[Ksummit-2013-discuss] DT bindings as ABI [was: Do we have people interested in device tree janitoring / cleanup?]

[Jason Cooper]

On Fri, Jul 26, 2013 at 02:41:10PM +0100, David Woodhouse wrote:
> On Fri, 2013-07-26 at 09:27 -0400, Jason Cooper wrote:
> > 
> > The other dynamic change that bears mentioning here is attributes which
> > have been configured by the bootloader.  For example, in mvebu, we have
> > the Schrodinger's Cat register.  It allows you to reconfigure the base
> > address of the registers from *within* that register range.  If the
> > bootloader does this, the DT needs to be updated to reflect the current
> > hardware configuration.  Otherwise, the kernel is stuck poking around at
> > memory addresses hoping to find something sane.
> > 
> > But this falls into the same category as you mentioned, but outside of
> > chosen {};.
> 
> Yeah, /chosen was given as an example of stuff that's almost
> *exclusively* "configuration" stuff.
> 
> But there's plenty outside there that can reasonably change.
> 
> It's OK to change the data, and of *course* the base address reported in
> the DT should actually match reality *today*, if it changes on the fly.
> 
> It's not OK to change the *schema*  in which those data are expressed.
> That's the ABI we're talking about.

Agreed, much more clear than what I was saying.

thx,

Jason.