On 22 May 2014 12:50, Ian Campbell <ijc@hellion.org.uk> wrote:
On Wed, 2014-05-21 at 14:39 +0300, Riku Voipio wrote:
>
> Hi,
>
> I've collected a list of where people install their dtb files these
> days;
>
> https://wiki.linaro.org/Platform/DeviceTreeConsolidation
>
>
> Every distribution has a slightly different variation of install
> location, which is not good - we can't tell end users that "this is
> the place you can expect to find your device tree files regardless of
> what distribution you choose".  Some questions I have here before we
> proceed discussing what would be the standardized location:
>
>
> 1) Anything missing of the pros and cons of different locations?

FWIW Debian will now arrange for the correct DTB for the platform to be
installed as /boot/dtb-$(uname -r) as well as the /usr/lib location.
WRT the use of `uname -r` and DTB as stable ABI, might it be sensible to
declare a search path type arrangement? i.e. try /path/with-uname-r/dtb
then /path/dtb ? For example people might consider packaging
https://git.kernel.org/cgit/linux/kernel/git/devicetree/devicetree-rebasing.git which doesn't have a uname in it.

In the wikipage I suggested we might want to use a version string instead of uname -r, if we move forward to separate repository. A search path is  bit over-engineering. We might suggest making dtb/ -> dtb-latest symlink the same way we often have vmlinuz -> vmlinux-3.x link.

I'd like the to keep the scope on the discussion clear:

The standard place where the distribution package drops compiled device tree files.

Else we end up like the last round where we just discussed what the ideal world would be...

> 2) Are you interested in moving to a standardized location if
> cross-distro list proposes one?

Installing the dtb for the current platform into some known location
easily accessed from bootloaders seems reasonable enough.

I'm more or less ambivalent about installing all of the possible DTB
files in a similar location though. I'm not sure what the use case for
that is. Wouldn't you also need to standardise on the dtb filename for
each platform and effectively make that ABI?      

Afaik if you use a u-boot with fdtdir option that is kind of the case already.



Ian.