adding OF_DYNAMIC proc interface

Stephen Warren swarren at wwwdotorg.org
Sat Sep 29 07:54:13 EST 2012


On 09/28/2012 03:29 PM, Benjamin Herrenschmidt wrote:
> On Fri, 2012-09-28 at 11:46 -0500, Alan Tull wrote:
>> Hello,
>>
>> The following patch adds a /proc/ofdt interface to add or remove device tree
>> nodes dynamically.
>>
>> Based on earlier feedback, I've changed my driver to use /proc instead of
>> creating a new ioctl (the old thread is at 
>> http://www.mail-archive.com/devicetree-discuss@lists.ozlabs.org/msg17333.html)
>>
>>
>> I was hoping to get some early feedback from others who might be interested
>> who were discussing this on an earlier thread about OF_DYNAMIC usage.
>>
>> This code doesn't do any notification for drivers yet. It can add multiple
>> nodes and they will show up properly under /proc/device-tree.  It has an
>> issue that shows up when removing nodes (it appears that the memory used by
>> proc gets corrupted after the add).
> 
> (Adding Arnd here)
> 
> Have you guys considered whether a better approach would be a file
> system ? IE, create a node by creating a directory, add files for
> properties etc... ?
> 
> It might need some trick to make the node "active" (in order to not
> internally in the kernel start exposing unfinished nodes), maybe a
> special file, maybe a permission trick ...

mkdir automatically creates status="disabled" or similar internally to
the kernel?


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