Re: [PATCH 1/1] of: of_reserved_mem: Ensure cma reserved region not cross the low/high memory

From: Laura Abbott
Date: Wed Dec 14 2016 - 17:28:55 EST

On 12/14/2016 12:45 PM, Rob Herring wrote:
> On Wed, Nov 23, 2016 at 5:37 AM, Jason Liu <jason.hui.liu@xxxxxxx> wrote:
>> Need ensure the cma reserved region not cross the low/high memory boundary
>> when using the dynamic allocation methond through device-tree, otherwise,
>> kernel will fail to boot up when cma reserved region cross how/high mem.
> The kernel command line code setting CMA already deals with this. Why
> don't we just call the CMA code (cma_declare_contiguous) to deal with
> this?
> Rob

That was proposed in the first version[1] but I think this is a generic
problem not specific to CMA. Even non-CMA reservations trying to span
zones could cause problems so the devicetree allocation code should
restrict reservations to a single zone.