[U-Boot-Users] Extremely tiny footprint

[Laurent Pinchart]

Hi Martin,

> > I would like to use U-Boot as a first-stage boot loader to program
> > flash memory on the target board. The idea is to perform a two-steps
> > procedure:
> >
> > 1. Program the first-stage boot loader in flash using JTAG (slow)
>
> There are JTAG programmers, which could work very fast (e. g. BDI2000
> with workspace enabled). The limiting factor is the flash itself,
> not the programmer, or the JTAG interface.
>
> > 2. The first-stage boot loader downloads the final boot loader
> > (full-featured U-Boot) using TFTP and writes it to flash (fast)
> >
> > To minimize time spent in step one, I need to make the first-stage
> > boot loader as small as possible (hopefully less than 32kB). Has
> > anyone ever stripped U-Boot that much ? Is there any documentation
> > available ?
>
> If programming speed is the only reason for your two-step approach,
> then IMO this is not reasonable. It would be a waste of your time. Use
> a faster JTAG programmer instead. Or you could buy the flashes
> preprogrammed.

Buying the flashes preprogrammed is not an option given the quantities.

We already have a BDI2000 which has issues programming the flash using the 
workspace, so it reverts to the slow pure JTAG mode. I still have to 
investigate this directly with Abatron, we haven't found a solution so far.

Even using the internal workspace, the BDI2000 is not a very practical 
solution, as it wouldn't be easy to integrate it in our test bench 
architecture. The price is also an issue. This is why I was looking for 
another solution. The alternative I thought of is using a pure JTAG 
programmer (slow) with a tiny ethernet-enabled boot loader. The Freescale 
JTAG commands used to control the processor are not documented, so I can't 
develop a faster JTAG-only alternative. Are you aware of any other solution ?

Laurent Pinchart