[U-Boot] [U-BOOT] [PATCH] env: reduce the stack footprint for the env buf

[Graeme Russ]

On 05/02/11 19:30, Wolfgang Denk wrote:
> Dear Lei Wen,
> 
> In message <AANLkTin-EBt+PA0TmdLBPAqo3pBjwmbNLdFUj2K-JOnX at mail.gmail.com> you wrote:
>>
>>> In which way do you think this will save any memory?
>>
>> This patch is not intend to save memory...
> 
> Then I don't understand at all what the benefit of that patch would
> be.
> 
>> One of our project need to confine the ddr usage of uboot in the smallest case,
>> not to pollute other area. So for us, the small stack is good one...
> 
> So it is still about saving memory...
> 
>> For now the uboot is relocated to the end of the dram, and malloc area is
>> almost a fix value, uboot would live happily in this area. But for env case,
>> it allocate a range which could be large, due to the CONFIG_ENV_SIZE
>> could be a big one, in the stack range. Because the stack is grown downwards,
>> so it takes more memory range than it is allocated in the malloc method.
> 

Sounds like you have allocated too small a region for your stack - try
increasing CONFIG_SYS_STACK_SIZE and decreasing CONFIG_SYS_MALLOC_LEN

> malloc arena and stack are adjacent.  If you have enough free room in
> the malloc arena for the environment buffers, but cannot afford to
> have them on your stack, then this means your malloc arena has lots of
> unused space.  Decrease the size of your malloc arena by the size of
> the environment buffer, and you reach the same goal as with your
> patch - actually you save more memory, as the code size of u-boot
> shrinks.
> 
> Can you please provide exact numbers?  How big is your RAM? What is
> the debug output of arch/*/lib/board.c without and with this patch on
> your system?  How big is your environment resp. the environment
> sectors?
> 

The only other thing I could think of that would make sense would be having
the malloc heap in a completely different memory segment to the stack -
odd, but possible

Regards,

Graeme