linux-kernel - Re: [PATCH v4 2/5] drivers/of: do not add memory for unavailable nodes

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Message-Id: <20161024182000.5g2f3w3x3oqrohqs@arbab-laptop.austin.ibm.com>
Date:   Mon, 24 Oct 2016 13:20:00 -0500
From:   Reza Arbab <arbab@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Alistair Popple <apopple@....ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tang Chen <tangchen@...fujitsu.com>, linux-mm@...ck.org,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Bharata B Rao <bharata@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>
Subject: Re: [PATCH v4 2/5] drivers/of: do not add memory for unavailable
 nodes

On Mon, Oct 24, 2016 at 09:24:04PM +1100, Michael Ellerman wrote:
>The code already looks for "linux,usable-memory" in preference to 
>"reg". Can you use that instead?

Yes, we could set the size of "linux,usable-memory" to zero instead of 
setting status to "disabled".

I'll send a v5 of this set which drops 1/5 and 2/5. That would be the 
only difference here.

>That would have the advantage that existing kernels already understand
>it.
>
>Another problem with using "status" is we could have device trees out
>there that have status = disabled and we don't know about it, and by
>changing the kernel to use that property we break people's systems.
>Though for memory nodes my guess is that's not true, but you never know ...

-- 
Reza Arbab