[PATCH] [RFC]: dtc: Add Kconfig option to pad device tree blob

[Eric Schikschneit]

Hello Tom,

The link that Simon sent does not add padding at the end. I have tried the approach with SYS_FDT_PAD first and my platform (imx6) still has issues when trying to modify the device tree from the board file. It still returns FDT_ERR_NOSPACE with that option. The commit I sent simply adds a Kconfig option to something we are already doing (passing the -p flag) on multiple platforms behind the scenes to the device tree compiler. I have tested and proven on my platform that this allows live modification of the device tree in the board file.


Eric Schikschneit

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________________________________
From: Tom Rini
Sent: Monday, May 5, 2025 1:09 PM
To: Simon Glass; Eric Schikschneit
Cc: u-boot at lists.denx.de
Subject: Re: [PATCH] [RFC]: dtc: Add Kconfig option to pad device tree blob

On Fri, May 02, 2025 at 08:10:33PM -0600, Simon Glass wrote:
> Hi Eric,
>
> On Fri, 2 May 2025 at 14:06, Eric Schikschneit
> <eric.schikschneit at novatechautomation.com> wrote:
> >
> > This will allow arch(s) that use device tree blobs to pad the end of the
> > device tree so they can be modified by board files at run time. This will
> > help prevent errors such as FDT_ERR_NOSPACE from occuring.
> >
> > Signed-off-by: Eric Schikschneit <eric.schikschneit at novatechautomation.com>
> > ---
> >  arch/Kconfig                 | 11 +++++++++++
> >  arch/arc/dts/Makefile        |  6 +++++-
> >  arch/arm/dts/Makefile        |  4 ++++
> >  arch/m68k/dts/Makefile       |  6 +++++-
> >  arch/microblaze/dts/Makefile |  6 +++++-
> >  arch/nios2/dts/Makefile      |  6 +++++-
> >  arch/powerpc/dts/Makefile    |  4 ++++
> >  arch/riscv/dts/Makefile      |  6 +++++-
> >  arch/sandbox/dts/Makefile    |  6 +++++-
> >  arch/x86/dts/Makefile        |  8 +++++++-
> >  10 files changed, 56 insertions(+), 7 deletions(-)
> >
>
> This is not a board-specific feature. You could try this:
>
> https://patchwork.ozlabs.org/project/uboot/patch/20241206131113.2865416-3-sjg@chromium.org/

Simon, can you please read your links before sending them to other
people? There's several things wrong with that patch so suggesting
someone else try it and see is not helpful.

Eric, for your platform can you expand the value used by SYS_FDT_PAD or
is that not updating things in the correct spot for your use case?

--
Tom