System Software Meeting Minutes, 2006-12-26

[Jonathan Corbet]

Mitch Bradley <wmb at firmworks.com> wrote:

> /proc/device-tree is working.  It requires a kernel patch and a
> (fairly low risk) firmware change.  Andres suggests that we try it out
> as-it, without first converting it to sysfs, and publicize it on LKML
> to get feedback.  When Corbet reappears, we will ask him for help with
> the sysfs conversion if that turns out to be necessary.  Andres will
> help Mitch package the patches.

I've reappeared - sort of.  Current weather forecasts suggest that some
skiing time before school restarts may be mandatory.

If I understand this patch, it's a means for exporting the firmware's
view of the hardware to user space.  I can pretty well guarantee that
any implementation based on /proc is not going to get into the mainline
kernel.  I, personally, would not even post it.

Sysfs is more possible.  Some thoughts on that:

 - Sysfs already implements a representation of the device tree.  It's
   worth pondering whether that representation can be extended to
   contain the desired information.

 - There are some firm rules about sysfs files; among other things, each
   must contain exactly one value in a textual representation.  So some
   of the /proc/device-tree files would have to be reworked to meet
   those expectations.

An alternative which may be worth considering is simply creating a new
virtual filesystem.  We could create olpcfs, put anything we want into
it, and there should be few complaints.  It could be mounted on /olpc or
wherever.  And it would all be pretty easy to do.

Just a thought.

jon