[U-Boot] boot-up time optimization. Where to start?

[Charles Manning]

On Thursday 05 May 2011 17:32:20 Wolfgang Denk wrote:
> Dear Alexander Stein,
>
> In message <201105030848.17576.alexander.stein at systec-electronic.com> you 
wrote:
> > This specific version was selected due to relocation problems on ARM. But
> > I expect the dcache doesn't have that big influence on the named code
> > part as the environment is already in RAM.
>
> Your expectation is most likely completely wrong.  Reading from /
> writing to uncached RAM is painfully slow compared to a system with
> caches turned on.  And if you - as I speculate - need to checksum a
> huge amount of data, this will delay things without need.

Caching has a huge effect on **all** code and is the first thing I'd play with 
in trying to speed things up.

I have been doing some stuff to speed omap3 booting. It was taking approx 4 
seconds from power up until the kernel started spewing boot messages. That is 
now down to less than 2 secs (including the funky omap3 romboot time, loading 
uboot from NAND and then loading the kernel from NAND). Only difference was 
turning on caching in uboot using the caching commands.

-- Charles