Hi there,
First let me introduce myself so you know what you're dealing with. My name is Peter and I'm a web designer by trade, messing around with embedded platforms in my spare time. However I'm only really getting started in the low level code aspect of it, so you'll have to excuse my inexperience and ignorance.
I'm playing with a Broadcom BCM7038 platform at the moment, and currently the bootloader starts in flash, inits the DRAM, copies the kernel image from flash into memory and starts it. What I'm looking to do is to init the memory and SATA HD, then load the kernel image from the HD and start it. U-Boot looks like a good choice to do this, but I'm having trouble getting started. I have the code for the original bootloader, including the ASM code with the reset vector and coprocessor bring-up code, but I'm having trouble figuring out how I would integrate that with U-Boot. I've read through the README and it's not really aimed for beginners (with good reason I guess)
I really could do with an overview of what U-Boot requires of my code, and what configuration changes I need to make to U-Boot to get it to use my code.