Where to put a large bootloader-supplied device tree on ARM ?

[Nicolas Pitre]

On Wed, 11 Jul 2012, Mitch Bradley wrote:
> On 7/8/2012 6:30 PM, Nicolas Pitre wrote:
> > On Fri, 6 Jul 2012, Mitch Bradley wrote:
> > 
> >> For now, I'm putting the initrd at the end of memory and the dtb
> >> below that.  That seems to work, but I'm unsure whether or not
> >> I'm just "getting lucky".
> > 
> > That's also perfectly fine.
> 
> Alas, that worked for machines with 512 MiB of main memory, but failed
> on 1 GiB machines.  My guess is that, when the initrd and dtb are near
> the top of a 1 GiB memory, the virtual address gets too near the top of
> the kernel's 1 GiB of virtual space (which starts at 0xc0000000),
> perhaps colliding with the VMALLOC space.

Indeed, that won't work in that case.

> Putting them just below the 128 MiB boundary seems to work.

Or at the 128MB mark, or any location between 64MB and 512MB should be 
fine in practice.


Nicolas