Re: [RFC PATCH 00/15] Add support for structured tags and v18 dtb version

Herve Codina
2026-03-12T07:54:08Z

Hi David,

On Tue, 10 Feb 2026 18:33:28 +0100
Herve Codina <herve.codina@bootlin.com> wrote:

> Recently, I sent a RFC series related to support for metadata and addon
> device-trees [1].
>
> During the discussion the concept of structured tags and "unknown" tags
> emerged as well as the need to have them handled as a prerequisite of
> support for metadata and addon.
>
> The conclusion was the need for a new dtb version (v18) with support
> for:
> - Structured tags and based on them, "unknown" tags.
> Those structured tags allow to have an standardized definition of
> tags with the capability of skipping a tag and its related data
> when a "unknown" tag is incountered by a given version of libfdt,
> dtc and tools. Those "unknown" tags are tags defined in future
> versions. Even if they exact meaning is unknown for an 'old'
> version, they structure is understood and the 'old' version can skip
> them without any errors if allowed.
>
> - Flags in the dtb header (dt_flags).
> The goal of this field is to have a placeholder to specify the
> type of dtb we are dealing with. For instance, addons dtb will set a
> flag in this placeholder
>
> - A last compatible version for writing purpose.
> The goal of the new dtb header field (last_comp_version_w) is to
> disable globally any modification. It works similarly to
> last_comp_version but for modification. It can be used to avoid any
> modification that could be done by an 'old' version and could lead
> to inconsistencies between the modification itself and some
> "unknown" tags.
>
> This RFC series implements those features and leads to the v18 dtb
> version.

I sent this series a month ago.

I know some patches have been applied but what's the plan for the remaining
ones?

Is there anything I can do to help move things forward?

Let me know if you want some rebase and/or modification and so a new version
of the series or if you need anything else that can help in moving forward.

Best regards,
Hervé