[PATCH 1/2] bloblist: Introduce BLOBLIST_PRIOR_STAGE options

[Simon Glass]

Hi Tom,

On Thu, 12 Dec 2024 at 08:11, Tom Rini <trini at konsulko.com> wrote:
>
> Introduce an option to control if we expect that a prior stage has
> created a bloblist already and thus it is safe to scan the address. We
> need to have this be configurable because we do not (and cannot) know if
> the address at CONFIG_BLOBLIST_ADDR is in regular DRAM or some special
> on-chip memory and so it may or may not be safe to read from this
> address this early.
>
> Signed-off-by: Tom Rini <trini at konsulko.com>
> ---
> Cc: Simon Glass <sjg at chromium.org>
> ---
>  common/Kconfig | 32 ++++++++++++++++++++++++++++++++
>  lib/fdtdec.c   | 11 +++--------
>  2 files changed, 35 insertions(+), 8 deletions(-)
>

Since this is the essentially the same as my OF_BLOBLIST patch, which
was rejected:

NAK

The issue is not whether some 'previous stage' set up a bloblist. For
example, if VPL_BLOBLIST_PRIOR_STAGE is enabled, that presumably means
that TPL set it up. But it doesn't mean that TPL put the FDT in there.

You are basically adding an option to tell U-Boot not to look at the
bloblist when setting up the FDT, since it might not be there yet and
the machine will hang. So confusing. Only the board author knows the
intended flow of boot, so just let the board author decide! Within
U-Boot you can infer from the bloblist options which phase actually
creates the bloblist, and there is some attempt to do this in
bloblist_init(), although it is pretty messy ATM. Anyway, As soon as
you say that some secret-source blob might create a bloblist, you need
a way to describe that. But again, only the board author knows.

Regards,
Simon