[U-Boot-Users] Stack Size for MPC8xx???

[U-Boot-Users] Stack Size for MPC8xx???

[Steven Scholz]

Hi there,

does someone know how big the stack is for an MPC8xx based boards?

I had this problem:

I started porting U-Boot to my new AT91RM9200 based board. After doing the flash 
code I tried "saveenv". Simple reading, writing and erasing was working. But the 
board crashed when doing "saveenv".

I found these lines in common/env_flash.c:

int saveenv(void)
{
...
#if defined(CFG_ENV_SECT_SIZE) && (CFG_ENV_SECT_SIZE > CFG_ENV_SIZE)
         ulong   flash_offset;
         uchar   env_buffer[CFG_ENV_SECT_SIZE];
#else
...
         /* copy old contents to temporary buffer */
         memcpy (env_buffer, (void *)flash_sect_addr, CFG_ENV_SECT_SIZE);

I have CFG_ENV_SECT_SIZE = 64K and CFG_ENV_SIZE=4K and realized that my stack 
was far to small to save an 64KB flash sector.

The funny thing is that I never worried about that issue. And it never seems to 
be a problem on our MPC8xx based boards...

Thanks.

-- 
Steven Scholz

imc Measurement & Control               imc Me?systeme GmbH
Voltastr. 5                             Voltastr. 5
13355 Berlin                            13355 Berlin
Germany                                 Deutschland
fon: +49 30 467090-0                    Tel: 030 / 467090-0
fax: +49 30 4631576                     fax: 030 / 4631576

[U-Boot-Users] Stack Size for MPC8xx???

[Wolfgang Denk]

Dear Steven,

in message <3F913F10.2010706@imc-berlin.de> you wrote:
> 
> does someone know how big the stack is for an MPC8xx based boards?

This is board-dependend - how much RAM do you have?

On MPC8xx the stack grows downward,  so  it  can  become  as  big  as
necessary  as  long  as  it does not colide with the exception vector
table or any data you put into RAM.

> I had this problem:
> 
> I started porting U-Boot to my new AT91RM9200 based board. After doing the flash 
...
> I have CFG_ENV_SECT_SIZE = 64K and CFG_ENV_SIZE=4K and realized that
> my stack 
> was far to small to save an 64KB flash sector.

This is one of the consequences of the  broken  design  we  inherited
from ARMBoot.

> The funny thing is that I never worried about that issue. And it never se
> ems to 
> be a problem on our MPC8xx based boards...

That's because PPC uses a different memory layout (as  documented  in
the README).

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
There is a time in the tides of men, Which, taken at its flood, leads
on to success. On the other hand, don't count on it.   - T. K. Lawson