Re: [RFC][PATCH] kbuild: Generate symbols for DTO application in DTBs

[Marek Vasut <marex@denx.de>]

On 4/7/22 14:30, Masahiro Yamada wrote:
> Hi Marek.
> (+CC Rob, DT ML)

Hi,

> On Thu, Apr 7, 2022 at 8:05 PM Marek Vasut <marex@denx.de> wrote:
>>
>> Emit symbols section in DTBs to permit symbol resolution when applying DTOs.
> 
> I CCed DT folks, but if I remember correctly, adding -@ globally
> was NACKed because it would increase blob size for platforms that
> do not need overlay.
> 
> 
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Masahiro Yamada <masahiroy@kernel.org>
>> ---
>> NOTE: I am sending this as RFC, because I suspect there is a better way how
>>        to pass extra flags to DTC during kernel build ?
>>        Maybe from shell environment somehow ?
> 
> 
> For local use, yes, you can add -@ from the command line.
> 
> Try this:
> 
>      DTC_FLAGS=-@  make ARCH=arm64 dtbs
> 
> 
> This is undocumented tip, but it seems to work
> for the current code.

This is real nice (and very much what I need), thank you.

>>        Or maybe b7e70391a5451 ("arm64: tegra: Enable device-tree overlay support")
>>        is the way to go about this ?
> 
> 
> Since commit 15d16d6dadf6947ac7f9a686c615995c5a426ce2,
> adding -@ is automatic for platforms that support overlay.
> 
> 
> If  <platform>-dtbs exists, -@ is automatically added.
> 
> See arch/arm64/boot/dts/xilinx/Makefile
> as an example code.

Is it now allowed to start upstreaming DT overlays then ?
That would be nice too.