Re: [PATCH v7 2/2] schemas: Add some common reserved-memory usages

[Rob Herring]

On Wed, Nov 8, 2023 at 5:38 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
>
> On Tue, 7 Nov 2023 at 19:07, Rob Herring <robh@xxxxxxxxxx> wrote:
> >
> >
> > All of this:
> >
>
> > > On Mon, 16 Oct 2023 at 15:54, Simon Glass <sjg@xxxxxxxxxxxx> wrote:
> > > >
> > > > It is not specific to EDK2. Imagine this boot sequence:
> > > >
> > > > - Platform Init (U-Boot) starts up
> > > > - U-Boot uses its platform knowledge to sets some ACPI tables and put
> > > > various things in memory
> > > > - U-Boot sets up some runtime code and data for the OS
> > > > - U-Boot jumps to the Tianocore payload **
> > > > - Payload (Tianocore) wants to know where the ACPI tables are, for example
> > > > - Tianocore needs to provide boot services to the OS, so needs to know
> > > > the memory map, etc.
> > > >
> > > > ** At this point we want to use DT to pass the required information.
> > > >
> > > > Of course, Platform Init could be coreboot or Tianocore or some
> > > > strange private binary. Payload could be U-Boot or something else.
> > > > That is the point of this effort, to build interoperability.
> >
> > [...]
> >
> > > > Perhaps the problem here is that Linux has tied itself up in knots
> > > > with its EFI stuff and DT fixups and what-not. But this is not that.
> > > > It is a simple handoff between two pieces of firmware, Platform Init
> > > > and Payload. It has nothing to do with the OS. With Tianocore they are
> > > > typically combined, but with this usage they are split, and we can
> > > > swap out one project for another on either side of the DT interface.
> >
> > Is perhaps the clearest description of the problem you want to solve.
> > It's clearly related to EFI though not the interface to the OS. IIRC,
> > "platform init" and "payload" are terms in the UEFI spec, right?
>
> No they are not. This is from the universal payload specification that
> is being drafted here
>
> https://universalpayload.github.io/spec/index.html
>
> but the UEFI specification does not use this terminology.

Then I'm confused as to what this is:

https://uefi.org/specs/PI/1.8/index.html

Rob