linux-kernel - Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

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Date:   Mon, 19 Sep 2016 20:11:39 +1000
From:   Balbir Singh <bsingharora@...il.com>
To:     Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Bharata B Rao <bharata@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        Alistair Popple <apopple@....ibm.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory
 nodes



On 15/09/16 06:06, Reza Arbab wrote:
> Respect the standard dt "status" property when scanning memory nodes in
> early_init_dt_scan_memory(), so that if the property is present and not
> "okay", no memory will be added.
> 
> The use case at hand is accelerator or device memory, which may be
> unusable until post-boot initialization of the memory link. Such a node
> can be described in the dt as any other, given its status is "disabled".
> Per the device tree specification,
> 
> "disabled"
> 	Indicates that the device is not presently operational, but it
> 	might become operational in the future (for example, something
> 	is not plugged in, or switched off).
> 
> Once such memory is made operational, it can then be hotplugged.
> 
> Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>

Makes sense, so basically a /memory@  with missing status or status = "okay"
are added, others are skipped. No memblocks corresponding to those nodes
are created either.

Balbir Singh