[U-Boot-Users] Re: Installing U-Boot on target via USB/serial using U-Boot commands
Jerry Van Baren
gerald.vanbaren at smiths-aerospace.com
Mon Sep 26 18:45:02 CEST 2005
Disclaimer: I'm not an ARM expert. I have a hard time even spelling ARM.
Joe Grisso wrote:
> See below.
>>It looks like this is a very simple loader. It writes to SRAM _only_
>>and then jumps to that program (JTAG loaders typically allow you to
>>write to flash, manipulate registers, and jump anywhere, single step,
>>etc.). Theoretically you could load u-boot this way, but nobody has
>>volunteered that they have done it so you would likely be blazing a new
> Yeah, and with only 16KB of onboard SRAM, I doubt you'd be able to load
> U-Boot in as a single image. I don't know if Atmel's host-side DFU app
> handles downloads larger than the size of SRAM either. So if not, one
> would have to write an app for that on the host as well.
Nope. U-boot is much more than 16K. The level of complexity just
stepped up a notch.
Looking some more at the description, the USB load is done only if no
"valid" load (the vectors have jump instructions in them) is found in a
bootable memory. This means that you would only get one chance to burn
the vectors - if your load in regular boot memory does not run properly,
the bootloader doesn't know to go back to USB boot and your hardware
will turn into a brick (recoverable only with a JTAG loader).
You need a JTAG loader/debugger. The USB mechanism would work for a low
budget loader once you have a working program to load, but using the USB
mechanism to load your initial boot loader will be a one shot failure.
>>Having said all that, this is pretty much off topic for u-boot. Only
>>after you get u-boot loaded into the target (and at least showing some
>>signs of life) would this become on topic for this list.
> Just out of curiosity, which list would be appropriate then? AT91 Users?
Sorry, I'm just an "idea" man :-/ lots of ideas, very little practice.
> Best Regards,
> Joe Grisso
> Detachment 3 Media, Ltd.
More information about the U-Boot