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.

-- 
dwmw2