[PATCH v3 00/22] passage: Define a standard for firmware data flow

[Simon Glass]

Hi Tom,

On Thu, 17 Apr 2025 at 15:54, Tom Rini <trini at konsulko.com> wrote:
>
> On Thu, Apr 17, 2025 at 03:38:07PM -0600, Simon Glass wrote:
> > Hi Tom,
> >
> > On Thu, 17 Apr 2025 at 15:24, Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Thu, Apr 17, 2025 at 12:15:42PM -0600, Simon Glass wrote:
> > >
> > > > This series adds a standard way of passing information between different
> > > > firmware phases. This already exists in U-Boot at a very basic level, in
> > > > the form of a bloblist containing an spl_handoff structure, but the intent
> > > > here is to define something useful across projects.
> > > >
> > > > The need for this is growing as firmware fragments into multiple binaries
> > > > each with its own purpose. Without any run-time connection, we must rely
> > > > on build-time settings which are brittle and painful to keep in sync.
> > > >
> > > > This feature is named 'standard passage' since the name is more unique
> > > > than many others that could be chosen, it is a passage in the sense that
> > > > information is flowing from one place to another and it is standard,
> > > > because that is what we want to create.
> > > >
> > > > The implementation is mostly a pointer to a bloblist in a register, with
> > > > an extra register to point to a devicetree, for more complex data. This
> > > > should cover all cases (small memory footprint as well as complex data
> > > > flow) and be easy enough to implement on all architectures.
> > > >
> > > > The emphasis is on enabling open communcation between binaries, not
> > > > enabling passage of secret, undocumented data, although this is possible
> > > > in a private environment.
> > > >
> > > > This series is available at u-boot-dm/pass-working
> > >
> > > Before I get into further feedback, my first bit of feedback is that
> > > this breaks transfer list support. I didn't check this on Raymond's QEMU
> > > but did test it on vexpress_fvp_bloblist and expect QEMU is also broken.
> > > The most likely reason I think is:
> > > >   passage: spl: Support passing the passage to U-Boot
> > > [snip]
> > > >   xferlist: Drop old xferlist code
> >
> > CI passes for me:
> >
> > https://source.denx.de/u-boot/custodians/u-boot-dm/-/pipelines/25806
>
> Sure, good, I was wondering about some of the other changes.
>
> As a reminder there are a number of CI labs (of which none are "Linaro",
> they still need to get moving on that, yes I'm calling them out here as
> a reminder to them) that monitor mainline directly (I push a tree, it
> triggers, they speak up if there's specific breakage) and indirectly
> (Toradex has given talks about their CI which includes weekly mainline
> U-Boot builds) those reports are equally as important as our GitLab and
> Azure pipelines.

I think my QEMU test is a good approach, since we can make it work on
any arch in CI, without need particular hardware.

>
> > > These are not the same. And they should be. And they should be using
> > > the register layout / values other projects use today.
> > >
> > > And I am bluntly uninterested in who shuffled the registers around and
> > > made them no longer agree. What TF-A is doing now is what's in the wild
> > > now. And shame on them if there wasn't a good reason for changing things
> > > either.
> >
> > They are the same and any difference is a bug, quite possibly in my
> > code. I am hoping that Raymond can point it out, as I believe I am
> > following the spec that we created.
> >
> > The xferlist is a little harder to maintain and it has a bit of an
> > unusual API. It's better to use global_data for this case.
>
> Yes, I'm not completely sure where the bug is but your code breaks the
> other platforms and you should have enough information at this point
> to run and reproduce it. If it's weirdly only vexpress_fvp_bloblist that
> breaks, I can tell you how that's run with transfer list. I can't just
> point CI at it because... nasm.us is down which means that coreboot
> can't build from source which means I can't rebuild our docker
> containers to include the TF-A blobs too.

Yes, I gave up with the TF-A thing, but when I hear from Raymond I'll
give it another crack. It can't be that hard. There are just too many
'in flight' things at present.

Regards,
Simon