[U-Boot] Most ARM CPU's have buggy clear_bss?

[Sughosh Ganu <urwithsughosh@gmail.com>]

hi,

On Wed Oct 27, 2010 at 10:26:06AM +0300, Darius Augulis wrote:

> IMO, if relocation is skipped, r4 should be loaded with value of
> _TEXT_BASE, not reloc address?
> It seems like r3 is prepared for this but, it's somehow missing? It's
> not used at all.
> Maybe it could be reason why I'm facing strange problem, when after
> relocating uboot with nand_spl no one command is not working.
> I debugged that command table is empty. I think this ASM code clears
> not bss area but something else.


<snip>

> 
> Also relocation code looks a bit strange:

 <snip>

> r0 is compared to r6, which contains reloc address. All instructions
> between loading r0 and comparison are confusing, because they do not
> impact comparison result.
> Also they do not matter in clear_bss so I think would be great to
> change code like this:
> 
>         mov     sp, r4
> 
>         adr     r0, _start
>         cmp     r0, r6
>         beq     clear_bss
>         ldr     r2, _TEXT_BASE
>         ldr     r3, _bss_start_ofs
>         add     r2, r0, r3              /* r2 <- source end address         */
> 
> Any comments are welcome!

  Not sure which core are you referring to. I checked for arm926ejs,
  and we have conditional code inclusion based on the definition of
  CONFIG_SYS_ARM_WITHOUT_RELOC. So the start address in both the cases
  is determined based on whether relocation is enabled or not.

-sughosh