[U-Boot] [PATCH 1/1] nios2 - adjust gbl data off to account for bd_info

[Graeme Russ <graeme.russ@gmail.com>]

Hi Alex,

On 02/21/2012 10:45 AM, Alex Hornung wrote:
>  * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>    using the space between that offset and the start of the malloc
>    region to allocate both a gd structure and a board info structure.
> 
>  * This fixes a memory corruption bug due to overlap of the malloc
>    region and the bd_info structure.
> 
> Signed-off-by: Alex Hornung <alex@alexhornung.com>
> ---
>  include/configs/nios2-generic.h |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/include/configs/nios2-generic.h b/include/configs/nios2-generic.h
> index 9ba35e8..17017a5 100644
> --- a/include/configs/nios2-generic.h
> +++ b/include/configs/nios2-generic.h
> @@ -131,7 +131,8 @@
>  #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
>  					 CONFIG_SYS_MALLOC_LEN)
>  #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
> -					 GENERATED_GBL_DATA_SIZE)
> +					 GENERATED_GBL_DATA_SIZE - \
> +					 GENERATED_BD_INFO_SIZE)
>  #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
>  
>  /*

Oh I really want to NAK this, but I think I might be out-voted

in arch/x86/lib/init_helpers.c I do:

bd_t bd_data;

int init_bd_struct_r(void)
{
	gd->bd = &bd_data;
	memset(gd->bd, 0, sizeof(bd_t));

	return 0;
}

So the bd struct is in bss

But everyone else (ARM, PPC) seems to do:

	addr_sp -= sizeof(bd_t);
	bd = (bd_t *) addr_sp;

Why?

Well I see that a lot of bd is setup while still running from flash, so bss
is not available. But is this really necessary?

And for the sake of one more copy and pointer adjustment, even gd could be
moved into bss which would save all the hackish calculations of sticking gd
and bd in a magic void below the stack

But maybe that's a battle for another day...

Oh, and Nios is particularly nasty - It has no init_r / init_f so there is
no support for relocation - Will there every be an intent to enable
relocation for Nios or is it pointless?

Regards,

Graeme