Subject: Re: [PATCH 1/1] of: of_reserved_mem: Ensure cma reserved region not
 cross the low/high memory
To: Rob Herring <robh+dt@kernel.org>, Jason Liu <jason.hui.liu@nxp.com>
References: <1479901021-25064-1-git-send-email-jason.hui.liu@nxp.com>
 <CAL_JsqLHh96D0VULuYfYC1P5K_Bbz6iRjizuYP3Mb6bdERbDnA@mail.gmail.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Frank Rowand <frowand.list@gmail.com>
From: Laura Abbott <labbott@redhat.com>
Message-ID: <833f99b1-d10b-27ba-e0f9-a7c6398fb63d@redhat.com>
Date: Wed, 14 Dec 2016 14:21:26 -0800
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On 12/14/2016 12:45 PM, Rob Herring wrote:
> On Wed, Nov 23, 2016 at 5:37 AM, Jason Liu <jason.hui.liu@nxp.com> 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.

Thanks,
Laura


[1] https://marc.info/?l=linux-kernel&m=147928325113103&w=2