[U-Boot-Users] TEXT_BASE

Michael Frey michael.frey at pepper.com
Wed Feb 5 21:25:53 CET 2003

So I am still confused.
My board's flash sits at 0x00000000 this is where I load u-boot.bin and 
TEXT_BASE is also the same.

This is also where the cpu jumps to to start executing.

How does u-boot know where to relocate itself to in RAM?

On Tuesday, February 4, 2003, at 05:28  PM, Wolfgang Denk wrote:

> [Let's keep the list Cc:ed or others  will  ask  the  same  questions
> again later. Well, they will anyhow :-( ]
> In message <8C12DADD-388E-11D7-8C12-00039390D626 at pepper.com> you wrote:
>> I am still a bit confused.  Should I set TEXT_BASE to 0x0000000 
>> because
>> that is where physical flash is located? or somewhere else.
> This depends. I don't  know  which  architecture  or  board  you  are
> talking  about.  On  PowerPC  for  example, you will need to have RAM
> mapped to physical address 0x0000 - at least if you ever want to  run
> Linux.
> The thing is that it is _you_ who defines the physical  address  map,
> and  who programs it with the memory controller of your board. In the
> resulting final mapping, TEXT_BASE is the start address of the U-Boot
> image.
> Let's stick with PPCBoot: after reset, a special temporary mapping is
> in place, which will always access memory using /CS0. Note that  this
> temporary  situation  has  nothing  to  do with the value defined for
> 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
> You know that feeling when you're leaning back  on  a  stool  and  it
> starts to tip over? Well, that's how I feel all the time.
> - Steven Wright
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