On Wed, Jan 28, 2015 at 04:13:17PM +0000, Russell King - ARM Linux wrote:

On Wed, Jan 28, 2015 at 09:57:18AM -0600, Rob Herring wrote:

quoted

I'm fine with that, but we just need to have a standard kernel
userspace interface in addition to something like
/proc/device-tree/bootreason. Perhaps this can be the default
implementation for the watchdog dev. Someday when we decide DT is crap
and have a new boot interface, we'll have people relying on
/proc/device-tree. I hope to be retired when that happens...

Anyone who thinks that DT can be replaced in the same way that we made
the mistake with ATAGs would really need their head examined.

As you point out, removing DT removes the /proc/device-tree/ sub-tree.
Whether we like it or not, that is a userspace API, one which we have
users of already.  That pretty much means that we can't remove DT for
existing platforms or any platform we have now converted to DT.

<ok, I'll go there!>

... and for platforms that can also be booted via ACPI? If we have to
convert the ACPI tables into a device-tree purely for /proc/device-tree,
then we may as well boot with the thing too :)

Seriously though, I don't see how we can maintain this directory for
ACPI, regardless of whether or not it's ABI.

Will