[U-Boot-Users] Where does u-boot start when booting Linux?

Allen Curtis acurtis at onz.com
Tue Oct 14 17:49:45 CEST 2003

At 07:47 AM 10/14/03, Wolfgang Denk wrote:
>In message < at> you wrote:
> > I was hoping that someone could give me a quick answer. When u-boot starts
> > Linux, does is start from the beginning for does it jump in somewhere past
> > decompress()?
>There no decompress() in the Linux kernel. So  U-Boot  always  starts
>the Linux kernel right from the beginning.

When compiling 82xx or 8xx kernels, you always get arch/ppc/boot/simple.

> > I have been looking at the Linux code and it doesn't appear that the 
> bdinfo
> > structure is being handled correctly for u-boot. There is an
> > CONFIG_EMBEDDEDBOOT option but even this only passes the boot parameter in
> > a few instances. Does u-boot fix this somehow?
>I think you are  looking  at  the  wrong  place.  Don;t  mistake  the
>bootstrap  loader  for  a  part of theLinux kernel. We don;t use this
>stuff at all.

I think I understand. For a very long time now I have been using 
zImage.embedded for booting. When I followed the u-boot instructions I used 
"vmlinux" which doesn't contain the boot loader. Right?

> > Another thing is embed_config() for the ADS8260 board, forces the 
> baud-rate
> > to 9600 but 2_4_devel is quite happy at 115200 as in u-boot. This is
> > interesting since I am trying to fix a serial baud-rate problem.
>All this stuff is completely irrelevant when using U-boot.

Thanks for the info. It has pointed me in a new direction. The problem I am 
having is the serial baud-rate is fine in u-boot but wrong when the kernel 
boots. Perhaps the clock dividers are setup differently by u-boot than 
expected by the 8260 implementation?

Suggestions welcome.

Thanks again!

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