On Wed, Aug 14, 2013 at 10:44:22AM -0600, Stephen Warren wrote:
On 08/14/2013 09:13 AM, Tom Rini wrote:
Hey all,
Do we have a document yet talking about the best practices for how we would like a hardware vendor to ship, store and possibly update a device tree, on the hardware? "However they like" seems likely to invite problems down the line with everyone trying their own thing. Thanks!
I don't believe there's any written guidance, no.
The initial guidance Grant gave (IIRC at the first Linaro Connect last year, or perhaps the ARM workshop in Prague, or perhaps also in various ARM kernel list threads?) was that the DTBs should be stored/accessed in exactly the same way as the kernel, which on many systems implies it's a file in /boot (although MTD partitions, ... are also possible kernel locations). The idea here was to explicitly make upgrading the DTB as easy as upgrading the kernel, and explicitly without having to upgrade any firmware, since that's a more dangerous process in most cases.
Now perhaps that advice was only intended to apply very early on when DT was really new on ARM, and has "aged out" by now? If so, I don't recall that every being explicitly mentioned or communicated later.
[snip out a bit more of Stephen's answer]
Yes, this notion certainly is the opposite of what was suggested on the cross-distro list, both as part of a "what should a bootloader provide to get commodity distros to support the board" thread and the "where should a device tree live in the filesystem" thread. Cc'ing them now because this is one of those things that feels like it needs solving, solving soon, and done in a way the least number of folks get surprised about it.