0, r1
>> -       bne     clbss_l
>> +       b       clbss_l
>> +clbss_e:
>>
>>  #ifndef CONFIG_SPL_BUILD
>>        bl coloured_LED_init
>

Thanks for your comments!
Regards, Christian

> Amicalement,
> --
> Albert.
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