[PATCH 2/2] ARM: move device tree mapping out of linear region

[Nicolas Pitre]

On Tue, 6 Oct 2020, Ard Biesheuvel wrote:

> On ARM, setting up the linear region is tricky, given the constraints
> around placement and alignment of the memblocks, and how the kernel
> itself as well as the DT are placed in physical memory.
> 
> Let's simplify matters a bit, by moving the device tree mapping to the
> top of the address space, right below the fixmap region, and create a
> read-only mapping for it that is independent of the size of the linear
> region, and how it is organized.

You say this is below the fixmap region but it is also worth mentioning 
it is right above the vmalloc region, and in doing so we lose the 
vmalloc access overflow guard area.

Also you should document your static mapping usage in 
Documentation/arm/memory.rst.


Nicolas