[U-Boot-Users] das u-boot and disc on chip

Wolfgang Denk wd at denx.de
Wed Mar 2 23:00:15 CET 2005

Dear Tolunay,

in message <42262F9B.7030509 at orkun.us> you wrote:
> I 100% agree that dealing with a separate NOR boot ROM is so much more 
> easier. However, I also see booting from NAND data flash with a small 
> boot readable sector is quickly becoming popular in lower cost/smaller 
> footprint/less power consumption equipment.

Yes - and you shift 90% of the problems that U-Boot  is  supposed  to
solve  (like easy debugging of the low level initialization sequence)
into this "small primary bootstrap loader".

> IMHO instead of denying this reality, perhaps we (as U-Boot 

I don't deny it. I just tend to ignore it -  like  I  ignore  systems
running (or crashing) those Windoze "software" ;-)

> developers/users) should make some enhancements to deal with this 
> situation in a formal supported way before too many forks occur.

Actually NO enhancements are needed. All is ready and in place,  it's
just  that  you  don't  get any support here for creating the primary
bootstrap loader. This is a different issue, which  is  unrelated  to
U-Boot.  U-Boot  can  live  with suh a situation fine - of course you
have to know _exactly_ what you are doing. See for  examplethe  Atmel
AT91RM9200  configuration  where  all  you  need  to  change  is  the
CONFIG_BOOTBINFUNC definition to either  use  an  external  bootstrap
loader or to have a real self-contained U-Boot image.

U-Boot was defined to solve certain problems  that  are  typical  for
board bringup; this worked pretty well - just see how many relatively
unexperienced  developers were able to port U-Boot to their hardware.
If you force U-Boot into a hostile environment, the same old problems
will have to be solved again - there is  nothing  U-Boot  can  do  to
prevent  this.  So  if you go that route, please don't expect to find
much help here on this list.

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
That was the thing about deserts. They had their  own  gravity.  They
sucked you into the centre.           - Terry Pratchett, _Small Gods_

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