building RaspPi Images

[Andrew Turner]

On Sat, 9 Feb 2013 23:03:38 -0800
Tim Kientzle <tim at kientzle.com> wrote:

> On Feb 9, 2013, at 10:20 PM, Brett Wynkoop wrote:
> > 
> > I was thinking that we should be able to generate a generic image
> > that will boot on both the Pi and the Bone.  Maybe a config file
> > that includes the needed drivers for both boards.
> 
> I've thought about this and believe it is pretty routine,
> though I've not had time to actually try implementing it.
> 
> This specific combination is simplified by the fact
> that the boot bits are so different, so you can just
> put them all on the same SD card image.
> 
> There are a few pieces you'll need to work through:
>   1. An MSDOS partition with all the boot bits from both systems
>   2. A kernel with all of the drivers for both systems
>   3. ubldr will need to identify the board somehow
>   4. ubldr will need to obtain the correct FDT
5. Update the kernel to allow it to be built for multiple boards. You
will need to at least fix:
 - locore.S generates a fixed VA -> PA map, it's not too hard to fix
   this, I've looked into it but don't have the time to get it into a
   usable state.
 - initarm calls a number of functions that have are implemented on a
   per SoC family case.
 - Update the IRQ mask/unmask/next irq functions to allow multiple
   implementations and pick the correct one on boot.
 - Ditto for DELAY, DMA, reset, etc functions.

I would suggest the first step is to get a kernel that can boot on the
BeagleBone and PandaBoard. As they both have Ti CPUs they are similar
enough we could skip some of the items in my list as they are already
using a common SoC specific code base.

Andrew