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:

quoted

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.