[PATCH 1/2] arm: mm: Ignore memory banks which are in front of the kernel when HIGHMEM is ON

[Nicolas Pitre]

On Wed, 13 Feb 2013, Michal Simek wrote:

> The Linux kernel has some requirements, limitations, etc,  that's all truth.
> 
> Placing the kernel to the main memory to any location you want which end
> up with kernel panic is from my point of view fault.

I may agree with that, up to a point.

> Saying that the kernel is always loaded withing the 16MB of memory is limitation
> but it doesn't mean that we shouldn't remove it.

The actual limitation should be 128MB for zImage.  It will relocate the 
final kernel binary within the first 16MB by itself.

> Ignoring the memory before the kernel can be one solution which I
> would like to discuss.
> What about the second patch used for !HIGHMEM case?

Highmem is irrelevant.

If you want to ignore memory that way, you must look at the _physical_ 
addresses for each bank, and simply truncate anything that is below 
PHYS_OFFSET.  The comparison should be trivial with physical addresses 
as they're not limited to 32 bits.


Nicolas