[RFC] Proposed location to host the firmware handoff specification.

Simon Glass sjg at chromium.org
Tue Jul 5 18:37:30 CEST 2022

Hi Rob,

On Tue, 5 Jul 2022 at 09:24, Rob Herring <robh at kernel.org> wrote:
> On Thu, Jun 30, 2022 at 3:24 AM Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi Jose,
> >
> > I don't think this is correct. TF-A is a project that aims to replace
> > U-Boot SPL (and perhaps other components) with more closed firmware,
> > e.g. the permissive license.
> >
> > This spec needs to be in a neutral place, not captive of one project.
> >
> > Given its close relationship to device tree, I suggest github.com/devicetree-org
> The only relationship to DT I see is DT is a payload as is ACPI. So I
> don't think dt.org is the right place.

Actually I was about to email you about this. Here's how I see it.

DT is a base structure to allow self-describing data to be stored.
This is in contrast with ACPI where there is just a header, but it is
not possible to read the data without specific parsing code for the
particular table types. Let's ignore ACPI for this discussion.

Unfortunately DT has an overhead and is too expensive for early
firmware use. It takes 3-4KB of code for libfdt as well as extra code
and data to read properties, etc.

Transfer List aims to bridge the gap, allowing simple C structures to
be put into a tagged data structure. The intention is that anything
more complex than that would use DT.

So there is at least some relationship: simple stuff = Transfer list,
complex stuff = DT.

The Transfer List spec specifies the data format for each entry type
(the analog to the schema). The DT provides the format and schema for
more complicated stuff.

We could perhaps put it in an entirely separate repo, but to me there
is a relationship with DT.


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