Re: devicetree repository separation/migration

On 2/20/2014 12:14 AM, Grant Likely wrote:

On Thu, Feb 20, 2014 at 4:58 AM, Frank Rowand [off-list ref] wrote:

quoted

On 2/19/2014 1:15 PM, Grant Likely wrote:

quoted

On Wed, Feb 19, 2014 at 8:16 PM, Frank Rowand [off-list ref] wrote:

quoted

On 2/19/2014 1:08 AM, Sascha Hauer wrote:

quoted

On Tue, Feb 18, 2014 at 02:44:15PM -0800, Tim Bird wrote:

quoted

I'm not in favor of separating the device tree information from the kernel.

If we switch, then whatever synchronization issues other projects
are having now with synching with the device tree info from the kernel will
just then become the problem of the kernel developers, who will then
have to sync with the device tree info from another repository.  If the
sync issues can't be solved now for them, why or how would it be solved
post-separation for us?  (It sounds like a zero-sum game of pain transfer
to me.)

I'm relatively unfamiliar with the arguments.  Can someone provide
a brief list of reasons this is needed, and how the inconvenience to Linux
kernel developers will be minimized, should it proceed?

quoted

One of the reasons for doing devicetrees is to separate the hardware
description from the code so that:
- Other OSes (and bootloaders) can use the same description to start on
  a given hardware
- A generic Kernel can be started on any hardware
- A hardware describes itself, makes itself more introspecitve so we can
  go away from very specialized kernels

Tim knows this ^^^^.  He was asking for the arguments for moving dts files
out of the linux kernel source tree.

We've made the decision that devicetree bindings need to be treated as
ABI, but as long as the .dts files live in the kernel there will
always be the temptation to just tweak things in lock-step and nobody
will notice. Splitting the files out gives that extra push to think
about whether changes to a binding will backwards compatible with a
tree that doesn't have those changes because the chances are a lot
higher that someone will hit that combination.

The other argument is shared source between
BSD/U-Boot/Barebox/Linux/etc. Until we have a separate .dts repo there
is no good way to share the database of hardware descriptions.

We could provide an easy export (see below).  What do you think?

Ian Campbell is already maintaining an export tree as a staging area
for an eventual split. He's had it up and running for almost a year
now:

http://xenbits.xen.org/gitweb/?p=people/ianc/device-tree-rebasing.git

g.

So there already is a "good way to share the database of hardware
descriptions" in addition to the one I provided.

-Frank
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