[U-Boot-Users] why jump at absolute address in start.S
Wolfgang Denk
wd at denx.de
Fri Jan 3 09:23:19 CET 2003
In message <3E1507CA.7000305 at sjtu.edu.cn> you wrote:
> I'm reading cpu/mpc8xx/start.S and found the following:
>
> /*
> * Calculate absolute address in FLASH and jump there
> */
>
> lis r3, CFG_MONITOR_BASE at h
> ori r3, r3, CFG_MONITOR_BASE at l
> addi r3, r3, in_flash - _start + EXC_OFF_SYS_RESET
> mtlr r3
> blr
>
> Why do we need to calculate the absolutely address?
We want to jump to the address where our ciode resides in flash
memory, so we must calculate the jump target.
> Why should we do it here, instead of everywhere?
Please read the chapter of the 8xx User's Manual about how the
processor starts from a reset.
Best regards, and a Happy New Year!
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
How much net work could a network work, if a network could net work?
More information about the U-Boot
mailing list