Re: [RFC PATCH v2 2/3] of: Add support for -@ when compiling overlays

From: Rob Herring
Date: Wed Apr 27 2022 - 17:24:52 EST

On Wed, Apr 27, 2022 at 02:52:42PM -0400, Detlev Casanova wrote:
> This commit adds an option to compile all device trees with -@ to add the
> symbol table to the Device Tree Blobs.

Why would we want to tie this to the kernel config?

Globally enabling it has already been discussed and rejected.

> It prepares the introduction of device tree overlays that are
> not applied on device trees at compile time (dtbo files.)
> These device tree overlays will be used by either a bootloader or a
> linux userspace tool to extend the base device tree.
> This is used e.g. for drivers that need device tree nodes for optional
> non plug and play devices, like an external DSI touchscreen panel that
> embeds different i2c devices to control it.

You can already set DTC_FLAGS per directory (and target?), so enable it
for the dtbs that have overlays.

> Signed-off-by: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
> ---
> drivers/of/Kconfig | 8 ++++++++
> scripts/Makefile.lib | 9 +++++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)