From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerry Van Baren Date: Mon, 26 Sep 2005 12:45:02 -0400 Subject: [U-Boot-Users] Re: Installing U-Boot on target via USB/serial using U-Boot commands In-Reply-To: <33099.10.0.0.16.1127751442.squirrel@webmail.det3.net> References: <4C4D1CD545F07B4EBEBE788A696F8B800E6D33@SBS.teletask.local> <4337F697.10105@smiths-aerospace.com> <33099.10.0.0.16.1127751442.squirrel@webmail.det3.net> Message-ID: <4338258E.1060807@smiths-aerospace.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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 >>path. > > > 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. gvb