On Mon, Jun 14, 2010 at 8:59 AM, Nicolas Pitre [off-list ref] wrote:

On Mon, 14 Jun 2010, David Gibson wrote:

quoted

On Sun, Jun 13, 2010 at 11:02:15PM -0600, Grant Likely wrote:
Indeed. =A0In fact, the general rule of thumb is really "put as much as
possible into the most easily replaced layer of the stack". =A0This is,
incidentally, why I've always been dubious about simple firmwares
supplying a flattened device tree rather than including the device
tree template in the kernel, cuboot style.

The biggest advantage, IMHO, for adding DT to ARM, is actually to
decouple the hardware config information and the kernel. =A0If in the end
the DT has to be shipped in the kernel then we're losing all this
advantage over the current state of things on ARM which still works
pretty well otherwise.

In the best case, the simple firmware simply has to retrieve the
flattened device tree from flash, and pass it to the kernel just like
some anonymous blob. =A0And the simple firmware only needs to provide a
way for that DT blob to be updatable, like through an upload of a
replacement blob that was prepared offline. =A0Just like a ramdisk image
or the like.

That doesn't need to be fancier than that, and the goal of having the DT
data tied to the hardware instead of the kernel is achieved.

exactly right.

g.