[U-Boot-Users] U-Boot-NG ?

[Stefan Roese <sr@denx.de>]

On Wednesday 04 July 2007, Sascha Hauer wrote:
> > > I once wondered why it takes _so_ long to get a prompt on my MPC5200
> > > board. The solution was simple: U-Boot was busy reading the environment
> > > from EEPROM several times.
> >
> > Yes. That is one of the reasons, why it is strongly discouraged to use
> > I2C EEPROM for environment storage.
>
> I know it is, and it was the customers decision to so, but I think using
> an I2C eeprom _should_ be no problem. It's just like any other memory
> device.

ACK.

> > If no output on the serial console always means: "problem with memory",
> > than this would be an easy indication for SDRAM problems. But I have seen
> > lots of other errors, that lead to a hangup in the very early boot stage.
> > Most of the time *before* SDRAM is initialized.
>
> Don't have the boards where DIMMs can be changed some kind of beeper or
> LED telling you about memory problems?

Some have some don't.

> > Don't get me wrong. I generally like this 2 stage approach. For example
> > it fits the NAND booting support (see nand_spl/*) where a small (4k on
> > 4xx) first stage loader is needed. I'm just a little hesitant about
> > dropping the full featured printf in early boot stages.
>
> I think we have little choice if we want 4k boot block support, early
> console output _and_ a maintainable tree.

Yes. The current nand_spl implementation has no serial output at all. And when 
problems occurred (which has already happened and *not* in the SDRAM init 
process, just CPU setup which can be quite complicated and can not be 
deferred to after SDRAM init), I would have really liked this output. I once 
had a version with such a hardcoded serial output, but dropped it after 
everything was working. I should have kept it in the source via some "debug" 
functions.

Best regards,
Stefan

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