[U-Boot] memory corruption on nios2 due to overlap of gbl data and malloc

[Graeme Russ]

Hi Mike,

On Thu, Mar 1, 2012 at 6:04 AM, Mike Frysinger <vapier at gentoo.org> wrote:
> On Tuesday 28 February 2012 18:32:57 Graeme Russ wrote:
>> And this is why I dislike the implementation - You have to do all sorts of
>> weird calucations to put things in the right place when, in fact, the
>> location of gd and bd in memory is totally irrelavent.
>
> right, that's why i minimized the pain for Blackfin users -- this is all
> handled in the arch's config-pre.h header.  board porters only need to declare
> the size of regions they care about (monitor and heap sizes).
>
>> Ow, ouch! - And that padding makes things more fun - The memory layout is
>>
>> U-Boot | gd | pad | bd | pad | heap
>
> fwiw, i documented the Blackfin memory layout:
> http://docs.blackfin.uclinux.org/doku.php?id=bootloaders:u-boot:memory-layout

I had a look at this and noticed that you statically allocate locations for
gd and bd (CONFIG_SYS_GBL_DATA_ADDR, CONFIG_SYS_BD_INFO_ADDR)

Considering that:

a) the gd pointer is in a register (P3) and thus easily locatable by a
   debugger, and;
b) the bd pointer is in gd

Is there any reason not to have gd and bd in BSS?

Regards,

Graeme