adding OF_DYNAMIC proc interface
Benjamin Herrenschmidt
benh at kernel.crashing.org
Sat Sep 29 07:29:00 EST 2012
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 ...
It should be at least considered rather than a new interface that tries
to re-implement semantics (such as notification) that are pretty much
already provided by a fs.
Also, what about the existing /proc/device-tree ?
Finally, if we are doing something new and for some reason not a fs,
what about using sysfs rather than /proc ? Really /proc is not a great
idea here.
Cheers,
Ben.
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