[U-Boot] [PATCH] Change kernel address in dataflash to match u-boot's size

[Alexandre Belloni]

On Mon, Jan 02, 2012 at 06:18:05AM +0100, Marek Vasut wrote :
> > On at91sam platforms, u-boot grew larger than the allocated size in
> > dataflash, the layout was:
> > bootstrap  0x00000000
> > ubootenv   0x00004200
> > uboot      0x00008400
> > kernel     0x00042000
> > 
> > u-boot with the defconfig doesn't seem to fit in 0x42000 - 0x8400 =
> > 0x39C00 bytes anymore. Loading the kernel from 0x44000 will make the
> > process easier for users using the default configuration but they'll
> > have to remember to flash the kernel at 0x44000.
> 
> You're just pushing it slowly further. That's bogus:
> 1) ubootenv is at weird offset ... why such a weird number? Also, what about 
> redund. env?

It is atmel's defaults they seem to do some magic with the environment
when flashing. I don't think this is necessary and don't have any issue
changing that.

> 2) u-boot itself is at weird offset ... just set it to some normal location and 
> let it be eg. up to 512kb big, to make sure you don't need to change it in the 
> future.

That makes sense, I though about it but I'm not so sure about the
available space in dataflash on all the at91sam evaluation kits.

> 3) Why is env at offset 0x4200 ... is the bootstrap exactly so big ? what about 
> erasing nor, you can't make sure you won't overwrite those 0x200 bytes safely 
> too, right ?
> 
> => I'd do the layout like this:
> 0x00000 - bootstrap
> 0x05000 - u-boot (align to block size)
> 0x85000 - env (~16kb)
> 0x89000 - env redund
> < note, here's some space, so align as necessary >
> 0x90000 - kernel
> 
> It wastes a bit, but it's ready for future growth
> 

As said, I let the defaults from ATMEL as they were. I don't know if
they had any specific reason to have the layout like that. Maybe they
had issue with the available space on the dataflash.

The bootstrap is around 4k. I'll try a new layout and come back with a
proposal. I'll also check that it fits in most dataflash sizes.

-- 
Alexandre Belloni