[U-Boot-Users] U-Boot Boot Sequence

Wolfgang Denk wd at denx.de
Sun Jan 12 21:16:02 CET 2003


in message <8911.1042398376 at www47.gmx.net> you wrote:
> Im currently looking closely to the boot sequence for the MPC8xx but cant
> exactly
> figure it out how it works. Every hint is appreciated. 

Did you read the README file? Section "System Initialization" ?

> Since most MPC8xx and MPCxx both start executing at adress 0x100 there

This is not necessarily true. It may be 0xFFF00100 as well, depending
on the HRCW...

> What I dont understand is, that the label _start (In cpu/mpc8xx/start.S)
> will be placed to the runtime
> adress 0x100, but resides in the .text section which according to the linker
> file 
> (take as example board/cogent/u-boot.lds)  wont probably start at adresse
> 0x100
> in the image. The .text section is located after the .interp section.

See the README.

> I have another question concerns the adress calculation 
> to in_flash label (Some guys already mentioned something about this on this
> list).

So what was not clear in the previous explanations?

> My question is why to calculate the branch to in_flash and why
> adding the CFG_MONITOR_BASE? (dont be angry I know the 
> same question has alredy been asked but....)

Which exact part of the previous explanations did you not understand?
It makes little sense to repeat the  explanations  if  they  are  not
clear enough for you.

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
In a survey taken several years ago, all  incoming  freshmen  at  MIT
were  asked  if  they  expected  to graduate in the top half of their
class. Ninety-seven percent responded that they did.

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