[U-Boot] IXP425 TEXT_BASE

[Darius Augulis <augulis.darius@gmail.com>]

On 08/04/2009 04:49 PM, Wolfgang Denk wrote:
> Dear Darius Augulis,
>
> In message<4A78342C.5090307@gmail.com>  you wrote:
>> usually TEXT_BASE is offset, which size depends on your requirements for
>
> No. TEXT_BASE is an absolute address.

yes, but depends on the physical RAM base and size.

>
>> stack size and memory size for malloc. If your DRAM base is 0x0 and
>> TEXT_BASE is 0xf80000, you will have almost 16Mb for stack and malloc
>> and your u-boot code will be linked and loaded to 0xf80000 address.
>> 16Mb is probably too much, or your DRAM base is not 0x0.
>
> On architectures like ARM (where the implementation is based on a
> broken concept of the system memory map) TEXT_BASE should always be
> chosen to be as high as possible to put the ("relocated") U-Boot code
> as close as possible to the very end of available RAM.  For systems
> with several RAM size options you have to set this according to the
> smallest possible RAM size, of course (which is a major PITA).

could you please explain more? why to the end of RAM?
for example I have 16MB RAM, base is 0x10000000. TEXT_BASE = 0x10400000.
Why is better to set this to 0x10F00000 ? To have more stack and malloc 
memory? But U-boot will never exceed such limit? Please explain where I 
am wrong. Thanks!

Darius A.


>
>
> Best regards,
>
> Wolfgang Denk
>